ASIAA SMA - Sub-Millimeter Array, ASIAA SMA
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Cryogenics Requirement

  • Provide a 4K working environment for SIS mixer operation
  • Long-term, reliable cooling in a remote observatory site
  • High cooling capacity for multi-band receiver operation

A commercial close-cycle refrigerator is used for the cooling inside the receiver. It is a three-stage cryo-cooler (4K, 10K, and 80K), and deliver more than 2.5W of cooling power at 4K. The cryo-cooler is a type of compound Gifford-McMahon (GM) and Joule-Thomson (JT) refrigerator. The GM fridge is used to pre-cool the circulating helium gas to its conversion point for the JT mechanism to kick in. This is then resulting the high cooling capacity of the fridge at 4K.

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