a low cost small - scale tunable x - ray source , comprising a spherical - electron injected inertial electrostatic confinement device . within a spherical containment vessel recirculatory focusing electrons are accelerated by a spherical grid within the vessel , and cause electron — electron collisions in a dense , central plasma core region of the sphere . the iec synchrotron source in a mechanism for generating tunable x - ray radiation is essentially equivalent to that for conventional synchrotron sources . the iec - ss operates at a much lower electron energy , but still gives the same x - ray energy due to the small - scale bending radius associated with the electron — electron interactions . the x - rays can be filtered for particular purposes using diffraction gratings , prisms or the like .