COMPARISON OF TOKAMAK DISRUPTION SIMULATIONS

The major disruption in tokamaks has been simulated by two apparently dissimilar models: a one-dimensional quasi-linear instability model coupled to the transport and a three-dimensional solution of the reduced MHD equations. Advocates of each approach claim to observe 'major disruptions' produced under different circumstances and apparently by different mechanisms. The paper compares the models and concludes that they exhibit many similar characteristics and that explanations exist for the observed discrepancies. The effect that different models of thermal transport have upon the plasma evolution is investigated. Although anomalous transport effects tend to make the plasma more unstable than INTOR type transport and produce disruptions under slightly different circumstances, the most important factor for determining the disruptive behavior appears to be the position of perfectly conducting shell in relation to the plasma edge.