MAXIMUM BOOTSTRAP CURRENT COMPATIBLE WITH BALLOONING-STABLE PRESSURE PROFILES
It is of interest to investigate the maximum contribution to the total plasma current that can be expected from the bootstrap current under the condition of MHD stability. Only ballooning modes are considered since the limits imposed by them on the total toroidal beta <beta-"t"> are in reasonable agreement with experimental observations presented, and since reactor operation close to these limits promises intrinsic stabilization of thermonuclear burn without large-scale fluctuations in the plasma parameters. The evaluation of the ballooning mode criterion is restricted to a geometry of circular flux surfaces and takes into account other modes only through limiting the safety factor q everywhere to values geq 1. According to the present model, we might therefore hope for a contribution from bootstrap currents in the range of 1/2 to 2/3 of the total plasma current, with rather modest losses in the maximum achievable <beta-"t">. This is conditional on realizing rather peaked density profiles. Even larger contributions from bootstrap currents (as well as larger stable values of <beta-"t">) could be hoped for if q(0) < 1 (as indicated by some experiments) or access to the second regime of stability could be achieved.
Bibliographic Reference: WRITE TO MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, 8046 GARCHING BEI MUENCHEN (GERMANY), MENTIONING REPORT IPP 5/17, 1987
Record Number: 1989126108400 / Last updated on: 1989-06-01
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