Project Title:

Three-Stage Linear Split-Stirling Cryocooler with 1 to 2K Magnetic Cold Stage

08.12-3708A
Three-Stage Linear Split-Stirling Cryocooler with
	1 to 2K Magnetic Cold Stage
APD Cryogenics, Inc.
1919 Vultee Street
Allentown, PA 18103
Ralph C. Longsworth  (215-481-3708)
ARC -- NAS2-12643

Abstract:

	 This project is aimed at developing a cryocooler for space-borne, infrared astronomical
telescopes which require 50 mW or less cooling at 1 to 2 K. It consists of a linear-drive,
three-stage, split-Stirling cryocooler which will produce refrigeration at 8 K to
cool a niobium-tin, alternating-current, superconducting magnet and a magnetic cold
stage. During Phase I, the design of the refrigerator was studied to determine the
size, weight and power input. Specific areas of innovation include: warm and cold,
flexible, suspension means; a concentric, three-stage expander with clearance seals;
a new, cold regenerator geometry; cold heat switches; and a conduction-cooled 8 K
ac superconducting magnet.
	The design studies confirmed the feasibility of the refrigerator concept to achieve
the desired goals in a practical design capable of achieving long life in space with
low noise and vibration levels. Results of the analysis show the cold end to have
a volume of about 6 liters and a weight of 22 kilograms while the compressor volume
is about 20 liters and weight is 64 kilograms. Total system power input is about
720 watts. Weights and power include magnetic shielding but not power supply components.

Potential Commercial Application:

Potential Commercial Application: Applications are in cost effective refrigeration
systems for cryo-pumps and cryo-electronic devices, including computers. With the
magnetic cold stage, the refrigerator will offer a competitive way of liquefying
helium (e.g., cooling magnets) and providing low temperatures for basic research.