Power Balance Models for Rotamak Plasmas

Abstract

Energy transfer processes are calculated for a range of rotamak plasmas which are modelled by equilibria with plasma pressure proportional to either the poloidal flux function or the square of this function. The latter case is more realistic, so it is used to study the conditions for which global power balance can be obtained for both the electrons and the ions. The absence of a toroidal magnetic field means that there is no neo-classical transport. Provided that the particle and energy diffusion remains classical when the plasma temperature increases, the energy confinement time is predicted to scale as n3/2 R8, where n is the density and R is the radius of the separatrix. As the plasma temperature increases, the dominant energy loss process changes from plasma recycling to electron thermal conductivity and then to ion thermal conductivity.