Cable demo of advanced version of the muon collider target and capture solenoids

The muon target solenoid is the first magnet in the muon beam production chain. This magnet will collect and capture both positive and negative muons produced by the proton beam impinging on the target. The target solenoid has a large bore, 1.2 m, to host the shielding required to absorb the substantial radiation heat load from the target. One of the design concepts considered is based on a High Temperature Superconducting (HTS) cable, shown in the image, which allows reaching the very high fields required, 20 T, operating at a cryogenic temperature of 20 K, with higher efficiency if compared to the liquid helium point used to date in all accelerators. The cable, inspired by those developed for advanced thermonuclear fusion reactor concepts [MIT] consists of a hollow copper profile with twisted grooves, hosting stacks of soldered HTS tapes (shown opened in a "flower" shape in the image). Gaseous helium at 20 K, 20 bar, flows in the central hole of the copper profile. The stainless steel jacket enclosing the soldered copper and HTS profile is the main structural reinforcement, supporting the large electromagnetic loads experienced by the coils at the extraordinary field level. Development of this concept profits greatly from the studies and tests in other fields of science and technology, and in particular the on-going effort towards the first fusion power plant.