In this paper, the effect of electron–electron (e–e) collisions on second harmonic electron cyclotron resonance plasma breakdown is studied. A previously developed kinetic model for stellarators has been completed by means of a collision operator derived from the Fokker–Planck equation. It is shown that, although e–e collisions are not important for initial growth rate predictions and play a minor role in the breakdown time calculation, they must be considered if a realistic evolution of the electron energy distribution function is desired. Moreover, it is seen that the introduction of the e–e collision processes is needed in order to obtain a correct description of the power balance during breakdown.
Nonlinear collisionless electron cyclotron interaction in the pre-ionisation stage