TPX magnet helium stub penetration and joining

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 10/sup -10/ std cc/sec, 2) remained so after 5 thermal cycles to 77/spl deg/K and pressurization to 100 atm, and 3) critical current degradation was limited to two of the 162 strands of the cable. A full description of the design and the testing program is presented in the paper.