Commercial Cryogenic Cold Heads

To cool both the atom beam and the carbon targets, commercial cryogenic cold heads are used. Both heads form part of a self-contained closed circuit through which compressed helium is pumped. The head which cools the atom beam is a model RGD210 (10 W cooling power at 80 K, 2 W at 20 K), and the head on which the target is mounted is a model RGD1245 (45 W cooling power at 80 K, 12 W at 20 K), both manufactured by Leybold. The pair of cold heads are driven by a single 6 kW compressor.

Both heads consist of two cooling stages. The first stages are cooled to ~35 K by expanding compressed helium via the Gifford-McMahon principle. The second stages, mounted on top of the first stages, are cooled by a similar principle; since they are mounted from a surface which is already chilled to ~35 K, the second stages are cooled further to ~10 K. Temperatures are measured using silicon thermodiodes.

This page last modified 26 October, 2007 by John Edridge