Stability of m = 1 mode in the presence of m = 0 perturbation in reversed field pinch

Stability of the m = 1 mode is examined in the presence of external m = 0 perturbations, i.e., toroidal field ripple arising from the discreteness of toroidal coils. Response of the plasma is taken into account self-consistently using the Bessel Function Model. The Δ' criterion and energy principle are applied to the system and the stability of the m = 1 resistive and ideal modes is shown to be improved by reducing the toroidal ripple. (author)