激光等离子体拍频波加速器中泵浦倒空的消除

泵浦倒空是限制激光等离子体拍频加速器概念成为现实的严重问题。本文从电子等离子体波拍频激发的弱相对论性方程出发,在光脉冲坐标中导出了对任意形状的泵浦脉冲消除倒空的条件。研究表明,只要泵浦光在脉冲中心有π位相突变,并且适当选取初始等离子体密度离谐,就可消除泵浦倒空。对于方形泵浦脉冲,本文数值计算了初始离谐随泵浦光强的变化关系,并证实了本文提出的消除泵浦倒空方法的正确性。 关键词：

THE ELIMINATION OF PUMP DEPLETION IN LASER-PLASMA BEAT-WAVE ACCELERATORS

The pump depletion is a severe problem which hinders the laser-plasma beat-wave accelerator concept from being practical. Starting with the weak relativistic equation of beat-wave excitation of electron plasma waves, we have derived the condition for eliminating the pump depletion in the frame moving with the light pulse for arbitrary pulse shapes. It is shown that the depletion can be eliminated by a phase jump of π at the center of the pump pulse and by the appropriate choice of initial plasma density detuning. The numerical calculation have yielded the dependence of the initial detuning on the pump intensity for square pump pulses, and have supported the methods used in this paper.