Current Penetration and Plasma Disruption

It is suggested that, in a tokamak discharge, the initial rapid current penetration and the disruptive instability may each be attributed to a type of nonlinear double-tearing instability which causes growth and overlap of radially separated magnetic islands. The ensuing reconnection and braiding of magnetic lines would enhance local radial heat and particle transport and could permit rapid redistribution of plasma current, inducing positive or negative spikes in the loop-voltage signal.