A closed-cycle 1 K refrigeration cryostat

• A closed-cycle 1 K cryostat, precooled by a 4 K pulse tube cryocooler, is developed for cooling a photon detector.
• The vibration from the pulse tube cryocooler is isolated from 1 K cooling station.
• A sealed 1 K instrumentation chamber allows for sample-in-vapor operation.
• The cryostat can provide 250 mW cooling power at 1.84 K.

A 1 K closed-cycle cryostat has been developed to provide continuous cooling to a photon detector below 2 K. A two-stage 4 K pulse tube cryocooler is used to liquefy evacuated vapor from a 1 K pumping port to form a closed-cycle refrigeration loop. A 1 K instrumentation chamber, attached to the 1 K cooling station, is designed to operate with helium inside and provide more uniform cooling. The design of the cryostat has no direct mechanical contact between the pulse tube cryocooler heat exchangers and the 1 K cooling station resulting in almost no vibration transfer to instrumentation chamber. The cryostat can reach a no-load temperature of 1.62 K and provide 250 mW cooling power at 1.84 K.