title:
Study of plasma heating in ohmically and auxiliary heated regimes in
  spherical tokamak Globus-M

abstract:
  The ion temperature behavior in the plasma core of the spherical tokamak
Globus-M (major radius 0.36 m, minor radius 0.24 m, torus aspect ratio 1.5,
toroidal magnetic field near the plasma axis 0.4 T, plasma current up to 0.3
MA) was studied by means of 12-channels neutral particle analyzer (NPA)
ACORD-12. The experiments were performed in ohmic regimes as well as in regimes
with the ion cyclotron resonance heating (ICRH) in the vicinity of fundamental
harmonic for hydrogen minority in deuterium bulk plasma and the neutral beam
injection (NBI). The total auxiliary power exceeded the magnitude of 0.8-1 MW.
The NPA provided the simultaneous measurements of deuterium and hydrogen energy
spectra and the percentage of both isotopes. The ion temperature was studied in
a wide range of the plasma current 0.08-0.3 MA and the plasma average density
(1-7)x1019 m-3 at various values of the plasma vertical elongation and the
triangularity. The experimental data were compared with the results of
numerical simulation. We employed a simple 1D model describing the ion energy
balance by using the neoclassical transport coefficients. The charge-exchange
losses were also taken into account. The experimentally measured ion
temperature dependence on the plasma current and plasma density differed from
the Artsimovich scaling law predictions well describing the ion heating in the
case of the neoclassical plateau regime in the conventional tokamak even at a
relatively low temperature in ohmic plasma. In particular strong, almost linear
plasma current temperature dependence was revealed. It indicates a dominating
role of trapped particles in the ion energy balance at a low aspect ratio. The
estimates of energy confinement time values derived from the magnetic
measurements in ohmic and auxiliary heating regimes are also presented.


title: Symmetry Breaking in Induced-Charge Electrophoresis

abstract:
  The electrophoretic motion of a conducting particle, driven by an induced
charge mechanism, is analyzed. The dependence of the motion upon particle shape
is embodied in four tensorial coefficients that relate the particle velocities
to the externally-applied electric field. Several families of particle shapes,
whose members are unaffected by the applied field, are identified via use of
symmetry arguments. Other particles translate and/or rotate in response to the
imposed field, even if their net electric charge vanishes. The coefficients are
represented as surface integrals of the electric potential over the particle
boundary, thereby eliminating the need to solve the flow field.


title:
Plasma production by helicon waves with single mode number in low
  magnetic fields

abstract:
  Radio-frequency discharges are performed in low magnetic fields (0-10 mT)
using three types of helicon-wave exciting antennas with the azimuthal mode
number of $|m|$ = 1. The most pronounced peak of plasma density is generated in
the case of phased helical antenna at only a few mT, where the helicon wave
with $|m| = 1$ is purely excited and propagates. An analysis based on the
dispersion relation well explains the density-peak phenomenon in terms of the
correspondence between the antenna one-wavelength and the helicon wavelength.
The $m=+1$ helicon wave propagates even in high magnetic fields where the
density peaks are not observed, but the $m=-1$ helicon wave disappers. It is
expected theoretically that the $m=-1$ helicon wave shows cutoff behavior in a
low density region, [M. Kramer, Phys. Plasmas 6, 1052 (1999)], and the cutoff
of $m=-1$ helicon wave experimentally observed coincides with the calculated
one.


title: Transport barrier formation by LHCD on TRIAM-1M

abstract:
  Internal transport barrier (ITB) has been obtained in full lower hybrid
current driven (LHCD) plasmas on a superconducting tokamak, TRIMA-1M (R=0.84m,
a x b=0.12mx0.18m, BT<8T). The formation of ITB depends on the current density
profile, j(r), varied by the power deposition of the lower hybrid (LH). The
plasma with ITB can be maintained by the LH power deposited around the foot
point of ITB up to 25 sec, which corresponds to more than 100 times of current
diffusion time, $\tau$L/R. ITB is terminated by the reduction of current drive
efficiency caused by metal impurities accumulation. In some condition,
self-organized slow sawtooth oscillations (SSSO) of plasma current, density,
temperature, and so on with the period comparable to the current diffusion time
have been also observed during ITB discharge. The oscillation has the
capability of particle exhaust, as the result, it may play an role in the
avoidance of the impurity accumulation and the dilution in the future steady
state fusion plasma with ITB, as the edge-localized mode in H-mode.


title:
Polarization reversal of electron cyclotron wave due to radial boundary
  condition

abstract:
  Propagation and absorption of electromagnetic waves with electron cyclotron
resonance (ECR) frequency are experimentally and theoretically investigated for
the case of inhomogeneously magnetized plasma column with peripheral vacuum
layer, when a left-hand polarized wave (LHPW) is selectively launched. The
polarization reversal from the LHPW to the right-hand polarized wave is found
to occur near the ECR point. As a result, it is clarified that the LHPW, which
has been considered not to be absorbed at the ECR point, is absorbed near the
ECR point. The phenomena can be explained by taking into account the effects of
the radial boundary conditions. In addition, it is found that the polarization
reversal point can be adjusted by the external parameters, for example, plasma
radius.


title:
Fluctuation-phase relation between positive and negative ions on
  pair-plasma electrostatic waves

abstract:
  Three kinds of electrostatic modes are experimentally observed to propagate
along magnetic-field lines for the first time in the pair-ion plasma consisting
of only positive and negative fullerene ions with an equal mass. It is found
that phase lags between the density fluctuations of positive and negative ions
vary from 0 to $\pi$ depending on the frequency and is fixed at $\pi$ in the
cases of ion acoustic and ion plasma waves, respectively. In addition, a new
mode with the phase lag about $\pi$ appears in an intermediate-frequency band
between the acoustic and plasma waves.


title:
The penetration of plasma clouds across magnetic boundaries : the role
  of high frequency oscillations

abstract:
  Experiments are reported where a collisionfree plasma cloud penetrates a
magnetic barrier by self-polarization. We here focus on the resulting anomalous
magnetic field diffusion into the plasma cloud, two orders of magnitude faster
than classical, which is one important aspect of the plasma cloud penetration
mechanism. Without such fast magnetic diffusion, clouds with kinetic beta below
unity would not be able to penetrate magnetic barriers at all. Tailor-made
diagnostics has been used for measurements in the parameter range with the
kinetic beta ? 0.5 to 10, and with normalized width w/r(gi) of the order of
unity. Experimental data on hf fluctuations in density and in electric field
has been combined to yield the effective anomalous transverse resistivity
eta(EFF). It is concluded that they are both dominated by highly nonlinear
oscillations in the lower hybrid range, driven by a strong diamagnetic current
loop that is set up in the plasma in the penetration process. The anomalous
magnetic diffusion rate, calculated from the resistivity eta(EFF), is
consistent with single-shot multi-probe array measurements of the diamagnetic
cavity and the associated quasi-dc electric structure. An interpretation of the
instability measurements in terms of the resistive term in the generalized (low
frequency) Ohm's law is given.


title: A Note on the Lorentz Transformations for Photon

abstract:
  We discuss transormation laws of electric and magnetic fields under Lorentz
transformations, deduced from the Classical Field Theory. It is found that we
can connect the resulting expression for a bivector formed with those fields,
with the expression deduced from the Wigner transformation rules for spin-1
functions of massive particles. This mass parameter should be interpreted
because the constancy of speed of light forbids the existence of the photon
mass.


title: Plasma Diagnostic and Performance of a Permanent Magnet Hall Thruster

abstract:
  Electric propulsion is now a sucessfull method for primary propulsion of deep
space long duration missions and for geosyncronous satellite attitude control.
Closed Drift Plasma Thruster, so called Hall Thruster or SPT (stationary plasma
thruster) were primarily conceived in USSR (the ancient Soviet Union) and now
it is been developed by space agencies, space research institutes and
industries in several countries such as France, USA, Israel, Russian Federation
and Brazil. In this work, we show plasma characteristics and performance of a
Hall Thruster designed with an innovative concept which uses an array of
permanent magnets, instead of an eletromagnet, to produce a radial magnetic
field inside its cylindrical plasma drift channel. Within this new concept, we
expect to develop a Hall Thruster within power consuption that will scale up to
small and medium size satellites. A plasma density and temperature space
profiles inside and outside the thruster channel will be shown. Space plasma
potential, ion temperature measurements based on doppler broadenning of
spectral lines and ion energy measurements are shown for different plasma
production regimes. Experimentaly measured propulsion and power consumption
will also be shown and compared with computational simulation models using the
same plasma experimental conditions. In both cases the results are showing a
thrust range between 40mN to 80mN which is close to the thrust levels obtained
with a commercial SPT 100 using 30% less electrical power.


title: Conditions for plasmoid penetration across magnetic barriers

abstract:
  The penetration of plasma clouds, or plasmoids, across abrupt magnetic
barriers (of the scale less than a few ion gyro radii, using the plasmoid
directed velocity) is studied. The insight gained earlier, from experimental
and computer simulation investigations of a case study, is generalised into
other parameter regimes. It is concluded for what parameters a plasmoid should
be expected to penetrate the magnetic barrier through self-polarization,
penetrate through magnetic expulsion, or be rejected from the barrier. The
scaling parameters are n(e), v(0), B(perp), m(i), T(i), and the width w of the
plasmoid. The scaling is based on a model for strongly driven, nonlinear
magnetic field diffusion into a plasma, which is a generalization of the
laboratory findings. The results are applied to experiments earlier reported in
the literature, and also to the proposed application of impulsive penetration
of plasmoids from the solar wind into the Earth's magnetosphere.


title: Melting of 2D Coulomb clusters in dusty plasmas

abstract:
  The melting of 2D dust clusters caused by one additional particle in the
lower layer has experimentally been observed to undergo a two-step transition,
which divides the phase of the cluster into three stages. The first transition
is a jump of the dust kinetic energy due to the onset of an instability of the
lower-layer particle, shifting the cluster from an ordinary to a hot
crystalline state. The second transition is the actual phase transition into a
liquid state, which occurs at a decisively lower gas pressure. The detailed
dynamical properties of the system during the transition were determined in
terms of the normal mode analysis.


title:
Accelerated electron populations formed by Langmuir wave-caviton
  interactions

abstract:
  Direct numerical simulations of electron dynamics in externally driven
electrostatic waves have been carried out using a relativistic two-fluid
one-dimensional Vlasov-Poisson code. When the driver wave has sufficiently
large amplitude, ion density holes (cavitons) form. The interaction between
these cavitons and other incoming Langmuir waves gives rise to substantial
local acceleration of groups of electrons, and fine jet-like structures arise
in electron phase space. We show that these jets are caused by wave-breaking
when finite amplitude Langmuir waves experience the ion density gradient at the
leading edge of the holes, and are not caused by caviton burn-out. An
analytical two-fluid model gives the critical density gradient and caviton
depth for which this process can occur. In particular, the density gradient
critically affects the rate at which a Langmuir wave, moving into the caviton,
undergoes Landau damping. This treatment also enables us to derive analytical
estimates for the maximum energy of accelerated electrons, and for the energy
spectrum along a phase-space jet. These are confirmed by direct numerical
simulations.


title: Observation of the molecular assisted recombination in a hydrogen plasma

abstract:
  We have presented the experimental observation of the spatial structure of
Molecular Assisted Recombination (MAR) including both dissociative
recombination and mutual neutralization channels in the detached hydrogen
plasma in the linear divertor plasma simulator, TPD-SheetIV. It is shown from
the results of mass-analysis (H2+, H3+) that dissociative recombination is
dominant in the center of the plasma over a range of low gas pressures. At the
same time, it is observed that the mutual neutralization in MAR via H- ion
formation, which is produced by dissociative electron attachment to H2(v),
occurs in the periphery of the plasma where cold electrons (~1 eV) are found.


title:
Reconstruction of Zeff profiles at TEXTOR through Bayasian source
  separation

abstract:
  The understanding of the behaviour of impurities is a critical issue in
tokamak physics. The ion effective charge Zeff provides a measure for impurity
concentration. On the TEXTOR tokamak (Julich, Germany), we run a diagnostic to
determine Zeff from the bremsstrahlung emissivity E. From radial profiles of E,
electron density ne and temperature Te, profiles for Zeff can be reconstructed.
However, their interpretation is difficult outside the plasma centre, because
of various uncertainties in E, ne and Te at the edge, which render the radial
matching of the different profiles problematic. Conversely, if it were possible
to obtain a set of line-integrated values for Zeff directly from the
line-integrated measurements of E, ne and Te, then these problems would be
avoided. Now, recent advances in the field of statistical signal processing
allow the extraction of an unknown signal from a signal mixture. In particular,
we describe a procedure for the single-channel Bayesian source separation of a
line-integrated Zeff signal from a line-integrated emissivity source, using as
a forward model a linearized version of the known functional dependence of Zeff
on E, ne and Te. Here, a line-integral over a traditionally obtained Zeff
profile may serve as a prior for the line-integrated Zeff signal. In this way,
precise information on the electron density and temperature may even become
superfluous for the determination of Zeff.


title: Analytical model of fast ion behavior in current hole tokamak plasmas

abstract:
  A qualitative theoretical approach is proposed for the study of fast ion
behavior in tokamak plasmas with a current hole. For the equilibrium magnetic
configuration in a current hole tokamak we employ a simplified model based on
an analytical approximation of the poloidal flux function shape. For that the
radial extent of the plasma core area with zero rotational transform is used as
a characteristic parameter. The modification of the fast ion orbit topology, as
caused by the current hole, is studied. The model yields manageable analytical
expressions describing completely the current hole effect on the confinement
domains as well as on the boundaries separating the regions of different-type
orbits in the constants-of-motion space. Subject of investigation is the
current hole effect, both on the convective transport of fast ions induced by
their slowing down as well as on the diffusive transport caused by pitch angle
scattering. The influence of slowing down on the distribution functions of
energetic particles (charged fusion products, NBI ions) in current hole tokamak
plasmas is calculated and illustrated. The approach proposed is tested for a
specific JET current hole scenario and the results are compared with numerical
Fokker-Planck predictions.


title:
Upper-hybrid and electron-cyclotron waves in a laboratory magnetoplasma:
  weak spatial dispersion and parametric effects

abstract:
  Radiation of short-wavelength plasma waves is studied in a cold (Te=0.5eV),
large (1.2m length, 70 cm diameter), uniform, Maxwellian laboratory
magnetoplasma in the upper-hybrid frequency range. Although the characteristic
parameter of spatial dispersion b2=VTe2/c2 is very small (b2<10-6), dispersion
characteristics of the upper hybrid plasma waves is found to be strongly
modified by the thermal motion of plasma electrons. Indeed, the resonance
cone-like dispersion of UH plasma waves has been observed only if the parameter
range satisfies simultaneously two inequalities: wc<w<2wc, wp<w<wuh. In this
parameter range, the maximal refractive index in the resonant directions has
been found to be limited by nmax~15; new UH mode with its dispersion determined
by conical refraction has been found in the vicinity of the upper hybrid
resonance (w=wuh). Wave dispersion at w<2wc, wp<w<wuh does not correspond to
the cold plasma approximation and is determined by thermal plasma waves
propagating along the ambient magnetic field. Special attention is given to the
wave propagation characteristics in the vicinity of the electron cyclotron
resonance. An interesting effect of reduced electron cyclotron damping has been
observed when two electromagnetic waves (w1=wc, w2=wc+Dw) propagate
simultaneously with Dw approximately equal to the lower hybrid frequency. This
effect can be explained as a three-wave parametric process, analogous to the
effect of electromagnetically induced transparency in three-level atomic
system. Reduced electron cyclotron damping is extensively studied as a function
of the beat frequency and the amplitude of the pump wave. Possible applications
of the observed effect in plasma physics and electronics are discussed.


title:
Nonlinear saturation of magnetic curvature driven Rayleigh Taylor
  instability in three dimensions

abstract:
  We present three dimensional fluid simulation results on the temporal
evolution and nonlinear saturation of the magnetic curvature driven
Rayleigh-Taylor (RT) instability. The model set of coupled nonlinear equations
evolve the scalar electric field potential $\phi$, plasma density $n$ and the
parallel component of the magnetic vector potential $\psi$. The simulations
have been carried out in two limits, (i) a low resistivity case in which RT is
the only linearly growing mode, and (ii) a high resistivity case where the
drift wave is unstable and for which the magnetic curvature parameter is set to
zero to ensure the absence of the RT growth. Our simulations show nonlinear
stabilization in both these limits. The stabilization mechanism is similar to
that observed in earlier two dimensional simulations, namely the generation of
zonal shear flows which decorrelate the radially extended unstable modes.
However the nature of the saturated nonlinear state in the 3d case differs from
that of 2d in some important ways such as by having significant levels of power
in short scales and by the presence of electromagnetic fluctuations. Though, in
the linear regime the electromagnetic effects reduce the growth rates, in the
nonlinear regime their presence hinders the process of stabilization by
inhibiting the process of zonal flow formation. Thus the parameter regime for
which nonlinear stabilization takes place is considerably reduced in three
dimensions.


title: Kinetic effects in strong Langmuir turbulence

abstract:
  Kinetic effects with regard to a one dimensional Langmuir soliton-like pulse
are investigated. Though thus far mainly transit-time accelerations have been
investigated regarding strong Langmuir turbulence, it is found that
ponderomotive reflections (generalized nonlinear Landau damping) may play
important roles also. The former may diffuse fast electrons up to relativistic
energies, while the latter reflects slow electrons as well as ions that have
speeds comparable with the group velocity of the pulse, and tend to form
flat-top electron distributions at and around the quasi-soliton.


title:
Non-linear temperature oscillations in the plasma centre on Tore Supra
  and their interplay with MHD

abstract:
  Regular oscillations of the central electron temperature have been observed
by means of ECE and SXR diagnostics during non-inductively driven discharges on
Tore Supra. These oscillations are sustained by LHCD, do not have a helical
structure and, therefore, cannot be ascribed as MHD phenomena. The most
probable explanation of this oscillating regime (O-regime) is the assumption
that the plasma current density (and, thus, the q-profile) and the electron
temperature evolve as a non-linearly coupled predator-pray system. The
integrated modelling code CRONOS has been used to demonstrate that the coupled
heat transport and resistive diffusion equations admit solutions for the
electron temperature and the current density which have a cyclic behaviour.
Recent experimental results in which the O-regime co-exists with MHD modes will
be presented. Because both phenomena are linked to details of the q-profile,
some interplay between MHD and oscillations may occur. The localisation of
magnetic islands allows to obtain an accurate picture of the q-profile in the
plasma core. In some case, MHD-driven reconnection helps in maintaining a
weakly inverted q-profile that is found to be, in the CRONOS simulations, a
necessary condition to trigger the oscillations.


title: MHD stability of fully non inductive discharges in Tore Supra

abstract:
  During the 2003 experimental campaign, the aim of realizing reliable fully
non inductive discharges has been successfully completed in Tore Supra. One the
major difficulties in optimizing this scenario comes from MHD stability issues.
Indeed, the current profile obtained with LH antennas in these experiments is
prone to the triggering of single or double tearing modes. Under certain
conditions, the discharges enters in a regime of permanent MHD activity. The
present work investigates the MHD properties of these fully non-inductive
discharges in the operational space defined by the toroidal magnetic field B,
the total plasma current Ip, and the mean parallel index of LH waves . Linear
MHD stability properties divide the operational space in regions separated by
rational values of the minimum of the safety factor. We discuss in our work the
localisation of the transition between benign MHD activity and the MHD regime.


title:
Propagation of finite amplitude electrostatic disturbances in an
  inhomogeneous magnetized plasma

abstract:
  A 1D2V open boundary Vlasov-Ampere code has been implemented with the aim of
making a detailed investigation of the propagation of finite amplitude
electromagnetic disturbances in an inhomogeneous magnetized plasma. The code is
being applied to study the propagation of an externally driven electromagnetic
signal, localized at one boundary of the integration interval, through a given
equilibrium plasma configuration with inhomogeneous plasma density and magnetic
field.


title:
Electrostatic ion-cyclotron instabilities modified by the parallel and
  perpendicular plasma flow velocity shears

abstract:
  The external and independent control of plasma flow velocity shears parallel
and perpendicular to magnetic field lines is realized using segmented
collisionless-plasma sources. Electrostatic ion-cyclotron instabilities are
observed to be suppressed by the perpendicular flow velocity shears, the
suppression physics of which is found to be distinguished into two aspects. On
the other hand, the parallel flow velocity shears are demonstrated to
destabilize the ion-cyclotron instabilities depending on the sign of the
parallel shear in the absence of field-aligned electron drift flow.


title: Te/Ti effects on JET energy confinement properties

abstract:
  Lately the question has been raised if a modification of the
energy-confinement scaling law with respect to the electron to ion temperature
ratio, Te/Ti, is required. Theoretically, like in e.g. the Weiland model, the
confinement is thought to degrade with Te/Ti and studies of the hot-ion
(Ti>/Te) mode seems to corroborate this. In this paper, it is shown that due to
a number of effects that cancel each other out, the energy confinement time
remains constant for Te/Ti>~1. The numerical study relies on a series of JET
shots specifically designed to reveal an effect of Te/Ti in the hot-electron
(Te>Ti) mode. A distinct effort was made to keep all current scaling-law
parameters constant, including the total heating power. The effects that
provide the constant confinement times have therefore nothing to do with the
global properties of the plasma, but are rather due to variations in the
temperature gradients which affects the transport locally.


title:
Integrated Fast Ignition Simulation of Cone-guided Targetwith Three
  Codes

abstract:
  It was reported that the fuel core was heated up to ~ 0.8 [keV] in the fast
ignition experimentswith cone-guided targets, but they could not theoretically
explain heating mechanisms and achievement of such high temperature. Thus
simulations should play an important role in estimating the schemeperformance,
and we must simulate each phenomenon with individual codes and integrate them
under the Fast Ignition Integrated Interconnecting code project. In the
previous integrated simulations, fast electronsgenerated by the laser-plasma
interaction were too hot to efficiently heat the core and we got only 0.096
[keV] temperature rise. Including the density gap at the contact surface
between the cone tip and theimploded plasma, the period of core heating became
longer and the core was heated by 0.162 [keV], ~69% higher increment compared
with ignoring the density gap effect.


title:
Reconstruction of the magnetic perturbation in a toroidal force-free
  circular plasma: application to the Reversed Field Pinch

abstract:
  A new method to obtain the radial profile of the magnetic perturbation in a
toroidal force-free plasma having circular cross section is developed. The
method is quite general and can be applied to any circular low-beta plasma once
suitable boundary conditions are imposed. In particular, due to its
characteristics, it is appropriate for describing the Reversed Field Pinch
(RFP) configuration. The curvilinear metric of the toroidal geometry is
described by adopting flux co-ordinates, and the magnetic field is expressed by
the contravariant representation with two independent potentials. The method
leads to a system of Newcomb-like equations in the two independent potentials
for modes with the same toroidal n-number and poloidal mode number m coupled by
toroidicity. The advantage of this description is that the potentials together
with the metric coefficients can be related in a straightforward manner to the
magnetic field. Moreover it is formally simple and maintains a similarity with
the cylindrical treatment. Indeed it is customary in RFPs to approach the
analysis of MHD instabilities by using cylindrical geometry. Nonetheless the
effect of a more realistic toroidal geometry can play an important role, and
indeed by applying the method to the Reversed Field eXperiment (RFX) plasma we
found that the toroidal effects on the magnetic perturbations are not
negligible.


title:
Measurement of electron sheath thickness and collection region of
  electric probe using laser photodetachment signals

abstract:
  A new type of laser photodetachment (LPD) technique has been developed for
the measurement of electron sheath thickness around an electrostatic probe and
for the measurement of the length of collection region of photodetached
electrons (PDE). When a thickness of the sheath formed around an electrostatic
probe is thicker than about 0.1 mm, modification of the temporal evolution of
the LPD signal is observed. By making use of the modification, we evaluated
sheath thickness around a cylindrical probe in the existence of the magnetic
field of 15 mT. It was found that the thickness of electron sheath along the
magnetic field was comparable to the calculated plane-parallel Child-Langmuir
sheath thickness when the probe-bias voltage was high. Furthermore, by
inserting a small screening object in the laser beam channel, we can measure
the sheath thickness from the modification of LPD signal. From the variation of
the signal intensity as scanning the screening object perpendicular to the
laser beam channel, we can observe the collection region of photodetached
electrons, because this procedure changes the relative displacement between
shadow and the probe electrode.


title:
Impact of dissipative effects on the macroscopic evolution of a Vlasov
  system

abstract:
  Numerical diffusion is introduced by any numerical scheme as soon as small
scales fluctuations, generated during the dynamical evolution of a
collisionless plasma, become comparable to the grid size. Here we investigate
the role of numerical dissipation in collisionless plasma simulations by
studying the non linear regime of the two stream instability. We show that the
long time evolution of the Vlasov - Poisson system can be affected by the used
algorithm.


title:
First Measurements of Electron Temperature Fluctuations by Correlation
  ECE on Tore Supra

abstract:
  Electron temperature fluctuation studies can help to understand the nature of
the turbulent transport in to-kamak plasmas. At Tore Supra, a 32-channel
heterodyne ECE radiometer has been upgraded with two chan-nels of 100 MHz
bandwidth and tunable central frequencies allowing the shift of the plasma
sample volume in the radial direction. With the sufficiently large video
bandwidth and the long sampling time, it is possible to reduce significantly
the thermal noise and to identify "true" high frequency components up to 200
kHz from the cross-correlation between these channels. First results of
temperature fluctuation measurements on Tore Supra are reported in this paper.


title:
Threshold of parametric decay instability accompanying electron
  Bernstein wave heating in spherical tokamaks

abstract:
  The parametric instability of upper hybrid wave decay into back scattered
upper hybrid wave and lower hybrid wave is considered for conditions of
inhomogeneous plasma of spherical tokamaks. The possibility of absolute
instability is demonstrated and the corresponding threshold is determined. It
is shown that the threshold power increases with pump frequency and electron
temperature. Threshold power is estimated for typical parameters of experiment
in MAST tokamak. It is shown that in this case parametrical reflection arises,
if probing power exceeds 90W/cm^2, which gives 30 kW for a beam of 10 cm
radius.


title: Three-dimensional PIC simulation of electron plasmas

abstract:
  The three-dimensional evolution of a pure electron plasma is studied by means
of a particle-in-cell code which solves the drift-Poisson system where kinetic
effects in the motion parallel to the magnetic field are taken into account.
Different results relevant to the nonlinear dynamics of trapped plasmas and
low-energy electron beams are presented.


title:
Coherent control of optical four-wave mixing by two-color
  $\omega$-$3\omega$ ultrashort laser pulses

abstract:
  A theoretical investigation on the quantum control of optical coherent
four-wave mixing interactions in two-level systems driven by two intense
synchronized femtosecond laser pulses of central angular frequencies $\omega$
and $3\omega$ is reported. By numerically solving the full Maxwell-Bloch
equations beyond the slowly-varying envelope and rotating-wave approximations
in the time domain, the nonlinear coupling to the optical field at frequency
$5\omega$ is found to depend critically on the initial relative phase $\phi$ of
the two propagating pulses; the coupling is enhanced when the pulses interfere
constructively in the center ($\phi=0$), while it is nearly suppressed when
they are out of phase ($\phi=\pi$). The tuning of the initial absolute phase of
the different frequency components of synchronously propapagating
$\omega$-$3\omega$ femtosecond pulses can serve as a means to control coherent
anti-Stokes Raman scattering (CARS) processes.


title: Stochastic acceleration in strong random fields

abstract:
  Diffusion of particles in velocity space undergoing turbulent field was
extensively studied in the problem of warm beam relaxation. Under low field
intensities the diffusion is described by the Fokker-Planck equation with the
diffusion coefficient given by quasilinear theory. This diffusion coefficient
is calculated on the free particle propagator and for weak fields its
renormalization due to orbit diffusion is not necessary. To study effects which
should be taken into account when the intensity of the turbulent field is
increased a numerical simulation of particle motion in the external field of
Langmuir waves with given k-spectrum and random phases is done. For strong
fields meansquare velocity evolution shows that ballistic regime in the very
beginning is changed for oscillatory one in the intermediate stage and later
for diffusion. Asymptotically it behaves like fractional power of elapsed time
with the exponent dependent on the particular field spectrum. Such evolution in
the whole temporal interval of simulation is recovered from the numerical
solution of generalized Fokker-Planck equation with time dependent diffusion
coefficient obtained from the microscopic approach. The analytical
approximation for this solution is also given.


title: Electromagnetic radiation from double layers

abstract:
  The background motivation, and some preliminary results, are reported for a
recently begun investigation of a potentially important mechanism for
electromagnetic radiation from space, Double Layer Radiation (DL-radiation).
This type of radiation is proposed to come from DL-associated, spatially
localized high frequency (hf) spikes that are driven by the electron beam on
the high-potential side of the double layer. It is known, but only
qualitatively, from laboratory experiments that double layers radiate in the
electromagnetic spectrum. In our experiment the spectrum has high amplitude
close to the plasma frequency, several hundred MHz. No clear theoretical model
exists today. The quantitative evaluation is complicated because measurements
are made in the near field of the radiating structure, and in the vicinity of
conducting laboratory hardware that distorts the field. Because the localized
electrostatic wavelengths (approximately 1 cm) can be relatively small compared
to the emitted electromagnetic wavelengths, the situation is further
complicated. We discuss the mutual influence between the ion density profile
and hf-spike formation, and propose that some kind of self-organization of the
density profile through the ponderomotive force of the hf spike might be
operating. First results regarding the electromagnetic radiation are reported:
the frequency, the time variation of the amplitude, and the spatial
distribution in the discharge vessel.


title:
Observation of self-organized criticality (SOC) behavior during edge
  biasing experiment on TEXTOR

abstract:
  The self-organized criticality (SOC) behavior of the edge plasma transport
has been investigated using the fluctuation data measured in the plasma edge
and the scrape-off layer of TEXTOR tokamak before and during the edge electrode
biasing experiments. In the "nonshear" discharge phase before biasing, both the
potential and density fluctuations clearly exhibit some of the characteristics
associated with SOC: (1) existence of f -1 power-law dependence in the
frequency spectrum, (2) slowly decaying long tails in the autocorrelation
function, (3) values of Hurst parameters larger than 0.5 at all the detected
radial locations, (4) non-Gaussian PDF of fluctuations and (5) radial
propagation of avalanche-like events in the edge plasma area. During the
biasing phase, with the generation of an edge radial electric field Er and
hence a sheared ErxB flow, the local turbulence is found to be well
decorrelated by the ErxB velocity shear, consistent with theoretical
predictions. Nevertheless, it is concomitantly found that the Hurst parameters
are substantially enhanced in the negative flow shear region and in the
scrape-off layer as well, which is contrary to theoretical expectation.
Implication of these observations to our understanding of plasma transport
mechanisms is discussed.


title:
Control of the chaotic state caused by the curent-driven ion acoustic
  instabilit and dynamical behavior using delayed feedback

abstract:
  Controlling chaos caused by the current-driven ion acoustic instability is
attempted using the delayed continuous feedback method, i.e., the time-delay
auto synchronization (TDAS) method introduced by Pyragas [Phys. Lett. A 170
(1992) 421.]. When the control is applied to the typical chaotic state, chaotic
orbit changes to periodic one, maintaining the instability. The chaotic state
is well controlled using the TDAS method. It is found that the control is
achieved when a delay time is chosen near the unstable periodic orbit
corresponding to the fundamental mode. Furthermore, when the delayed feedback
is applied to a periodic nonlinear regime and arbitrary time delay is chosen,
the periodic state is leaded to various motions including chaos. As a related
topic, the synchronization between two instabilities of autonomous discharge
tubes in a glow discharge is studied. Two tubes are settled independently and
interacting each other through the coupler consisted of variable resister and
capacitor. When the value of resister is changed as the strength of coupling,
coupled system shows a state such as chaos synchronization.


title: Surprising Symmetries in Relativistic Charge Dynamics

abstract:
  The eigenspinor approach uses the classical amplitude of the algebraic
Lorentz rotation connecting the lab and rest frames to study the relativistic
motion of particles. It suggests a simple covariant extension of the common
definition of the electric field: the electromagnetic field can be defined as
the proper spacetime rotation rate it induces in the particle frame times its
mass-to-charge ratio. When applied to the dynamics of a point charge in an
external electromagnetic field, the eigenspinor approach reveals surprising
symmetries, particularly the invariance of some field properties in the rest
frame of the accelerating charge. The symmetries facilitate the discovery of
analytic solutions of the charge motion and are simply explained in terms of
the geometry of spacetime. Symmetries of the uniformly accelerated charge and
electric dipole are also briefly discussed.


title: Minimal Gravitomagnetism

abstract:
  We show that Feynman's proof applies to Newtonian gravitation, implying thus
the existence of gravitational analogous of the electric and magnetic fields
and the corresponding Lorentz-like force. Consistency of the formalism require
particular properties of the electric and magnetic-like fields under Galilei
transformations, which coincide with those obtained in previous analysis of
Galilean electromagnetism.


title:
Development of compact gas treatment system using secondary emission
  electron gun

abstract:
  It is well known that the non-thermal plasma processes using electrical
discharge or electron beam are effective for the environmental pollutant
removal. Especially, the electron beam can efficiently remove pollutant,
because a lot of radicals which are useful to remove pollutant can be easily
produced by high-energy electrons. We have developed a compact 100kV secondary
emission electron gun to apply NOX removal. The device offers several inherent
advantages such as compact in size, wide and uniform electron beam. Besides,
the device offers good capability in high repetition rate pulsed operation with
easy control compared with glow discharge or field emission control cathode
guns. In present study, the NOX removal characteristics have been studied under
the increased gun voltage, varied pulsed electron beam parameters such as
current density and pulse width as well as gas flow rate. The experimental
results indicate a better NOX removal efficiency comparing to other high-energy
electron beam and electrical discharge processing.


title: Neutrinos and the Weak Interactions

abstract:
  We show that neutrinos and electrons share the same theoretical structure,
and satisfy parallel relations particularly of the Large Number kind. We then
argue that the neutrino can be described as a ``cold'' electron in a sense that
is detailed, and thereby the weak interactions are indeed a weak form of
electromagnetism.


title:
Particle-in-cell simulations of high energy electron production by
  intense laser pulses in underdense plasmas

abstract:
  The propagation of intense laser pulses and the generation of high energy
electrons from the underdense plasmas are investigated using two dimensional
particle-in-cell simulations. When the ratio of the laser power and a critical
power of relativistic self-focusing is the optimal value, it propagates stably
and electrons have maximum energies.


title:
Control of fluctuations in ECR plasma by applying multipole magnetic
  fields

abstract:
  The control of fluctuations generated in an electron cyclotron resonance
(ECR) plasma is attempted by changing microwave powers. It is found that when a
cage is introduced in the vacuum chamber, the fluctuations change from
turbulent state to chaotic state in the high microwave power region while it
changes from chaotic state to periodic state in the low microwave power region.
This result suggests that the geometry of the cage affects the state of the
instability. Moreover it is found that the superposition of multicusped fields
created by small permanent magnets reduces the chaotic dimension of the
instability. When pulsed multipole magnetic fields are also added to external
magnetic fields, the fluctuations are suppressed.


title:
Disperson relation of finite amplitude Alfven wave in a relativistic
  electron- positron plasma

abstract:
  The linear dispersion relation of a finite amplitude, parallel, circularly
polarized Alfv\'en wave in a relativistic electron-positron plasma is derived.
In the nonrelativistic regime, the dispersion relation has two branches, one
electromagnetic wave, with a low frequency cutoff at
$\sqrt{1+2\omega_p^2/\Omega_p^2}$ (where $\omega_p=(4\pi n e^2/m)^{1/2}$ is the
electron/positron plasma frequency), and an Alfv\'en wave, with high frequency
cutoff at the positron gyrofrequency $\Omega_p$. There is only one forward
propagating mode for a given frequency. However, due to relativistic effects,
there is no low frequency cutoff for the electromagnetic branch, and there
appears a critical wave number above which the Alfv\'en wave ceases to exist.
This critical wave number is given by $ck_c/\Omega_p=a/\eta$, where
$a=\omega_p^2/\Omega_p^2$ and $\eta$ is the ratio between the Alfv\'en wave
magnetic field amplitude and the background magnetic field. In this case, for
each frequency in the Alfv\'en branch, two additional forward propagating modes
exist with equal frequency. A simple numerical example is studied: by
numerically solving the coupled system of fluid and Maxwell equations, normal
incidence of a finite amplitude Alfv\'en wave on an interface between two
electron-positron plasmas of different densities is considered.


title: Longitudinal oscillations in a nonextensive relativistic plasma

abstract:
  The dispersion relation of longitudinal electrostatic oscillations in a
relativistic plasma is studied in the context of the nonextensive statistics
formalism proposed by Tsallis [C. Tsallis, J. Stat. Phys. {\bf 52}, 479
(1988)], where nonextensivity is characterized by a parameter $q$ in Tsallis's
entropy. $q=1$ corresponds to the usual Boltzmann-Gibbs, extensive statistics
formalism. In the nonrelativistic regime, normalizability of the equilibrium
distribution function implies that $-1\leq q\leq\infty$. We show that in the
relativistic regime much tighter constraints must be satisfied, namely $0\leq q
\leq 1+ k_B T/mc^2$, where $k_B$ is the Boltzmann constant, $T$ is the
temperature of the plasma, and $m$ is the particle mass. Then we study
longitudinal oscillations in a proton-electron plasma, assuming immobile
protons, and electrons whose distribution function maximizes Tsallis's entropy.
The dispersion relation of these oscillations is written in integral form for
the long wavelength limit. Explicit expressions in terms of generalized
hypergeometric functions can be found for all possibles values of $q$ in the
ultra-relativistic regime.


title:
Development of supersonic plasma flows by use of a magnetic nozzle and
  an ICRF heating

abstract:
  A high-beta, supersonic plasma flow plays a crucial role in MHD phenomena in
space and fusion plasmas. There are a few experimental researches on production
and control of a fast flowing plasma in spite of a growing significance in the
magnetized-plasma flow dynamics. A magneto-plasma-dynamic arcjet (MPDA) is one
of promising devices to produce a supersonic plasma flow and has been utilized
as an electric propulsion device with a higher specific impulse and a
relatively larger thrust. We have improved the performance of an MPDA to
produce a quasi-steady plasma flow with a transonic and supersonic Mach number
in a highly-ionized state. There are two methods in order to control an
ion-acoustic Mach number of the plasma flow exhausted from an MPDA: one is to
use a magnetic Laval nozzle to convert a thermal energy to a flow energy and
the other is a combined system of an ion heating and a divergent magnetic
nozzle. The former is an analogous method to a compressible air flow and the
latter is the method proposed in an advanced thruster for a manned
interplanetary space mission. We have clarified the plasma flow characteristics
in various shapes of a magnetic field configuration. It was demonstrated that
the Mach number of the plasma flow could increase up to almost 3 in a divergent
magnetic nozzle field. This paper reports recent results on the flow field
improvements: one is on a magnetic-Laval-nozzle effects observed at the muzzle
region of the MPDA, and the other is on ICRF (ion-cyclotron-range of frequency)
heating of a supersonic plasma by use of a helical antenna.


title: Multi-scale magnetic field intermittence in the plasma sheet

abstract:
  This paper demonstrates that intermittent magnetic field fluctuations in the
plasma sheet exhibit transitory, localized, and multi-scale features. We
propose a multifractal based algorithm, which quantifies intermittence on the
basis of the statistical distribution of the 'strength of burstiness',
estimated within a sliding window. Interesting multi-scale phenomena observed
by the Cluster spacecraft include large scale motion of the current sheet and
bursty bulk flow associated turbulence, interpreted as a cross-scale coupling
(CSC) process.


title:
Potential of a moving test charge in a dusty plasma in the presence of
  grain size distribution and grain charging dynamics

abstract:
  It is well known that the form of grain size distribution strongly influences
the linear dielectric response of a dusty plasma. In previous results [IEEE
Trans. Plasma Sci. 29, 182 (2001)], it was shown that for a class of size
distributions, there is an equivalence to a Lorentzian distribution of
mono-sized particles. The electrostatic response to a slowly moving test
charge, using a second order approximation can then be found [Phys. Lett. A
305, 79 (2002)]. It is also well known [Phys. Plasmas 10, 3484 (2003)] that the
dynamical charging of grains in a dusty plasma enhances the shielding of a test
charge. It seems natural at this stage to seek the combined effects of grain
size distribution and grain charging dynamics to a test charge moving through
the dusty plasma. Here we consider the effects of both grain size distribution
and dynamical grain charging to a test charge moving slowly in a dusty plasma
by expressing the plasma dielectric response as a function of both grain size
distribution and grain charging dynamics. Both analytical as well as the
numerical results are presented. It is interesting to note that the previous
results can be retrieved by choosing appropriate values for different
parameters. This kind of study is relevant for both laboratory and space
plasmas.


title:
Formation of convective cells in the scrape-off layer of the CASTOR
  tokamak

abstract:
  Understanding of the scrape-off layer (SOL) physics in tokamaks requires
diagnostics with sufficient temporal and spatial resolution. This contribution
describes results of experiments performed in the SOL of the CASTOR tokamak
(R=40 cm, a = 6 cm) by means of a ring of 124 Langmuir probes surrounding the
whole poloidal cross section. The individual probes measure either the ion
saturation current of the floating potential with the spatial resolution up to
3 mm. Experiments are performed in a particular magnetic configuration,
characterized by a long parallel connection length in the SOL, L_par ~q2piR. We
report on measurements in discharges, where the edge electric field is modified
by inserting a biased electrode into the edge plasma. In particular, a complex
picture is observed, if the biased electrode is located inside the SOL. The
poloidal distribution of the floating potential appears to be strongly
non-uniform at biasing. The peaks of potential are observed at particular
poloidal angles. This is interpreted as formation of a biased flux tube, which
emanates from the electrode along the magnetic field lines and snakes q times
around the torus. The resulting electric field in the SOL is 2-dimensional,
having the radial as well as the poloidal component. It is demonstrated that
the poloidal electric field E_pol convects the edge plasma radially due to the
E_pol x B_T drift either inward or outward depending on its sign. The
convective particle flux is by two orders of magnitude larger than the
fluctuation-induced one and consequently dominates.


title: Moving weakly relativistic electromagnetic solitons in laser-plasmas

abstract:
  A case of moving one-dimensional electromagnetic (EM) solitons formed in a
relativistic interaction of a linearly polarized laser light with underdense
cold plasma is investigated. The relativistic Lorentz force in an intense laser
light pushes electrons into longitudinal motion generating coupled
longitudal-transverse wave modes. In a weakly relativistic approximation these
modes are well described by a dynamical equation of the generalized nonlinear
Schrodinger type, with two additional nonlocal terms [1]. An original
analytical solution for a moving EM soliton case is here calculated in an
implicit form. The soliton motion down-shifts the soliton eigen-frequency while
decreases its amplitude. An influence of the soliton velocity on stability
properties is analytically predicted.


title:
Multi-ion-species effects on magnetosonic waves and energy transfer in
  thermal equilibrium plasmas

abstract:
  Magnetosonic waves propagating perpendicular to an external magnetic field
are studied with attention to the effect of multiple ion species. First, power
spectra of magnetic field fluctuations and autocorrelation functions in thermal
equilibrium plasmas are numerically obtained. In a multi-ion-species plasma,
besides $\omega \simeq kv_{\rm A}$ mode, numerous waves are present near many
different ion cyclotron frequencies. The autocorrelation function of the
quasi-mode consisting of these waves is not recovered to its initial value,
owing to the phase mixing of these waves. Next, with particle simulations,
evolution of a macroscopic perpendicular disturbance is investigated. In a
multi-ion-species plasma, this disturbance is damped. The energy is transferred
to from the magnetic field to the ions.


title:
Similarities between the generation and dynamics of concentric and non-
  concentric multiple double layers

abstract:
  We report new experimental results on the generation and dynamics of multiple
double layers in front of a positively biased electrode immersed in a
DP-machine plasma. Depending on the geometry or the dimensions of the
electrode, this complex space charge configuration can appear in two different
modes. If the electrode is small with respect to the plasma size, the
phenomenon appears as a set of concentric luminous shells with different
intensities. If the electrode has large dimensions, or a one-dimensional
geometry, the spherical double layers appear adjacent to each other, as equally
separated luminous plasma blobs. Our experimental investigations prove that in
both of cases we deal with almost the same phenomenon. The same elementary
processes, namely electron-neutral impact excitations and ionizations, play the
key role in the generation and dynamics of each structure. This is emphasized
in the static current-voltage characteristic of the electrode, which shows
similar jumps of the current, associated with hysteresis.


title: Plasma turbulence measured by fast sweep reflectometry on TORE SUPRA

abstract:
  Traditionally devoted to electron density profile measurement we show that
fast frequency sweeping reflectometry technique can bring valuable and
innovative measurements onto plasma turbulence. While fast frequency sweeping
technique is traditionally devoted to electron density radial profile
measurements we show in this paper how we can handle the fluctuations of the
reflected signal to recover plasma density fluctuation measurements with a high
spatial and temporal resolution. Large size turbulence related to
magneto-hydrodynamic (MHD) activity and the associated magnetic islands can be
detected. The radial profile of the micro-turbulence, which is responsible for
plasma anomalous transport processes, is experimentally determined through the
fluctuation of the reflected phase signal.


title:
A comparative analysis of the EEDF obtained by regularization methods
  and by a least-squares fitting

abstract:
  To establish the electron energy distribution function (EEDF), the second
derivative of a Langmuir probe current-voltage (I-V) characteristic is
numerically integrated using the Tikhonov singular value decomposition
regularized method. A comparison of the numerically intagrated EDDF and by a
least-squares fitting is discussed. The used I-V haracteristic is measured in
an ECR plasma source using a cylindrical probe and the plasma parameters are
determined by the Laframboise theory. This technique allows a rapid analysis of
plasma parameters at any gas pressure. The obtained EEDF, for the case of the
ECR plasma source, shows the existence of two groups of electrons with
different temperatures. This result is associated with the collisional
mechanism heating taking place in ECR plasma sources, where low pressure plasma
is sustained by electron impact ionization of the ground state molecules or
atoms by energetic electrons arising in the resonance zone.


title:
The Electric Discharge in Superhigh Density Gas at Current Amplitude up
  to 5x10^5 A

abstract:
  The investigations of powerful discharge in high density hydrogen were
carried out on an installation with preliminary adiabatic compression. The
experiments were performed under the following conditions: stored energy of the
capacitive storage - 140-450 kJ, charging voltage - 8.0-14.0 kV, discharge
current amplitude- 200-600 kA, current rise rate - 10^9-10^10 A/s. The maximum
particle density nmax, achieved just before the discharge, was about 2.0x10^22
cm-3. It was observed one or several compression of the discharge channel. The
moments of contractions corresponds a increase of voltage on discharge gap and
feature on a curve of a current. Arc parameters were calculated on the basis of
the channel model. It was established that increase of the initial density of
particles at increase of a current rate of rise results in reduction of arc
diameter with increase of channel temperature.


title: Electron cyclotron current drive efficiency in an axisymmetric tokamak

abstract:
  The neoclassical transport theory is applied to calculate electron cyclotron
current drive (ECCD) efficiency in an axisymmetric tokamak in the
low-collisionality regime. The tokamak ordering is used to obtain a system of
equations that describe the dynamics of the plasma where the nonlinear
ponderomotive (PM) force due to high-power RF waves is included. The PM force
is produced around an electron cyclotron resonant surface at a specific
poloidal location. The ECCD efficiency is analyzed in the cases of first and
second harmonics (for different impinging angles of the RF waves) and it is
validated using experimental parameter values from TCV and T-10 tokamaks. The
results are in agreement with those obtained by means of Green's function
techniques.


title: Turbulent particle transport in magnetized fusion plasma

abstract:
  The understanding of the mechanisms responsible for particle transport is of
the utmost importance for magnetized fusion plasmas. A peaked density profile
is attractive to improve the fusion rate, which is proportional to the square
of the density, and to self-generate a large fraction of non-inductive current
required for continuous operation. Experiments in various tokamak devices (AUG,
DIII-D, JET, TCV, TEXT, TFTR) have indicated the existence of an anomalous
inward particle pinch. Recently, such an anomalous pinch has been unambiguously
identified in Tore Supra very long discharges, in absence of toroidal electric
field and of central particle source, for more than 4 minutes [1]. This
anomalous particle pinch is predicted by a quasilinear theory of particle
transport [2], and confirmed by non-linear turbulence simulations [3] and
general considerations based on the conservation of motion invariants [4].
Experimentally, the particle pinch is found to be sensitive to the magnetic
field gradient in many cases [5, 6, 7, 8], to the temperature profile [5, 9]
and also to the collisionality that changes the nature of the microturbulence
[10, 11, 12]. The consistency of some of the observed dependences with the
theoretical predictions gives us a clearer understanding of the particle pinch
in tokamaks, allowing us to predict more accurately the density profile in
ITER.


title: Investigation of a 1-D Fluid Probe Model for Mach Probe Measurements

abstract:
  In this paper we show how a two dimensional fluid model can be used to
interpret data obtained from an inclined Mach-probe or a Gundestrup probe. We
use an analytical approximation of the solution of the differential equations
describing the relation between the plasma flow and the measured ion saturation
currents at the probe's surface. The parameters of this analytical solution are
determined by comparison with the exact numerical solution of the equations. In
this way we are able to measure the parallel as well as the perpendicular Mach
numbers over the whole parameter range with a minimum accuracy of 90%.


title: Dynamics of relativistic solitons

abstract:
  Relativistic solitons are self-trapped, finite size, electromagnetic waves of
relativistic intensity that propagate without diffraction spreading. They have
been predicted theoretically within the relativistic fluid approximation, and
have been observed in multi-dimensional particle in cell simulations of laser
pulse interaction with the plasma. Solitons were observed in the laser
irradiated plasmas with the proton imaging technique as well. This paper
reviews many theoretical results on relativistic solitons in electron-ion
plasmas.


title:
Experimental study of the recombination of a drifting low temperature
  plasma in the divertor simulator Mistral-B

abstract:
  In a new divertor simulator, an ultra-cold (Te<1 eV) high density recombining
magnetized laboratory plasma is studied using probes, spectroscopic
measurements, and ultra-fast imaging of spontaneous emission. The Mistral-B
device consists in a linear high density magnetized plasma column. The ionizing
electrons originate from a large cathode array located in the fringing field of
the solenoid. The ionizing electrons are focused in a 3 cm diameter hole at the
entrance of the solenoid. The typical plasma density on the axis is close to
2.10^18 m-3. The collector is segmented into two plates and a transverse
electric field is applied through a potential difference between the plates.
The Lorentz force induces the ejection of a very-low temperature plasma jet in
the limiter shadow. The characteristic convection time and decay lengths have
been obtained with an ultra-fast camera. The study of the atomic physics of the
recombining plasma allows to understand the measured decay time and to explain
the emission spectra.


title: Photoassociative Production and Trapping of Ultracold KRb Molecules

abstract:
  We have produced ultracold heteronuclear KRb molecules by the process of
photoassociation in a two-species magneto-optical trap. Following decay of the
photoassociated KRb*, the molecules are detected using two-photon ionization
and time-of-flight mass spectroscopy of KRb$^+$. A portion of the metastable
triplet molecules thus formed are magnetically trapped. Photoassociative
spectra down to 91 cm$^{-1}$ below the K(4$s$) + Rb (5$p_{1/2}$) asymptote have
been obtained. We have made assignments to all eight of the attractive Hund's
case (c) KRb* potential curves in this spectral region.


title:
Stable soliton complexes and azimuthal switching in modulated Bessel
  optical lattices

abstract:
  We address azimuthally modulated Bessel optical lattices imprinted in
focusing cubic Kerr-type nonlinear media, and reveal that such lattices support
different types of stable solitons, whose complexity increases with growth of
lattice order. We reveal that the azimuthally modulated lattices cause single
solitons launched tangentially to the guiding rings to jump along consecutive
sites of the optical lattice. The position of the output channel can be varied
by small changes of the launching angle.


title: First result on a laser-heated emissive probe

abstract:
  The floating potential of a probe, emitting a sufficiently high electron
current, yields a fairly accurate approximation of the plasma potential. This
is an advantage in comparison to the conventional Langmuir probe where, after
determination of the electron temperature Te, the plasma potential can only be
derived indirectly from the formula Vpl = Vfl + aTe, where a is a function of
the ratio of the electron to the ion saturation currents (a is around 2.4 in a
magnetised hydrogen plasma). In addition, an emissive probe also works if there
are electron drifts or beams in the plasma. Emissive probes are usually
realised by small directly heated loops of W-wire. Drawbacks of this design are
the limited lifetime, the low electron emissivity of W and the voltage drop
across the wire. We have developed a new type of emissive probe, which is
heated by an infrared high-power diode laser with a maximum output power of 50
W. The probe consists of a small cylinder of LaB6. The probe was inserted into
the edge region of the VINETA helicon discharge plasma. Basic features of
emissive probes were verified.


title:
Anti-ExB flow field associated with a vortex formation in a partially
  ionized plasma

abstract:
  A high-density magnetized plasma has been studied for understanding of plasma
dynamics in partially ionized plasmas. Ion flow field has been obtained
experimentally, and is shown to be associated with a vortex formation. The most
remarkable result is that the direction of rotation is opposite to that of the
ExB drift. Measurement of neutral density profile reveals that there is a steep
density gradient of the neutrals around the vortex, suggesting that the
generation of inward momentum of the neutrals due to the density gradient. The
momentum is transfered to ion with charge-exchange collision, and cause
effective force on the ion. The present experiment shows that this effective
force may dominate the ambipolar-electric field and drive the anti-ExB vortical
motion of ions.


title: Density fluctuations in the tendem mirror Gamma 10

abstract:
  The tandem mirror GAMMA 10 utilizes an electron cyclotron resonance heating
(ECRH) for forming a confinement potential. Density fluctuation is observed
using microwaves, such as interferometer, reflectometry and Fraunhofer
diffraction (FD) method. An ultrashort-pulse reflectometry has an advantage of
detecting fluctuation locally. The wave number can be obtained by the FD
method. In the edge plasma region electrostatic probes are used. Fluctuation
with coherent mode in several kHz is excited in the hot-ion mode plasma. When
the ECRH is applied, electron density in the central cell increases gradually.
On the contrary, intensity of the density fluctuation decreases and coherent
mode is suppressed. Its frequency also varies with the density increase. In
that time, radial potential distribution, i.e., electric field, changes along
with the formation of plug potential. From this behaviour it is deduced that
the fluctuation deeply relates to the potential formation and improvement of
the confinement.


title:
Relaxation of potential, flows, and density in the edge plasma of CASTOR
  tokamak

abstract:
  Decay times of plasma flows and plasma profiles have been measured after a
sudden biasing switch-off in experiments on the CASTOR tokamak. A biased
electrode has been used to polarize the edge plasma. The edge plasma potential
and flows have been characterized by means of Langmuir and Mach probes, the
radiation was measured using an array of bolometers. Potential profiles and
poloidal flows can be well fitted by an exponential decay time in the range of
10 - 30 microseconds when the electrode biasing is turn off in the CASTOR
tokamak. The radiation shows a slower time scale (about 1 ms), which is linked
to the evolution in the plasma density and paticle confinement.


title:
THE CAVES Project - Collaborative Analysis Versioning Environment
  System; THE CODESH Project - Collaborative Development Shell

abstract:
  A key feature of collaboration in science and software development is to have
a {\em log} of what and how is being done - for private use and reuse and for
sharing selected parts with collaborators, which most often today are
distributed geographically on an ever larger scale. Even better if this log is
{\em automatic}, created on the fly while a scientist or software developer is
working in a habitual way, without the need for extra efforts. The {\tt CAVES}
and {\tt CODESH} projects address this problem in a novel way, building on the
concepts of {\em virtual state} and {\em virtual transition} to provide an
automatic persistent logbook for sessions of data analysis or software
development in a collaborating group. A repository of sessions can be
configured dynamically to record and make available the knowledge accumulated
in the course of a scientific or software endeavor. Access can be controlled to
define logbooks of private sessions and sessions shared within or between
collaborating groups.

categories: physics.data-an cs.DC hep-ex physics.comp-ph


title:
A study of magnetically-supported dc discharge in cylindrical and
  inverted cyclindrical configuration

abstract:
  We have investigated apparently stochastic fluctuations of
magnetically-supported dc discharge in cylindrical coaxial configuration. In
the system the electric field had radial direction while the magnetic field was
applied axially. The discharge vessel length was 12 centimetres. Working gas
was typically argon at pressure of several Pa, magnetic field 10-50 mT. The
contribution describes experimental results - frequency and phase analysis of
the instabilities, which we detected in our experimental system in both the
conventional and inverted magnetron configurations. We bring also 2-D PIC model
of the dc discharge under conditions, which can be achieved in the experimental
apparatus.


title:
Production of overdense plasmas by launching 2,45 GHz electron cyclotron
  waves in a helical device

abstract:
  For production of low temperature plasmas with low collisionality, 2.45GHz
microwave power up to 20kW is injected perpendicularly to the toroidal field at
very low toroidal field Bt


title: Ion acceleration during internal magnetic reconnection events in TST-2

abstract:
  Characteristics of ion acceleration in the internal magnetic reconnection
events (IRE) have been studied by means of a neutral particle energy analyzer
(NPA) in Tokyo Spherical Tokamak (TST-2). The major and minor radii are 0.38 m
and 0.25m, respectively. The magnetic field strength is 0.3T and the maximum
plasma current is up to 140 kA. The electron and ion temperatures are 0.4-0.5
keV and 0.1 keV, respectively and the electron density is ~1x1019 m-3. The NPA
can be scanned toroidally from q = 74° (cw) to q = 114° (ccw), where q
= 90° corresponds to the perpendicular sightline. The direction of the
plasma current is cw. The NPA signals are digitized at every 50 ms. The NPA is
calibrated in the energy range of 0.1 keV < E < 8.4 keV. When the IRE occurs,
it is observed that the plasma current increases by ~ 20% and the loop voltage
drops from 0.6 V to-5 V for ~ 0.1 ms. The enhanced charge exchange flux is
observed by more than one order of magnitude at ~ 1 keV for this reconnection
phase. The ion temperature increases by 80 eV at IREs. The angle q dependence
of increment of Ti shows that DTi (q = 74°) is higher than that for q =
114°. This observation suggests that an ion is accelerated initially in the
direction of magnetic field lines. The time evolution of the ion distribution
function is simulated with a Fokker-Planck code taking into account the
electric field effects.


title:
Generation of quasi static magnetic field in the relativisitic
  laser-plasma interactions

abstract:
  The magnetic field generation by a relativistic laser light irradiated on a
thin target at the oblique incidence is investigated using a two dimensional
particle-in-cell simulation. The surface magnetic field inhibits the electron
transport towards the inside plasma, when an incident angle exceeds the
critical angle, which depends on the laser and plasma parameters.


title:
Simulations of dusty plasmas using a special-purpose computer system for
  gravitational N-body problems

abstract:
  Simulations of dusty plasmas were performed using GRAPE-6, a special-purpose
computer designed for gravitational N-body problems. The collective behaviour
of dust particles, which are injected into the plasma, was studied by means of
three-dimensional computer simulations. As an example of a dusty plasma
simulation, we have calculated movement of dust particles in plasmas under
microgravity conditions. In this simulation, a dust-free region called the
"void" is observed in the dust cloud. Another example was to simulate
experiments on Coulomb crystals in plasmas. Formation of a Coulomb crystal was
observed under typical laboratory conditions. For the simulation of a dusty
plasma in microgravity with 3x10^4 particles, GRAPE-6 can perform the whole
operation 1000 times faster than by using a Pentium4-1.6GHz CPU.


title: Estimation of Power Balance in Steady State LHCD Discharges on TRIAM-1M

abstract:
  On TRIAM-1M, a long duration discharge for more than 5 h was achieved
successfully by fully non-inductive lower hybrid current drive. Heat load
distribution to the plasma facing components (PFCs) in the 5 h discharge was
investigated by using calorimetric measurements. The injected RF power was
coincident with the total amount of heat load to PFCs estimated by calorimetric
measurement. The power balance including the portion of direct loss power of
fast electron, heat flux due to the charge exchange process was able to be
estimated in this long duration discharge.


title:
Characterisitics of the hall current surrounding a magnetized
  filamentary plasma

abstract:
  The hall current in the periphery of a filamentary plasma with the inwardly
directed radial electric field, Er has been investigated experimentally by
utilizing a TPD type dc discharge. When the cusp magnetic filed B$\theta$ is
applied perpendicular to the stationary background magnetic field Bz, the hall
current by the ErxB$\theta$ drift of electrons is induced in the periphery of
the magnetized filamentary plasma.


title:
Effects of laser wavelength and density scalelength on absorption of
  ultrashort intense lasers on solid-density targets

abstract:
  Hot electron temperatures and electron energy spectra in the course of
interaction between intense laser pulse and overdense plasmas are reexamined
from a viewpoint of the difference in laser wavelength. The hot electron
temperature measured by a particle-in-cell simulation is scaled by $I$ rather
than $I \lambda^2$ at the interaction with overdense plasmas with fixed ions,
where $I$ and $\lambda$ are the laser intensity and wavelength, respectively.


title: Review of Results from the FN-II Dense Plasma Focus Machine

abstract:
  The FN-II is a small dense plasma focus (4.8 kJ at 36 kV), operated at the
Universidad Nacional Autonoma de Mexico. Substantial effort has been dedicated
to the study of the anisotropy in the neutron and hard X-ray radiation.
Concerning the former, it has been observed that there is an anisotropic
distribution superposed on a far larger isotropic one. These clearly separated
effects can be interpreted as the consequence of two different neutron emission
mechanisms. The angular distribution of hard X-rays and ions is also studied
within the chamber with TLD and CR-39 detectors respectively. Two maxima are
found around the axis of the device for X rays within the 20-200 keV range.


title:
Development of a precise size-controllable pellet injector for the
  detailed studies of ablation phenamena and mechanism

abstract:
  From the viewpoint of performance of nuclear fusion plasmas, pellet injection
experiments have been actively carried out in many toroidal devices in the
sense of controlling density profile, obtaining high density or improved
confinement, and diagnostic purposes. In order to have a common measure of
pellet ablation, the regression study has been performed as an international
cooperation activity, obtaining "IPAD" (International Pellet Ablation Database)
>. However, these are an empirical scaling, and the mechanism of pellet
ablation still remains to be studied. According to the code calculations based
on a typical pellet ablation model (e. g., so-called the neutral gas shielding
model), it is understood that the penetration depth into plasma is always quite
sensitive to the pellet size. If the pellet size is too large, the pellet
passes through the plasma, and if it is too small, it is trapped at the plasma
surface. Also, an effective or suitable range of the pellet size for a certain
plasma is generally very narrow, and this range largely varies depending on
each plasma size and plasma parameters. Thus, the precise controllability of
the pellet size, especially the size controllability with continuously variable
system will be quite effective in order to carry out the detailed studies on
pellet ablation and associated phenomena. A pellet injector of new type with
precisely and continuously controllable system of pellet size is being
developed. This has a unique mechanics and structure of producing a frozen
pellet in extremely low temperature region. In the device presently developed
in this research, we will precisely adjust the length of the cylindrical pellet
($\Phi$ 1.0mm) from 0.5 to 3 mm by using the special "length restriction
rod".


title:
Numerical analysis of flow characteristics of an atmospheric plasma
  torch

abstract:
  The atmospheric plasma is regarded as an effective method for surface
treatments because it can reduce the period of process and does not need
expensive vacuum apparatus. The performance of non-transferred plasma torches
is significantly depended on jet flow characteristics out of the nozzle. In
order to produce the high performance of a torch, the maximum discharge
velocity near an annular gap in the torch should be maintained. Also, the
compulsory swirl is being produced to gain the shape that can concentrate the
plasma at the center of gas flow. Numerical analysis of two different
mathematical models used for simulating plasma characteristics inside an
atmospheric plasma torch is carried out. A qualitative comparison is made in
this study to test the accuracy of these two different model predictions of an
atmospheric plasma torch. Numerical investigations are carried out to examine
the influence of different model assumptions on the resulting plasma
characteristics. Significant variations in the results in terms of the plasma
velocity and temperature are observed. These variations will influence the
subsequent particle dynamics in the thermal spraying process. The uniformity of
plasma distribution is investigated. For analyzing the swirl effects in the
plenum chamber and the flow distribution, FVM (finite volume method) and a
SIMPLE algorithm are used for solving the governing equations.


title: Dressed (Renormalized) Coordinates in a Nonlinear System

abstract:
  In previous publications dressed coordinates and dressed states has been
introduced. Specifically, a system composed by a harmonic oscillator
interacting linearly with an infinity set of other oscillators has been
treated. In this paper we show how to generalize such dressed coordinates and
dressed states to a nonlinear version of this system. Also we clarify some
misunderstandings about the concept of dressed coordinates. Indeed now we
prefer to call them renormalized coordinates to emphasize the analogy with the
renormalized fields in quantum field theory.


title:
Studies of a hollow cathode discharge using mass spectrometry and
  electrostatic probe techniques

abstract:
  Hollow cathode discharges (HCD) are capable of generating dense plasmas and
have been used for development of high-rate, low-pressure, high-efficiency
processing machines. The geometric feature of a HCD promotes oscillations of
hot electrons inside the cathode, thereby enhancing ionization, ion bombardment
of inner walls and other subsequent processes. At the same power the hollow
cathode exhibits plasma density one to two orders of magnitude higher than that
of conventional planar electrodes. The aim of the present studies was to obtain
experimental observations about the main features of a dc hollow cathode
discharge in order to evaluate its capability of generating compounds in the
plasma medium, by reaction between sputtered species from the cathode and
radicals from the gas discharge. Especial interest is focused on aluminum
nitride (AlN) formation which is very desirable if a deposition of thin film of
this material is concerned. Plasma properties were inferred from the
current-voltage characteristics of a single Langmuir probe positioned at the
inter-cathode space. Through mass spectrometry technique some species in the
plasma gas phase could be monitored for various operating conditions of the
discharge. This mass analysis together with the probe measurements gives
guidance for optimization of AlN generation in the discharge consequently for
deposition of thin films of this material.


title: Coherent structures in an electron beam

abstract:
  The formation and evolution of coherent structures in a low-energy electron
beam produced in a Malmberg-Penning trap is investigated by means of CCD
diagnostics. The electrons are emitted from a thermionic cathode and their
energy is controlled by an acceleration grid. By varying the spatial
distribution of the energy of emitted electrons, different space charge effects
are observed, as, e. g., a sharp or a gradual transition to a space charge
dominated regime. The variation of the coherent structures along the beam is
studied by varying the electron density or/and the value of the confined
magnetic field. The observed processes are interpreted using a tridimensional
particle-in-cell code which solves the Vlasov-Poisson system in zeroth order
drift approximation.


title: Extension and its characteristics of ECRH plasma in the LHD

abstract:
  One of the main objectives of the LHD is to extend the plasma confinement
database for helical systems and to demonstrate such extended plasma
confinement properties to be sustained in steady state. Among the various
plasma parameter regimes, the study of confinement properties in the
collisionless regime is of particular importance. Electron cyclotron resonance
heating (ECRH) has been extensively used for these confinement studies of the
LHD plasma from the initial operation. The system optimizations including the
modification of the transmission and antenna system are performed with the
special emphasis on the local heating properties. As the result, central
electron temperature of more than 10 keV with the electron density of 0.6 x
10$^{19}$ m$^{-3}$ is achieved near the magnetic axis. The electron temperature
profile is characterized by a steep gradient similar to those of an internal
transport barrier observed in tokamaks and stellarators. 168 GHz ECRH system
demonstrated efficient heating at over the density more than 1.0 x 10$^{20}$
m$^{-3}$. CW ECRH system is successfully operated to sustain 756 s discharge.


title: Electron dynamics at the initial stage of floating-sheath formation

abstract:
  The problem of sheath formation in front of a conductive planar plate
inserted into the plasma is formulated. Initially, the plate is assumed to be
neutral. It is shown that the charging-up process of the plate is accompanied
by the excitation of electron plasma waves.


title: Nonlinear left-handed metamaterials

abstract:
  We analyze nonlinear properties of microstructured materials with negative
refraction, the so-called left-handed metamaterials. We demonstrate that the
hysteresis-type dependence of the magnetic permeability on the field intensity
allows changing the material properties from left- to right-handed and back.
Using the finite-difference time-domain simulations, we study wave transmission
through the slab of nonlinear left-handed material, and predict existence of
temporal solitons in such materials. We demonstrate also that nonlinear
left-handed metamaterials can support both TE- and TM-polarized self-trapped
localized beams, spatial electromagnetic solitons. Such solitons appear as
single- and multi-hump beams, being either symmetric or antisymmetric, and they
can exist due to the hysteresis-type magnetic nonlinearity and the effective
domains of negative magnetic permeability.


title:
Study of the Unilamellar Vesicle Structure via Sans on the Base of the
  SFF Model

abstract:
  The parameters of the polydispersed unilamellar vesicle population are
analyzed on the basis of the separated form-factors model for three different
type of membranes. The neutron scattering length density across the membrane is
simulated on the base of the HH-model with the linear water distribution.


title:
From classical to modern ether-drift experiments: the narrow window for
  a preferred frame

abstract:
  Modern ether-drift experiments look for a preferred frame by measuring the
difference \Delta \nu in the relative frequencies of two cavity-stabilized
lasers, upon local rotations of the apparatus or under the Earth's rotation. If
the small deviations observed in the classical ether-drift experiments were not
mere instrumental artifacts, by replacing the high vacuum in the resonating
cavities with a dielectric gaseous medium (e.g. air), the typical measured
\Delta\nu\sim 1 Hz should increase by orders of magnitude. This prediction is
consistent with the characteristic modulation of a few kHz observed in the
original experiment with He-Ne masers. However, if such enhancement would not
be confirmed by new and more precise data, the existence of a preferred frame
can be definitely ruled out.


title:
Noise Statistics in Optically Pre-Amplified DPSK Receivers with Optical
  Mach-Zehnder Interferometer Demodulation

abstract:
  This paper presents for the first time a comprehensive study of noise
statistics by use pdf.


title:
Estimation of the Adriatic sea water turnover time using fallout 90Sr as
  a radioactive tracer

abstract:
  Systematic, long term measurements, starting in 1963, of 90Sr activity
concentrations in sea water have been performed at four locations (cities of
Rovinj, Rijeka, Split and Dubrovnik) along the Croatian coast of the Adriatic
sea. In addition, fallout samples were collected in the city of Zadar. 90Sr
activity concentrations are in good correlation with the fallout activity, the
coefficient of correlation being 0.72. After the nuclear moratorium on
atmospheric nuclear bomb tests in 1960s, 90Sr activity concentrations in sea
water exponentially dropped from 14.8 +/- 2.4 Bq/m3 in 1963 to 2.0 +/- 0.3
Bq/m3 in 2003. In the same period, the total annual 90Sr land surface deposit
in Zadar fell by three orders of magnitude, from 713.3 Bq/m2 in 1963 to 0.4
Bq/m2 in 2003. Using strontium sea water and fallout data, a mathematical model
was developed to describe the rate of change of 90Sr activity concentrations in
the Adriatic sea water and estimate its mean residence time in the Adriatic. By
fitting the experimental data to a theoretically predicted curve, the mean
residence time of 90Sr in the Adriatic sea water was estimated to be
approximately 3.4 +/- 0.4 years, standard deviation being calculated by Monte
Carlo simulations. As in physical oceanography 90Sr can be used as effective
radioactive tracer of water mass transport, this value also reflects the upper
limit for turnover time of the Adriatic sea water. The turnover time of 3.4
years for the Adriatic sea water is in reasonable agreement with the value
which was estimated, by studying water flows through the Strait of Otranto, to
be on the order of 1 year.


title: Whistler wave plasma production in CHS

abstract:
  Rf plasma production in Whistler waves range of frequency f/fci >1 is applied
on the compact helical system (CHS) in a steady state operation with low
toroidal magnetic field strength, where f and fci are rf and ion cyclotron
frequencies, respectively. Maximum rf power and pulse width are is170kW and 10
msec at 9MHz, respectively. The line averaged plasma density <ne> as high as
2x10^18 m-3 (He plasma) is produced in the region of toroidal magnetic field
strength on magnetic axis B=100G~1.5kG and the electron temperature measured at
plasma periphery is about 20eV. The wave magnetic field strength measured at
the plasma periphery showed the evidence of the toroidal eigen modes of the
Whistler waves. The additional long pulse microwave heating of 2.45GHz
(>200msec) is applied and it sustains the plasmas while the microwave itself
can not ignite plasmas when B<600G.


title:
Multigrid iterative algorithm using pseudo-compressibility for
  three-dimensional mantle convection with strongly variable viscosity

abstract:
  A numerical algorithm for solving mantle convection problems with strongly
variable viscosity is presented. Equations for conservation of mass and
momentum for highly viscous and incompressible fluids are solved iteratively by
a multigrid method in combination with pseudo-compressibility and local time
stepping techniques. This algorithm is suitable for large-scale
three-dimensional numerical simulations, because (i) memory storage for any
additional matrix is not required and (ii) vectorization and parallelization
are straightforward. The present algorithm has been incorporated into a mantle
convection simulation program based on the finite-volume discretization in a
three-dimensional rectangular domain. Benchmark comparisons with previous two-
and three-dimensional calculations including the temperature- and/or
depth-dependent viscosity revealed that accurate results are successfully
reproduced even for the cases with viscosity variations of several orders of
magnitude. The robustness of the numerical method against viscosity variation
can be significantly improved by increasing the pre- and post-smoothing
calculations during the multigrid operations, and the convergence can be
achieved for the global viscosity variations up to 1e10.


title: High Resolution He-like Argon And Sulfur Spectra From The PSI ECRIT

abstract:
  We present new results on the X-ray spectroscopy of multicharged argon,
sulfur and chlorine obtained with the Electron Cyclotron Resonance Ion Trap
(ECRIT) in operation at the Paul Scherrer Institut (Villigen, Switzerland). We
used a Johann-type Bragg spectrometer with a spherically-bent crystal, with an
energy resolution of about 0.4 eV. The ECRIT itself is of a hybrid type, with a
superconducting split coil magnet, special iron inserts which provides the
mirror field, and a permanent magnetic hexapole. The high frequency was
provided by a 6.4 GHz microwave emitter. We obtained high intensity X-ray
spectra of multicharged F-like to He-like argon, sulfur and chlorine with one
1s hole. In particular, we observed the $1s2s^{3}S_1 \to 1s^2^{1}S_0 M1$ and
$1s2p^{3}P_2 \to 1s^2^{1}S_0 M2$ transitions in He-like argon, sulfur and
chlorine with unprecedented statistics and resolution. The energies of the
observed lines are being determined with good accuracy using the He-like M1
line as a reference.


title: Modified Zakharov equations for plasmas with a quantum correction

abstract:
  Quantum Zakharov equations are obtained to describe the nonlinear interaction
between quantum Langmuir waves and quantum ion-acoustic waves. These quantum
Zakharov equations are applied to two model cases, namely the four-wave
interaction and the decay instability. In the case of the four-wave
instability, sufficiently large quantum effects tend to suppress the
instability. For the decay instability, the quantum Zakharov equations lead to
results similar to those of the classical decay instability except for quantum
correction terms in the dispersion relations. Some considerations regarding the
nonlinear aspects of the quantum Zakharov equations are also offered.


title: Theory of the singlet exciton yield in light-emitting polymers

abstract:
  This paper presents a possible explanation for the enhanced singlet exciton
yield in light emitting polymers. We propose a theory of electron-hole
recombination via inter-molecular inter-conversion from inter-molecular weakly
bound polaron pairs (or charge-transfer excitons) to intra-molecular excitons.
This theory is applicable to parallel polymer chains. A crucial aspect of the
theory is that both the intra-molecular and inter-molecular excitons are
effective-particles, which are described by both a relative-particle
wavefunction and a center-of-mass wavefunction. This implies two electronic
selection rules. (1) The parity of the relative-particle wavefunction implies
that inter-conversion occurs from the even parity inter-molecular
charge-transfer excitons to the strongly bound intra-molecular excitons. (2)
The orthonormality of the center-of-mass wavefunctions ensures that
inter-conversion occurs from the charge-transfer excitons to the lowest branch
of the strongly bound exciton families, and not to higher lying members of
these families. The inter-conversion is then predominately a multi-phonon
process, determined by the Franck-Condon factors. These factors are
exponentially smaller for the triplet manifold than the singlet manifold
because of the large exchange energy.


title: An estimate of the inter-system crossing time in light-emitting polymers

abstract:
  The reported enhanced singlet-exciton yields in light-emitting polymers over
the statistical limit of 25% has attracted wide experimental and theoretical
attention. Most theoretical estimates of the singlet-exciton yield depend
crucially on estimates of the inter-system crossing rates induced by spin-orbit
coupling. In this paper we use the experimentally determined phosphorescent
life-time and energy of the lowest-lying triplet state, as well as calculated
values of Huang-Rhys factors to estimate the spin-orbit matrix element and
inter-system crossing time between the lowest-lying singlet and triplet states.


title: Fluctuation-Driven Molecular Transport in an Asymmetric Membrane Channel

abstract:
  Channel proteins, that selectively conduct molecules across cell membranes,
often exhibit an asymmetric structure. By means of a stochastic model, we argue
that channel asymmetry in the presence of non-equilibrium fluctuations, fueled
by the cell's metabolism as observed recently, can dramatically influence the
transport through such channels by a ratchet-like mechanism. For an
aquaglyceroporin that conducts water and glycerol we show that a previously
determined asymmetric glycerol potential leads to enhanced inward transport of
glycerol, but for unfavorably high glycerol concentrations also to enhanced
outward transport that protects a cell against poisoning.


title: X-ray properties of the transient pulsar 3A 0535+262 in quiescence

abstract:
  We present the timing and spectral properties of the transient Be/X-ray
binary pulsar 3A 0535+262 during quiescence using three observations with the
narrow field imaging instruments (NFI) of BeppoSAX. Assuming a distance of 2
kpc for this system, the 2-10 keV X-ray luminosities measured from the three
observations are in the range of 1.5-4.0 $\times$ 10$^{33}$ erg s$^{-1}$,
indicating a very low rate of accretion. We report the detection of pulsations
at a very low luminosity of 2 $\times$ 10$^{33}$ erg s$^{-1}$ during one of the
three observations, though at this accretion rate the system is expected to be
in the centrifugally inhibited regime. The X-ray spectra for the unpulsed
observations are best modeled as power law type while a combined model of power
law and black-body is required to fit the pulsed spectrum.


title:
Rubidium Spectroscopy at 778-780 nm with a Distributed Feedback Laser
  Diode

abstract:
  We have performed high resolution spectroscopy of rubidium with a single mode
continuous wave distributed feedback (DFB) laser diode. The saturation spectrum
of the D_2-line of 85Rb and 87Rb was recorded with a resolution close to the
natural line width. The emission frequency was actively stabilized to
Doppler-free transitions with a relative accuracy of better than 7 parts in
10^9 using commercially available servo devices only. An output power of 80 mW
was sufficient to allow for two-photon spectroscopy of the 5S-5D-transition of
87Rb. Further, we report on the spectral properties of the DFB diode, its
tuning range and its frequency modulation properties. The line width of the
diode laser, determined with high resolution Doppler free two photon
spectroscopy, was 4 MHz without applying any active stabilization techniques.
For time scales below 5 us the line width drops below 2 MHz.


title:
Perfect Optical Solitons: Spatial Kerr Solitons as Exact Solutions of
  Maxwell's Equations

abstract:
  We prove that spatial Kerr solitons, usually obtained in the frame of
nonlinear Schroedinger equation valid in the paraxial approximation, can be
found in a generalized form as exact solutions of Maxwell's equations. In
particular, they are shown to exist, both in the bright and dark version, as
linearly polarized exactly integrable one-dimensional solitons, and to reduce
to the standard paraxial form in the limit of small intensities. In the
two-dimensional case, they are shown to exist as azimuthally polarized
circularly symmetric dark solitons. Both one and two-dimensional dark solitons
exhibit a characteristic signature in that their asymptotic intensity cannot
exceed a threshold value in correspondence of which their width reaches a
minimum subwavelength value.


title:
A time projection chamber with optical readout for charged particle
  track structure imaging

abstract:
  We report about a nuclear track imaging system which is designed to study in
detail the ionization topology of charged particle tracks in a low-pressure
gas. The detection method is based on a time projection chamber (TPC) filled
with low-pressure triethylamine (TEA). Ionization electrons produced by
energetic charged particles are three-dimensionally imaged by recording light
from electron avalanches with an intensified CCD system. The detector permits
to inves-tigate the spatial ionization distributions of particle tracks in gas,
of equivalent length and resolution in tissue of 4 mm and 40 nm (RMS),
respectively. We explain the relevance of this technique for dosimetry,
describe the experimental method and the basic operation parameters. First
results of the chamber response to protons and alpha particles are presented.


title:
Digital imaging of charged particle track structures with a low-pressure
  optical time projection chamber

abstract:
  We describe first results obtained with a track structure imaging system for
measuring the ionisation topology of charged particles in a low-pressure gas.
The detection method is based on a time projection chamber (TPC) filled with
low-pressure triethylamine (TEA). Images of ionisation tracks of electrons,
protons, and heavier ions are presented and analysed.


title:
Imaging of microscopic features of charged-particle tracks in a
  low-pressure gas

abstract:
  An imaging system for measuring the spatial distribtion of charged particle
tracks in a low-pressure gas is presented. The method is based on an optically
read out time projection chamber. Results of experiments with fast heavy ions
are shown.


title:
Development and application of an optical TPC for charged particle track
  structure imaging in microdosimetry

abstract:
  An imaging system for measuring the track structure of charged particles in a
low-pressure gas is presented. We describe the experimental method and compare
experimental results with first results of a simulation of the chamber
response.