The Development of 100 kA Current Leads for a Superconducting Transmission Line Magnet

A pair of current leads to power a transmission line magnet cooled at liquid helium temperature has been designed and developed at Fermilab. The leads were designed to carry 100 kA dc current. Each lead consists of a warm end, a heat exchanger section and a cold end. The warm end is a half moon shaped plate brazed to cylinder. The heat exchanger section is made of 202 copper rods arranged in a staggered pattern. Each rod is 6.35 mm in diameter and 1650 mm in length. The rods were soft-soldered into 12.7 mm deep holes at both warm and cold ends. The helium gas flow, guided by anodized aluminum baffles along the lead length, allows for a relatively high heat transfer coefficient between the current carrying rods and cooling helium gas. The current leads were successfully tested with a ramping current of up to 104 kA. The current lead design, assembly work and the test results are presented