ALMA MEMO #437

Miniature, Modular Heat Sinks for ALMA Cryostats

D. Koller, J. Effland, A. R. Kerr, K. Crady and F. Johnson (NRAO)

2002/12/02

Proposed receiver cartridges for ALMA may utilize up to 96 wires for SIS mixer bias, IF amplifier bias, thermometry and other functions [1]. To reduce heating of the mixer block and minimize the load on the 4 K refrigerator stage, heat sinks will be required on the 80 K, 12 K and 4 K stages. The present concept for the receiver cartridges requires disassembly of each thermal stage to effect repairs. Heat sinks utilizing connectors simplify disassembly, thus improving the mean time to repair. The large number of wires and connections will require a simple, reliable heat sink capable of being mass-produced for the expected 64 receiver cartridges.

The main body of this report describes two different heat sink designs utilizing Nanonics "Dualobe" connectors configured in a modular arrangement for simple installation in receiver cryostats. In Appendix B, a simpler but less effective heat sink is described. The measured thermal performance of all the heat sinks is presented.

View a pdf version of ALMA Memo #437.