三角激光脉冲尾波加速粒子模拟

电子俘获是激光尾波场加速电子的主要机理，增大电子的初速度可以使更多的电子被尾波场俘获.提出三角脉冲激发尾波加速电子的方案，三角脉冲平缓上升沿激发受激Raman散射，用以初步加速电子，三角脉冲陡峭下降沿激发尾波场，将更多的电子加速到接近光速.2D3V粒子模拟结果证实了这一点.同时表明：脉冲长度为几个等离子体波长的超强激光在稀薄等离子体中传播时，还激发侧向Raman散射.在侧向受激Raman散射中，静电波增长最快的波矢模式为k_p=(2ω_p/ω₀ 关键词： 有质动力 电子俘获 前向受激Raman散射 侧向受激Raman散射

PIC simulation of the wake field acceleration driven by triangle-shaped laser pulse

“Electron trapping” is the main acceleration mechanism in the laser wakefield acceleration, and the theoretical analysis indicates that more electrons are trapped when the initial velocity of the electrons are increased. A new wakefield acceleration scheme named “triangle-shaped laser pulse wakefield acceleration” is proposed and tested by 2D3V PIC simulation. The slow-rising part of the triangle-shape will excites stimulated Raman scattering(SRS) which preheats electrons while the sharp-descending part of the pulse drives the wakefield to trap more electrons. Our simulation also indicates that the side stimulated Raman scattering (SSRS) is the main instability when the length of the incident laser pulse is greater than the plasma wavelength. Furthermore, the electrostatic wave mode with the greatest growth rate in SSRS is always the one with the largest wave vector k_p=(2ω_p/ω₀)^1/2, and the scattering angle satisfies θ=cos^-1(2ω_p/ω₀).