Asymmetric reconnection and stochasticity in tokamaks

A model of the asymmetric internal reconnection occurring in toroidal geometry when pressure effects are taken into account is proposed. This model predicts a toroidal modulation of the current sheet, which is strong and mainly pressure driven for a rather low shear value on the q=1 surface. This modulation gives magnetic field line stochasticity in the vicinity of the m=1 separatrix, increasing during the reconnection process and reaching a value that can explain a complete expulsion of the electronic energy before the completion of the reconnection if the central value of the safety factor is somewhat below 0.8. This model is compared with a full toroidal MHD simulation including toroidal harmonics up to n=11