Neoclassical Drift of Circulating Orbits Due toToroidal Electric Field in Tokamaks

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

Princeton University. Plasma Physics Laboratory.

关键词: Tokamaks, Particle Dynamics, Neoclassical Drift, Tokamak, Circulating Particles;    Charged Particles;    70 Plasma Physics And Fusion Technology;    Electric Fields;    Aspect Ratio;   

RP-ID  :  PPPL-4639
RP-ID  :  DE-ACO2-09CH11466
RP-ID  :  1029993

美国|英语

来源: UNT Digital Library

【 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.