Short profile rectangular helium cryostat made from nickel-iron alloy

A short profile (40 cm), long length (2.50 m) rectangular helium cryostat has been designed, built and tested for maintaining electronic chips at a stable 9.0 Kelvin temperature. Heat load, and thermal stresses were major design considerations. The distance from room temperature to liquid nitrogen intercept temperature is only 8 centimeters. Liquid nitrogen temperature to liquid helium temperature occurs in 13 centimeters. An alloy known as Invar, 36% Nickel, balance Iron, was used to fabricate the vessel walls and liquid nitrogen heat intercept tubing because of it’s low coefficient of thermal expansion. The cryostat accepts fifty-one, 3.5 cm×42.5 cm devices that extend 26.7 cm into the cryostat. Tight clearance fits to the liquid nitrogen and liquid helium intercepts are maintained. Gaseous helium is used within the cryostat for heat transfer.