Plasma shape effects on sawtooth / internal kink stability and plasma shaping using electron cyclotron wave current profile tailoring in TCV

摘要

The effect of plasma shaping (triangularity and elongation) on sawtooth stability is addressed as well as the technique of current profile broadening using off - axis ECH to enlarge the operational range towards higher elongations. The plasma shape strongly influences the sawtooth period and amplitude. This effect is emphasized by ECH, with the sawtooth period becoming shorter at low triangularity or at high elongation; for these plasma shapes, the pressure profile inside the q=1 surface remains essentially flat throughout the sawtooth cycle.