Electron cyclotron current drive (ECCD) is not only a powerful heating source for tokamaks. By driving current in specific locations within the tokamak, dangerous magnetic islands, which can grow large enough to ultimately destroy the plasma confinement, can be suppressed. On the DIII-D tokamak, we developed several techniques to better align ECCD with these magnetic islands, allowing for robust control of the instability.

Notably, application of ECCD has other uses as well, including as a diagnostic to better determine the structure of the magnetic equilibrium. For future machines, where diagnostic availability will be limited, it will be essential to make the most out of every instrument. Exploring advanced uses for ECCD systems to simultaneously control and diagnose the plasma could open up avenues for synergistic deployment on demonstration devices.

Selected publications on this subject:

Experimental evidence of ECCD-based NTM suppression threshold reduction during mode locking on DIII-D
Nelson, A. O., Logan, N., Choi, W., Strait, E. J. & Kolemen, E., Plasma Physics and Controlled Fusion 62, 094002 (2020).

Electron cyclotron emission based q-profile measurement and concept for equilibrium reconstruction
Nelson, A. O., Austin, M. E. & Kolemen, E., Plasma Physics and Controlled Fusion 61, 085013 (2019).

Simultaneous detection of neoclassical tearing mode and electron cyclotron current drive locations using electron cyclotron emission in DIII-D
Nelson, A. O., La Haye, R. J., Austin, M. E., Welander, A. S. & Kolemen, E., Fusion Engineering and Design 141, 25–29 (2019).