相位反射产生的激光场空洞现象及其与激光等离子体参数相关性研究

理论研究和数值模拟研究表明激光在等离子体中诱导的等离子体密度调制可以起类似布拉格反射镜的作用，使得后面的入射光在等离子体平均密度远低于临界密度的区域就对入射光产生相位反射.相位反射的发生会影响激光在等离子体中的传播，例如激光在等离子体中相对传播时会出现激光场空洞现象.进一步的理论和数值模拟研究表明，相位反射持续发生的时间以及反射率的高低与等离子体的密度、等离子体区域的长度、激光强度以及脉宽等因素密切相关，这些都会对激光在等离子体中的传输产生影响. 关键词： 相位反射 密度调制 激光等离子体 粒子模拟

Vacancy of laser field induced by phase reflection in underdense plasmas and its relation to laser-plasma parameters

It is shown theoretically and by particle- in-cell simulations that the plasma density modulation produced by laser in underdense pre-plasmas can serve as a Bragg reflector, which results in phase reflection occurring at low-density plasma area. The phase reflection can influence the laser propagating in plasmas, such as the vacancy of laser field induced by two laser pulses counter-propagating in plasmas. It is also shown that the period of phase reflection and the reflectivity are related with the plasma density, thickness, intensity and the duration of laser.