Natural elongation and triangularity of low aspect ratio tokamak plasma

The dependence of the natural elongation k and triangularity δ for low aspect ratio tokamak plasma on the aspect ratio A for different internal inductance li and poloidal beta βp was investigated numerically. It is found that the effects of li and βp on k can be described in terms of an effective aspect ratio. Numerical results show that the dependence of k on li can be explicitly fitted by an expression k = 1 + g1 (li)A-2 + g2(li)A-4 and the effect of βp on k is not negligible. No explicit dependence of δ on li and βp has been found from these results. (7 figs.)