THERMAL INSTABILITY AND DISRUPTIONS IN A TOKAMAK
This paper develops a theoretical model, in which it is predicted that a major cause of anomalous confinement and disruptions in tokamaks is thermal instability. Due to the large thermal conductivity along magnetic field lines, the confinement is assumed to be poor in regions where the lines of force have an ergodic behaviour in contrast to the regions where the magnetic surfaces are nested (laminar case or islands). The ergodic region results from the interaction between chains of islands. It is shown that thermal islands can grow, when P-v/q is negative, where P-v is the net power input to the electrons in the island (excluding thermal conduction) and q is the radial gradient of the safety factor q. Conclusions are drawn on the occurrence of disruptions (critical electron density) and on confinement in the outer region of the plasma. Finally, suggestions are made to increase the critical density at which disruptions occur.
Bibliographic Reference: 10TH INTERNATIONAL CONFERENCE ON PLASMA PHYSICS AND CONTROLLED NUCLEAR FUSION RESEARCH, LONDON (UK), SEPT. 12-19, 1984 WRITE TO THE PUBLICATIONS OFFICER, JET JOINT UNDERTAKING, ABINGDON, OXON, OX14 3EA (UK), MENTIONING REPORT JET-P(84)05, 1984
Record Number: 1989123096400 / Last updated on: 1987-01-01
Available languages: en