Plasma Cross-Section Viewed from Alpha Particle Confinement

Abstract

Axisymmetric toroidal configuration is considered from a view point of alpha particle confinement. In particular, an elliptically deformed configuration with multifold magnetic axes and low aspect ratio limit of tori are investigated in detail. Ellipticity of the cross-section and the split of magnetic axis need larger current as an absolute container of alphas. Low-aspect-ratio limit of the torus is able to absolutely confine alpha particles produced on the magnetic axis if the toroidal current is about 1.5 times larger than that required in the slender torus. The optimized cross-section in this case is oblate rectangle (the ratio between the width and the height being about equal to 1.22) and the necessary current to marginally confine all the alpha particle produced near the elliptic magnetic axis is 6 MA.