Systematic Analysis of Current Decay Time during Disruption in HYBTOK-II Tokamak

In order to estimate the electromagnetic force acting on vessel components during tokamak disruptions, an accurate prediction of the plasma current decay time is necessary. We have verified a current decay model based on a simple series circuit with a plasma resistance and an inductance. The circuit is employed for establishment of a plasma current decay time database using disruptive discharges in a small tokamak HYBTOK-II. An increase in the decay rate of the plasma current during the current quench phase was observed in experiments associated with an increase in the plasma resistance. This experimental result is consistent with the prediction of the model.