A SEMI-EMPIRICAL SCALING LAW FOR THE BETA-LIMIT IN TOKAMAKS
A limited numerical optimisation of the current and pressure profiles in Tokamaks of various shapes and aspect ratios has led to a simple scaling law for the maximum volume averaged beta which can be reached before the onset of ideal MHD instabilities: beta < 2.0-2.5 mu-omicron I/Ba, where I is the total current, B the toroidal field at the centre of the plasma and a the minor plasma radius in the equatorial plane. The limit is set by the appearance of a n = 1 free boundary instability, neglecting the possible stabilizing effect of a shell. The highest betas attained in tokamaks equipped with strong auxiliary heating are shown to be very near the limit given by this scaling law in spite of their very different conditions of operation. Possible implications are discussed.
Bibliographic Reference: WRITE TO CENTRE DE RECHERCHES EN PHYSIQUE DES PLASMAS, ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE, 21, AVENUE DES BAINS, CH-1007 LAUSANNE (SWITZERLAND), MENTIONING REPORT LRP 239/84, 1984
Record Number: 1989123009000 / Last updated on: 1987-01-01
Available languages: en