The LSST Camera has a higher cryogenic heat load than previous CCD telescope cameras due to its large size (634 mm
diameter focal plane, 3.2 Giga pixels) and its close coupled front-end electronics operating at low temperature inside the
cryostat. Various refrigeration technologies are considered for this telescope/camera environment. MMR-Technology’s
Mixed Refrigerant technology was chosen. A collaboration with that company was started in 2009. The system, based on
a cluster of Joule-Thomson refrigerators running a special blend of mixed refrigerants is described. Both the advantages
and problems of applying this technology to telescope camera refrigeration are discussed. Test results from a prototype
refrigerator running in a realistic telescope configuration are reported. Current and future stages of the development
program are described.