Tokamak transport code simulations with drift wave models

Abstract

Simple models for the dissipative trapped electron, circulating electron and toroidal ion temperature gradient drift modes, together with the effect of low-m tearing mode islands, are incorporated into a standard tokamak transport code to study anomalous energy transport in tokamaks, primarily in the Doublet HI tokamak. In simulations of Doublet III in the Ohmic regime, low density neo-Alcator scaling is obtained. At high density the ion temperature gradient mode contributes strongly to the saturation of the energy confinement time. In the beam heating regime, the model predicts that the energy confinement time has weak density and magnetic field dependence, degradation with power and favourable current scaling. The generality of the drift wave model is further tested by simulating smaller tokamaks (ISX-A, Alcator A, Alcator C) as well as the largest tokamak, JET.