ROLES AND PRODUCTION MECHANISM OF ENERGETIC PARTICLES AT SELF-ORGANIZATION IN REP

本研究的目的是对日本京都工业大学STE-2 RFP中高能粒子的产生机制有所了解。在第一年，建造了一个x射线探针，由金属靶和带有聚酯过滤器的表面势垒二极管组成。同时，研究了导电壳（b/a，其中b和a分别为等离子体和壳小半径）距离对REP等离子体性能的影响，以改善RFP放电。结果表明，随着壳体接近度的提高，放电阻力降低了2倍（b/a=1.07 [] SY.scharw.[）1.02)。在接下来的一年里，用x射线探针在STE-2上进行了高能电子研究。得到的主要结果如下：(1)在r/a>0.7的边缘区域，我们观察到能量在400-500 eV左右的非热电子，远高于体电子温度40-50 eV。（ii）高能电子沿着磁力线流动，即它们被中心区域的欧姆电场加速。（iii）高能电子密度随填充压力的增大而减小。高能电子密度的压力依赖性是RFP的第一个观察结果。因此，将结果与快速电子产生机制的理论模型进行详细比较，有助于理解RFP等离子体动力学。我们还对电动势（EMF）探针技术的应用进行了估计，该技术是一个定向探针和一个磁拾取线圈的组合。在一定的等离子体条件下，用该探针可以估计磁流体动力学（MHD）发电机项<vxB>。

The purpose of the present research is to obtain some insights into production mechanism of energetic particles in STE-2 RFP at Kyoto Instute of Technology. During the first year, an X-ray probe, consisting of a metal target and a surface barrier diode with polyester filters, was constructed. And, at the same time, effects of the proximity of conducting shell (b/a, where b and a are the plasma and shell minor radii, respectively) on REP plasma performance were studied for improving the RFP discharges. It was found that discharge resistance decreased by a factor of 2 with an improved shell proimity (b/a=1.07(] SY.scharw.[)1.02). During the following year, energetic electron studies were performed with the X-ray probe in STE-2 with the close fitting shell. The major results obtained are as follows: (i) We have observed non-thermal electrons with energies around 400-500 eV, much higher than the bulk electron temperature of 40-50 eV, in the edge region r/a>0.7. (ii) The energetic electrons flow along the magnetic field line in the sense that they are accelerated by the Ohmic electric field in the central region. (iii) The energetic electron density decreases with an increase in fill pressure. The pressure dependence of the energetic electron density is the first observation in RFP's. Thus, a detailed comparison of the results with theoretical models of production mechanism of fast electrons is beneficial to understanding the RFP plasma dynamics. We have also made an estimate for applying the technique of an electromotive force (EMF) probe which is a combination of a directional probe and a magnetic pickup coil. It has been found that under certain plasma conditions, we can estimate the magnetohydrodynamic (MHD) dynamo term <vxB> with this probe.