Mitigating Radiation Impact on Superconducting Magnets of the Higgs Factory Muon Collider

TL;DR

This paper presents a detailed simulation-based design of a protection system for superconducting magnets in a Muon Collider Higgs Factory, effectively mitigating radiation-induced heat loads and preventing quench conditions.

Contribution

It introduces a novel, simulation-validated protection system with tungsten masks and liners to reduce heat load and protect superconducting magnets in a Muon Collider.

Findings

Protection system reduces heat load by a factor of 100.

Peak power density kept below quench limit.

Effective mitigation of radiation damage in superconducting magnets.

Abstract

Recent discovery of a Higgs boson boosted interest in a low-energy medium-luminosity Muon Collider as a Higgs Factory (HF). A preliminary design of the HF storage ring (SR) is based on cos-theta Nb3Sn superconducting (SC) magnets with the coil inner diameter ranging from 50 cm in the interaction region to 16 cm in the arc. The coil cross-sections were chosen based on the operation margin, field quality and quench protection considerations to provide an adequate space for the beam pipe, helium channel and inner absorber (liner). With the 62.5-GeV muon energy and 2 x 10^12 muons per bunch, the electrons from muon decays deposit about 300 kW in the SC magnets, or unprecedented 1 kW/m dynamic heat load, which corresponds to a multi-MW room temperature equivalent. Based on the detailed MARS15 model built and intense simulations, a sophisticated protection system was designed for the entire SR to bring the peak power density in the SC coils safely below the quench limit and reduce the dynamic heat load to the cold mass by a factor of 100. The system consists of tight tungsten masks in the magnet interconnect regions and elliptical tungsten liners optimized for each magnet.