SUMMERS D.D. JET共同研究機構, 実験第I部門, 主任研究員
MARGAN P.D. JET共同研究機構, 実験第I部門, 主任研究員
GOWERS C. JET共同研究機構, 実験第I部門, 主任研究員
NIELSEN P. JET共同研究機構, 実験第I部門, 研究員
COSTLEY A.E. JET共同研究機構, 実験第I部門, グループリーダー
松尾 敬二 九州大学, 総合理工学研究科, 助手 (10199755)
梶原 寿了 九州大学, 総合理工学研究科, 助教授 (00185779)
矢野 栄宣 九州大学, 総合理工学研究科, 助手 (20117279)
内野 喜一郎 九州大学, 総合理工学研究科, 助教授 (10160285)
益田 光治 九州大学, 総合理工学研究科, 教授 (40038097)
STOTT P.E. JET共同研究機構, 実験第I部門長, シニアスタッフ長
P.D Morgan JET共同研究機構. 実験第一部門, 主任研究員
P Nielsen JET Joint Undertaking, 主任研究員
D.D.R Summer JET共同研究機構. 実験第一部門, 主任研究員
C Gowers JET共同研究機構. 実験第一部門, 主任研究員
A.E Costley JET共同研究機構. 実験第一部門, グループリーダー
御手洗 修 熊本工業大学, 助教授 (00181925)
P.E Stott JET共同研究機構, シニア・スタッフ・実験第一部門, 部門長
C. Gowers JET Joint Undertaking
A E Costley JET Joint Undertaking
MITARAI O Kumamoto Institute of Technology
MATSUO K Kyushu University
KAJIWARA T Kyushu University
P.D. Morgan JET Joint Undertaking
UCHINO K Kyushu University
YANO H Kyushu University
P.E. Stott JET Joint Undertaking
MASUDA M Kyushu University
D.D.R. Summers JET Joint Undertaking
the objective of this research is to apply the laser-aided plasma diagnostic methods developed Kyushu University, to a fusion plasma device with large dimension, which has a limited optical access due to the presence of large heating systems, divertor plates and neutron shielding during DT burning (and eventually a cryostat for superconducting magnets), and to verify their usefulness. We have performed three research programmes for this purpose. These are, (1) to measure electron temperature and density with high spatial and temporal resolutions, (2) to investigate a possibility of measuring electron density fluctuations, which have been believed to be responsible for an anomalously fast plasma losses across a magnetic field, and (3) to investigate a possibility of measuring density and velocity ditribution of aloha particles confined in a magnetic field. Main results of the study is as follows.
For the item (1), JET had previously introduced a LIDAR Thomson scattering t overcome the sh
ortcoming of the conventional Thomson scattering, which required two large windows, for measurements of electron temperature and density. However, the spatial resolution of the LIDAR Thomson scattering, decided by the responce time of a photomultiplier, of more than 120 mm was sometimes not sufficient. We have developed a technique to utilize a streak camera as a detector to improve the responce time of the detector, and consequently the spatial resolution was improved to 50 mm. Using this device, a fine structure of electron density has been emerged, especially at the plasma edge and during the pellet-fueled discharges, where a large density density gradient existed. In to order to improve the temporal behavior of these measurements, a new laser is required and we proposed t get such a laser using a laser pulse compression scheme.
For the item (2), We studied an applicability of laser phase contrast method, which we have developed for measurements of electron density fluctuations, to JET plasmas, and found that this is feasible. Also, a theoretical study was carried out about the localization of electron density fluctuations on a reflectometer measurement, and it was found that fluctuations at the reflecting laser most profoundly affected the signal.
And for the item (3), the effect of velocity distribution on the measured signal of gyrotron scattering was assessed theoretically, and the measurement accuracy was discussed based on the result. In addition, a preparation of the gyrotron experiment was made, together with the JET staff, for the main DT experiment planned from the latter half of the year 1993.
In addition to these programmes, in the course of this collaboration, we have recognized the importance of measuring atomic hydrogen density at the divertor region. For this measurement, we proposed two-photon excited laser induced fluorescence, which we have developed at our laboratory, and design study for JET was performed.
Summarizing these results, we gained a very valuable information of fusion plasmas using laser diagnostics, and showed potentials of new diagnostics. These findings will be used for the design and execution of measurements on the next generation of fusion machine, such as ITER.