Eddy currents calculation in the TEXTOR 94 modified liner/vacuum vessel system during plasma disruption

The Dynamic Ergodic Divertor—to be installed inside the vacuum vessel of the TEXTOR 94 tokamak—requires a new liner design. The new liner represents a thin toroidal shell with numerous holes. One-third of the liner shell, facing the ergodic coils, is cut out for purposes of the ergodic divertor structures. To sustain the electromagnetic loads the cut-off edges of the inconel liner shell are reinforced with massive steel structures. Edges of the liner holes are reinforced with different types of steel structures. Calculation of the induced currents in the liner and vacuum vessel and electromagnetic forces on the structures due to interaction of the induced currents with the electromagnetic field during a plasma disruption is presented. The eddy currents in the segments of the vacuum vessel separated by bellows form closed loops. Because of numerous ports in the vacuum vessel and numerous holes in the liner, there are currents flowing perpendicular to the toroidal magnetic field. This leads to bending and twisting of the structures. The calculated electromagnetic forces were used for the subsequent structural analysis.