Design of Rotating Resonant Magnetic Perturbation Coil System in the STOR-M Tokamak

S. Elgriw, J. Adegun, M. Patterson, A. Rohollahi, D. Basu, M. Nakajima, A. Hirose, C. Xiao

The interaction between resonant magnetic perturbations (RMP) [1] and plasma is an active topic in the fusion energy research. RMP involves the use of radial magnetic fields generated by external coils installed on a tokamak device. The resonant interaction between the plasma and the RMP fields has many favorable effects such as suppression of instabilities and improvement of discharge parameters in tokamaks. The RMP technique has been successfully implemented in the STOR-M tokamak. A set of (m = 2, n = 1) helical coils carrying a current pulse was used to study the effects of RMP on magnetic islands [2], plasma rotation [3], and other edge plasma parameters. The current RMP coil system creates only a stationary magnetic field that does not rotate with the magnetic islands. A new design of RMP system is being developed for the STOR-M tokamak. The system consists of a number of external saddle coils distributed in the poloidal and toroidal directions. The saddle coils will be powered by AC power supply to generate a rotating RMP field. The advantage of producing a rotating RMP with variable phase and frequency is the possibility to stabilize the targeted magnetic islands without mode locking which is a major cause for plasma disruptions. Numerical simulations have been carried out to calculate several parameters for the new RMP system such as the self-inductance of the saddle coils, the magnetic field generated by the coils, as well as the dominant modes. The dominant mode generated by the new RMP coil system may be tuned to (2, 1) with a significant contribution from (2, 3) and (2, 5) modes.

*Supported by NSERC and Fedoruk Centre

References:

1. T. C. Hender et al 1992 Nucl. Fusion 32 2091
2. S. Elgriw et al 2011 Nucl. Fusion 51 113008
3. S. Elgriw et al 2016 Plasma Phys. Control. Fusion 58 045002