Gram per gram, Helium 3 is the world’s most expensive substance. CRC’s gas-light sub-Kelvin sorption coolers have been designed to make the best possible use of this scarce resource. By buffering the ultra-cold stage with either one or two intermediate stages, we reduce the heat load on the ultra-cold head and hence lower the running temperature and lengthen the run time. As our coolers are sealed systems, no helium gas is consumed during operation and our units never need to be recharged or re-filled. Our latest design, the 300mK continuous cooler, even offers unlimited run time.

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Our GL10 single-shot sorption cooler adds an extra ultracold stage to the GL7. The load buffering provided by this additional stage enables the unit to reach a base temperature below 250mK, with sizeable heat buffering capacity at several temperatures points below 4K. It is even possible to add a second ultracold stage to the GL10 to increase the cooling power at the lowest temperature, see an example of the GL10 Twin in the Gallery.


The CC7 is a compact continuous ~300mK sorption cooler that is designed to interface to a low-power GM cryocooler. The CC7 has two helium 3 and two helium 4 modules. Each 3-4 module set works like a conventional two-stage (GL7) single-shot sorption cooler. The two ‘sides’ of the CC7 are cycled alternately to keep the central split condenser permanently cold. The split condenser is the cold head of the CC7.

The CC7 is run under software control to operate the switching sequences required to keep the unit running indefinitely. The CC7 split condenser shows small temperature fluctuations when the cycle hands over from one side to the other. There is considerable scope for the end-user to smooth out these fluctuations; the best optimisation scheme will depend on the cryogenic environment and on the heat load this imposes on the CC7. Residual fluctuations can be smoothed out using PID feedback to a load resistor mounted on the split condenser, though this will increase the average temperature of the split condenser.