在激光尾场加速中电子密度和初始动量对其自注入及加速的影响

The Effects for Density and Initial Momentum of Electrons on the Self-Injection and Acceleration in Laser Wakefield Acceleration

利用哈密顿理论给出了等离子体电子在尾场中捕获及其加速与激光、等离子体参量的关系表达式.讨论了等离子体电子密度和初始动量对电子自注入和加速的影响机制.研究结果表明:静止电子不能被尾场捕获并加速,而具有一定初始动量的电子容易自注入至激光尾场中并得到加速.等离子体密度越小,激光尾场场强越强,电子将获得更大的能量.2维粒子模拟结果与理论结论一致.所得结果对超强超短脉冲激光尾场加速电子的方案具有理论指导意义.

The equation of electron momentum in the wakefield during the laser-plasma interaction has been derived by using the Hamiltonian theory. The dependences of electron self-injection and acceleration on the plasma density and initial momentum have been discussed in detail. It is found that electrons with certain initial momentum can be trapped and accelerated forward in the wakefield, while electron with Px0=0 participates in the wake field oscillation. The lower the plasma density is, the larger the electron momentum is, i. e. , the electron gains more energy. The theoretical results are consist with those of PIC simulations. The results may be significant theoretically to the mechanism of uhraintense laser-wakefield acceleration.