两种Z箍缩X射线总能量测量技术对比

摘要

薄膜量热计和闪烁探测系统是国内常用于 Z 箍缩辐射总能量测量的两种诊断手段。两种方法基于完全不同的诊断原理，通过对比其诊断结果可以提高 Z 箍缩 X 射线总能量测量的精度，加深对 Z 箍缩的理解。采用上述两种诊断装置对“强光一号”加速器 Z 箍缩实验中多种材料和构型的负载辐射总能量进行了测量。结果表明，对于 Al 丝阵负载，无论是单排还是双排平面丝阵，随着负载参数的变化，两种手段总能量测量结果均发生改变且呈正比，二者符合较好；但对于镀膜 W 丝阵两种方法的诊断结果差异较为明显，随着丝间距的增大，量热计测量结果明显减小，但闪烁探测系统的测量结果却变化较小，二者不再呈比例关系。通过模拟计算对产生上述现象的原因进行了分析，可以得出如下结论：（1）闪烁探测系统对低能光子响应较高，且响应能谱范围较量热计宽，因此所有的总能量测量结果比量热计测量结果略大；（2）Al 丝阵等离子体辐射能谱分布范围较宽，主要辐射能段处于两种测量手段响应都比较平坦的区间内，因此两种手段测量结果符合较好；（3）W 丝阵辐射主要集中在1 keV 以下的软 X 射线能段，处于镍薄膜全吸收范围内，因此量热计测量结果应该是比较准确的；（4）对于闪烁探测系统测量结果对镀膜 W 丝阵负载参数不敏感的现象，一种可能的解释是：随着 W 丝阵丝间距增大，等离子体滞止时刻的温度减低，导致能谱软化，但辐射谱型向闪烁体灵敏度较高的方向移动。因此虽然总能量降低了，但闪烁探测系统的测量结果变化却不大；（5）辐射中电子的影响同样不可忽视。%Resistive bolometer and scintillant detection system are two mainly Z-pinch X-ray yield measure techniques which are based on different diagnostic principles.Contrasting the results from two methods can help with increasing precision of X-ray yield measurement.Experiments with different load material and shape were carried out on the “QiangGuang-I”facility.For Al wire arrays,X-ray yields measured by the two techniques were largely consistent.However,for insulating coating W wire ar-rays,X-ray yields taken from bolometer changed with load parameters while data from scintillant detection system hardly changed.Simulation and analysis draw conclusions as follows:(1)Scintillant detection system is much more sensitive to X-ray photons with low energy and its spectral response is wider than the resistive bolometer.Thus,results from the former method are always larger than the latter.(2)The responses of the two systems are both flat to Al plasma radiation.Thus,their results are consistent for Al wire array loads.(3)Radiation form planar W wire arrays is mainly composed of sub-keV soft X-ray.X-ray yields measured by the bolometer is supposed to be accurate because of the nickel foil can absorb almost all the soft X-ray.(4) By contrast,using planar W wire arrays,data from scintillant detection system hardly change with load parameters.A possible explanation is that while the distance between wires increases,plasma temperature at stagnation reduces and spectra moves to-ward the soft X-ray region.Scintillator is much more sensitive to the soft X-ray below 200 eV.Thus,although the total X-ray yield reduces with large diameter load,signal from the scintillant detection system is almost the same.(5)Both Techniques af-fected by electron beams produced by the loads.