Disruption Induced Voltages and Loads on Torus Sectors

The rapid decay of magnetic flux during a plasma disruption induces voltages, currents, and Lorentz loadings in nearby electrically-conducting material. Present designs employ toroidal shells or shell segments near the plasma. These shells are divided into sectors for assembly and maintenance considerations, but may have toroidally-continuous conducting paths due to the need for vacuum boundaries. Voltages induced across sector gaps may initiate arcing and subsequent material damage. In addition, induced eddy currents in the shells can interact with the toroidal field and generate large net torques on a sector. A finite element model was used to estimate the induced sector gap voltages and net overturning moments following a 10 ms disruption. The number of shells, toroidal continuity, resistivity, and shell thicknesses were varied. Results are presented that show the effects of these changes on the sector gap voltages and induced loads.