强激光在等离子体中的传播特性

Non-Relativistic Intense Laser Propagation Characteristics in the Plasmas

分别讨论了在非相对论条件下短脉冲和长脉冲激光在完全电离的等离子体中的传播持性。短脉冲情况下 ,激光的有效瑞利长度会增加 ,但不会出现自导引 ;长脉冲激光的传播取决于激光功率和等离子体温度之比 ,当该比值超过一定阈值时会出现自导引现象 ,激光束被限制在一个相对稳定的通道内 。

In the non-relativistic limits, long pulses and ultra-short pulses laser propagation characteristics in the fully-ionized plasma are discussed. The electron density distribution can be derived from the balance of the pondermotive force with the thermal force in long pulses and with the electrostatic force in ultra-short regime. Using the source-dependent expansion (SDE) method, the laser field propagation characteristics in plasma can be described through the numerical solution of the enveloped equation. In long pulses, the self-guiding, which means the laser spot size oscillates in the spread direction, will appear if the ratio of the laser power and the plasma temperature exceeds the threshold. The guiding cannel is steady in some initial laser spot size and the optimal condition to produce the narrowest steady channel is found. In ultra-short pulses, the effective Rayleigh length of laser increases but self-guiding does not occur according to the numerical solution and theoretic analysis.