Plasma simulation to analyze velocity distribution characteristics of pseudospark-sourced electron beam
Hai-Long Li(李海龙)1,†, Chen-Fei Hu(胡陈飞)1, Che Xu(徐彻)1, Yong Yin(殷勇)1, Bin Wang(王彬)1, Lin Meng(蒙林)1, and Mao-Yan Wang(王茂琰)2
1School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China 2School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, China
Pseudospark-sourced electron beam is a promising candidate for driving vacuum electronic devices to generate millimeter wave and terahertz wave radiation as it has a very high combined beam current density. However, the inherent velocity spread of the beam, which is difficult to measure in experiment, has a great influence on the operating frequency and efficiency of the vacuum electronic device. In this paper, the velocity distribution characteristics of the electron beam produced by a single-gap hollow cathode electron gun are numerically studied and a three-dimensional kinetic plasma simulation model of a single-gap hollow cathode electron gun is built by using particle in cell and Monte Carlo collision methods in Vorpal. Based on the simulation model, the time-dependent evolution of the plasma formation inside the hollow cathode and electron beam generation process are observed. It is demonstrated that the pseudospark-sourced electron beam has a relatively large velocity spread. The time-dependent velocity distribution of the beam is analyzed, and the dependence of the beam velocity distribution under various operating conditions such as anode–cathode potential difference, gas pressure, and cathode aperture size are also studied.
* Project supported by the Sichuan Science and Technology Program, China (Grant No. 2019YJ0188) and the National Natural Science Foundation of China (Grant Nos. 61671116 and 11905026).
Cite this article:
Hai-Long Li(李海龙)†, Chen-Fei Hu(胡陈飞), Che Xu(徐彻), Yong Yin(殷勇), Bin Wang(王彬), Lin Meng(蒙林), and Mao-Yan Wang(王茂琰) Plasma simulation to analyze velocity distribution characteristics of pseudospark-sourced electron beam 2020 Chin. Phys. B 29 105101
Fig. 1.
2D schematic view of simulated structure.
Collision
elastic collisions between electrons and argon atoms
excitation collisions between electrons and argon atoms
ionization collisions between electrons and argon atoms
Boundary
electrons and argon ions absorbed by metal boundary
secondary electrons from argon ions impacting on the metal surfaces
Table 1.
Physical processes in simulation.
Fig. 2.
At cathode voltage −10 kV and gas pressure 30 Pa: (a) potential distribution at 11 ns, (b) seed electrons (green) and new electrons (blue) distribution at 11 ns, (c) potential distribution at 15 ns, and (d) seed electrons (green) and new electrons (blue) distribution at 15 ns.
Fig. 3.
Time-dependent properties of PS-sourced electron beam, showing (a) waveform of discharge current and beam current, (b) time-dependent axial mean velocity of electrons, (c) time-dependent radial mean velocity of electrons, and (d) electron beam velocity distributions at different moments.
Fig. 4.
Axial velocity-dependent electron density distributions of electron beam at (a) different gas pressures, (b) different cathode voltages, and (c) different cathode aperture sizes.
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