title:
Influence of bounce resonance effects on the cyclotron wave
  instabilities in dipole magnetospheric plasmas with anisotropic temperature

abstract:
  In this paper, we derive the dispersion equations for field-aligned cyclotron
waves in an axisymmetric dipole magnetospheric plasmas with both the
bi-Maxwellian and bi-Lorentzian distribution functions. To evaluate the
contribution of trapped particles to the transverse current density components
the Vlasov equation is solved using a standard method of switching to new
variables associated with conservation integrals; new time-like variable is
introduced (instead of the geomagnetic latitude angle) to describe the
bounce-motion of trapped particles along the geomagnetic field; the perturbed
electric field and current density components are Fourier-decomposed over the
length of the geomagnetic field lines. As a result, the transverse permittivity
elements are expressed by summation of bounce-resonant terms including the
double integration in velocity space, the resonant denominators, and the
corresponding phase coefficients. Due to geomagnetic field nonuniformity, the
wave-particle resonance conditions in magnetospheric plasmas are entirely
different from ones in the straight magnetic field; the all spectrum of the
electric field is present in the given current density harmonic; the left- and
right-hand polarized waves are coupled. To have some analogy with the linear
theory of cyclotron waves in the straight magnetic field, we assume that the
n-th harmonic of the electric field gives the main contribution to the n-th
harmonic of the current density, and the connection of the left- and right-hand
polarized waves is small. In this case, the dispersion equations for cyclotron
waves have the simplest form and are suitable to analyze the instabilities of
both the electron- and ion-cyclotron waves accounting for the bounce resonance
effects.


title: On the Quantum Aspects of Geophysics

abstract:
  We introduce a simple quantum mechanical justification for the formation of
folded mountains. It is very appealing to develop this idea to a theory of {\it
Quantum Geophysics}


title: Programming matrix optics into Mathematica

abstract:
  The various non-linear transformations incurred by the rays in an optical
system can be modelled by matrix products up to any desired order of
approximation. Mathematica software has been used to find the appropriate
matrix coefficients for the straight path transformation and for the
transformations induced by conical surfaces, both direction change and position
offset. The same software package was programmed to model optical systems in
seventh-order. A Petzval lens was used to exemplify the modelling power of the
program.


title:
Long-range/short-range separation of the electron-electron interaction
  in density functional theory

abstract:
  By splitting the Coulomb interaction into long-range and short-range
components, we decompose the energy of a quantum electronic system into
long-range and short-range contributions. We show that the long-range part of
the energy can be efficiently calculated by traditional wave function methods,
while the short-range part can be handled by a density functional. The analysis
of this functional with respect to the range of the associated interaction
reveals that, in the limit of a very short-range interaction, the short-range
exchange-correlation energy can be expressed as a simple local functional of
the on-top pair density and its first derivatives. This provides an explanation
for the accuracy of the local density approximation (LDA) for the short-range
functional. Moreover, this analysis leads also to new simple approximations for
the short-range exchange and correlation energies improving the LDA.


title: Sum rules in the oscillator radiation processes

abstract:
  We consider the problem of an harmonic oscillator coupled to a scalar field
in the framework of recently introduced dressed coordinates. We compute all the
probabilities associated with the decay process of an excited level of the
oscillator. Instead of doing direct quantum mechanical calculations we
establish some sum rules from which we infer the probabilities associated to
the different decay processes of the oscillator. Thus, the sum rules allows to
show that the transition probabilities between excited levels follow a binomial
distribution.


title:
Discussing the Relationship between the Static and Dynamic Light
  Scattering

abstract:
  Both the static $(SLS) $ and dynamic $(DLS) $ light scattering techniques are
used to obtain the size information from the scattered intensity, but the
static radius $R_{s}$ and the apparent hydrodynamic radius $R_{h,app}$ are
different. In this paper, the relationship between SLS and DLS is discussed
using dilute water dispersions of two different homogenous spherical particles,
polystyrene latexes and poly($N$-isopropylacrylamide) microgels, with a simple
assumption that the hydrodynamic radius $R_{h}$ is in proportion to the static
radius $R_{s}$, when Rayleigh-Gans-Debye approximation is valid. With the
assistance of the simulated data, the apparent hydrodynamic radius $R_{h,app}$
has been discussed. The results show that the apparent hydrodynamic radius is
different with the mean hydrodynamic radius of particles and is a composite
size obtained from averaging the term $\exp (-q^{2}D\tau) $ in the static size
distribution $G(R_{s}) $ with the weight $R_{s}^{6}P(q,R_{s}) $.


title: Non-sequential double ionization of molecules in a strong laser field

abstract:
  We consider the final stage of double ionization of $\rm O_2$ molecules by
short linearly polarized laser pulses. The saddles of the effective adiabatic
potential energy close to which simultaneous escape of electrons from a
molecule takes place are identified. The analysis of the saddles and numerical
simulations of the ionization indicate that to observe clear signatures of
simultaneous electron escape in double ionization of $\rm O_2$ molecules
stronger and much shorter laser pulses than those used in the recent experiment
[E. Eremina, {\it et al}, Phys. Rev. Lett. {\bf 92}, 173001 (2004)] should be
applied.


title:
A General Method for the Determination of Matrix Coefficients for High
  Order Optical System Modelling

abstract:
  The non-linear transformations incurred by the rays in an optical system can
be suitably described by matrices to any desired order of approximation. In
systems composed of uniform refractive index elements, each individual ray
refraction or translation has an associated matrix and a succession of
transformations correspond to the product of the respective matrices. This
paper describes a general method to find the matrix coefficients for
translation and surface refraction irrespective of the surface shape or the
order of approximation. The choice of coordinates is unusual as the orientation
of the ray is characterised by the direction cosines, rather than slopes; this
is shown to greatly simplify and generalise coefficient calculation. Two
examples are shown in order to demonstrate the power of the method: The first
is the determination of seventh order coefficients for spherical surfaces and
the second is the determination of third order coefficients for a toroidal
surface.


title: A Method to Polarize Stored Antiprotons to a High Degree

abstract:
  Polarized antiprotons can be produced in a storage ring by spin--dependent
interaction in a purely electron--polarized hydrogen gas target. The polarizing
process is based on spin transfer from the polarized electrons of the target
atoms to the orbiting antiprotons. After spin filtering for about two beam
lifetimes at energies $T\approx 40-170$ MeV using a dedicated large acceptance
ring, the antiproton beam polarization would reach $P=0.2-0.4$. Polarized
antiprotons would open new and unique research opportunities for spin--physics
experiments in $\bar{p}p$ interactions.


title:
Design of two-dimensional photonic crystal defect states for quantum
  cascade laser resonators

abstract:
  Current quantum cascade lasers based upon conduction band electron
transitions are predominantly TM (electrical field normal to the epitaxial
direction) polarized. Here we present a study of localized defect modes, with
the requisite TM polarization, in connected square and hexagonal lattice
two-dimensional (2D) photonic crystals for application as quantum cascade laser
resonators. A simple group-theory based analysis is used to produce an
approximate description of the resonant modes supported by defects situated at
different high symmetry points within the host photonic lattice. The results of
this analysis are compared with 2D finite-difference time-domain (FDTD)
simulations, showing a close correspondence between the two analyses, and
potential applications of the analysis in quantum cascade laser design are
considered.


title:
Karhunen-Loeve analysis of complex spatio-temporal dynamics of
  thin-films optical system

abstract:
  Application of Karhunen-Loeve decomposition (KLD, or singular value
decomposition) is presented for analysis of the spatio-temporal dynamics of
wide-aperture vertical cavity surface emitting laser (VCSEL), considered as a
thin-layer system. KLD technique enables to extract a set of dominant
components from complex dynamics of system under study and separate them from
noise and inessential underlying dynamical behavior. Properties of KLD spectrum
and structure of its main components are studied for different regimes of
VCSEL. Along with the analysis of VCSEL, a brief survey of KLD method and its
usage for theoretical and experimental description of nonlinear dynamical
systems is presented.


title: The 3D structure of the Lagrangian acceleration in turbulent flows

abstract:
  We report experimental results on the three dimensional Lagrangian
acceleration in highly turbulent flows. Tracer particles are tracked optically
using four silicon strip detectors from high energy physics that provide high
temporal and spatial resolution. The components of the acceleration are shown
to be statistically dependent. The probability density function (PDF) of the
acceleration magnitude is comparable to a log-normal distribution. Assuming
isotropy, a log-normal distribution of the magnitude can account for the
observed dependency of the components. The time dynamics of the acceleration
components is found to be typical of the dissipation scales whereas the
magnitude evolves over longer times, possibly close to the integral time scale.


title: $e^+ + H$ direct annihilation above the positronium formation threshold

abstract:
  A long-standing problem with the solution of the Schr\"odinger equation has
been its inability to account for the electron-positron annihilation in
positron hydrogen scattering above the positronium formation threshold. This
letter shows that this problem has been resolved by the use of the modified
Faddeev equations. A number of $e^- e^+$ annihilation cross sections in the
energy gap between $Ps(1s)$ and $H(n=2)$ thresholds are reported for both the
positron plus hydrogen incoming channel as well as the proton plus positronium
incoming channel. However the indirect annihilation cross sections after
formation of the positronium themselves are well known, they will not be
included in this report.


title:
Theoretical and numerical investigation of the shock formation of dust
  ion acoustic waves

abstract:
  We present a theoretical and numerical study of the self-steepening and shock
formation of large-amplitude dust ion-acoustic waves (DIAWs) in dusty plasmas.
We compare the non-dispersive two fluid model, which predicts the formation of
large amplitude compressive and rarefactive dust ion-acoustic (DIA) shocks,
with Vlasov/fluid simulations where ions are treated kinetically while a
Boltzmann distribution is assumed for the electrons.


title: Wavelet analysis of magnetic turbulence in the Earth's plasma sheet

abstract:
  Recent studies provide evidence for the multi-scale nature of magnetic
turbulence in the plasma sheet. Wavelet methods represent modern time series
analysis techniques suitable for the description of statistical characteristics
of multi-scale turbulence. Cluster FGM (fluxgate magnetometer) magnetic field
high-resolution (~67 Hz) measurements are studied during an interval in which
the spacecraft are in the plasma sheet. As Cluster passes through different
plasma regions, physical processes exhibit non-steady properties on
magnetohydrodynamic (MHD) and small, possibly kinetic scales. As a consequence,
the implementation of wavelet-based techniques becomes complicated due to the
statistically transitory properties of magnetic fluctuations and finite size
effects. Using a supervised multi-scale technique which allows existence test
of moments, the robustness of higher-order statistics is investigated. On this
basis the properties of magnetic turbulence are investigated for changing
thickness of the plasma sheet.


title: Atomic Clocks and Constraints on Variations of Fundamental Constants

abstract:
  We consider an application of precision frequency measurements to searches
for possible time variations of the fundamental physical constants. Current
laboratory constraints on variations of the fine structure constant alpha and
other fundamental constants are presented.


title: Nonlinear whitlerons

abstract:
  Recently, observations from laboratory experiments have revealed amplitude
modulation of whistlers by low-frequency perturbations. We here present
theoretical and simulation studies of amplitude modulated whistler solitary
waves (whistlerons) and their interaction with background low-frequency density
perturbations created by the whistler ponderomotive force. We derive a
nonlinear a nonlinear Schrodinger equation which governs the evolution of
whistlers in the presence of finite-amplitude density perturbations, and a set
of equations for arbitrary large amplitude density perturbations in the
presence of the whistler ponderomotive force. The governing equations studied
analytically in the small amplitude limit, and are solved numerically to show
the existence of large scale density perturbations that are self-consistently
created by localized whistlerons. Our numerical results are in good agreement
with recent experimental results where the the formation of modulated whistlers
and solitary whister waves were formed.


title: Multifractal Analysis of Human Retinal Vessels

abstract:
  In this work it is shown that vascular structures of the human retina
represent geometrical multifractals, characterized by a hierarchy of exponents
rather then a single fractal dimension. A number of retinal images from the
STARE database (www.parl.clemson.edu/stare) are analyzed, corresponding to both
normal and pathological states of the retina. In all studied cases a clearly
multifractal behavior is observed, where capacity dimension is always found to
be smaller then the information dimension, which is in turn always smaller then
the correlation dimension, all the three being significantly lower then the DLA
(Diffusion Limited Aggregation) fractal dimension. We also observe a tendency
of images corresponding to the pathological states of the retina to have lower
generalized dimensions and a shifted spectrum range, in comparison with the
normal cases.


title:
Quantum Limited DPSK Receivers with Optical Mach-Zehnder Interferometer
  Demodulation

abstract:
  We present an analysis of quantum-limited DPSK receivers with optical
Mach-Zehnder interferometer (MZI) demodulation. It is shown for the first time
that the quantum limits for DPSK/MZI receivers with single-port and balanced
detections exactly differ from 3-dB in receiver sensitivity, obtained by both
Poisson and Gaussian noise statistics.


title:
Semiclassical ionization dynamics of the hydrogen molecular ion in an
  electric field of arbitrary orientation

abstract:
  Quasi-static models of barrier suppression have played a major role in our
understanding of the ionization of atoms and molecules in strong laser fields.
Despite their success, in the case of diatomic molecules these studies have so
far been restricted to fields aligned with the molecular axis. In this paper we
investigate the locations and heights of the potential barriers in the hydrogen
molecular ion in an electric field of arbitrary orientation. We find that the
barriers undergo bifurcations as the external field strength and direction are
varied. This phenomenon represents an unexpected level of intricacy even on
this most elementary level of the dynamics. We describe the dynamics of
tunnelling ionization through the barriers semiclassically and use our results
to shed new light on the success of a recent theory of molecular tunnelling
ionization as well as earlier theories that restrict the electric field to be
aligned with the molecular axis.


title:
Excitation energies, hyperfine constants, E1, E2, M1 transition rates,
  and lifetimes of (6s2)nl states in Tl I and Pb II

abstract:
  Energies of np (n=6-9), ns (n=7-9), nd (n=6-8), and nf (n=5-6) states in Tl I
and Pb II are obtained using relativistic many-body perturbation theory.
Reduced matrix elements, oscillator strengths, transition rates, and lifetimes
are determined for the 72 possible electric-dipole transitions.
Electric-quadrupole and magnetic-dipole matrix elements are evaluated to obtain
np(3/2) - mp(1/2) (n,m=6,7) transition rates. Hyperfine constants A are
evaluated for a number of states in 205Tl. First-, second-, third-, and
all-order corrections to the energies and matrix elements and first- and
second-order Breit corrections to energies are calculated. In our
implementation of the all-order method, single and double excitations of
Dirac-Fock wave functions are included to all orders in perturbation theory.
These calculations provide a theoretical benchmark for comparison with
experiment and theory.


title: Long sandwich modules for photon veto detectors

abstract:
  Long lead-scintillator sandwich modules developed for the BNL experiment
KOPIO are described. The individual 4 m long module consists of 15 layers of 7
mm thick extruded scintillator and 15 layers of 1 mm lead absorber. Readout is
implemented via WLS fibers glued into grooves in a scintillator with 7 mm
spacing and viewed from both ends by the phototubes. Time resolution of 300 ps
for cosmic MIPs was obtained. Light output stability monitored for 2 years
shows no degradation beyond the measurement errors. A 4 m long C-bent sandwich
module was also manufactured and tested.


title:
Enhanced Doppler Effect in the Upper Hybrid Resonance Microwave
  Backscattering Experiment

abstract:
  Observations of enhanced Doppler frequency shift effect of the highly
localized microwave backscattering in the upper hybrid resonance are reported.
The experiment is performed at FT-2 tokamak, where a steerable focusing antenna
set, allowing off equatorial plane plasma extraordinary wave probing from high
magnetic field side, was installed. A separate line less than 1.5 MHz wide and
shifted by up to 2 MHz is routinely observed in the backscattering spectrum
under condition of accessible upper hybrid resonance. The enhanced frequency
shift is explained by the growth of poloidal wave number of the probing wave in
the resonance. The new scheme for local diagnostics of fluctuations poloidal
rotation based on this effect is proposed.


title: CADe tools for early detection of breast cancer

abstract:
  A breast neoplasia is often marked by the presence of microcalcifications and
massive lesions in the mammogram: hence the need for tools able to recognize
such lesions at an early stage. Our collaboration, among italian physicists and
radiologists, has built a large distributed database of digitized mammographic
images and has developed a Computer Aided Detection (CADe) system for the
automatic analysis of mammographic images and installed it in some Italian
hospitals by a GRID connection. Regarding microcalcifications, in our CADe
digital mammogram is divided into wide windows which are processed by a
convolution filter; after a self-organizing map analyzes each window and
produces 8 principal components which are used as input of a neural network
(FFNN) able to classify the windows matched to a threshold. Regarding massive
lesions we select all important maximum intensity position and define the ROI
radius. From each ROI found we extract the parameters which are used as input
in a FFNN to distinguish between pathological and non-pathological ROI. We
present here a test of our CADe system, used as a second reader and a
comparison with another (commercial) CADe system.


title:
Nanoparticles designed from low pressure plasma as model for
  astrophysical dust clouds

abstract:
  IR spectra gained from laboratory investigations on analogue materials are an
important tool for the interpretation of astronomical IR data and the
understanding of the observed phenomena in DISM. Dust particles grown in
argon/acetylene low pressure plasma are proposed for a new analog. We test the
validity of proposed analog according to the criteria from the literature. We
also present preliminary results of nitrogen band at 4.62 \$mu$m, which has
been identified in dense cold dust.


title:
GPCALMA: A Tool For Mammography With A GRID-Connected Distributed
  Database

abstract:
  The GPCALMA (Grid Platform for Computer Assisted Library for MAmmography)
collaboration involves several departments of physics, INFN sections, and
italian hospitals. The aim of this collaboration is developing a tool that can
help radiologists in early detection of breast cancer. GPCALMA has built a
large distributed database of digitised mammographic images (about 5500 images
corresponding to 1650 patients) and developed a CAD (Computer Aided Detection)
software which is integrated in a station that can also be used for acquire new
images, as archive and to perform statistical analysis. The images are
completely described: pathological ones have a consistent characterization with
radiologist's diagnosis and histological data, non pathological ones correspond
to patients with a follow up at least three years. The distributed database is
realized throught the connection of all the hospitals and research centers in
GRID tecnology. In each hospital local patients digital images are stored in
the local database. Using GRID connection, GPCALMA will allow each node to work
on distributed database data as well as local database data. Using its database
the GPCALMA tools perform several analysis. A texture analysis, i.e. an
automated classification on adipose, dense or glandular texture, can be
provided by the system. GPCALMA software also allows classification of
pathological features, in particular massive lesions analysis and
microcalcification clusters analysis. The performance of the GPCALMA system
will be presented in terms of the ROC (Receiver Operating Characteristic)
curves. The results of GPCALMA system as "second reader" will also be
presented.


title: GPCALMA: a Grid-based tool for Mammographic Screening

abstract:
  The next generation of High Energy Physics (HEP) experiments requires a GRID
approach to a distributed computing system and the associated data management:
the key concept is the Virtual Organisation (VO), a group of distributed users
with a common goal and the will to share their resources. A similar approach is
being applied to a group of Hospitals which joined the GPCALMA project (Grid
Platform for Computer Assisted Library for MAmmography), which will allow
common screening programs for early diagnosis of breast and, in the future,
lung cancer. HEP techniques come into play in writing the application code,
which makes use of neural networks for the image analysis and proved to be
useful in improving the radiologists' performances in the diagnosis. GRID
technologies allow remote image analysis and interactive online diagnosis, with
a potential for a relevant reduction of the delays presently associated to
screening programs. A prototype of the system, based on AliEn GRID Services, is
already available, with a central Server running common services and several
clients connecting to it. Mammograms can be acquired in any location; the
related information required to select and access them at any time is stored in
a common service called Data Catalogue, which can be queried by any client. The
result of a query can be used as input for analysis algorithms, which are
executed on nodes that are in general remote to the user (but always local to
the input images) thanks to the PROOF facility. The selected approach avoids
data transfers for all the images with a negative diagnosis (about 95% of the
sample) and allows an almost real time diagnosis for the 5% of images with high
cancer probability.


title:
A high-level programming-language implementation of topology
  optimization applied to steady-state Navier-Stokes flow

abstract:
  We present a versatile high-level programming-language implementation of
nonlinear topology optimization. Our implementation is based on the commercial
software package Femlab, and it allows a wide range of optimization objectives
to be dealt with easily. We exemplify our method by studies of steady-state
Navier-Stokes flow problems, thus extending the work by Borrvall and Petersson
on topology optimization of fluids in Stokes flow [Int. J. Num. Meth. Fluids
2003; 41:77--107]. We analyze the physical aspects of the solutions and how
they are affected by different parameters of the optimization algorithm. A
complete example of our implementation is included as Femlab code in an
appendix.


title:
Spatial and time-dependent distribution of plasma parameters in the
  metal-halide arc lamp

abstract:
  It was shown by several authors that closed high pressure arc a.c. discharge
in mercury vapors with addition of metal halide cannot be described in frames
of the local thermodynamic equilibrium (LTE) model. However some plasma
parameters (electron and high lying excited states densities as well as Hg
metastable levels densities) are assumed to be in equilibrium with electron
temperature and these assumptions are applied in plasma diagnostics. To verify
these supposition the method of local plasma spectroscopy based on spatial and
temporal distribution of spectral line profiles was developed. The experimental
set up is based on diffraction spectrometer with large aperture, spatial
scanning device and photodetector, which allows to carry out the measurements
in chosen phases of current period. The software for data acquisition and
processing is based on LabVIEW system. The original method of joint data
processing was applied to data arrays containing spatial, spectral and temporal
distribution of a source surface radiance. The method is based on principal
component theory, it takes into account the correlation between spectral
emissivities inside spectral line profiles and allows ...


title:
Poloidal inhomogeneity of the particle fluctuation induced fluxes near
  of the LCFS at lower hybrid heating and improved confinement transition at
  the FT-2 tokamak

abstract:
  This paper deals with the new spectral and microturbulence experimental data
and their analysis, which show, that the radial electric field Er generated at
the LH heating (LHH) in the FT-2 is high enough to form the transport barriers.
The ETB is formed when LHH is switched off. The radial fluctuation-induced
EB drift flux densities near LCFS in SOL are measured at two different
poloidal angles. For this purpose two Langmuir probes located at low and high
field sides of the torus are used. Registration of the poloidal and radial
components of the electric field and density fluctuations at the same time
during one discharge permits to measure the poloidal asymmetry of the transport
reduction mechanism of the radial and poloidal particle fluxes in the SOL. The
absolute E(~) fluctuation levels show dependence on the sign of Er
shear. The modification of the microscale turbulence by the poloidal Er x B
rotation shear EB at the L - H transition near LCFS is also
studied by X-mode fluctuation Reflectometry. The new data were obtained by
spatial spectroscopic technique.


title: Noether methods for fluids and plasmas

abstract:
  Two applications of the Noether method for fluids and plasmas are presented
based on the Euler-Lagrange and Euler-Poincare variational principles, which
depend on whether the dynamical fields are to be varied independently or not,
respectively. The relativistic cold laser-plasma equations, describing the
interaction between an intense laser field with a cold relativistic electron
plasma, provide a useful set of equations amenable to both variational
formulations. The derivation of conservation laws by Noether method proceeds
from the Noether equation, whose form depends on the variational formulation
used. As expected, the expressions for the energy-momentum conservation laws
are identical in both variational formulations. The connection between the two
Lagrangian densities is shown to involve the mass conservation and Lin
constraints associated with the cold relativistic electron fluid.


title: A new electromagnetic wave in a pair plasma

abstract:
  A new nonlinear electromagnetic wave mode in a plasma is reported. Its
existence depends on the interaction of an intense circularly polarized
electromagnetic wave with a plasma, where quantum electrodynamical
photon--photon scattering is taken into account. As an illustration, we
consider a pair plasma and show that the new mode can be significant in
astrophysical settings and in the next generation laser-plasma systems.


title: Kinetic fluctuations in the inhomogeneous plasma

abstract:
  Using the Langevin approach and the multiscale technique, a kinetic theory of
the time and space nonlocal fluctuations in the collisional plasma is
constructed. In local equilibrium a generalized version of the Callen-Welton
theorem is derived. It is shown that not only the dissipation but also the time
and space derivatives of the dispersion determine the amplitude and the width
of the spectrum lines of the electrostatic field fluctuations, as well as the
form factor. There appear significant differences with respect to the
non-uniform plasma. In the kinetic regime the form factor is more sensible to
space gradient than the spectral function of the electrostatic field
fluctuations. As a result of the inhomogeneity, these proprieties became
asymmetric with respect to the inversion of the frequency sign. The differences
in amplitude of peaks could become a new tool to diagnose slow time and space
variations in the plasma.


title: Impurity transport in plasma edge turbulence

abstract:
  The turbulent transport of minority species/impurities is investigated in 2D
drift-wave turbulence as well as in 3D toroidal drift-Alfven edge turbulence.
The full effects of perpendicular and -- in 3D -- parallel advection are kept
for the impurity species. Anomalous pinch effects are recovered and explained
in terms of Turbulent EquiPartition (TEP)


title: Theory of solitary waves in complex plasma lattices

abstract:
  A comprehensive analytical theory for nonlinear excitations related to
horizontal (longitudinal, acoustic mode) as well as vertical (transverse,
optical mode) motion of charged dust grains in a dust crystal is presented.
Different types of localized excitations, similar to those well known in solid
state physics, are reviewed and conditions for their occurrence and
characteristics in dusty plasma crystals are discussed. By employing a
continuum approximation (i.e. assuming a long variation scale, with respect to
the inter-particle distance) a dust crystal is shown to support nonlinear
kink-shaped supersonic solitary excitations, associated with longitudinal dust
grain displacement, as well as modulated envelope localized modes associated
with either longitudinal or transverse oscillations. Although a one-dimensional
crystal is considered for simplicity, the results in principle apply to a
two-dimensional lattice if certain conditions are satisfied. The effect of
mode-coupling is also briefly considered. The relation to previous results on
atomic chains, and also to experimental results on strongly-coupled dust layers
in gas discharge plasmas, is briefly discussed.


title: Lagrangean formulation of ion- and dust-ion-acoustic waves

abstract:
  Ion-acoustic modes propagating in unmagnetized dusty plasmas are studied by
applying a generic collisionless fluid model. An Eulerian-to-Lagrangean
variable transformation leads to a new system of evolution equations, which may
be combined into a single (rather complex) equation for the mean ion density.
The linear and weakly nonlinear oscillations regimes are studied and their
modulational stability is investigated. This study extends known previous
results on the Lagrangian description of electron- or ion-acoustic
electrostatic plasma modes. The relevance with the description of dust-ion
acoustic waves propagating in a dusty plasma is also discussed.


title: Intrinsic localized modes in dust lattices

abstract:
  Intrinsic Localized Modes (ILM) (or Discrete Breathers, DB) are localized
oscillatory modes known to occur in atomic or molecular chains characterized by
coupling and/or on-site potential nonlinearity. Quasi-crystals of charged
mesoscopic dust grains (dust lattices), which have been observed since hardly a
decade ago, are an exciting paradigm of such a nonlinear chain. In
gas-discharge experiments, these crystals are subject to forces due to an
externally imposed electric and/or magnetic field(s), which balance(s) gravity
at the levitated equilibrium position, as well as to electrostatic inter-grain
interaction forces. Despite the profound role of nonlinearity, which may be due
to inter-grain coupling, mode- coupling and to the sheath environment, the
elucidation of the nonlinear mechanisms governing dust crystals is still in a
preliminary stage. This study is devoted to an investigation, from very first
principles, of the existence of discrete localized modes in dust layers.
Relying on a set of evolution equation for transverse charged grain
displacements, we examine the conditions for the existence and sustainance of
discrete localized modes and discuss the dependence of their characteristics on
intrinsic plasma parameters. In addition, the possibility of DB stabilisation
via an external force is discussed.


title:
Nonlinear software sensor for monitoring genetic regulation processes
  with noise and modeling errors

abstract:
  Nonlinear control techniques by means of a software sensor that are commonly
used in chemical engineering could be also applied to genetic regulation
processes. We provide here a realistic formulation of this procedure by
introducing an additive white Gaussian noise, which is usually found in
experimental data. Besides, we include model errors, meaning that we assume we
do not know the nonlinear regulation function of the process. In order to
illustrate this procedure, we employ the Goodwin dynamics of the concentrations
[B.C. Goodwin, Temporal Oscillations in Cells, (Academic Press, New York,
1963)] in the simple form recently applied to single gene systems and some
operon cases [H. De Jong, J. Comp. Biol. 9, 67 (2002)], which involves the
dynamics of the mRNA, given protein, and metabolite concentrations. Further, we
present results for a three gene case in co-regulated sets of transcription
units as they occur in prokaryotes. However, instead of considering their full
dynamics, we use only the data of the metabolites and a designed software
sensor. We also show, more generally, that it is possible to rebuild the
complete set of nonmeasured concentrations despite the uncertainties in the
regulation function or, even more, in the case of not knowing the mRNA
dynamics. In addition, the rebuilding of concentrations is not affected by the
perturbation due to the additive white Gaussian noise and also we managed to
filter the noisy output of the biological system


title:
Nonlinear waves on the surface of a dielectric liquid in a strong
  tangential electric field

abstract:
  The nonlinear dynamics of the free surface of an ideal dielectric liquid in a
strong electric field is studied. The equation for the evolution of surface
electrohydrodynamic waves is derived in the approximation of small
surface-slope angles. It is established that the equation can be solved for
liquids with sufficiently high values of the permittivity. This makes it
possible to describe the interaction of the counter-propagating waves.


title: Nonlinear theory of dust lattice mode coupling in dust crystals

abstract:
  Quasi-crystals formed by charged mesoscopic dust grains (dust lattices),
observed since hardly a decade ago, are an exciting paradigm of a nonlinear
chain. In laboratory discharge experiments, these quasi-lattices are formed
spontaneously in the sheath region near a negative electrode, usually at a
levitated horizontal equilibrium configuration where gravity is balanced by an
electric field. It is long known (and experimentally confirmed) that
dust-lattices support linear oscillations, in the longitudinal (acoustic mode)
as well as in the transverse, in plane (acoustic-) or off-plane (optic-like
mode) directions. Either due to the (typically Yukawa type) electrostatic
inter-grain interaction forces or to the (intrinsically nonlinear) sheath
environment, nonlinearity is expected to play an important role in the dynamics
of these lattices. Furthermore, the coupling between the different modes may
induce coupled nonlinear modes. Despite this evidence, the elucidation of the
nonlinear mechanisms governing dust crystals is in a rather preliminary stage.
In this study, we derive a set of (coupled) discrete equations of motion for
longitudinal and transverse (out-of-plane) motion in a one dimensional model
chain of charged dust grains. In a continuum approximation, i.e. assuming a
variation scale which is larger than the lattice constant, one obtains a set of
coupled modified Boussinesq-like equations. Different nonlinear solutions of
the coupled system are discussed, based on localized travelling wave ansatze
and on coupled equations for the envelopes of co-propagating quasi-linear
waves.


title:
Planar LAAPDs: Temperature Dependence, Performance, and Application in
  Low Energy X-ray Spectroscopy

abstract:
  An experiment measuring the 2S Lamb shift in muonic hydrogen mup is being
performed at the Paul Scherrer Institute, Switzerland. It requires small and
compact detectors for 1.9 keV x rays (2P-1S transition) with an energy
resolution around 25% at 2 keV, a time resolution better than 100 ns, a large
solid angle coverage, and insensitivity to a 5 T magnetic field. We have chosen
Large Area Avalanche Photodiodes (LAAPDs) from Radiation Monitoring Devices as
x-ray detectors, and they were used during the last data taking period in 2003.
For x-ray spectroscopy applications, these LAAPDs have to be cooled in order to
suppress the dark current noise, hence, a series of tests were performed to
choose the optimal operation temperature. Specifically, the temperature
dependence of gain, energy resolution, dark current, excess noise factor, and
detector response linearity was studied. Finally, details of the LAAPDs
application in the muonic hydrogen experiment as well as their response to
alpha particles are presented.


title:
Modulated envelope localized wavepackets associated with electrostatic
  plasma waves

abstract:
  The nonlinear amplitude modulation of known electrostatic plasma modes is
examined in a generic manner, by applying a collisionless fluid model. Both
cold (zero-temperature) and warm fluid descriptions are discussed and the
results are compared. The moderately nonlinear oscillation regime is
investigated by applying a multiple scale technique. The calculation leads to a
Nonlinear Schrodinger-type Equation (NLSE), which describes the evolution of
the slowly varying wave amplitude in time and space. The NLSE admits localized
envelope (solitary wave) solutions of bright- (pulses) or dark- (holes, voids)
type, whose characteristics (maximum amplitude, width) depend on intrinsic
plasma parameters. Effects like amplitude perturbation obliqueness, finite
temperature and defect (dust) concetration are explicitly considered. The
relevance with similar highly localized modulated wave structures observed
during recent satellite missions is discussed.


title:
Developement of real time diagnostics and feedback algorithms for JET in
  view of the next step

abstract:
  Real time control of many plasma parameters will be an essential aspect in
the development of reliable high performance operation of Next Step Tokamaks.
The main prerequisites for any feedback scheme are the precise real-time
determination of the quantities to be controlled, requiring top quality and
highly reliable diagnostics, and the availability of robust control algorithms.
A new set of real time diagnostics was recently implemented on JET to prove the
feasibility of determining, with high accuracy and time resolution, the most
important plasma quantities. With regard to feedback algorithms, new
model–based controllers were developed to allow a more robust control of
several plasma parameters. Both diagnostics and algorithms were successfully
used in several experiments, ranging from H-mode plasmas to configuration with
ITBs. Since elaboration of computationally heavy measurements is often
required, significant attention was devoted to non-algorithmic methods like
Digital or Cellular Neural/Nonlinear Networks. The real time hardware and
software adopted architectures are also described with particular attention to
their relevance to ITER.


title: The frequency of electron-ion collisions in a hot plasma

abstract:
  It is shown that the anomalous resistivity, thermal conductivity, and
magnetic pressure of hot plasmas can be explained by the assumption that the
collisional electron-ion cross-section becomes constant above some critical
temperature. This constant is determined by the size of ion (its electron
envelope). It is shown also that this assumption follows from the consideration
of interaction of a hot plasma with thermal radiation.


title:
Dielectric Resistive Plate Chamber as a detector for time-of-flight
  measurements

abstract:
  Principles of operation, construction and first test results of a Dielectric
Resistive Plate Chamber (DRPC) are described. The detector has shown stability
of operation in the avalanche mode of gas amplfication within a wide range of
applied voltages. Double-gap DRPCs have demonstrated the MIP registration
efficiency of 97% and the time resolution of 180-200 ps. No changes in DRPC
operation have been observed with test beam intensities up to 10^3 Hz/cm^2.


title: Design and Construction of a TPC using GEM Foils for Gas Amplification

abstract:
  The challenging physics program at the International Linear Collider (ILC)
poses stringent requirements on the performance of its tracking system. A large
volume time projection chamber (TPC) is considered a good candidate for such a
tracker. Whereas conventional TPCs used a wired based gas amplification system,
a future TPC is likely to make use of micro pattern gas detectors as e. g. gas
electron multipliers (GEMs) for gas amplification. This talk gives an overview
over recent achievements from the R&D activities to build a TPC with a GEM
based gas amplification system. This includes charge transfer studies through
multiple GEM structures, field cage design and spatial resolution measurements
in high magnetic fields.


title:
Self-stresses and Crack Formation by Particle Swelling in Cohesive
  Granular Media

abstract:
  We present a molecular dynamics study of force patterns, tensile strength and
crack formation in a cohesive granular model where the particles are subjected
to swelling or shrinkage gradients. Non-uniform particle size change generates
self-equilibrated forces that lead to crack initiation as soon as strongest
tensile contacts begin to fail. We find that the coarse-grained stresses are
correctly predicted by an elastic model that incorporates particle size change
as metric evolution. The tensile strength is found to be well below the
theoretical strength as a result of inhomogeneous force transmission in
granular media. The cracks propagate either inward from the edge upon shrinkage
and outward from the center upon swelling.


title: Analytical theory of Doppler reflectometry in slab plasma model

abstract:
  Doppler reflectometry is considered in slab plasma model in the frameworks of
analytical theory. The diagnostics locality is analyzed for both regimes:
linear and nonlinear in turbulence amplitude. The toroidal antenna focusing of
probing beam to the cut-off is proposed and discussed as a method to increase
diagnostics spatial resolution. It is shown that even in the case of nonlinear
regime of multiple scattering, the diagnostics can be used for an estimation
(with certain accuracy) of plasma poloidal rotation profile.


title: Spatial and Wavenumber Resolution of Doppler Reflectometry

abstract:
  Doppler reflectometry spatial and wavenumber resolution is analyzed within
the framework of the linear Born approximation in slab plasma model. Explicit
expression for its signal backscattering spectrum is obtained in terms of
wavenumber and frequency spectra of turbulence which is assumed to be radially
statistically inhomogeneous. Scattering efficiency for both back and forward
scattering (in radial direction) is introduced and shown to be inverse
proportional to the square of radial wavenumber of the probing wave at the
fluctuation location thus making the spatial resolution of diagnostics
sensitive to density profile. It is shown that in case of forward scattering
additional localization can be provided by the antenna diagram. It is
demonstrated that in case of backscattering the spatial resolution can be
better if the turbulence spectrum at high radial wavenumbers is suppressed. The
improvement of Doppler reflectometry data localization by probing beam focusing
onto the cut-off is proposed and described. The possibility of Doppler
reflectometry data interpretation based on the obtained expressions is shown.


title: Accurate spectroscopy of Sr atoms

abstract:
  We report the frequency measurement with an accuracy in the 100 kHz range of
several optical transitions of atomic Sr : $^1S_0- ^3P_1$ at 689 nm, $^3P_1-
^3S_1$ at 688 nm and $^3P_0- ^3S_1$ at 679 nm. Measurements are performed with
a frequency chain based on a femtosecond laser referenced to primary frequency
standards. They allowed the indirect determination with a 70 kHz uncertainty of
the frequency of the doubly forbidden $5s^2^1S_0- 5s5p^3P_0$ transition of
$^{87}$Sr at 698 nm and in a second step its direct observation. Frequency
measurements are performed for $^{88}$Sr and $^{87}$Sr, allowing the
determination of $^3P_0$, $^3P_1$ and $^3S_1$ isotope shifts, as well as the
$^3S_1$ hyperfine constants.


title:
Intermittency in the Enstrophy Cascade of Two-dimensional
  Fully-developed Turbulence: Universal Features

abstract:
  Intermittency (externally induced) in the two-dimensional (2D) enstrophy
cascade is shown to be able to maintain a finite enstrophy along with a
vorticity conservation anomaly. Intermittency mechanisms of three-dimensional
(3D) energy cascade and 2D enstrophy cascade in fully-developed turbulence
(FDT) seem to have some universal features. The parabolic-profile approximation
(PPA) for the singularity spectrum f(a) in multi-fractal model is used and
extended to the appropriate microscale regimes to exhibit these features. The
PPA is also shown to afford, unlike the generic multi-fractal model, an
analytical calculation of probability distribution functions (PDF) of
flow-variable gradients in these FDT cases and to describe intermittency
corrections that complement those provided by the homogeneous fractal model.


title:
Precision spectroscopy and density-dependent frequency shifts in
  ultracold Sr

abstract:
  By varying the density of an ultracold $^{88}$Sr sample from $10^9$ cm$^{-3}$
to $> 10^{12}$ cm$^{-3}$, we make the first definitive measurement of the
density-related frequency shift and linewidth broadening of the $^1S_0$ -
$^3P_1$ optical clock transition in an alkaline earth system. In addition, we
report the most accurate measurement to date of the $^{88}$Sr $^1S_0 - ^3P_1$
optical clock transition frequency. Including a detailed analysis of systematic
errors, the frequency is ($434 829 121 312 334 \pm 20_{stat} \pm 33_{sys}$) Hz.


title:
Numerical Study of Two-fluid Flowing Equilibria of Helicity-driven
  Spherical Torus Plasmas

abstract:
  Two-fluid flowing equilibrium configurations of a helicity-driven spherical
torus (HD-ST) are numerically determined by using the combination of the finite
difference and the boundary element methods. It is found from the numerical
results that electron fluids near the central conductor are tied to an external
toroidal field and ion fluids are not. The magnetic configurations change from
the high-$q$ HD-ST ($q$>1) with paramagnetic toroidal field and low-$\beta$
(volume average $\beta$ value, ($<\beta>\approx$ 2 %) through the
helicity-driven spheromak and RFP to the ultra low-$q$ HD-ST (0<q<1) with
diagmagnetic toroidal field and high-$\beta$ ($\beta\approx 18\%) as the
external toroidal field at the inner edge region decreases and reverses the
sign. The two-fluid effecs are more significant in this equilibrium transition
when the ion diagmagnetic drift is dominant in the flowing two-fluid.


title:
Plasma heating due to X-B mode conversion in a cylindrical ECR plasma
  system

abstract:
  Extra Ordinary (X) mode conversion to Bernstein wave near Upper Hybrid
Resonance (UHR) layer plays an important role in plasma heating through
cyclotron resonance. Wave generation at UHR and parametric decay at high power
has been observed during Electron Cyclotron Resonance (ECR) heating experiments
in toroidal magnetic fusion devices. A small linear system with ECR and UHR
layer within the system has been used to conduct experiments on X-B conversion
and parametric decay process as a function of system parameters. Direct probing
{\em in situ} is conducted and plasma heating is evidenced by soft x-ray
emission measurement. Experiments are performed with hydrogen plasma produced
with 160-800 W microwave power at 2.45 GHz of operating frequency at $10^{-3}$
mbar pressure. The axial magnetic field required for ECR is such that the
resonant surface (B = 875 G) is situated at the geometrical axis of the plasma
system. Experimental results will be presented in the paper.


title:
Modeling of a chlorine high-density plasma submitted to a static
  magnetic field

abstract:
  This paper extends the results of a recently developed one-dimensional model
aiming to describe the characteristics of a magnetized chlorine high-density
plasma. In this work, the dependence of the plasma characteristics on the
magnetic field intensity is investigated. It is shown that the dissociation
degree and the relative weight of the various charged species is strongly
influenced by the magnetic field when the gas pressure is low enough. In
contrast, at higher pressure, the plasma is essentially composed of negative
ions, and molecular neutrals and ions, independently of the field intensity. It
is further demonstrated that diffusion needs to be considered in order to
correctly predict the plasma behavior.


title:
Pulsations of the electron-positron plasma in the field of optical
  lasers

abstract:
  The possibility to observe vacuum electron-positron pair creation due to a
powerful optical laser pulse is discussed. We employ a quantum kinetic
formulation of the problem with a source term describing the vacuum pair
production in a homogeneous electric field with arbitrary time dependence
(dynamical Schwinger mechanism). For a periodic field weak in comparison with
the critical value E_{cr}=m^2/|e|, the electron-positron plasma density changes
approximately periodically with twice the field frequency. Under these
conditions, the mean value $<n>$ for the density per period in the volume
lambda^3 is a more appropriate characteristic quantity than the residual
density n_r which is taken over an integer number of field periods and
calculated using the imaginary time method. The value <n> is proportional to
the squared field intensity and does not depend on the frequency. We show that
in terms of the parameter <n> an optical laser can be more effective than a
X-ray one. We expect that it is possible to observe the vacuum creation effect
not only by means of the planned X-ray free electron lasers but already at
present-day optical lasers.

categories: physics.plasm-ph hep-ph physics.acc-ph quant-ph


title:
Reply to "Comment on 'Stimulated Raman adiabatic passage from an atomic
  to a molecular Bose-Einstein condensate'"

abstract:
  In the Comment by M. Mackie \textit{et al.} [arXiv: physics/0212111 v.4], the
authors suggest that the molecular conversion efficiency in atom-molecule
STIRAP can be improved by lowering the initial atomic density, which in turn
requires longer pulse durations to maintain adiabaticity. Apart from the fact
that the mean-field approximation becomes questionable at low densities, we
point out that a low-density strategy with longer pulses has several problems.
It generally requires higher pulse energies, and increases radiative losses. We
also show that even within the approximations used in the Comment, their
example leads to no efficiency improvement compared to our high-density case.
In a more careful analysis including radiative losses neglected in the Comment,
the proposed strategy gives almost no conversion owing to the longer pulse
durations required.


title: Plasma Heating by an Electron Beam in Corrugated Magnetic Field

abstract:
  New experimental results from the multimirror trap GOL-3 are presented.
Deuterium plasma of $~10^21 m^-3$ density is heated by a high power
relativistic electron beam (peak parameters are ~1 MeV, ~25 kA, ~8 $\mu$s, ~120
kJ). Magnetic system of the facility is a 12-meter-long axisymmetrical solenoid
with corrugated magnetic field, which consists of 55 cells with
$B_max/B_min$=4.8/3.2 T. Collective plasma heating by the electron beam results
in peak electron temperature ~2 keV. To this time the ions are also
collectively heated by gradients of electron pressure in the cells of the trap.
Ion temperature increases above 1 keV and confines at the high level for ~1 ms.
Dense hot plasma in GOL-3 trap emits D-D neutrons for ~1 ms. Details of
collective plasma heating by the beam in the corrugated magnetic field will be
presented in the paper. New physical mechanism of effective heating of plasma
ions, substantially dependent on the corrugation of the magnetic field, is
discussed. Experiments with complete multimirror configuration of the GOL-3
facility have shown the significant improvement of energy confinement time
comparing with simple solenoidal configuration. Axial currents, which exist in
the system, cause sheared helical structure of the magnetic field. The safety
factor q is shown to be below unity on the axis.


title:
Observation of the ion-ion instability and its suppression mechanism in
  a dusty double plasma device

abstract:
  Ion-ion instability is excited due to the counter streaming of ion beams in
any plasma system. An experiment has been carried out to observe the ion-ion
instability in dusty plasma and in presence of different gas compositions viz.,
H2, Ar, Xe and He. The experiment is performed in a double plasma device
consisting of 90 cm in diameter and 120 cm in length and separated by a mesh
grid of 81% optical transparency. Glass beads of 10 mm average dust
distributions are used as a dust grains for the whole set of experiment and are
allowed to fall within a particular region of plasma column inside the system.
The growing and suppression of ion-ion instability is observed by translating
the probe spatially with respect to different dust density compositions and
compared the same also in presence of other gasses. The suppression mechanism
of this kind of instability in plasmas was explained by RF pumps[1]. However,
in this experimental finding the suppression phenomena are discussed in terms
of dust density inside the system. The instability is found to be suppressed
completely at a critical dust density (Ndcr). The complete set of experimental
results will be tried to explain with the numerical solution of Van der Pol
Equation.


title:
Stabilization of burn conditions in an ITER FEAT like tokamak with
  uncertainities in the helium ash confinement time

abstract:
  In this work we demostrate using a two-temperature volume average 0D model
that robust stabilization, with regard the hellium ash confinement time, of the
burn conditions of a tokamak reactor with the ITER FEAT design parameters can
be achieved using Radial Basis Neural Networks (RBNN). Alpha particle
thermalization time delay is taken into account in this model. The control
actions implemented by means of a RBNN, include the modulation of the DT
refueling rate, a neutral He-4 injection beam and auxiliary heating powers to
ions and to electrons; all of them constrained to lie within allowable range
values. Here we assume that the tokamak follows the IPB98(y,2) scaling for the
energy confinement time, while the helium ash confinement time is assumed to be
independently estimated on-line. The DT and helium ash confinement times are
assumed to keep a constant relationship at all times. An on-line noisy
estimation of the helium ash confinement time is simulated by corrupting it
with pseudo Gaussian noise.


title:
Formation of Conic Cusps at the Surface of Liquid Metal in Electric
  Field

abstract:
  The formation dynamics is studied for a singular profile of a surface of an
ideal conducting fluid in an electric field. Self-similar solutions of
electrohydrodynamic equations describing the fundamental process of formation
of surface conic cusps with angles close to the Taylor cone angle 98.6 are
obtained. The behavior of physical quantities (field strength, fluid velocity,
surface curvature) near the singularity is established.


title: Selective production of metallic carbon nanotubes

abstract:
  In this report, we discuss whether the optimal electric field to promote the
growth of armchair- type nanotubes (metallic character) evaluated using the
previous Huckel-Poisson method can be applied at the tip of a nanotube in a
realistic system. Setting the cross-section of a nanotube and the external
field by the sheath, we estimate an effective area at the sheath edge. Since
the electric charge distribution in a nanotube caused by the external electric
field was determined in our previous study, we obtained the electric field
distribution out of a nanotube by solving the Poisson equation and clarified
the structure of the electric field lines. By determining the effective area,
we show the optimal interval of the catalyst metal, which is necessary to
selectively grow the metallic nanotubes. When nanotubes grow thickly during the
initial stage of growth, a strong electric field cannot be applied to the tips
of the tubes. As a tube grows and the tube length increases, we found that the
optimal electric field decreased. To maintain the chemical activity at the tip,
the sheath electric field must be decreased. We estimated the decreasing rate
of the sheath field to the tube length.


title:
Investigation of initiation of gigantic jets connecting thunderclouds to
  the ionosphere

abstract:
  The initiation of giant electrical discharges called as "gigantic jets"
connecting thunderclouds to the ionosphere is investigated by numerical
simulation method in this paper. Using similarity relations, the triggering
conditions of streamer formation in laboratory situations are extended to form
a criterion of initiation of gigantic jets. The energy source causing a
gigantic jet is considered due to the quasi-electrostatic field generated by
thunderclouds. The electron dynamics from ionization threshold to streamer
initiation are simulated by the Monte Carlo technique. It is found that
gigantic jets are initiated at a height of ~18-24 km. This is in agreement with
the observations. The method presented in this paper could be also applied to
the analysis of the initiation of other discharges such as blue jets and red
sprites.


title:
Short-range exchange and correlation energy density functionals: beyond
  the local density approximation

abstract:
  We propose approximations which go beyond the local density approximation for
the short-range exchange and correlation density functionals appearing in a
multi-determinantal extension of the Kohn-Sham scheme. A first approximation
consists in defining locally the range of the interaction in the correlation
functional. Another approximation, more conventional, is based on a gradient
expansion of the short-range exchange-correlation functional. Finally, we also
test a short-range generalized-gradient approximation by extending the
Perdew-Burke-Ernzerhof exchange-correlation functional to short-range
interactions.


title: Virtual Displacement in Lagrangian Dynamics

abstract:
  The confusion and ambiguity encountered by students, in understanding virtual
displacement and virtual work, is addressed in this article. A definition of
virtual displacement is presented that allows one to express them explicitly
for both time independent and time dependent constraints. It is observed that
for time independent constraints the virtual displacements are the
displacements allowed by the constraints. However this is not so for a general
time dependent case. For simple physical systems, it is shown that, the work
done on virtual displacements by the constraint forces is zero in both the
situations. For allowed displacements however, this is not always true. It is
also demonstrated that when constraint forces do zero work on virtual
displacement, as defined here, we have a solvable mechanical problem. We
identify this special class of constraints, physically realized and solvable,
as the ideal constraints. The concept of virtual displacement and the principle
of zero virtual work by constraint forces are central to both Lagrange's method
of undetermined multipliers, and Lagrange's equations in generalized
coordinates.


title: Special Relativity as a Physical Theory

abstract:
  A modest aim of this pedagogical presentation is to analyze, critically,
certain fundamental physical concepts to illustrate the physical principles
behind the special theory of relativity and, hence, to also illustrate the
limitations of its applicability.


title: Electron Landau damping in a laboratory dipole magnetic field plasma

abstract:
  Transverse and longitudinal dielectric permittivity elements are derived for
radio frequency waves in a laboratory dipole magnetic field plasma (LDMFP)
accounting for the finite ring current radius. The main feature of LDMFP is the
fact that, in contrast to planetary magnetospheric plasmas, the untrapped
(circulating) particles can exist/circulate (together with the trapped
particles) along the equilibrium magnetic field lines. To estimate the wave
power absorbed in LDMFP the perturbed electric field and current density
components are decomposed in a Fourier series over the poloidal angle. The wave
absorption is expressed by the summation of contributions of all harmonics of
the perturbed electric field and both the diagonal and non-diagonal dielectric
permittivity elements. In this paper, we analyze numerically the separate
contributions of the trapped and untrapped electrons to the imaginary part of
the longitudinal permittivity elements in LDMFP with an equilibrium
(Maxwellian) distribution functions of plasma particles in velocity space. This
information is necessary to estimate the collisionless wave dissipation by
electron Landau damping. The computations are carried out in a wide range of
the wave frequencies.


title:
Theory of a stable strong electrostatic double layer generated in a
  two-grid Franck-Hertz tube

abstract:
  There is a classic alternative to the Franck-Hertz experiment designed to
show more than a recurrence of the first excited state. Instead of being
subjected to a rising potential between source and accelerating grid, electrons
are now accelerated in less than one excitation mean-free-path by an extra
grid, and then drift towards the second grid across a large equipotential
region. In this arrangement one must face the difficulty that the space
potential between the grids is strongly modified by space charges. A recent
analysis of this experiment with mercury showed that there is a particular form
of discharge that generates and sustains the ideal design dynamically. The
inevitable variations of potential inside the intergrid volume are then
confined within a narrow sheath, a free double layer, joining two field-free
plasma regions. The position of the double layer can be controlled so as to
optimize the experiment. In the present paper, those phenomena are studied
theoretically in steady-state conditions. The essence of the method is to
specify velocity distributions for electrons and ions and use them to solve the
Poisson equation. Vortex-type functions are used for trapped particles and
mono-energetic beams for free particles. The model explains the change of
position of the double layer and provides a natural explanation of a threshold
condition for its amplitude that governs the transition between two critical
configurations, in accordance with experiment. Stability and minimum
field-energy considerations lead to a unique solution in a four-dimensional
parameter space where the Langmuir ratio is equal to one. The method is
adaptable to other experiments on double layer formation under discharge
conditions and correctly predicts the values of several plasma parameters.


title:
Hamiltonian treatment of time dispersive and dissipative media within
  the linear response theory

abstract:
  We develop a Hamiltonian theory for a time dispersive and dissipative (TDD)
inhomogeneous medium, as described by a linear response equation respecting
causality and power dissipation. The canonical Hamiltonian constructed here
exactly reproduces the original dissipative evolution after integrating out
auxiliary fields. In particular, for a dielectric medium we obtain a simple
formula for the Hamiltonian and closed form expressions for the energy density
and energy flux involving the auxiliary fields. The developed approach also
allows to treat a long standing problem of scattering from a lossy
non-spherical obstacle and, more generally, wave propagation in TDD media.

categories: physics.class-ph math-ph math.MP physics.gen-ph


title:
An investigation of the temperature dependency of the relative
  population inversion and the gain in EDFAs by the modified rate equations

abstract:
  The dependence of the relative population inversion in Er3+-doped fiber
amplifiers (EDFAs) upon temperature and cross sections, taking into account the
amplified spontaneous emission (ASE), are investigated theoretically by the
modified rate equation model for 980 nm and 1470 nm pumping conditions. For the
temperature range from 0 to +50 oC and at the different signal wavelengths, the
temperature and cross section dependent gain characteristics with respect to
pump powers are also examined in detail for the both conditions. As a
consequence, the dependence of the performance of EDFAs on temperature for 980
nm pumping is weaker than that for 1470 nm pumping, not only at room
temperature but also at the temperature range of 0 to +50 oC. However, the
performance of EDFAs is more efficient at the pumping wavelength of 1470 nm
than that of 980 nm for a wide range of temperature and high-pump powers. The
results of this theoretical model are a good agreement with the experimental
ones in the literature.


title:
Influence of dissociative recombination on the LTE of argon
  high-frequency plasmas at atmospheric pressure

abstract:
  This work presents a few preliminary results from a collisional-radiative
(CR) model intended to describe an argon microwave (2.45 GHz) plasma at
atmospheric pressure. This model aims to investigate the influence of
dissociative recombination products on the Saha-Boltzmann plasma equilibrium.
The model is tested through comparison with experimental results obtained in an
argon plasma column generated by a traveling electromagnetic surface-wave,
which is suitable to perform a parametric investigation of the plasma. It is
shown that dissociative recombination predominantly populates the 4s levels and
the ground state. It is further observed that it strongly influences the
population of the levels, specially those of lower energy. However, the higher
levels (close to the ionization limit) appear to be in equilibrium whatever the
plasma density. This allows assuming that the excitation temperature Texc
determined from the upper levels in the atomic system in the Boltzmann-plot is
equal to Te.


title:
Lagrangian Velocity Correlations and Absolute Dispersion in the
  Midlatitude Troposphere

abstract:
  Employing daily wind data from the ECMWF, we perform passive particle
advection to estimate the Lagrangian velocity correlation functions (LVCF)
associated with the midlatitude tropospheric flow. In particular we decompose
the velocity field into time mean and transient (or eddy) components to better
understand the nature of the LVCF's. A closely related quantity, the absolute
dispersion (AD) is also examined.
  Given the anisotropy of the flow, meridional and zonal characteristics are
considered separately. The zonal LVCF is seen to be non-exponential. In fact,
for intermediate timescales it can either be interpreted as a power law of the
form $\tau^{-\alpha}$ with $ 0<\alpha<1$ or as the sum of exponentials with
differing timescales - both interpretations being equivalent. More importantly
the long time correlations in the zonal flow result in a superdiffusive zonal
AD regime. On the other hand, the meridional LVCF decays rapidly to zero.
Before approaching zero the meridional LVCF shows a region of negative
correlation - a consequence of the presence of planetary scale Rossby waves. As
a result the meridional AD, apart from showing the classical asymptotic
ballistic and diffusive regimes, displays transient subdiffusive behaviour.


title:
Nonlinear dynamics of electromagnetic pulses in cold relativistic
  plasmas

abstract:
  In the present analysis we study the self consistent propagation of nonlinear
electromagnetic pulses in a one dimensional relativistic electron-ion plasma,
from the perspective of nonlinear dynamics. We show how a series of Hamiltonian
bifurcations give rise to the electric fields which are of relevance in the
subject of particle acceleration. Connections between these bifurcated
solutions and results of earlier analysis are made.


title:
A novel approach for the temperature dependency of saturated signal
  power in EDFAs

abstract:
  The temperature dependency of the saturated signal power for the transition
in erbium-doped fiber amplifiers (EDFAs) pumped at 980 nm and 1480 nm pump
wavelengths within a temperature range from 20 to 60 oC are investigated by a
novel approach. For 1480 nm pumping regime, it is seen that the saturated
signal power increases more quickly than that of 980 nm pumping regime, with
the increasing temperature. The variation in the saturated signal power with
temperature is nearly constant at 980 nm pumping regime. In addition, the
population inversion with respect to the increasing normalized signal power is
examined and it is seen that it is independent of temperature for 980 nm but it
strongly depends on temperature for 1480 nm especially at lower normalized
signal powers.


title:
Study of Possible Scintillation Mechanism Damage in PbWO4 Crystals After
  Pion Irradiation

abstract:
  We employed two independent methods to study possible damage to the
scintillation mechanism in lead tungstate crystals due to irradiation by a 34
GeV pion beam. First, 10 crystals were irradiated simultaneously over 30 hours
by a narrow beam, so that only a small region of each crystal was affected. We
studied the effect of the irradiation on the light output non-uniformity. If a
localized degradation was observed, it would indicate damage to the
scintillation mechanism. Secondly, we detected light output using two
phototubes attached to sides of a crystal. Since these phototubes detect
scintillation light only from a small localized region, the effect of
transmission loss should be minimal. We did not see any statistically
significant evidence for scintillation mechanism damage with either method. The
effect is consistent with zero, and the upper limit is 0.5% at 95% C.L.


title: Quasi-geostrophic kinematic dynamos at low magnetic Prandtl number

abstract:
  Rapidly rotating spherical kinematic dynamos are computed using the
combination of a quasi geostrophic (QG) model for the velocity field and a
classical spectral 3D code for the magnetic field. On one hand, the QG flow is
computed in the equatorial plane of a sphere and corresponds to Rossby wave
instabilities of a geostrophic internal shear layer produced by differential
rotation. On the other hand, the induction equation is computed in the full
sphere after a continuation of the QG flow along the rotation axis.
Differential rotation and Rossby-wave propagation are the key ingredients of
the dynamo process which can be interpreted in terms of $\alpha\Omega$ dynamo.
Taking into account the quasi geostrophy of the velocity field to increase its
time and space resolution enables us to exhibit numerical dynamos with very low
Ekman (rapidly rotating) and Prandtl numbers (liquid metals) which are
asymptotically relevant to model planetary core dynamos.


title: Production of a large diameter ECR plasma for plasma processing

abstract:
  A large diameter plasma over 300 mm in diameter is produced by electron
cyclotron resonance (ECR) discharges using a newly developed large diameter
chamber of 400 mm in inner diameter. It is found that the electron temperature
decreases as nitrogen gas is added to pure argon plasma, which is considered
that nitrogen molecules absorb the electron energy into the vibrational energy
and lead to the decrease of the electron temperature. Moreover, it is found
that the plasma uniformity is improved by adding nitrogen gas, suggesting that
the adjunction of nitrogen gas is effective for producing uniform and low
electron temperature plasma.


title: Potential structure of a plasma hole in a rotating magnetized plasma

abstract:
  We have observed spontaneous formation of a stationary vortex structure in a
rotating magnetized plasma produced in a linear ECR plasma device named HYPER-I
at National Institute for Fusion Science. The vortex appears with a deep
density-cavity, plasma hole, in its center, and is identified as a dissipative
vortex in viscous fluids (Burgers vortex) [1]. The kinematic viscosity
estimated from the vorticity profile and the ion flow field is 4 orders of
magnitude higher than the classical value, which may be attributable to
insufficiency of the Debye shielding or the breaking of quasi-neutrality. Here
we present the results of potential measurements and the evaluation of
quasi-neutrality breaking. It is revealed that the potential has a bell-shaped
axisymmetric structure localized inside the core region, in which its maximum
value exceeds 5 Te. Using Poisson's equation, degree of quasi-neutrality
breaking is evaluated, which shows 3 orders of magnitude larger than that of
usual laboratory plasma. The strong electric field produced by this
quasi-neutrality breaking drives the supersonic rotation of the plasma hole. It
should be mentioned that the degree of quasi-neutrality breaking in the ambient
region of the plasma hole is comparable to that of usual laboratory plasma.
Hence the plasma hole can be considered as the structure of a nonneutral core
surrounded by a quasi-neutral plasma. It is of great interest to study the
fluctuations associated with the connected structure of the nonneutral and the
quasi-neutral plasma, especially the interfacial layer in between. Our
preliminary observation shows that the pronounced fluctuations exist in the
interfacial layer. [1] K. Nagaoka, A. Okamoto, S. Yoshimura, M. Kono, and M. Y.
Tanaka, Phys. Rev. Lett. 89 (2002) 075001


title: Growth of ordered dusty structures in the glow discharge

abstract:
  In plasma of direct-current glow discharge the dependence of ordered dusty
structure volume, shape and density on plasma conditions were investigated. The
structure is formed in a field of volume charge. In experimental investigations
we used the aluminum oxide macroparticles with diameter up to 60 microns (size
distribution function was not determined). Discharge tube was established
vertically, has an internal diameter 2.6 cm and space gap between electrodes 45
cm. Particles were injected from the top end of the discharge tube into the
plasma of spectral purity neon. Repeatability of randomized experiment results
was better than 5% of the measured values. The areas of existence of various
dusty ordered structures and their dependence on physical conditions in plasma
(discharge current and pressure) were determined. When the interparticle
distance in the structure is constant and particle positions have good time
stability this structure was defined like "plasma crystal". Otherwise, we
observed process of the "dusty crystal" melting and in that case structure was
defined like "dusty liquid". Experimental data were obtained by using
computer-based measure system, which lets us to see, record and analyse images
of the macroparticle structure in "laser sheet" cross section. Experimental
investigations of dusty structure growth by consistent dosed injections of the
macroparticles into the glow discharge plasma are carried out. These
experiments with good statistical reliability showed that the mean
interparticle distance inside the structure is constant regardless of the
structure volume. Invariability of the structure volume during the process of
dusty crystal melting was established.


title: Control of fine particles by oscillating external forces in plasmas

abstract:
  A novel technique for the control of fine particle behavior is developed and
demonstrated experimentally. The technique is called a time-averaged particle
driving (TAPD) method. This method contains an application of positive pulses
to two point-electrodes placed facing each other with some distance in plasmas
with fine particles. When the positive pulses are applied alternatively with a
repetition period that is shorter than the particle response time, the
particles feel only time-averaged force because of the large mass and are
transported around the center between two point-electrodes. This method is
quite effective for converging fine particles in the plasma.


title: Quantum electrodynamical modes in pair plasmas

abstract:
  We predict the existence of new nonlinear electromagnetic wave modes in pair
plasmas. The plasma may be either non-magnetized or immersed in an external
magnetic field. The existence of these modes depends on the interaction of an
intense circularly polarized electromagnetic wave with a plasma, where the
nonlinear quantum vacuum effects are taken into account. This gives rise to new
couplings between matter and radiation. We focus on pair plasmas, since the new
modes are expected to exist in highly energetic environments, such as pulsar
magnetospheres and the next generation of laser--plasma systems.


title: Modeling the electromagnetic properties of the SCUBA-2 detectors

abstract:
  SCUBA-2 is the next-generation replacement for SCUBA (Sub-millimetre Common
User Bolometer Array) on the James Clerk Maxwell Telescope. Operating at 450
and 850 microns, SCUBA-2 fills the focal plane of the telescope with
fully-sampled, monolithic bolometer arrays. Each SCUBA-2 pixel uses a
quarter-wave slab of silicon with an implanted resistive layer and backshort as
an absorber and a superconducting transition edge sensor as a thermometer. In
order to verify and optimize the pixel design, we have investigated the
electromagnetic behaviour of the detectors, using both a simple
transmission-line model and Ansoft HFSS, a finite-element electromagnetic
simulator. We used the transmission line model to fit transmission measurements
of doped wafers and determined the correct implant dose for the absorbing
layer. The more detailed HFSS modelling yielded some unexpected results which
led us to modify the pixel design. We also verified that the detectors suffered
little loss of sensitivity for off-axis angles up to about 30 degrees.


title:
Current-Driven Dust Ion-Cyclotron Waves in Presence of a Transverse DC
  Electric Fields in Magnetized Plasma with Charge Fluctuations

abstract:
  The current-driven electrostatic ion-cyclotron (EIC) instability is studied
in presence of a transverse dc electric fields in a collisional magnetized
dusty plasma. We derive the appropriate charging equation self consistently by
using the Vlasov equation.


title:
Inhomogeneous Energy - Density Driven Instability in Presence of a
  Transverse DC Electric Fields in a Magnetized Plasma Cylinder

abstract:
  Temporal evolution of the inhomogeneous energy density driven instability
(IEDDI) is examined in presence of a nonuniform transverse dc electric field in
collisional magnetized plasma cylinder. Using experimentally known parameters
relevant to IEDDI, we have estimated the growth rate for $\nu$=1, 2 and 3
nonlocal eigenmodes.


title: Phase-Space Holes in an Electron-Beam-Plasma

abstract:
  It is shown in an electron-beam-plasma system that phase-space holes evolve
dynamically in electron time scales from appearance to collapse. The holes are
synchronized with a wave packet dominated by a beam mode, and their velocity
radii depend on the packet crest amplitudes. This suggests that the holes are
induced by a self-trapping phenomenon. It seems from the observed images that
the trapped-beam is hard to be detrapped while the packet grows linearly, but
easy to be done after that.


title: Anthropic Reasoning in Cosmology: A Historical Perspective

abstract:
  This paper explores the evolution of the so called "anthropic reasoning" in a
historical perspective. It takes under scrutiny the appearance of "anthropic"
considerations in various stages of modern cosmology, focusing also on some
very little known papers.


title:
Investigation of the specific plasma potential oscillations with
  geodesic acoustic mode frequencies by heavy ion beam probing

abstract:
  Investigation of the specific oscillations with frequencies 15-30 kHz on the
T-10 tokamak (R= 150cm, a = 30 cm) with Heavy Ion Beam Probe (HIBP) diagnostic
was conducted in regimes with off-axis ECRH (B = 2.33 T, Ip= 220 kA, r_ECRH=12
cm). Previous experiments in OH regimes have shown that "20 kHz" modes are
mainly the potential fluctuations. These oscillations are seen on the signals
of HIBP, Langmuir probes and reflectometry. They should cause the fluctuations
of the poloidal rotation, i.e. the torsional plasma oscillations with m=0,
called as the zonal flows. The HIBP sample volume was localized at r = 24 - 29
cm. It was observed that both in OH and ECRH regimes, the power spectrum of
potential oscillations has a form of solitary quasi-monochromatic peak with the
contrast range of 3-5. The frequency of "20 kHz" mode is varied in the region
of observation; it diminishes to the plasma edge from 20 kHz at 22-24 cm till
13-15 kHz at 28-29 cm. After ECRH switch-on, the frequency increases,
correlating with growth of the electron temperature Te, measured by 2-nd ECE
harmonic on the nearest chord 24 cm. Analysis have shown that frequency of the
"20 kHz" mode is varied with local T_e: f_20 ~ T_e**1/2 that is similar to a
theoretical scaling for Geodesic Acoustic Modes (GAM): f_GAM ~ c_s/R ~
T_e**1/2, where cs is a sound speed. The absolute frequencies are close to GAM
values within a factor of unity (1.12-1.5).


title:
Shift and broadening of sodium nS-3P and mD-3P transitions in high
  pressure NaCd and NaHg discharges

abstract:
  We report measurements of the Stark shifts and Stark widths of sodium
spectral lines corresponding to nS-3P and mD-3P transitions. Measurements have
been made on AC driven high pressure NaHg and NaCd discharges. Electron density
has been determined from the measurements of the Stark shift of sodium 7S-3P
spectral line. The electron temperature and the density of neutral particles
have been determined analyzing the shape of the measured sodium atomic lines,
comparing the calculated and the observed line profiles. Electron density and
temperature range from 6x1021 to 1x1022 m-3, and from 3800 to 4100 K
respectively. Dependeces of measured Stark shifts and Stark widths on electron
density and temperature hace been investigated. The final results have been
compared with available theoretical and experimental data.


title:
Modelling the mechanism of cell inactivation by light ions at different
  energy values

abstract:
  For efficient application of protons and light ions in radiotherapy, detailed
knowledge and realistic models of the corresponding radiobiological mechanism
are necessary. Basic characteristics of this mechanism have been represented
within a probabilistic two-stage model. The processes that occur immediately
after the traversals of individual particles and the response of cell to the
total damage formed by all the particles have been distinguished. The model
involves a probabilistic description of DNA damage formation and repair
processes, too.


title: Large Deviation Approach to the Randomly Forced Navier-Stokes Equation

abstract:
  The random forced Navier-Stokes equation can be obtained as a variational
problem of a proper action. By virtue of incompressibility, the integration
over transverse components of the fields allows to cast the action in the form
of a large deviation functional. Since the hydrodynamic operator is nonlinear,
the functional integral yielding the statistics of fluctuations can be
practically computed by linearizing around a physical solution of the
hydrodynamic equation. We show that this procedure yields the dimensional
scaling predicted by K41 theory at the lowest perturbative order, where the
perturbation parameter is the inverse Reynolds number. Moreover, an explicit
expression of the prefactor of the scaling law is obtained.


title: Orbits in a central force field: Bounded orbits

abstract:
  The nature of boundedness of orbits of a particle moving in a central force
field is investigated. General conditions for circular orbits and their
stability are discussed. In a bounded central field orbit, a particle moves
clockwise or anticlockwise, depending on its angular momentum, and at the same
time oscillates between a minimum and a maximum radial distance, defining an
inner and an outer annulus. There are generic orbits suggested in popular texts
displaying the general features of a central orbit. In this work it is
demonstrated that some of these orbits, seemingly possible at the first glance,
are not compatible with a central force field. For power law forces, the
general nature of boundedness and geometric shape of orbits are investigated.


title: Simple 8085 microprocessor compatible I/O card

abstract:
  A simple interfacing project with the 8085-microprocessor kits available in
under graduate college labs has been discussed. The interface card to study the
I-V characteristics of a p-n diode emphasizes how the microprocessor can be
used to do experiments in physics. Also, since the whole project was done
within Rs400/- it can easily be popularized.


title: Stabilization of vector solitons in optical lattices

abstract:
  We address the properties and dynamical stability of one-dimensional vector
lattice solitons in Kerr-type cubic medium with harmonic transverse modulation
of refractive index. We discovered that unstable families of scalar lattice
solitons can be stabilized via the cross-phase modulation (XPM) in the vector
case. It was found that multi-humped vector solitons that are unstable in
uniform media where XPM strength is higher than that of self-phase modulation,
can also be stabilized by the lattice.


title:
Analysis of the Drift Instability Growth Rates in Non-Ideal
  inhomogeneous Dusty Plasmas

abstract:
  In this paper we introduce an algebraic form of the dispersion relation for a
non ideal inhomogeneous dusty plasma in order to improve drastically the
calculation of the drift instability growth rate. This method makes use of the
multipole approximation of the Z dispersion function, previously published, and
valid for the entire range. A careful analysis of the solutions spectra of this
kind of polynomial equation permits us to calculate easily the growth rate of
the drift instability for the ion-dust and dust acoustic mode. The value of the
parallel to magnetic field wavelength for which the instability reaches the
maximal value is carefully localized and discussed. The unstable dust-ion and
dust acoustic mode are discriminated and analyzed in function of the density
gradient, Te/Ti - ratio, and dust grain radius.


title: Intermittent transport in edge plasmas

abstract:
  The properties of low-frequency convective fluctuations and transport are
investigated for the boundary region of magnetized plasmas. We employ a
two-dimensional fluid model for the evolution of the global plasma quantities
in a geometry and with parameters relevant to the scrape-off layer of confined
toroidal plasmas. Strongly intermittent plasma transport is regulated by
self-consistently generated sheared poloidal flows and is mediated by bursty
ejection of particles and heat from the bulk plasma in the form of blobs.
Coarse grained probe signals reveal a highly skewed and flat distribution on
short time scales, but tends towards a normal distribution at large time
scales. Conditionally averaged signals are in perfect agreement with
experimental measurements.


title: Drift ordered short mean free path closure

abstract:
  The complete short mean free path description of magnetized plasma in the
drift ordering has recently been derived. The results correct the previous
expressions for the ion pressure anisotropy (or parallel ion viscosity) and the
perpendicular ion viscosity - the ion gyro-viscosity is unchanged. In addition,
the electron problem is solved for the first time to obtain the electron
pressure anisotropy (parallel electron viscosity) and the electron
gyro-viscosity - the perpendicular electron viscosity is negligible. The
results have been used to obtain a reduced fluid description appropriate to the
edge of a tokamak. In addition, the complete description has been used to
evaluate the radial transport of toroidal angular momentum that determines the
radial electric field and flows in a tokamak.


title: The compact mirrors with high pressure plasmas

abstract:
  At present, the GDT facility of the Budker Institute Novosibirsk, which is an
axially symmetric magnetic mirror device of gas dynamic trap type, is being
upgraded. The first stage of the upgrade is the Synthesised Hot Ion Plasmoid
(SHIP) experiment. The experiments will be performed in a small mirror section
that is installed at one side of the GDT. The magnetic field on axis will be in
the range of 1-7 T and the mirror ratio will amount 1.2-1.4. The mirror is
filled with background plasma streaming in from the central cell. Two neutral
beam injectors perpendicularly inject a total current up to 120 equ. Amperes of
hydrogen atoms with an energy of 25 keV as pulse with a duration of about 1 ms.
Ionisation of the beams generates the high-energetic ion component with the
high density and mean energy about 17 keV. The plasma bata ~ 0.8. This
contribution explains the concept of the SHIP experiment and presents the
results of SHIP simulation. The first experimental activity is also presented.


title:
Stability of off-axis motion for intense particle beams in periodically
  focusing channels

abstract:
  A general equation for the centroid motion of free, continuous, intense beams
propagating off-axis in solenoidal periodic focusing fields is derived. The
centroid equation is found to be independent of the specific beam distribution
and may exhibit unstable solutions. A new Vlasov equilibrium for off-axis beam
propagation is also obtained. Properties of the equilibrium and the relevance
of centroid motion to beam confinement are discussed.


title:
Spatial homogeneity of optically switched semiconductor photonic
  crystals and of bulk semiconductors

abstract:
  This paper discusses free carrier generation by pulsed laser fields as a
mechanism to switch the optical properties of semiconductor photonic crystals
and bulk semiconductors on an ultrafast time scale. Requirements are set for
the switching magnitude, the time-scale, the induced absorption as well as the
spatial homogeneity, in particular for silicon at lambda= 1550 nm. Using a
nonlinear absorption model, we calculate carrier depth profiles and define a
homogeneity length l_hom. Homogeneity length contours are visualized in a plane
spanned by the linear and two-photon absorption coefficients. Such a
generalized homogeneity plot allows us to find optimum switching conditions at
pump frequencies near v/c= 5000 cm^{-1} (lambda= 2000 nm). We discuss the
effect of scattering in photonic crystals on the homogeneity. We experimentally
demonstrate a 10% refractive index switch in bulk silicon within 230 fs with a
lateral homogeneity of more than 30 micrometers. Our results are relevant for
switching of modulators in absence of photonic crystals.


title: Radiation-Hard Opto-Link for the Atlas Pixel Detector

abstract:
  The on-detector optical link of the ATLAS pixel detector contains
radiation-hard receiver chips to decode bi-phase marked signals received on PIN
arrays and data transmitter chips to drive VCSEL arrays. The components are
mounted on hybrid boards (opto-boards). We present results from the opto-boards
and from irradiation studies with 24 GeV protons up to 33 Mrad (1.2 x 10^15
p/cm^2).


title:
A numerical study of the alpha model for two-dimensional
  magnetohydrodynamic turbulent flows

abstract:
  We explore some consequences of the ``alpha model,'' also called the
``Lagrangian-averaged'' model, for two-dimensional incompressible
magnetohydrodynamic (MHD) turbulence. This model is an extension of the
smoothing procedure in fluid dynamics which filters velocity fields locally
while leaving their associated vorticities unsmoothed, and has proved useful
for high Reynolds number turbulence computations. We consider several known
effects (selective decay, dynamic alignment, inverse cascades, and the
probability distribution functions of fluctuating turbulent quantities) in
magnetofluid turbulence and compare the results of numerical solutions of the
primitive MHD equations with their alpha-model counterparts' performance for
the same flows, in regimes where available resolution is adequate to explore
both. The hope is to justify the use of the alpha model in regimes that lie
outside currently available resolution, as will be the case in particular in
three-dimensional geometry or for magnetic Prandtl numbers differing
significantly from unity. We focus our investigation, using direct numerical
simulations with a standard and fully parallelized pseudo-spectral method and
periodic boundary conditions in two space dimensions, on the role that such a
modeling of the small scales using the Lagrangian-averaged framework plays in
the large-scale dynamics of MHD turbulence. Several flows are examined, and for
all of them one can conclude that the statistical properties of the large-scale
spectra are recovered, whereas small-scale detailed phase information (such as
e.g. the location of structures) is lost.


title: The case of the trapped singularities

abstract:
  A case study in bifurcation and stability analysis is presented, in which
reduced dynamical system modelling yields substantial new global and predictive
information about the behaviour of a complex system. The first smooth pathway,
free of pathological and persistent degenerate singularities, is surveyed
through the parameter space of a nonlinear dynamical model for a
gradient-driven, turbulence-shear flow energetics in magnetized fusion plasmas.
Along the route various obstacles and features are identified and treated
appropriately. An organizing centre of low codimension is shown to be robust,
several trapped singularities are found and released, and domains of
hysteresis, threefold stable equilibria, and limit cycles are mapped.
Characterization of this rich dynamical landscape achieves unification of
previous disparate models for plasma confinement transitions, supplies valuable
intelligence on the big issue of shear flow suppression of turbulence, and
suggests targeted experimental design, control and optimization strategies.


title:
Extraction of coherent structures in a rotating turbulent flow
  experiment

abstract:
  The discrete wavelet packet transform (DWPT) and discrete wavelet transform
(DWT) are used to extract and study the dynamics of coherent structures in a
turbulent rotating fluid. Three-dimensional (3D) turbulence is generated by
strong pumping through tubes at the bottom of a rotating tank (48.4 cm high,
39.4 cm diameter). This flow evolves toward two-dimensional (2D) turbulence
with increasing height in the tank. Particle Image Velocimetry (PIV)
measurements on the quasi-2D flow reveal many long-lived coherent vortices with
a wide range of sizes. The vorticity fields exhibit vortex birth, merger,
scattering, and destruction. We separate the flow into a low-entropy
``coherent'' and a high-entropy ``incoherent'' component by thresholding the
coefficients of the DWPT and DWT of the vorticity fields. Similar thresholdings
using the Fourier transform and JPEG compression together with the Okubo-Weiss
criterion are also tested for comparison. We find that the DWPT and DWT yield
similar results and are much more efficient at representing the total flow than
a Fourier-based method. Only about 3% of the large-amplitude coefficients of
the DWPT and DWT are necessary to represent the coherent component and preserve
the vorticity probability density function, transport properties, and spatial
and temporal correlations. The remaining small amplitude coefficients represent
the incoherent component, which has near Gaussian vorticity PDF, contains no
coherent structures, rapidly loses correlation in time, and does not contribute
significantly to the transport properties of the flow. This suggests that one
can describe and simulate such turbulent flow using a relatively small number
of wavelet or wavelet packet modes.