Measurement of the Energy Fluence Radiated by a Z-Pinch X-Ray Source Using a Pinhole Array as an Attenuator

Z-pinches can be used as a soft X-ray source to investigate the radiation coupling of planetary materials such as Fe and Al and the response of the sample to stress waves. In these experiments, the energy fluence on the sample must be measured, and a novel measurement presented in this article is just designed to determine the energy fluence incident on the target. The measurement system consists of a pinhole array and a nickel foil bolometer, while the pinhole array is used to attenuate the X-ray flux in an achromatic manner. Compared with the traditional means, this method is a direct measurement of the energy fluence, while the traditional way is deducing the fluence value based on the premise of an inverse-square radial dependence along a line-of-sight distance. Furthermore, this new method allows reduction of the X-ray intensity to avoid saturation problems while avoiding the spectral dependency of thin-film filters. This achromatically filtered bolometer has been installed on the Qiangguang-I facility to monitor the energy fluence on the target located 5 cm from the Z-pinch source, the diameters of samples are usually 1 cm or so, and the corresponding solid angles are 0.01p. The experimental results show that the pinhole array is feasible to be used as an attenuator. Furthermore, it can mitigate the nonuniformity of the radiation flux on the target when the Z-pinch X-ray source is distorted by magnetohydrodynamics (MHD) instability. The measured data on Qiangguang-I show that the energy fluence incident on the test object obeys the inverse-square law when the distance is bigger than 5 cm.