EFDA-JET-CP(09)06/05

Nonlinear and Kinetic Effects on ResistiveWall Mode Stability

The ultimate performance limit in advanced tokamak scenario operation is often set by the Resistive Wall Mode (RWM). However, operation above the stability limit for RWM onset is important in order to achieve economically-attractive plasma performance in advanced tokamak regimes, which aim at steady-state operation with high plasma pressure and a large fraction of non-inductively driven current. Various experiments have shown that the RWMcan be stabilised in such a way that the plasma can operate above the no-wall b-limit. Recent experiments with nearly balanced neutral beam injection have found a critical velocity for RWMstabilisation well below that found in previous magnetic braking experiments. There is naturally much interest in understanding the passive stabilisation occurring from kinetic effects which is thought to underlie these results. Various models have been presented to explain the RWM damping due to kinetic effects, such as sound-wave damping, ion Landau damping, or the precessional drift resonance with thermal ions.
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