Fokker-Planck theory of electron cyclotron assisted startup and breakdown in tokamaks
The kinetic theory of plasma startup in a tokamak in the presence of electron cyclotron resonance heating is discussed. The linear theory of the X-mode and the upper-hybrid converted mode damping in low density and temperature plasmas is discussed and then the kinetic equation for the electron velocity distribution f(v) is considered. In general f(v) is determined by the perpendicular electron cyclotron quasilinear diffusion operator, the parallel electric field, elastic and inelastic electron-neutral collisions and various losses. Two different time scales are identified, namely, the elastic electron-neutral collision time v(e)(-1) and the much longer ionisation time v(i)(-1), with v(e) much greater than v(i). This legitimises a two time scale ordering procedure for which the velocity distribution is determined by the quasilinear diffusion and v(e) and the ionisation rate is computed using the Fokker-Planck solution for f(v). Approximate results for the ionisation rate are presented.
Bibliographic Reference: Report: EUR-CEA-FC-1484 EN (1993) 23 pp.
Availability: Available from CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR)
Record Number: 199310704 / Last updated on: 1994-11-29
Original language: en
Available languages: en