Three dimensional calculation of misalignment forces for the TPX vacuum vessel

During a plasma disruption eddy currents are induced in all the conducting structures surrounding a tokamak plasma. There is a very real possibility that large structures, such as a tokamak vacuum vessel, are either (1) imperfectly formed and are not bodies of revolution or (2) not perfectly aligned with the plasma, TF coils and PF coils. Previous work in this field has dealt with these concerns by calculating forces and currents on sets of displaced circular filaments. We have performed several studies on this subject using the computer code SPARK. The SPARK code models arbitrary surfaces in three dimensions and gives results frequently different from the simple filament calculations. This paper summarizes several types of perturbation from perfect geometry and summarizes the trends observed.