Virtual anode as a source of low-frequency oscillations of high-current electron beams

Abstract

The research into the transportation of a relativistic electron beam with an above-critical current in the cylindrical drift chamber in the presence of an ion stream is described. The theoretical analysis of the electron-ion formation dynamics is based on a particle-in-cell (PIC) method. It shows that at a joint injection of a supercritical electron beam and a low-energy low-current ion beam in the drift chamber a virtual anode may appear along with an electron virtual cathode. This virtual anode pulsates periodically. Numerical results obtained for hydrogen and nitrogen ions show that the ratio of pulsation frequencies is in inverse proportion to the ion mass ratio. Oscillations of a virtual anode result in a time modulation of electron and ion currents at the same frequency at the drift chamber output.