PIC/MC-Simulation of Helium Ionization by a Relativistic Electron Beam With a Distributed Virtual Cathode

A gas discharge in gaseous helium in the vicinity of a distributed virtual cathode (VC) formed in a tubular magnetized relativistic electron beam when it is reintroduced into a cylindrical cavity is simulated and numerically investigated. The “KARAT” code, based on the particle-in-cell (PIC)/Monte Carlo (MC) method, was used. The dynamics of the electron beam, the time evolution of the phase space distributions of the particles, the physical parameters, and the space-time characteristics of the plasma are calculated. It is shown that, under the action of an electron beam, dense plasma appears in the cavity in the form of a thin-walled cylinder of great length, the concentration of which can reach 10
¹³
cm
^-3
. It turned out that plasma is substantially inhomogeneous along its length and its denser section corresponding to the location of the distributed VC. The instant of charge overcompensation of electrons is shown to be a function of the concentration of helium atoms in the cavity. The instant of charge balance was reached more rapidly with increased helium pressure, which indicates an increase in the rate of discharge development.