Conceptual design of a superconducting magnet for a 200 MWeMHD engineering test facility

A 6 T superconducting magnet system conceptual design has been completed for the U.S. Department of Energy´s 200 MWeEngineering Test Facility. The 1000 tonne magnet will be built of two grades of pool-cooled NbTi cable superconductor supported in 26 layers of stacked epoxy-plastic plates which form each 60° rectangular saddle coil half. Each coil half will be enclosed in a stainless steel vessel which contains the liquid helium that cools the coils and provides some structural support against the electromagnetic forces. The main force containment structure, external to the LHe vessels and located in the vacuum chamber, is designed for maximal access to structural and coil containment vessel welds for purposes of routine inspection. An LN2-cooled thermal radiation shield is situated between the force containment structure and the outer vacuum vessel. Fiberglass-epoxy low-heat-leak struts position and hold the cold mass in place in the vacuum vessel and also withstand gravity, seismic and magnetic interaction loading. The magnet system, warm bore liner and roll-aside mechanism provided for channel changeout will be discussed as well as such interfacing considerations as fringe field effects on personnel and control instrumentation.