Numerical studies of the beta limit in the first region of stability for n = ∞ ballooning modes in advanced-shaped tokamaks are presented. A higher beta value than corresponds to the present conventional beta scaling is expected for advanced-shaped tokamaks with sufficient triangularity/indentation. Extremely elongated configurations without appropriate triangularity do not lead to an increase in critical beta. Dee or bean shapes with sharply tipped cross-sections are more favourable for achieving high beta values than those with round-tip cross-sections having nearly the same safety factor profile. A new beta scaling for elongated ellipse, Dee- and bean-shaped tokamaks is derived.
Beta enhancement of tokamak plasma with nearly circular cross-section