The world's first milli-Kelvin cryo-cooler, transforming the use of the milli-Kelvin temperature domain in the same way 4 K cryo-coolers have for the liquid helium region
20 November 2011
The cooler has dimensions 120 mm width, 56 mm depth and 300 mm height.
This project funded by EPSRC is to develop and construct the world's first milli-Kelvin cryo-cooler, transforming the use of the milli-Kelvin temperature domain in the same way 4 K cryo-coolers have for the liquid helium region. It will enable those inexperienced with such low temperatures to easily access very low temperatures in a bench top system. We are constructing a small cooler module, a continuous adiabatic demagnetisation refrigeration (cADR) which will extend any 4 K cryo cooler to a milli-Kelvin (<100 mK) cryo cooler. Current 4 K pulse tube coolers can reach 4 K from room temperature within 2 hours, we anticipate a further 2 hours for the cADR to achieved <100 mK, giving a complete cool down from room temperature to <100 mK in 4 hours. By controlling the ADR's various magnetic fields, the proposed cryo-cooler module can provide a highly stable temperature anywhere from the base temperature of the attached 4 K cryo-cooler to <100 mK. This therefore represents a complete cryo-cooler solution and thus extreme ease of use for a technology which is still large and cumbersome.
The technology to enable this for a ground based system has come about by the large investment in developing Adiabatic Demagnetisation Refrigerator (ADR) technology for future space missions at the Mullard Space Science Laboratory (MSSL).