The RFX toroidal field winding design

RFX is a 2 MA Reversed Field Pinch (RFP) experiment based on toroidal magnetic confinement, presently under construction at Padova. It is the largest RFP ever built and is expected to prove the fusion potential of this alternative line, in a scale similar to the present generation tokamaks. The RFX Toroidal Field Winding consists of 48 coils, which can be connected in many series/parallel configurations according to the toroidal field programming required for plasma operation, Easy maintenance was specified as one of the most important design targets. For this reason each coil consists of two identical half coils connected at the equatorial plane of the machine. This choice implies additional technical problems to be solved. In order to be in alignement, the half coils are placed into grooves machined in an aluminium shell, which also has the function of withstanding the overturning moment caused by to the interaction between the current and the poloidal field. Stainless steel clamping belts are provided around the coils to withstand their electromagnetic expansion forces and to keep them in the grooves. Thermal expansion of the half coils takes place freely along the grooves, due to thin layers of low-friction material placed on the coil surfaces. The demountable joints which connect the conductors of the half coils are designed to allow thermal expansion. Two basic alternative solutions were considered for the electric contacts: The first based on a Multi-Contact® plug-in system, the second on bolted joints. © 1988 IEEE