Diamagnetic drift stabilized ballooning modes in a 3D heliotron

An analysis of kinetic ballooning modes is presented, ray trajectories for the inward shifted Large Helical Device configuration at modest $$ and with an anisotropic pressure profile due to the hot particles are evaluated and an estimate of the marginal stability is computed using the Weyl formula. The Weyl formula indicates that the finite diamagnetic drifts of the hot particles displaces the minimum phase space volume to lower frequencies; however, its magnitude is higher than when these drift effects are ignored.