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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。
The electrical pulse radiation generated by the interaction between pulsed laser and metal target was measured experimentally in SG-Ⅲ prototype apparatus. The peak gradient of the electric pulse is 3 kV / m, the spectral range is about 50 MHz ~ 2 GHz, at 160 MHz There are obvious characteristic peaks, the signal duration of about 60 ns. The research shows that the electric dipole radiation is one of the sources of the electromagnetic pulse signal during the shooting process. The characteristic peak with the frequency of 160 MHz is calculated from the theoretical model and the pulse peak gradient of the probe point is calculated to be about 2 kV / m. The total power of about 105 W, the energy conversion rate of about 10-6, the radiation power is approximately proportional to the 4/3 power laser energy, shows that the greater the laser energy, the higher the power density, the greater the electrical pulse radiation intensity. The measurement of the electromagnetic pulse generated by the laser and the target on a large laser device plays an important guiding role in the protection of the electromagnetic radiation generated by a large laser device and has potential application value in the fields of plasma diagnosis and the like.