Quasi-stationary high β plasmas and fast particle instabilities in the COMPASS-D tokamak with ECRH and LHCD

Quasi-stationary, high β tokamak plasmas (βNdia ≈ 2) have been developed in the COMPASS-D tokamak using ECRH. These regimes are sustained for 20 energy confinement times and are limited by the duration of the heating pulse. For the first time, fast particle instabilities are observed with strong electron heating only. The plasmas are sawtooth free and the most dangerous (m = 2, n = 1) neoclassical tearing modes are avoided. The scenario is a result of the optimization of the timing of the heating pulse and application of LHCD.