Drift wave stability of inverted gradient profiles in tokamaks

The stability theory of the drift wave and trapped electron mode is extended to include the dissipative contributions from electrons in three collisionality regimes. Application of the theory to the inverted profiles (∇n∇T<0) shows a substantial gain in stability over normal profiles (∇n∇T≳0) for ν*e<0.3 and a destabilization for ν*e≳1.0.