Drift wave transport and origin of the disruption phenomenon – a theoretical model

The purpose of this paper is to demonstrate that the turbulence spectra and the electron heat fluxes derived from the theory of drift wave saturation presented recently are consistent with the discharge data from two tokamaks. It is shown that the calculated rapid increase in transport with increasing linear growth rate explains the observed relaxation of the profiles towards a weakly unstable state with respect to the trappedelectron instability. It is further suggested that the occurrence of sawtooth oscillations of the core can be interpreted in terms of drift instability quenching and anomalous heat flux clamping in the surrounding gradient layer. The high-density limit derived from this assumption agrees well with the observations.