Stable Confinement of High-Beta Collisionless Toroidal Plasmas

Abstract

High-$\ensuremath{\beta}$, collisionless, toroidal multipole equilibria with parameters $n=5\ifmmode\times\else\texttimes\fi{}{10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$, ${T}_{i}=200$ eV, ${T}_{e}=25$ eV, and bridge $\ensuremath{\beta}=8$% have been obtained in the University of California at Los Angeles dodecapole. The equilibrium is characterized by perturbed vacuum magnetic fields, flat internal pressure profile with sharp edge, and a steep hoop bridge profile 2 ion-gyroradii wide centered on the separatrix. The transition from diffuse profiles at low $\ensuremath{\beta}<1$% to sharp profiles at high $\ensuremath{\beta}>~5$% is observed. A stable equilibrium is observed in excess of 400 Alfv\'en times.