Developments of Laser-Aided Plasma Diagnostics for Fusion Plasmas

点击翻译按钮获取中文摘要

In the rmonuclear fusion research, the breskeven plasma condition has been attained, and preparations are underway for the real D-T fusion burning experiments. Here, tritium handling and neutron-induced radioactivity of wall materials are the most cirtical issues, and realization of remote handling has been pursued. Regarding the plasma diagnostics, it is necessary to get as many data as possible from limited port access.This research was planned to test the laser-aided plasma diagnostics, which had been developed by the present principal investigator and his collaborators, to JET plasmas. The JET project plans to undertake a real DT fusion-burning experiment.The contents of the research are three-folds.(1) LIDAR Thomson scatteringThomson scattering for measurements of electron temperature (T_e) and density (n_e) usually requires large laser input/output ports and a scattering observation ports. However, it is difficult to install these ports to a fusion burning plasma machine, because … More of the presence of tritium breeding blankets and superconducting magnets. LIDAR Thomson scattering mostly solves this difficulty, and the collaborative research has been carried out between the group of Kyusyu University and JET for the last ten years.The researches are divided into two studies. One is to measure T_e and n_e in the core plasmas routinely and reliably. This has been very successful, as the core LIDAR system is now routinely supplying data of T_e and n_e at the spatial resolution of 90 mm at 2 Hz. Also, the streak camera system for improving the spatial resolutuin is working successfully, yielding the spatial resolution of 50 mm. On the other hand, the LIDAR system looking at the divertor region is yet to produce scattering signal, because of the difficulty of alignment of the laser and detection optics. Further collaborative studies will be carried out after the termination of this collaboration study.(2) Collective Thomson scatteringThe first data of collective Thomson scattering, oftained in 1995, have been thoroughly analyzed, and the directions of improvement have been considered.The big impact of the present research is the formation of study group of the collective Thomson scattering using a CO_2 laser formed by the Japanese, European and American researchers, and the first activity took place in December 1996. Actual measurement plans on JT-60U at JAERI were discussed, and the experiment will start from the fiscal year 1998.(3) Planning of burning plasm diagnostics in generalThoughout the execution of this collabrative research, the mutual trust of Dr.P.E.Stott and the present principal inrstigator has brought about the formation of the Expert Group of Diagnostics for ITER (International Thermonuclear Experimental Reactor), together with Dr.K.Young of Princeton University. The work in the present collaborative research has been reflected in this Expert Group activities, and international meetings have been organized. Less