A kinetic model for second harmonic electron cyclotron breakdown in stellarators, based on the results obtained from non-linear wave-particleinteraction theory, is presented. A set of particle balance equations that describes the H2 ionization chain by means of an electron momentumspace discretization is introduced and solved by numerical integration. The time evolutionof the various species densities is determined and breakdown relatedpredictions are obtained for different prefill pressure conditions and different values of injected power. Analysis of the TJ-IIstellarator experimental data shows good agreement with the theoretical results. This is the first time, to the authors' knowledge, that precise predictions are directly compared with experimental behaviour.
High power density electron cyclotron experiments in the L2M stellarator
Nonlinear collisionless electron cyclotron interaction in the pre-ionisation stage