A class of high $εβp$ equilibria in strongly shaped finite aspect ratio tokamak plasmas

A class of very high poloidal beta $(βp)$ equilibria is exhibited in which $εβp$ (ε is the inverse aspect ratio) exceeds analytic equilibrium limits previously anticipated from simplified large aspect ratio models, as well as previous experimental equilibrium limits. The extension in these limits is shown to be due to a combination of finite aspect ratio effects and strong cross section shaping. In a conventional aspect ratio configuration, equilibria with $εβp=3$ exist, which is 50% higher than both the previously observed record and the analytically predicted limit. For very low aspect ratio with $ε−1=1.4,$ typical of spherical tori, values of $εβp=5$ are possible.