Abstract
A disruption is a dramatic event during which the tokamak plasma magnetic confinement degrades, plasma moves towards the wall and loses its thermal energy and current on an extremely short time scale. Understanding of the underlying physical processes behind disruptions is among important issues in the tokamak plasmas research because disruptions cause various mechanical and thermal loads in the vacuum vessel.
The article presents an introduction to disruption causes, processes and consequences. Special attention is given to toroidally asymmetrical disruptions because they induce large sideway forces and the rotation of asymmetry might lead to a resonance with the natural frequency of the vacuum vessel (this is of particular concern for ITER).
Further, the investigation of plasma current toroidal asymmetries during disruptions might complement the theory of Hiro currents flowing in the vacuum vessel. Possibilities of disruptions studies using magnetic diagnostics on COMPASS are discussed.
The standard settings of Mirnov coils data acquisition system cannot cope with the wide range of values of raw unintegrated signals during the discharge flat-top and disruption which results into the corruption of numerically integrated signal. This considerably affects the calculated plasma current asymmetry.
A method of combination of two acquisition channels with different settings is proposed to resolve this problem.