Performance of Magnet Leads for RHIC

Abstract

Three different conventional gas cooled power leads have been developed at Brookhaven National Laboratory for use in the Relativistic Heavy Ion Collider (RHIC). The RHIC cryogenic system will contain over 500 leads, which will be responsible for as much as 24% of the total 4.5 K refrigerator heat load. Leads optimized for 6300 A and for 1600 A are constructed with variable heat transfer segments and conductor cross sections so as to operate frost free over a wide range of currents without compromising safety or efficiency. A second type, which consists of a 12 lead bundle each carrying 150 A, is an improvement of an existing design, where parallel conductors are pressed into the perimeter of a plastic core. Each type of lead was optimized for minimum refrigeration load while maintaining a margin of safety in the event of coolant flow loss. The 6300 A and 1600 A leads will operate at 0.06 g/s-kA up to and including their design currents, and the 12x150 Amp lead bundle was stable at 0.09 g/s-kA. A mathematical model of each type of lead, which includes warm end components connecting it to the power supply and cold end superconductor, has been developed. The design and test result for each type of lead is presented here, and comparisons are made to their theoretically predicted performance.

Work performed under contract with the US Department of Energy