Title: Effect of bootstrap current on MHD equilibrium beta limit in heliotron plasmas
Abstract: The effect of bootstrap current on the beta limit of MHD equilibria is studied systematically by an iterative calculation of MHD equilibrium and the consistent bootstrap current in high beta heliotron plasmas. The LHD machine is treated as a standard configuration heliotron with an L = 2 planar axis. The effects of vacuum magnetic configurations, pressure profiles and the vertical field control method are studied. The equilibrium beta limit with consistent bootstrap current is quite sensitive to the magnetic axis location for finite beta, compared with the currentless cases. For a vacuum configuration with the magnetic axis shifted inwards in the torus, even in the high beta regimes, the bootstrap current flows to increase the rotational transform, leading to an increase in the equilibrium beta limit. On the contrary, for a vacuum configuration with the magnetic axis shifted outwards in the torus, even in the low beta regimes, the bootstrap current flows so as to reduce the rotational transform; therefore, there is an acceleration of the Shafranov shift increase as beta increases, leading to a decrease in the equilibrium beta limit. The pressure profiles and vertical field control methods influence the equilibrium beta limit through the location of the magnetic axis for finite beta. These characteristics are independent of both device parameters, such as magnetic field strength, and device size in the low collisional regime.
Publication Year: 2001
Publication Date: 2001-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 16
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