Maximum-Beta Experimental Study of Spherical Tokamak by Use of Merging/Reconnection Heating and Neutral Beam Heating

2014 Fiscal Year Final Research Report

• Project/Area Number: 22246119
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Nuclear fusion studies
• Research Institution: The University of Tokyo
• Principal Investigator: ONO Yasushi 東京大学, 新領域創成科学研究科, 教授 (30214191)
• Co-Investigator(Kenkyū-buntansha): SAKAKITA Hajime 独立行政法人産業技術総合研究所, エネルギー技術研究部門, 主任研究員 (90357088) ; INOMOTO Michiaki 東京大学, 大学院新領域創成科学研究科, 准教授 (00324799) ; SHIMIZU Toshifumi 独立行政法人宇宙科学研究機構, 宇宙科学研究本部, 准教授 (60311180)
• Project Period (FY): 2010-04-01 – 2015-03-31
• Keywords: ベータ限界 / プラズマ合体 / 中性粒子ビーム / 球状トカマク / 磁場反転配位 / 磁気リコネクション / プラズマ加熱 / 圧力駆動型不安定

Outline of Final Research Achievements

We found significant reconnection heating energy that scales with square of reconnecting (poloidal) magnetic field and used it to form an ultra-high beta (~40%) spherical tokamak (ST) partly through the field-reversed configuration. The high-beta STs produced within short reconnection time suffer from high-beta ballooning kink instabilities with toroidal mode numbers 20-100, causing plasma ejections as well as significant decrease in plasma density and thermal energy. However, we succesfully suppress them when the merging and/or a neutral beam (NB) injection form hollow current and thermal pressure profiles close to the absolute minimum-B configuration. The toroidal shear flow controlled by NB and the conductive shells on the seperatrix are also found to suppress those high-n mode, though we should avoid the mode lock to the conductive wall which is dangerous to the high beta STs.

Free Research Field

プラズマ核融合工学