Studies of compact toroid injection into spherical torus and its propagation process

1. 在HIST器件中，我们通过对器件的改进，延长了螺旋驱动球面等离子体的放电持续时间。我们全面研究了n=1不稳定性和弛豫在ST和球斑等离子体电流产生过程中的作用。对于球标来说，n=1模式活度在电流驱动机制中起着重要作用。对于ST构型，n=1模式倾向于被外环面场稳定。因此，我们提出重复等离子体注入和合并过程是电流驱动的必要条件。我们利用FACT装置确定了紧凑环面（CT）等离子体在外场中传播的特性。在外场和JFT-2M装置中观察到CT的位移运动。我们已经得出结论，这种现象是洛伦兹力J_gxB_<ext>的原因。研究发现，外加磁场对CT等离子体有明显的减速作用，但霍尔效应可能会减小漂移区的阻力。

1. In the HIST device, we have extended discharge duration time of helicity-driven spherical torus plasma by improvements of the device. We have examined comprehensively the role of the n=1 instability and relaxation on current generation processes for ST and spheromak plasmas. For the spheromak, n=1 mode activity plays an important role in current drive mechanism. For the ST configuration, n=1 mode tends to be stabilized by the external toroidal field. So we have proposed that repetitive plasmoid injection and merging process are essential for current drive.2. We have identified the characteristics of the Compact Torus (CT) plasma propagating in an external field using the FACT device. The shift motion of CT has been observed in the external field as well as in the JFT-2M device. We have concluded that this phenomenon is responsible for the Lorentz force J_gxB_<ext>. It has been found that the external magnetic field apparently decelerates the CT plasma, but the Hall effect may be able to reduce the drag force in the drift region.