The effects of incident light wavelength difference on the collective stimulated Brillouin scattering in plasmas
Qiang Wang, Zhichao Li, Z. J. Liu, Tao Gong, Wen-shuai Zhang, Tao Xu, Bin Li, Ping Li, Xin Li, Chunyang Zheng, L. H. Cao, Xincheng Liu, K. Q. Pan, H. Zhao, Yonggang Liu, Bo Deng, Lifei Hou, Yingjie Li, Xiangming Liu, Yulong Li, Xiaoshi Peng, Zanyang Guan, Qiangqiang Wang, Xingsen Che, Sanwei Li, Qiang Yin, Wei Zhang, Liqiong Xia, Peng Wang, Xiaohua Jiang, Liang Guo, Qi Li, Minqing He, Liang Hao, Hongbo Cai, Wudi Zheng, Shiyang Zou, Dong Yang, Feng Wang, Jiamin Yang, Baohan Zhang, Yongkun Ding, X. T. He
Abstract
The first laser–plasma interaction experiment using lasers of eight beams grouped into one octad has been conducted on the Shenguang Octopus facility. Although each beam intensity is below its individual threshold for stimulated Brillouin backscattering (SBS), collective behaviors are excited to enhance the octad SBS. In particular, when two-color/cone lasers with wavelength separation 0.3 nm are used, the backward SBS reflectivities show novel behavior in which beams of longer wavelength achieve higher SBS gain. This property of SBS can be attributed to the rotation of the wave vectors of common ion acoustic waves due to the competition of detunings between geometrical angle and wavelength separation. This mechanism is confirmed using massively parallel supercomputer simulations with the three-dimensional laser–plasma interaction code LAP3D.