石墨锥型高能激光全吸收能量计设计

Design of Graphite-Cone-Absorption-Cavity Absolute Energy Meter for High Energy Laser

在高能激光能量计吸收体上很长时间内均存在较大的温度梯度,这导致吸收体真实温度的测量非常困难,材料的比热、传感器的响应度和吸收体的热损失对测量准确度的影响较显著,模拟了吸收体上温度场特性,提出了一种利用多个分立的热电偶传感器测量吸收体的温升的方法,通过对热电偶的间距以及在吸收体中的深度加以控制,可以准确地反映吸收体上每一小部分的平均温度,从而达到对比热和传感器响应度修正的目的;采取措施大幅降低热损失比例,并结合实际温度场分布和系统热平衡时间对热损失可以获得热损失占比;利用光线追迹方法可以大幅简化吸收体吸收率研究,以实际光束和吸收腔参数为模拟对象计算了吸收腔的吸收率,并对测量结果进行修正。在分析了系统各个环节的测量不确定度的基础上估算出设计的激光能量计的测量不确定度约为5.8%(k=2),采用现场比对方法验证该测量不确定度的合理性。

There is great temperature gradient in the absorber of the high energy laser energy meter for a long time, which results in great difficulties in measuring the real temperature of the absorber. In this situation, the accuracy of the energy meter is affected by the heat specific of the material, the responsibility of the temperature sensors and the heat loss. The temperature field of the absorber is simulated, and then a method that multiple discrete thermocouple sensors are used to measure the temperature rise of absorbers is introduced. The average temperature of each small segment in the absorber can be exactly obtained by controlling the distance of the adjacent thermocouples and the depth of the thermocouples, so as to calibrate the heat specific and the responsibility of the temperature sensors. The measurements are taken to decrease the rate of the heat loss and the heat loss can also be calibrated after obtaining the real temperature distribution and the time of the thermal equilibrium. The research on the absorption coefficient is facilitated with the ray tracing method. The absorption coefficients with the parameters of the real beams and the real absorption cavity are calculated and the measurement results are calibrated. According to the uncertainty of the each process, the estimate of the measurement uncertainty of the laser energy meter is 5.8% （k=2）, and the rationality of the measurement uncertainty is verified with the comparison method.