Field Compensation in Electron-Ion Collider Magnets With a Passive Superconducting Shield

This paper presents work under a Small Business Innovation Research Phase I grant to Particle Beam Lasers, Inc. and Brookhaven National Laboratory to develop a passive superconducting shield as an alternative to the present design of an active shield with superconducting coils. This shielding provides a nearly field-free region for the electron beam near the high-gradient quadrupole for the proton beam in the interaction region (IR) of the proposed electron ion collider. Several materials are being examined for this shielding-tubes of low- or high-temperature superconductors (LTS or HTS), LTS sheets, and HTS tapes. Supplementing this shielding is an iron ring between the superconducting shield and beam tube to counter any decay in shielding currents. If successfully developed, demonstrated, and shown to be compatible with the magnet designs of all the IR magnets, this technique will provide an economical and technically excellent solution that reduces the need to operate IR magnets at higher current. This paper will summarize the latest design studies and test results both at 77 K for the shielding by the bulk-HTS tube and at 4 K for the shielding by tubes of HTS or LTS.