Instability and transport driven by electron temperature gradient close to critical

The electron temperature gradient (ETG) driven instability in toroidal plasmas of parameter regimes close to stability boundaries is studied with gyrokinetic theory. Emphasis is placed on calculations of the maximum growth rate and threshold temperature gradient of the modes. Algebraic formulae for the maximum growth rate and for the critical gradient are presented. Estimations for electron thermal transport induced by ETG turbulence are formulated. The results are compared and shown to be in line with experimental observations.