Non-linear stability of magnetic modes in tokamaks
The operation of tokamaks is affected by instabilities: (i) large-scale instabilities (macroscopic modes or tearings) which prevent attainment of a high central temperature and sometimes bring the discharge to an abrupt halt; (ii) small-scale instabilities (microscopic modes, microtearings) of a turbulent nature, which are responsible for anomalous transport, thus limiting energy confinement time. The main topic is the investigation of magnetic modes, i.e. fluctuations of vector potential, by studying the effects of pressure on tearings and microtearings. A synthesis is presented of the results of investigations into the non-linear collision regime for three mechanisms: mean curvature, diamagnetism, and bootstrap. Attention is then shifted to the regime in which collisions are dominated by diffusion - a regime apparent in the growth of islands, and which gives rise to stability thresholds higher than those obtained in the collision case.
Bibliographic Reference: Paper presented: Troisième Congrès de la Sociète Française de Physique - Plasma, Nancy (FR), September 16-18, 1992
Availability: Available from (1) as Paper FR 37068 ORA
Record Number: 199211501 / Last updated on: 1994-11-29
Original language: fr
Available languages: fr