Neoclassical Drift of Circulating Orbits Due toToroidal Electric Field in Tokamaks

Hong, Qin ; Guan, Xiaoyin ; Fisch, Nathaniel J.

关键词: ASPECT RATIO;    CHARGED PARTICLES;    ELECTRIC FIELDS;    RUNAWAY ELECTRONS;    VELOCITY Tokamaks;    Particle Dynamics;    Neoclassical drift;    Tokamak;    Circulating Particles;   

DOI  :  10.2172/1029993
RP-ID  :  PPPL-4639
PID  :  OSTI ID: 1029993
Others  :  TRN: US1200429

学科分类：原子、分子光学和等离子物理

美国|英语

来源: SciTech Connect

【 摘 要 】

In tokamaks, Ware pinch is a well known neoclassical effect for trapped particles in response to a toroidal electric field. It is generally believed that there exists no similar neoclassical effect for circulating particles without collisions. However, this belief is erroneous, and misses an important effect. We show both analytically and numerically that under the influence of a toroidal electric field parallel to the current, the circulating orbits drift outward toward the outer wall with a characteristic velocity O ({var_epsilon}{sup -1}) larger than the E x B velocity, where {var_epsilon} is the inverse aspect-ratio of a tokamak. During a RF overdrive, the toroidal electric field is anti-parallel to the current. As a consequence, all charged particles, including backward runaway electrons, will drift inward towards the inner wall.