Stirling and pulse tube coolers
Stirling and pulse tube coolers are regenerative coolers based on a pressure wave generated by a compressor (usually mechanical) and a cold finger, using a mobile (Stirling) or a fixed (pulse tube) regenerator. The heat is extracted at the cold end when the gas expands, and rejected at the warm end when the gas is compressed.
Long-life Stirling coolers based on the Oxford design have been used on several European and non-European missions. A number of single-stage and two-stage Stirling coolers have been developed in the past, enabling cooling to between 10 K and 100 K.
Current developments are focussed on the improvement of multi-stage Stirling coolers to support the needs of future Science missions, such as XEUS. Astrium UK, together with RAL (UK), are currently developing a cooler which provides up to 390 mW of cooling capacity at 15 K with less than 200W input power, or 10 mW at 6 K (goal).
Due to their simpler design, pulse tube coolers are now widely used to provide cooling down to 50 K. Air Liquide (F), together with Thales Cryogenics (NL) and CEA (F), have developed a Large Pulse Tube Cooler which provides more than 2 W of cooling capacity at 50 K with 160 W of input power, sufficient to satisfy the needs of future Earth Observation missions such as Meteosat 3rd Generation.
Future developments will investigate the possibility of reaching lower temperatures by the use of multi-stage pulse tube coolers.
Last update: 2 May 2007