Equilibrium of toroidal pinches surrounded by pressureless plasma

Bobeldijk, C.

doi:10.1088/0032-1028/10/5/110

Cited by 3 publications

(2 citation statements)

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“…Experiments [6][7][8] showed plasmas with a |3 of approximately 20% to be in a tokamak-like equilibrium, at only a modest shift of the magnetic axis. The theory for these equilibria (and their stability) was also given at that time [7,9]. There are two reasons that these equilibria are possible.…”

Section: Introductionmentioning

confidence: 99%

“…First of all it is the best, or very close to the best, profile for stability of kink modes [11,12]. Secondly, a flat q-profile corresponds to a broad current density profile which means a large total current and this leads to a small equilibrium shift [9]. Thirdly, a flat q-profile is easy to program, because it simply requires the waveforms of the applied poloidal and toroidal fields to be similar.…”

Section: Introductionmentioning

confidence: 99%

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Tokamak-like equilibria at beta close to unity

Mann

Laan

1979

Nucl. Fusion

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This paper describes a computer study of tokamak equilibria, which resulted in configurations at β-values close to one. The cross-section that was studied most intensely was a vertical racetrack with an elongation of two to one. A circular cross-section and a D-shaped vessel did not allow equilibria at as high a β as the racetrack. The safety factor q was kept greater than one everywhere, and the q-profile was kept flat. The corresponding broad current profile has been observed in pinches, where it has a very favourable influence on equilibrium and stability. This favourable influence also displays itself in the equilibria computed; even at a peak β of 82%, the magnetic axis shifts over only 37% of the half-width of the cross-section. The outer boundary of the cross-section was assumed to be a flux surface (e.g. a metal shell). Stability of localized modes was studied by means of the Mercier criterion; it was possible to satisfy this criterion, except in the vicinity of the magnetic axis. Calculations with narrow pressure profiles showed that the plasma did not contract to a round shape; the broad current profile apparently helps to maintain the elongated shape of the plasma. The very high β-values reported here are of interest for extrapolations of fast pulsed tokamaks. It is also important to note that even a modest broadening of the current profile in a conventional tokamak would improve the stability and reduce the shift at moderate β.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%