双束“自陷”激光驱动的电子等离子体波的拍频激发

本文提出并详细研究了应用两束“自陷”激光激发电子等离子体波(EPW)来维持等离子体拍频加速器(PBWA)中光束及其激发的EPW的会聚。文中导出了EPW饱和振幅所满足的方程,自洽地研究了泵浦光束的“自陷”条件,并解析地得到了最佳离谐条件及其对应的最佳初始等离子体密度以及EPW的最大振幅。在高斯型自陷泵浦光束情况下,文中应用数值法计算了EPW的横向分布。对于一定的离谐参量,此分布呈现出独特的性质。此外,本文还得到了由泵浦光束的非均匀性所产生的EPW电场的径向分量,并简要地讨论了它对PBWA中粒子加速的影响。关键词：

EXCITATION OF ELECTRON PLASMA WAVES BY BEATING TWO SELF-TRAPPED LASER BEAMS

This paper presents and analyzes the focusing of pump beams and the excited EPW (electron plasma wave) in a PBWA (plasma-beat-wave accelerator) by beating two self-trapped laser beams. The equations governing the saturated amplitudes of EPW in nonuniform pump beams have been derived analytically. With these, the condition for self-trapping of pump beams has been studied self-consistently. The optimum frequency mismatch parameter and the corresponding optimum initial plasma density as well as the maximum amplitde of the EPW have been obtained analytically. The transverse distribution of the EPW for Gaussian pump profiles has been calculated numerically and shows peculiar characteristics for certain frequency mismatch parameters. In addition, the component of the EPW electric field due to the nonuninformity of pump beams has been obtained and its influence on particle acceleration in PBWA has been briefly discussed.