Free energy minimization approach to penetration of resonant magnetic perturbations in tokamaks

By applying the principle of minimum free energy an analytical model for the plasma response to externally applied resonant magnetic perturbations (RMPs) is proposed. The results are compared with ATTEMPT code calculations [D. Reiser et al., Phys. Plasmas 16, 0042317 (2009)] and reproduce qualitatively and quantitatively the numerical results on the collisionality dependence of RMP penetration characteristics. Strong increase in the radial electric field with reduced screening at RMPs above a certain threshold is also reproduced by the model.