Feedback control of kink and tearing modes via novel ECH modulation

An effective suppressor signal for the control of both magnetohydrodynamic and tearing modes can be obtained from the transverse energy deposition via electron cyclotron resonance in the electrons in tokamaks. Feedback modulation of a purely transverse electron cyclotron heating beam can then result in a near instantaneous suppressor signal of an extra radial non-thermal 'pressure' of appropriate amplitude and phase to stabilize the mode. Power estimates for large and medium size tokamaks appear to be modest and practical. (letter to the editor)