The Westinghouse team has extended the Lawrence Livermore National Laboratory advanced conceptual design for the TPX PF magnets through preliminary design. This is the first time superconducting PF magnets have been designed for application in a tokamak. Particular challenges were encountered and solved in developing the coil insulation system, welding the helium stubs, and winding the coil. We fabricated a coil using copper stranded CIC conductor, to surface manufacturability issues and demonstrate our solutions.In the paragraphs that follow, we describe aspects of the PF magnet system preliminary design, and discuss our solutions to some of the most challenging aspects of the preliminary design.

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In support of the TPX magnet project, a program was initiated to develop a technique to attach the helium cooling piping to the cable in conduit conductor. The requirements placed on the technique were high reliability without degrading either the properties of the superconductor or the structural performance of the conductor at the attachment point. The design that evolved consisted of piercing a hole with a roto-broaching tool and TIG welding of the stub to the conductor. The results of the testing that was performed indicated: 1) this joint was leak tight at a sensitivity of lO-"std cdsec, 2) remained so after 5 thermal cycles to 77°K and pressurization to 100 a h , and 3) critical current degradation was limited to two of 1.he 162 strands of the cable. A full description of the design and the testing program is presented in the paper.