Sideways wall force produced during tokamak disruptions

A critical issue for ITER is to evaluate the forces produced on the surrounding conducting structures during plasma disruptions. We calculate the non-axisymmetric 'sideways' wall force F-x, produced in disruptions. Simulations were carried out of disruptions produced by destabilization of n = 1 modes by a vertical displacement event (VDE). The force depends strongly on gamma tau(wall), where gamma is the mode growth rate and tau(wall) is the wall penetration time, and is largest for gamma tau(wall) = constant, which depends on initial conditions. Simulations of disruptions caused by a model of massive gas injection were also performed. It was found that the wall force increases approximately offset linearly with the displacement from the magnetic axis produced by a VDE. These results are also obtained with an analytical model. Disruptions are accompanied by toroidal variation of the plasma current I-phi. This is caused by toroidal variation of the halo current, as verified computationally and analytically.