Compact toroid injection method for fueling magnetized high temperature plasmas

本文从实验和理论上研究了用于磁化高温等离子体的紧凑环形线圈（CT）注入方法。该方法有望成为聚变堆等大型装置集中加料的先进加料方法之一。在日本原子力科学研究所JFT-2 M托卡马克装置上，用HIT-CTI（姬路Institute of Technology-CT Injector）进行了CT注入实验。在以300 km/s速度注入CT的情况下，在环向场为0.8 T的等离子体中，获得了线平均电子密度的增加<ext>。观察到<ext>等离子体枪内电极极性为负时CT向-u×B_（u为CT速度）方向移动，极性为正时CT向+u×B_方向<ext>移动。此外，我们还测量到CT被B_2减速<ext>，并且<ext>随着B_2强度的<ext>增加，CT在B_2中的穿透长度变短。结果表明，CT注入到磁化靶等离子体中时，会产生倾斜不稳定性，这种不稳定性的增长与CT穿透的时间尺度相似，并伴随着CT磁场与靶磁场之间的磁场重联。

Compact toroid (CT) injection method for fueling a magnetized high temperature plasma has been studied experimentally and theoretically. This method is expected to be one of the advanced fueling methods for central fuelling in a large grade device like fusion reactor. CT injection experiments have been carried out in JFT-2M tokamak at JAERI using HIT-CTI (Himeji Institute of Technology-CT Injector) An increase in the line-average electron density was obtained in the plasmas with toroidal field of 0.8 T in the case of CT injection with velocity of 300 km/s.We have studied an effect on CT transportation in the drift tube due to an external field, B_<ext> which is crossing perpendicularly to the drift tube in the FACT device at Himeji Institute of Technology. We observed that CT shifted in the direction of -u×B_<ext> (u is CT velocity) when the polarity of inner electrode of plasma gun was negative and in the direction of +u×B_<ext> when the polarity was positive. Moreover, we measured CT was decelerated by B_<ext> and the penetration length into B_<ext> becaome shorter as the strength of B_<ext> increased.The fuelling process by a CT injection has been investigated by using MHD numerical three dimensional simulations, where CTs are injected into a magnetized plasma region. The results showed that an injected CT into a magnetized target plasma suffered from a tilting instability, which grew with a similar timescale to that of the CT penetration which was accompanied by magnetic reconnection between the CT magnetic field and target magnetic field.