Aluminum Stabilized Superconducting Prototype Cable Development for the Mu2e Transport Solenoid

The Fermilab Mu2e experiment seeks to measure the rare process of direct muon to electron conversion in the field of a nucleus. The experiment makes use of three large superconducting solenoids: the production solenoid (PS), the transport solenoid (TS), and the detector solenoid (DS). The TS is an “S-shaped” solenoid with a warm-bore aperture of half a meter and field between 2.5 and 2.0 T. The three solenoids are based on four different types of Al stabilized NbTi conductors. All the conductors are composed of a Rutherford cable embedded in an aluminum matrix through a conforming process. This paper describes the various steps that led to the successful procurement of 3 km of Al-stabilized prototype cable for the Mu2e TS. The main cable properties and results of electrical and mechanical tests are presented and discussed for each stage of the cable development process. Results are compared to design values to show how the prototype cable lengths satisfied all the design criteria starting from the NbTi wires all the way to the Al-stabilized cables. Following the successful completion of this initial phase, the TS prototype cable is currently being used to manufacture a prototype TS coil in industry. The cable production phase has recently been launched, with the goal of producing 700 km of superconducting wire for a total of 44 km of TS Al-stabilized cable needed to build the entire Transport Solenoid system.