Development of Measuring System of Density and Velocity Distribution Function of Atomic Hydrogen in the Edge Region of High-Temperature Plasmas

到目前为止，人们已经很好地认识到，了解粒子行为，特别是原子氢行为，是有效控制高温等离子体密度和长期保持高温等离子体的先决条件。为此，上述研究人员提出开发一种利用双光子激发的激光诱导荧光(LIF)技术。该方案是用高功率的喇曼位移ArF激光将原子氢从基态(n=1)激发到n=3或n=4，并探测到在Balmer跃迁产生的荧光。通过两年的研究，取得了以下成果：(1)在利用ArF激光及其拉曼频移光激发双光子的可能方案中，(A)(205*2)nm，(B)(193+219)nm，(C)(193+195)nm，从实验和理论上评价了最佳方案。这里，通过TH…的第一次斯托克斯转换获得205 nm处的光，并通过第二次斯托克斯转换获得219 nm处的光在D_2气体中获得了更多的ArF激光，在H_2气体中通过ArF激光的转动喇曼频移获得了195 nm的激光。因此，(A)和(B)同时工作，并且来自这两个过程的可获得的信号比(C)大10倍。因此，我们得出结论：(A)和(B)相结合是达到此目的的最佳方案。(2)利用滴定过程，我们对系统进行了校准，得到原子氢密度的测量误差在&lt；正负&gt；20(3)通过测量激光聚焦时沿激光路径的荧光信号，我们估计了激光光束的大小，当该方案应用于高温等离子体中的实际测量时，得到了更好的信号强度估计。(4)基于上述结果，我们估计了设想的JFT-2M上的光学系统的可获得的信噪比。(5)利用研究小组开发的分析技术对原子氢行为进行了深入的研究。然后，建立了扩散系数和粒子约束时间的详细数据库。较少

It has by now been well recognized that understanding of particle behavior, in particular atomic hydrogen behavior, is prerequisite for effective density control and long-time maintenance of high-temperature plasmas. For this purpose, the above investigators proposed to develop a technique of the laser-induced fluorescence (LIF) using the two-photon excitation. The scheme is to excite atomic hydrogen from its ground leved (n=1) to n=3 or n=4 using powerful Raman-shifted ArF laser light, and the resultant fluorescence at Balmer transitions is to be detected. By the two-year-project, the following results have been obtained.(1) Among the possible excitation schemes for the two-photon excitation using ArF laser and its Raman shifted lights, namely (a) (205*2) nm, (b) (193+219) nm, and (c) (193+195) nm, the best scheme was experimentally and theoretically assessed. Here, the light at 205 nm was obtained by the first Stokes conversion and that at 219 nm by the second Stokes conversion of th … More e ArF laser in D_2 gas, and that at 195 nm by the rotational Raman shifting of the ArF laser in H_2 gas. For this reason, (a) and (b) are operative at the same time, and the obtainable signal from the both processes are 10 times larger than for (c). Therefore, we conclude that the combination (a) and (b) to be the best scheme for the purpose.(2) Using the titration process, we calibrated the system, yielding the measurement error of atomic hydrogen density to be within <plus-minus>20(3) By measuring fluorescence signals along the laser beam path when the laser was focused, we estimated the laser beam size, yielding better estimate of the signal intensity when the scheme is to be applied to actual measurements in high-temperature plasmas.(4) Based upon the above results, we estimated obtainable SN ratios for an envisaged optical system on JFT-2M.(5) Atomic hydrogen beheviour was also thoroughly investigated using the analysis technique developed by the investigators'group. Then, detailed database has been accumulated for diffusion coefficients and particle confinement time. Less