State Feedback for Control of Multimode Plasma Instabilities

Using the concet of " normal mode states" of a plasma, a state feedback scheme is developed by which eigenfrequencies can be placed in stable half of the complex frequency plane. All the dynamic states of a plasma instability are approximately recovered from a single properly placed sensor signal via a state reconstructor. Then state feedback is used based on this approximate set of states. The resulting control information is introduced into the plasma via a single properly placed suppressor to stabilize all unstable modes without destabilizing any originally stable ones.