The cryostat design has been developed and refined by the I.L.L. over many years, and provides the following unique features:
- The complete separation of the variable temperature insert and the helium container by the liquid nitrogen shield which allows the insert to be heated to 300K with no increase in the consumption of liquid helium.
- The separation of the cooling system and the sample well, thus considerably reducing the risk of blockage in the cooling system.
- A design of cold valve which allows an ‘all or little’ operation. The valve can be opened for rapid cooling and when closed maintains a flow, thus eliminating regulation problems. Furthermore, the valve can be removed from the cold cryostat should any maintenance be required.
- An overpressure facility is provided on the helium can so that temperatures above 5 K can be maintained without liquid helium circulation pumps.
- All separate volumes are fitted with pressure relief valves with the exception of the liquid nitrogen container which is open to the atmosphere.
- A carefully designed sample holder is provided on which samples can be mounted in close contact with a temperature sensor. The baffles on this sample holder ensure correct thermal coupling between the sample holder and the cooling gas.