Production of Aluminum Stabilized Superconducting Cable for the Mu2e Transport Solenoid

The Fermilab Mu2e experiment [1], [2] , currently under construction at Fermilab, has the goal of measuring the rare process of direct muon to electron conversion in the field of a nucleus. The experiment features three large superconducting solenoids: the production solenoid (PS), the transport solenoid (TS), and the detector solenoid (DS). The TS is an “S-shaped” solenoid that sits in between the PS and the DS producing a magnetic field ranging between 2.5 and 2.0 T. This paper describes the various steps that led to the successful procurement of over 740 km of superconducting wire and 44 km of Al-stabilized Rutherford cable needed to build the 52 coils that constitute the Mu2e TS cold mass. The main cable properties and results of electrical and mechanical test campaigns are summarized and discussed. Critical current measurements of the Al-stabilized cables are presented and compared to expected critical current values as measured on extracted strands from the final cables after chemical etching of the aluminum stabilizer. A robust and reliable approach to cable welding is presented, and the effect of cable bending on the transport current is also investigated and presented.