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 γτ_wall, where γ is the mode growth rate and τ_wall is the wall penetration time, and is largest for γτ_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_φ. This is caused by toroidal variation of the halo current, as verified computationally and analytically.