Circuit Equation Formulation of Resistive Wall Mode Feedback Stabilization Schemes
Authors: M. Okabayashi, N. Pomphrey, and R. Hatcher
Recently, various schemes for controlling the resistive wall mode have been proposed. Here, we formulate the problem of resistive wall mode feedback control utilizing concepts from electrical circuit theory. We consider each of the coupled elements (the perturbed plasma current, the poloidal passive shell system, and the active coil system) as lumped-parameter electrical circuits obeying the usual laws of linear circuit theory. An inductance matrix describes the interactions between the coupled circuits. The off-diagonal elements (mutual inductances) are related to the geometry of the coupled components and provide a means for evaluating the merits of proposed feed-back schemes. The roles of the perturbed plasma current, the passive shell, and the active coil elements are easily identifiable and the physics for control of n greater than or equal to 1 modes can be compared with the theoretical and experimental results of n = 0 vertical position control.