Peer-Reviewed Journal Details
Mandatory Fields
I T Chapman, V Igochine, M Maraschek, P J Mc Carthy, G Tardini, the ASDEX Upgrade ECRH Group and the ASDEX Upgrade Team
Plasma Physics and Controlled Fusion
Sawtooth control using electron cyclotron current drive in the presence of energetic particles in high performance ASDEX Upgrade plasmas
Optional Fields
energetic particles sawtooth control asdex upgrade tokamak
Sawtooth control using steerable electron cyclotron current drive (ECCD) has been demonstrated in ASDEX Upgrade plasmas with a significant population of energetic ions in the plasma core and long uncontrolled sawtooth periods. The sawtooth period is found to be minimized when the ECCD resonance is swept to just inside the q = 1 surface. By utilizing ECCD inside q = 1 for sawtooth control, it is possible to avoid the triggering of neoclassical tearing modes (NTMs), even at significantly higher pressure than anticipated in the ITER baseline scenario. Operation at 25% higher normalized pressure has been achieved when only modest ECCD power is used for sawtooth control compared to identical discharges without sawtooth control when NTMs are triggered by the sawteeth. Modelling suggests that the destabilization arising from the change in the local magnetic shear caused by the ECCD is able to compete with the stabilizing influence of the energetic particles inside the q = 1 surface.
Grant Details