Simulation of free-streaming electrons in a uniform plasma

  • 楊 宗桓

Student thesis: Master's Thesis


This thesis is to study the free-streaming electrons moving in a uniform background plasma in numerical simulation Free-streaming electrons can be generated in our parallel plate capacitor bank (PPCB) system under construction Uniform plasma can be generated by glow discharge The simulation code of free-streaming electrons is implemented via Vlasov solver Vlasov solver is usually used to simulate plasma phenomena in kinetic regime Two-stream instability is used to benchmark the code The energy conservation is checked and energy growth rate of two-stream instability calculated from simulation results and theory are compared The free-streaming electrons is simulated with thermal velocity vth = 1 beam velocity vb = 2 3 4 5 respectively Ratios between the number density of the free-streaming electrons and the background electron density γ = 0 5 1 2 respectively Therefore there are 12 different initial conditions were simulated Instabilities occur when beam velocity vb = 3 and vb = 4 No instability occurs for vb = 2 and vb = 5 In vb = 2 instability vb is diffused by electron of thermal motions In vb = 5 the relative velocity between electrons and the background plasma is too large so that they don’t interact with each other The growth rate is the highest when γ = 1 Nevertheless the growth rate in different γ doesn’t change over 10% between different γ we simulated
Date of Award2018 Aug 30
Original languageEnglish
SupervisorPo-Yu Chang (Supervisor)

Cite this