Improvement of Spheromak-Plasma Confinement

这项研究计划旨在改善大阪大学SPEROMAK装置CTCC-II的等离子体约束。通过这项研究，我们希望增加我们对粒子物理和等离子体物理的了解。我们调查了以下五个主题1.用TSC(普林斯顿托卡马克模拟程序)进行稳定性分析。2.中心导电极和扼流对带磁通孔的球马克等离子体的影响。3.等离子体自转对等离子体平衡量的影响。4.具有压力梯度的通量芯球面的平衡性和稳定性。5.电子回旋共振吸收对电流驱动的影响。1.对于轴对称的阻性磁流体微扰，球面是稳定的。为了解释实验结果，扩散系数和导热系数的值应该比经典的Spitzer值大100倍左右。2.中心导电杆的稳定效应取决于等离子体电流的分布。这解释了等离子体寿命的实验结果。当产生磁通空穴时，等离子体约束急剧增强。满足Mercier准则的磁轴上的β比最大值为6%。通过使用优化的压力分布来评估该值。3.极向磁场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绕其对称轴的旋转来定性地解释这种差异。第四、五、四、五、通过上述调查，我们一定达到了上述研究方案的目的。

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.