Theory of hot particle stability

The investigation of stabilization of hot particle drift reversed systems to low frequency modes has been extended to arbitrary hot beta β H , for systems that have unfavorable field‐line curvature. Steep profile equilibria are considered where the thickness of the pressure drop Δ, is less than plasma radius r p . The analysis describes layer modes which have mΔ/r p (2)/(3) . When robust stability conditions are fulfilled, the hot particles will have their bounce frequency less than their grad‐B drift frequency. This allows for a low bounce frequency expansion to describe the axial dependence of the magnetic compressional response. Such as expansion provides for another negative energy source in the theory, with the system then being susceptible to the drift compressional instability if dβ H /d r >dβ w /d r, where β w is the beta of the background plasma. If robust stabilization conditions are not fulfilled, the regions of fragile stability are extremely small if the MHD‐like modes, the diamagnetic compressional and drift‐compressional modes are to be simultaneously avoided.