神光-Ⅲ原型高功率激光装置电磁脉冲辐射

Investigation of electromagnetic pulse emission from Shenguang high power laser facilities

实验测量了神光-Ⅲ原型装置上脉冲强激光与金属靶相互作用产生的电脉冲辐射,电脉冲峰值梯度为3 k V/m,频谱范围大约在50 MHz～2 GHz,在160 MHz等处有明显的特征峰,信号持续时间大约60 ns。本文研究表明电偶极辐射是打靶过程产生电磁脉冲信号的来源之一,由理论模型计算得到频率为160 MHz的特征峰,并计算出探测点电场脉冲峰值梯度约为2 k V/m,辐射总功率约105 W,能量转换率约10-6,辐射功率近似正比于激光能量的4/3次方,可见激光能量越大,功率密度越高,电脉冲的辐射强度越大。大型激光装置上的激光与靶作用产生的电磁脉冲测量,对大型激光装置产生的电磁辐射的防护有重要指导作用,在等离子体诊断等领域也有潜在应用价值。

Electromagnetic pulse emission of Shenguang-III prototype laser facilities from pulse-laser-irradiated metallic target is evaluated by using B-dot. An electric signal lasting for about 60ns is detected in the experiment, with radiated field up to 3 kV/m and frequency bins for 0.1GHz-2 GHz which has an obvious peak at 160 MHz. The results demonstrate that the model of dipole radiation is one of the major mechanisms of electromagnetic pulse emission from laser-target interaction. The dipole radiation model can produce about 105 W, 160 MHz central frequency electromagnetic pulse with an energy conversion efficiency of 10-6 according to the calculation, and the electric field of antenna position is about 2 kV/m. This experiment evaluates the electromagnetic pulse emission from pulse-laser-irradiated metallic target on Shenguang-III prototype laser facilities, which is of great significance for shielding electromagnetic disturbance of diagnostics on large laser facilities. Moreover, investigation of electromagnetic pulse emission may have many potential applications.