Equilibrium and Stability of a Tokamak with Non-Circular Cross Section

I. Equilibrium and Local Instability

Abstract

Under the condition which the shell has a shape of a non-circular cross section, the equilibrium equation, ∇p=j×B, is analysed by means of the expansion in the inverse of the aspect ratio, ε, and the equilibrium of a Tokamak with a non-circular cross section is considered. The plasma with βp∇√ε are treated. For such plasmas, the criterion for the stability against local disturbances is obtained for arbitrary current distributions and compared with one in the case of round toroidal plasmas. As a result, it is shown that suitable variations of the cross section improve the stability condition.