Improvement of Plasma Confinement in Helical Systems

螺旋聚变系统比托卡马克型装置具有主要优势，因为没有等离子体电流中断和可靠的稳态操作。因此，改善螺旋系统的等离子体约束对于开发更好的聚变反应堆具有重要意义。目前，日本的LHD（大型螺旋装置）正在建设中，CHS（紧凑螺旋系统）正在运行中。另一方面，德国提出了W7-X（Wendelstein 7-X）项目，并正在进行W7-AS实验。这两个项目的相互讨论非常有用。 本财年，六名日本科学家访问了德国马克斯普朗克等离子体物理研究所，讨论了以下项目：（1）LHD项目与W7X计划的比较。对两个项目中等离子体限制的概念进行了比较和检查。特别是LHD的螺旋偏滤器和W7AS的岛状偏滤器应该在不久的将来进行详细讨论。(2)CHS和W7AS实验的比较。讨论了两个装置的实验数据，并对约束模型进行了检查。此外，一位科学家访问了德国和西班牙，以获取有关德国恒星和西班牙TJ-II螺旋项目的信息，并讨论未来的研究合作计划。在下一个财政年度，这些合作研究应作为文部科学省国际科学研究计划的资助加速进行。

Helical fusion systems have major advantage over Tokamak-type devices because of no plasma current disruptions and reliable steady-state operations. Therefore, it is important to improve the plasma confinement of helical systems for developing better fusion reactors.At present, in Japan, LHD(Large Helical Device) is under construction, and CHS(Compact Helical System) is in operation. On the other hand, in Germany, the W7-X(Wendelstein 7-X) project is proposed and the W7-AS experiments are being carried out. It is very useful to discussed with each other for both projects.In this fiscal year, six Japanese scientists visited to Max-Planck Institute for Plasma Physics in Germany to discuss the following items :(1) Comparisons between LHD Projects and the W7X Plan. The concepts of plasma confinements in both projects are compared and checked. Especially, the helical divertor of LHD and the island divertor of W7AS should be discussed in details in the near future.(2) Comparisons between CHS and W7AS experiments. Experimental data from two devices are discussed, and the confinement models are checked.Moreover, one scientist visited Germany and Spain for getting informations on the Germany steralleters and the spanish TJ-II heliac project, as well as to discuss on the future research collaborations plan.In the next fiscal year, these collaboration researches should be accelerated as a Grant under The Monbusho International Scientific Research Program.