CRITICAL DENSITY AND DISRUPTIONS IN A HEATED THERMONUCLEAR TOKAMAK DISCHARGES
The study of the existence of a critical density limit has been extended to the case of thermonuclear alpha particle heated regime. An O-D model including sources and sinks affecting the evolution of ions and electrons temperatures and of electrons and alpha particle densities with auxiliary neutral injected power has been developed. Analytic expression for critical density is given in terms of auxiliary projected power P**N. Critical density value increases fast enough for small P**N to give a large safety margin. Only at shutdown power periods critical density can be crossed. In this case, the heat content of alpha particles in the discharge can contribute to smooth out the temperature drop off up to the point where heat transport doubles. Then temperature drops to a new equilibrium value, which can be made above the limiting value for which position control system of the plasma cannot forbid the plasma current to drop off itself: the important phenomenon of disruption. So it is possible to use the alpha particles themselves as a new preventive control against disruptions.
Bibliographic Reference: WRITE TO CEA MENTIONING REPORT EUR-CEA-FC-1254 EN, 1985
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Record Number: 1989124028000 / Last updated on: 1987-01-01
Available languages: en