Peter Shirron | Search NASA

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A Four-Stage Continuous ADR for Space Missions

The cryogenics group at NASA-Goddard has provided adiabatic demagnetization refrigerators (ADRs) for cooling detectors to sub-Kelvin temperatures in space. These ADRs were single-shot devices that produced cooling at 0.05 K for tens of hours before needing to be recycled. Our group also developed a four-stage laboratory ADR system which holds one stage continuously at 0.05K, or colder, while using the other stages to pump heat from the continuous stage up to a heat sink near 4K. This continuous ADR (CADR) provides a useful cooling power that is more than 10 times greater at 0.050 K than what was required by the single-shot space systems. Over the past several years, this system was updated so that it can withstand the rigors of a launch into space. We describe this development process and report its final results.

Continuous ADR↗

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Development of an Ultra-Low-Temperature 5-Stage Continuous Adiabatic Demagnetization Refrigerator That Provides Cooling at Two Unique Temperatures

The cryogenics group at NASA-Goddard has built several adiabatic demagnetization refrigerators (ADRs) for cooling detectors to sub-Kelvin temperatures in a lab, balloon, or space environment. The effort presented here describes the development of a new 5-stage adiabatic demagnetization refrigerator capable of providing continuous cooling at 35 mK with a cooling power double that previously demonstrated at this temperature. It will also provide a separate continuous temperature platform near 1 K. This system will be qualified using flight-like conditions, culminating in an ADR that is ready for the rigors of spaceflight by the end of the effort.

ADR↗

NASA NTRSDate not supplied

A Four-Stage Continuous ADR for Space Missions

The cryogenics group at NASA-Goddard has provided adiabatic demagnetization refrigerators (ADRs) for cooling detectors to sub-Kelvin temperatures in space. These ADRs were single-shot devices that produced cooling at 0.05 K for tens of hours before needing to be recycled. Our group also developed a four-stage laboratory ADR system which holds one stage continuously at 0.05K, or colder, while using the other stages to pump heat from the continuous stage up to a heat sink near 4K. This continuous ADR (CADR) provides a useful cooling power that is more than 10 times greater at 0.050 K than what was required by the single-shot space systems. Over the past several years, this system was updated so that it can withstand the rigors of a launch into space. We describe this development process and report its final results.

Continuous ADR↗

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On-Orbit Performance of the Adiabatic Demagnetization Refrigerator on XRISM

The X-ray Imaging and Spectroscopy Mission (XRISM) observatory was launched on Sep 7, 2023 from Tanegashima Space Center in Japan. Resolve, one its two instruments, performs high-resolution spectroscopy in the soft x-ray band (0.2-13 keV) using a 6x6 microcalorimeter array. The array cooled to 50 mK by a 3-stage ADR, which is linked to both a liquid helium dewar (at <1.2 K) and a Joule-Thomson (JT) cryocooler operating at <4.5 K. While liquid helium is present, two of the ADR stages provide detector cooling at 50 mK and auxiliary cooling to 0.5 K to intercept some parasitic heat loads, while rejecting waste heat to the helium. Once the helium is exhausted, Resolve enters a cryogen-free mode in which all three ADR stages are operated to provide detector cooling at 50 mK and to continuously cool the helium tank to 1.4 K. In this mode, waste heat is rejected to the JT cryocooler. Cryogen-free operation can be sustained as long as the JT and other cryocoolers remain fully operational. At launch, the helium tank contained approximately 35.6 liters of liquid. Within a few days, the helium cooled below 1.15 K, with an estimated 35.0 liters remaining. With an expected time average heat load of 0.68 mW, the helium lifetime was projected to exceed 4 years, but measurements of He volume on orbit suggest a significantly longer lifetime. Details of the ADR’s design and performance are presented.

x-ray astromony↗

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Measuring the Liquid Helium Volume on XRISM and Predicting the Liquid Lifetime

The XRISM/Resolve instrument uses an adiabatic demagnetization refrigerator (ADR) to cool microcalorimeters to 50 mK. The cryogenic system to support the ADR consists of a liquid helium dewar and 5 cryocoolers that provide a semi-redundant system. Operation of the ADR requires either a liquid helium heat sink at 1.2 K or 4.5 K heat sink provided by a multi-stage cryocooler system. The 5 cryocoolers also provide thermal protection to the liquid helium dewar. To calculate the expected lifetime of the liquid helium system, the liquid helium volume was measured before launch and several techniques were employed to determine on-orbit boil off rate.

Michael Dipirro↗