Abstract
Sawtooth control using electron cyclotron current drive (ECCD) has been demonstrated in ITER-like plasmas with a large fast ion fraction, wide q = 1 radius and long uncontrolled sawtooth period in DIII-D. The sawtooth period is minimized when the ECCD resonance is just inside the q = 1 surface. Sawtooth destabilization using driven current inside q = 1 avoids the triggering of performance-degrading neoclassical tearing modes (NTMs), even at much higher pressure than required in the ITER baseline scenario. Operation at βN = 3 without 3/2 or 2/1 NTMs has been achieved in ITER demonstration plasmas when sawtooth control is applied using only modest ECCD power. Numerical modelling qualitatively confirms that the achieved driven current changes the local magnetic shear sufficiently to compensate for the stabilizing influence of the energetic particles in the plasma core.
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call