Numerical simulation of experiments on the MHD instability of tokamak plasmas

A numerical simulation of the dynamics of the tearing-mode instability has been carried out. The mutual effects of magnetic islands and of the plasma energy balance are taken into account (diffusion of the current density is included). The calculated results agree satisfactorily with the experimental data available in terms of the locations in which the instability occurs and the suppression of the instability if the plasma current is raised fast enough. There may exist quasisteady regimes with an oscillating perturbation amplitude. Negative peaks on the discharge voltage: characteristic of the disruptive instability: may appear when the originally unstable current profiles change