Cryogenics: A new cryocooler
A new cryocooler has been demonstrated at the National Institute of Standards and Technology (NIST) that combines small-size, rapid cooling, low temperatures and high efficiency. It is a "pulse tube" design that uses oscillating helium gas to transport heat, achieving very low temperatures (-223°C) in a matter of minutes without any cold moving parts. The device operates at 120 Hz compared with the usual 60 Hz, which enables use of a much smaller oscillator to generate gas flow, as well as faster cool-down. Pulse tube cryocoolers are more durable than the conventional Stirling cryocoolers typically used in applications where small size is essential such as cooling infrared sensors in space-based instruments used to measure the temperature and composition of the atmosphere and oceans for studies of global warming and weather forecasting, and cooling night-vision sensors for tanks, helicopters and airplanes. The NIST researchers hope to increase operating frequencies to 1000 Hz in the future; this could enable development of chip-scale cryocoolers.