非均匀等离子体中1/4临界密度附近受激散射的非线性演化  

Nonlinear evolution of stimulated scattering near 1/4 critical density

作　　者：吴钟书 赵耀 翁苏明 陈民 盛政明 Wu Charles F.;Zhao Yao;Weng Su -Ming;Chen Min;Sheng Zheng -Ming(Key Laboratory for Laser Plasmas, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China;Key Laboratory of High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences, Shanghai 201800, China;Tsung-Dao Lee Institute, Shanghai 200240, China)

机构地区：[1]上海交通大学物理与天文学院,激光等离子体教育部重点实验室,上海200240 [2]中国科学院上海光学精密机械研究所高功率激光物理联合实验室,上海201800 [3]李政道研究所,上海200240

出　　处：《物理学报》2019年第19期155-164,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11775144);上海市自然科学基金(批准号:19YF1453200)资助的课题~~

摘　　要：本文采用粒子模拟方法,针对长脉冲激光在非均匀等离子体中的传输过程,特别是在 1/4 临界密度附近,等离子体中受激散射的非线性演化现象,进行了细致的模拟研究.研究结果表明:在 1/4 临界面附近所产生的受激拉曼散射不稳定性,其散射光在等离子体中被捕获,并在该区域形成电磁孤子.电磁孤子的振幅随着不稳定性的发展而提高,并由此而产生一个有质动力场驱动周围的电子运动,离子随后被电荷分离场加速,最终形成准中性的密度坑.在单个密度坑形成后,由于该密度坑周围等离子体密度和温度产生了变化,使得等离子体中逐渐形成更多的密度坑.这些密度坑将等离子体分割成不连续的密度分布,而这种密度分布最终明显地抑制了受激拉曼散射和受激布里渊散射不稳定性的发展.Based on particle-in-cell simulations, the propagation of intense long pulse lasers in non-uniform plasma, and particularly, the formation of plasma density cavities caused by the nonlinear evolution of stimulated Raman scattering (SRS) near the quarter critical density, and its effects on parametric instabilities have been studied. It is found that the stimulated Raman scattering instability developed near the quarter critical density leads to the trapping of scattered light and subsequent formation of a local electromagnetic solitary wave. Its amplitude increases with the development of the SRS instability, which pushes surrounding electrons and ions to form a quasi-neutral density cavity. When the first density cavity is formed, the plasma density evolves in such a way that more density cavities are formed during the laser interaction and subsequently the plasma is split into a few discontinuous portions. This new density profile finally tends to suppress the development of both SRS and the stimulated Brillouin scattering (SBS) instabilities considerably.

关 键 词：受激拉曼散射 电磁孤子 激光传输 PIC 粒子模拟 

分 类 号：O53[理学—等离子体物理]