Ultra low temperatures in a helium transport vessel: a dilution refrigerator to achieve 30 mK by continuous absorption pumping
G. J. Batey, J. P. White, W. D. Duncan, A. F. Simpson, and V.A. Mikheev
Oxford Instruments Scientific Research Division, Old Station Way, Eynsham, Witney, Oxon, OX8 ITL, U.K.
( Submitted November 18, 1996 )
A novel design of dilution refrigerator (DR) is described for continuous operation inside a transport Dewar with a neck diameter more than 51 mm. The time required for cooling the mixing chamber from room temperature to 30 mK is 3.5-4.5 h. Warming up to 300 K reguires 0.5-1.0 h. The cooling power achieved is 40 mikroW at 100 mK. The DR is fitted with 6 mm line of sight access down to the mixing chamber. A distinguishing feature of this refrigerator is the absence of a traditional gas handling system, which makes it easy to transport in a small car and quickly commission in a new laboratory within a few hours.