Infrared-image diagnostics of a low-energy, high-current electron beam transported through a plasma channel in a guide magnetic field

Summary form only given. Results of studying the energy density distribution of a wide-area (up to 60 cm²), low-energy (10-30 keV), high-current (up to 25 kA) pulsed (~ 3 μs) electron beam transported through a plasma channel in a guide magnetic field are presented. Beam focusing and redistribution of the beam energy density in the cross section was performed with the use of hollow cylinders made of ferromagnetic materials (magnetic field concentrators) and placed behind the target made of 185-μm-thick stainless steel foil. Temperature distributions of the back side of the target, which correspond to the beam energy distribution, were measured by thermal imager. For this purpose, the concentrator was temporarily removed aside with the help of electromagnet during the pause (about 1 s) between a beam pulse and recording a thermogram. Thus, during the pause, the optical path became free for infrared radiation of the target. The experiments have confirmed improving the beam uniformity with the use of hollow magnetic field concentrators and agree good with computer calculations of magnetic flux density [1].