Resistive Wall Mode Feedback Stabilization in Burning Plasma Experiments

A simple model is used to analyze the systems for feedback stabilization of the resistive wall mode (RWM) in proposed burning plasma experiments. In ITER, the presence of several conducting structures close to the control coils, but far from the plasma, leads to a slow feedback response time compared to the time scale of the RWM growth. In FIRE, the copper shell passive stabilizer sets a relatively long time scale for the RWM growth; therefore, the effects of higher resistivity structures close to the coils and far from the plasma are nearly negligible. RWM feedback control should be able to raise the stable _N up to near the ideal-wall limit in FIRE with moderate requirements on the feedback electronics bandwidth.