Critical β analyses with ferromagnetic and plasma rotation effects and wall geometry for a high β steady state tokamak

The critical beta is shown to be decreased by ferromagnetic effect by about 8% for μ/μ0∼2, μ and μ0 denote the permeability of ferromagnetic wall and vacuum, respectively, for tokamak of aspect ratio 3. The existence of the stability window opened by both effects of the toroidal plasma rotation and the plasma dissipation, which was not observed for high aspect ratio tokamak, is found for tokamak of aspect ratio 3. The effect of ferromagnetism on them is also investigated. The critical beta analyses of NCT (National Centralized Tokamak) plasma using VALEN code are started with stabilizing plate and vacuum vessel geometry with finite resistivity, and the results for passive effect of stabilizing plate are obtained. The calculations including stabilizing effect of the vacuum-vessel and also active feedback control are also performed for present design of NCT plasma. (author)