The short-circuiting system for one poloidal gap of the RFX shell

The eddy currents flowing in the RFX stabilizing shell during plasma discharges can produce stray fields at the two poloidal gaps, which increase the plasma-wall interaction and the input power necessary to sustain the discharge. In order to improve the effectiveness of a feedback control system on the stray field, one poloidal gap can be short-circuited. A removable system has been designed which can be installed without any dismount or machining of the existing components. Electromagnetic and mechanical finite element analyses and experimental tests were carried out to assess the effectiveness of the system, in terms of maximum current in the contacts, stray field in the plasma region and reliability of the clamping system.