LCP heater thermal performance test results and unique test techniques

The Large Coil Program (LCP) magnet requires integral heaters capable of normalizing conductor half-turns to simulate energy deposition. During a series of tests to determine the cryogenic thermal performance of our LCP conductor, we evaluated the relative thermal performance of two prototype heater installation methods which were tested using a unique heater power control circuit. The prototype heaters were installed in two LCP conductors which were part of a 15-conductor test array used during the conductor thermal performance testing. Results are given comparing the thermal performance of the two heaters, one installed with indium foil and the other "soldered" with Woods metal. The performance of the Woods metal installation agreed closely to the finite element model predicted conductor thermal response to fast, high-power heater pulses, both in maximum temperature rise and time characteristics of the rise and recovery. The sluggish thermal response of the conductor with the cold-welded indium ribbon-secured heater demonstrated that intimate thermal coupling of the heater elements to the conductor is mandatory. The heater control circuitry is described which was developed in support of this test and provided transient heater power durations down to 5 msec and at power inputs up to 3000 watts. A brief description also is given of the transient and steady-state data acquisition systems used as well as the interface between the heater control circuitry and the remote computer used to control the transient testing.