参加報告：HEDS diagnostics course in Spring quarter of 2025（大阪大学・JINYUAN DUN）

カリフォルニア大学サンディエゴ校とローレンス・リバモア国立研究所が提供する大学院レベルの高エネルギー密度プラズマ計測に関する10回のオンライン講義が拠点事業の一環として行われました。
参加したJINYUAN DUNさんからの報告です。

During the spring of 2025, I have the opportunity to attend the High-Energy-Density Science (HEDS) diagnostics course held by Lawrence Livermore National Laboratory (LLNL), Sandia National Laboratory (SNL), UC San Diego (UCSD), General Atomics, and the Japan Society for the Promotion of Science (JSPS). The lecture mainly focused on the diagnostics technologies for HED plasmas experiments, with the physics basics behind different diagnostics, and the engineering of the measurement techniques. The lectures cover three large facilities: National Ignition Facility (NIF) at LLNL, OMEGA laser facility at the University of Rochester, and Z machine at Sandia National Laboratories.

The whole lecture introduced several different diagnostic techniques within 4 topics: Fusion-related diagnostic engineering, optical diagnostics, X-ray diagnostics, and generalized techniques. The fusion-related diagnostics mainly focused on neutron diagnostics, including DT reaction yield measurement, temperature and density measurement, nuclear burn measurement, time-of-flight (TOF) measurement, and neutron imaging, and the fusion target fabrication techniques, including optical, X-ray, and interferometry techniques for judging the smoothness of the fusion fuel capsule. Finally, we have learned an overview of the diagnostic engineering requirements, which are crucial in our experiment at ILE. The optical diagnostics part mainly includes Thomson Scattering techniques, for both optical and X-ray, and the Velocity Interferometer System for Any Reflector (VISAR) technique. The Thomson scattering is a powerful diagnostic technique, which can provide us with detailed plasma conditions, for both temperature and density; and the VISAR diagnostic provides us with the capability to accurately measure the velocity of the shock front. The X-ray diagnostics part mainly discussed the hohlraum temperature measurement, spectroscopy, and imaging techniques, and this part is most related to my research. I have systematically learned about the diode array detector (Dente) for hohlraum radiation temperature measurement, the advanced time-resolved measurement using X-ray streak cameras and ns-gated hybrid CMOS detector in NIF, the details for both solar opacity experiment and fusion implosion experiment, and very detailed X-ray/particle radiography techniques. This information gives me a huge help and provides me with excellent references for my own research. Finally, in the last part, we have learned about different diagnostics techniques on Z-pinch facilities, and most importantly, we have learned about the data analysis techniques. In my personal opinion, the data analysis should have the same importance as the digitized diagnostics. A fully digitized diagnostics system can be coupled with a large-scale analysis system, providing us with the standardized data format for analysis, just like in the high-energy physics area, and the scientists can work much more efficiently with such platforms.

This lecture provided me with a valuable opportunity to learn about the scientific progress at NIF and gave me extremely valuable information and knowledge for my research. There are only a few facilities around the world working on the solar opacity experiments, so it is very important to obtain as much information from them to upgrade our own experiments. I am very glad that my supervisor, Prof. Shinsuke Fujioka, provided me with the information and the opportunity. The experience and knowledge I have gained from the lecture will help me with future research.