Improvement of Spheromak-Plasma Confinement

本研究计划旨在改善大阪大学球形标记装置CTCC-II的等离子体约束。通过这项研究，我们期望增加我们在球标和等离子体物理方面的物理知识。我们调查了以下五个主题。稳定性分析的TSC（普林斯顿托卡马克模拟代码）。2. 中心导电极和阻塞电流对带磁通孔的球形等离子体的影响。3. 等离子体旋转对等离子体平衡量的影响。4. 压力梯度下磁芯球标的平衡与稳定性。5. 电子回旋共振吸收对电流驱动的影响。上述课题的主要结果如下：1. 在轴对称电阻MHD扰动下，球标是稳定的。为了解释实验结果，扩散系数和热导率的值应该比经典（斯皮策）的值大100倍左右。2. 中心导电极的稳定性效应取决于等离子体电流分布。这解释了等离子体寿命的实验结果。当磁通洞产生时，等离子体约束得到显著增强。满足Mercier准则的磁轴β比最大值不超过6%。这个值是通过使用优化的压力分布来评估的。3. 极向和环向磁场的实验结果与理论结果相差不大。我们可以通过考虑等离子体围绕其对称轴的旋转来定性地解释这种差异。我们在第4课中研究了电流驱动的基本问题。和5。从上述调查中，我们肯定达到了上述研究计划的目的。

This research program aims to improve the plasma confinement of the spheromak device, CTCC-II, at Osaka University. Through this study, we expect to increase our physical knowledge on the spheromak and plasma physics. We have investigated the following five subjects.1. Stability analysis by the TSC (Princeton Tokamak Simulation Code). 2. Effects, of the central conducting pole and the choking current on the spheromak plasma with flux hole. 3. Effects of the plasma rotation on the plasma equilibrium quantities. 4. Equilibrium and stability of the flux-core spheromak with the pressure gradient. 5. Effects of the current drive using the electron cyclotron resonance absorption.The main results obtained on the above subjects are the following. 1. The spheromak is shown to be stable against the axially symmetric resistive MHD perturbations. The values of the diffusion coefficient and the thermal conductivity should be about 100 times larger than those of the classical (Spitzer's) values to explain experimental results. 2. The stability effects of the central conducting pole depend on the plasma-current distribution. This explains the experimental result on the plasma life time. The plasma confinement is sharply enhanced when the flux hole is generated. The maximum values of beta ratio on the magnetic axis, under which the Mercier criterion is satisfied, is at most 6%. This value is evaluated by use of the optimized pressure distribution. 3. There is a small difference between experimental and theoretical results on the poloidal and toroidal magnetic fields. We can show this difference is qualitatively explained by considering the plasma rotation about its symmetric axis. We have investigated basic problems on the current drive in the subjects 4. and 5.From the above investigations, we have surely achieved the purpose of the research program mentioned above.