Simulations of laser plasma instabilities using a particle-mesh method

Abstract

A physical model is presented for the study of parametric instabilities in inertial confinement fusion (ICF), which considers the coupling of the incident and scattered electromagnetic waves with plasma electrons and ions. Specially, this model is solved numerically with the particle-mesh method, where the plasma is represented by macro-particles both for electrons and ions, and the velocity and position of each macro-particle are numerically updated by using the particle-mesh method. The developed particle-mesh code in one-dimensional geometry (PM1D) is utilized to study the development of parametric instabilities at the nonlinear stages, where electron plasma wave breaking, particle trapping, hot electron generation and density cavity formation can occur. Particle-in-cell (PIC) simulations are carried out to verify this PM1D code. By comparison, it is found that this PM1D code is able to capture the kinetic effects and precisely describe the developments of parametric instabilities at nonlinear stages as the PIC simulations while saving the computation time obviously. Furthermore, a test simulation of the stimulated Raman scattering evolution up to 200 ps verifies the robustness of this PM1D code.

Anomalous hot electron generation via stimulated Raman scattering in plasma with up-ramp density profiles

“…In the kinetic regime with k p λ D ⩾ 0.29, it is prone to get the frequency-broadened spectrum associated with electron trapping. However, in this regime, phenomena such as wavebreaking are more likely to occur [38]. In the fluid regime with k p λ D < 0.29, LDI will take place, which could be one of the saturation mechanisms of SRS.…”

CBETor: a hybrid-kinetic particle-in-cell code for cross-beam energy transfer simulation

“…The main methods to study parametric instability include the three-wave coupling model [14], fluid simulation [15,16] and kinetic simulation [17][18][19][20][21]. The three-wave-coupling model can predict physical properties, such as instability growth rate through reasonable linearization approximation, which has high computational efficiency but ignores kinetic and nonlinear effects.…”

“…Fully kinetic simulation including the Vlasov method [17][18][19] and the particle-in-cell (PIC) method [20] can accurately simulate the kinetic and nonlinear effects, but the computational cost is very large because the fast electron time scale must be resolved. If the considered physical process is dominated by ion motion, such as SBS or CBET, hybrid-PIC modeling (fluid electron/particle ion) [21][22][23] is an appropriate method, which can not only obtain dominant characteristics of the physical system, but also greatly improve computational efficiency.…”