Sample Loading and Accelerated Cooling of Cryogen-free Dilution Refrigerators

We present results from system tests of top and bottom loading cryogen-free dilution refrigerators which enable cool-down times from room temperature to mK temperatures in 6 to 8 hours. The loading and unloading processes take only a few minutes to perform and the cooling procedure is fully automated. Sample temperatures of less than 10 mK have been achieved with up to 8 coaxial cables and 25 DC-wires connected to the sample holder. We also present cool-down tests of a beam line dilution refrigerator with a 35 kg mass installed on the mixing chamber. A heat pipe was developed to accelerate the cooling of large experimental payloads and the mass was cooled from room temperature to 30 mK in less than 28 hours.