Analysis of the formation of structures and chaotic dynamics in a nonrelativistic electron beam with a virtual cathode in the presence of a decelerating field

Abstract

1 Note a certain relation between oscillations in such an electron system with deceleration and oscillations in the BarkhausenKurz oscillator [19] and oscillations in an electron-wave oscillator with a decelerating field ([20, Chapter 5] Abstract -A nonrelativistic electron beam with a virtual cathode situated in the diode gap with a decelerating field is experimentally and theoretically studied. A 1D model of the electron beam in the presence of a decelerating field is constructed. Nonlinear nonstationary processes in this system are investigated by means of numerical analysis of the model. The processes are described and interpreted with regard to formation and interaction of structures in the electron flow. The theoretical results are qualitatively confirmed by the experimental data showing that the system under study can be considered as a promising controlled source of chaotic oscillations in the microwave range.

Influence of background gas ionization on oscillations in a virtual cathode with a retarding potential

“…The role of ions in the VC formation and dynamics manifests itself most strongly in the so-called low-voltage vircator with the retarding electric field. [16][17][18][19] In this device the reflecting potential is applied to the output grid of the drift space. 16 The value of the reflecting potential is a control parameter of the system.…”

“…Oscillatory regimes exist also when the reflecting potential exceeds the accelerating voltage. [16][17][18] The low-voltage vircator operates in a long pulse or even in a dc regime and the ions which appear in the drift region due to impact ionization of a residual gas, cannot be treated as immobile during the beam pulse. All these processes, namely, the VC formation, the gas ionization, and the ions motion, should be considered simultaneously and selfconsistently in this device.…”

Effect of self-magnetic fields on the nonlinear dynamics of relativistic electron beam with virtual cathode

“…The oscillating VC is known to appear in an electron beam when the beam current exceeds a certain critical value, I cr (space charge limiting (SCL) current) 1,19 , and the beam space charge is strong enough in order to form a potential barrier (VC) which reflects the electrons back to the injection plane. The mechanisms of the VC formation have been investigated in detail in case of the one-dimensional (1D) electron beam motion (fully magnetized beam) 7,12,[20][21][22] , with the critical beam current value being analytically defined for this case in Ref. 19 .…”