Compact toroid injection method for fueling magnetized high temperature plasmas

本文从实验和理论两方面研究了致密环面注入磁化高温等离子体的方法。该方法有望成为核聚变等大型装置中心加注的先进加注方法之一。在JAERI的JFT-2M托卡马克上，利用hiti - cti（姬路理工大学CT注入器）进行了CT注入实验，当CT注入速度为300 km/s时，在环形场为0.8 T的等离子体中获得了线平均电子密度的增加。在Himeji工业大学的FACT装置中，我们研究了垂直穿过漂移管的外场B_<ext>对漂移管中CT输运的影响。我们观察到，当等离子枪内电极极性为负时，CT向-u×B_<ext>方向移动（u为CT速度），当极性为正时，CT向+u×B_<ext>方向移动。此外，我们测量到CT被B_<ext>减速，并且随着B_<ext>强度的增加，进入B_<ext>的穿透长度变短。利用MHD三维数值模拟研究了CT注入的加注过程，其中CT注入磁化等离子体区域。结果表明，CT注入磁化后的靶等离子体中，存在倾斜不稳定性，其增长与CT穿透的时间尺度相似，并伴有CT磁场与靶磁场的磁重联。

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.