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Studies of Laser-Aided Plasma Diagnostics on Fusion Machine

聚变机激光辅助等离子体诊断研究

基本信息

批准号：
03044110
负责人：
MURAOKA Katsunori
金额：
$ 3.84万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03044110/
关键词：
Laser Diagnostics Fusion Plasmas JET LIDAR Thomson Scattering Steak Camera Collective Thomson Scattering Atomic Hydrogen Two-Photon Excited Laser Fluorescence レ-ザ-計測核融合プラズマ LIDAR法レ-ザ-蛍光法ポンプダイバ-タ電子温度・密度水素原子密度

项目摘要

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 … More 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. Less

本研究的目的是将九州大学开发的激光辅助等离子体诊断方法应用于大尺寸聚变等离子体装置，并验证其有效性，该装置由于在DT燃烧期间存在大型加热系统、偏滤器板和中子屏蔽（以及最终用于超导磁体的低温恒温器）而具有有限的光学访问。为此，我们开展了三项研究计划。这三个目标是：（1）以高的空间和时间分辨率测量电子温度和密度;（2）研究测量电子密度涨落的可能性，电子密度涨落被认为是导致等离子体在磁场中快速损耗的原因;（3）研究测量磁场中Aloha粒子的密度和速度分布的可能性。研究的主要结果如下：对于第（1）项，JET先前引入了LIDAR Thomson散射，以克服Sham散射。 ...更多信息传统的汤姆逊散射需要两个大窗口，用于测量电子温度和密度。然而，由光电倍增管的响应时间决定的LIDAR汤姆逊散射的空间分辨率超过120 mm有时是不够的。我们已经开发了一种技术，利用条纹相机作为探测器，以提高响应时间的探测器，从而提高了空间分辨率为50毫米。使用这种设备，已经出现了一个精细的结构的电子密度，特别是在等离子体边缘和弹丸燃料放电，其中存在一个大的密度密度梯度。为了改善这些测量的时间特性，需要一种新的激光器，我们提出了用激光脉冲压缩的方法来获得这种激光器。对于第（2）项，我们研究了我们发展的用于测量电子密度起伏的激光相衬法对JET等离子体的适用性，发现这是可行的。对反射计测量中电子密度起伏的局部化问题进行了理论研究，发现反射激光处的起伏对信号的影响最大，对第（3）项，从理论上分析了速度分布对回旋散射测量信号的影响，并在此基础上对测量精度进行了讨论。此外，还与JET的工作人员一起为计划于1993年下半年进行的主要DT实验做了回旋管实验的准备工作。除了这些计划外，在这种合作过程中，我们认识到了测量偏滤器区氢原子密度的重要性。为此，我们提出了双光子激发激光诱导荧光技术，并进行了JET的设计研究，总结了这些结果，获得了聚变等离子体激光诊断的重要信息，展示了新的诊断方法的潜力。这些发现将用于设计和执行下一代聚变机器，如ITER的测量。少