Passive gas-gap heat switches for use in adiabatic demagnetization refrigerators

Shirron, Peter; Canavan, Edgar R.; DiPirro, Michael; Jackson, M.; Panek, John; Tuttle, James

doi:10.1063/1.1472143

Cited by 23 publications

(10 citation statements)

References 3 publications

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“…Another solution for heat switches for this design are passive gas-gap heat switches which have been used by Shirron et al 8 They offer good switching ratio and a quick switching time. On one hand, being passive is an advantage in the way it does not require any control and limits the complexity of the control.…”

Section: Other Heat Switchesmentioning

confidence: 99%

A miniature continuous adiabatic demagnetization refrigerator with compact shielded superconducting magnets

Duval

Cain

Timbie

2004

Millimeter and Submillimeter Detectors for Astronomy II

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Cryogenic detectors for astrophysics depend on cryocoolers capable of achieving temperatures below ≈ 100 mK. In order to provide continuous cooling at 50 mK for space or laboratory applications, we are designing a miniature adiabatic demagnetization refrigerator (MADR) anchored at a reservoir at 5 K. Continuous cooling is obtained by the use of several paramagnetic pills placed in series with heat switches. All operations are fully electronic and this technology can be adapted fairly easily for a wide range of temperatures and cooling powers. We are focusing on reducing the size and mass of the cooler. For that purpose we have developed and tested magnetoresistive heat switches based on single crystals of tungsten. Several superconducting magnets are required for this cooler and we have designed and manufactured compact magnets. A special focus has been put on the reduction of parasitic magnetic fields in the cold stage, while minimizing the mass of the shields. A prototype continuous MADR, using magnetoresistive heat switches, small paramagnetic pills and compact magnets has been tested. A design of MADR that will provide ≈ 5 µW of continuous cooling down to 50 mK is described.

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Section: Other Heat Switchesmentioning

confidence: 99%

A miniature continuous adiabatic demagnetization refrigerator with compact shielded superconducting magnets

Duval

Cain

Timbie

2004

Millimeter and Submillimeter Detectors for Astronomy II

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“…One innovation in the design of the ADR is the use of passive gas-gap heat switches [3]. In these switches, by carefully controlling the amount of 3 He gas relative to the surface area of an internal getter, it is possible to set up conditions so that the 3 He gas adsorbs onto the getter below a given temperature (tailorable from 0.2 K to above 5 K) and desorbs above that temperature.…”

Section: Adr Parametersmentioning

confidence: 99%

A Rapid Turnaround Two-Stage Adiabatic Demagnetization Refrigerator for Cooling to 50 mK

Shirron¹,

DiPirro²,

Panek³

et al. 2006

AIP Conference Proceedings

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Many research and development programs require rapid access to very low temperatures (-50 mK). For detector development, relatively large experiment volumes are also needed for tests involving integrated detectors and readout amplifiers (which may need to be stationed at a different temperature). To provide this capability in a versatile, fast turnaround system, we have constructed a two-stage adiabatic demagnetization refrigerator (ADR) that is operated in a simple bucket-style dewar. The ADR/cryostat is separated into two concentric inserts; the outer insert supports two 3.3 T magnets, magnet leads and magnetic shielding, and the inner one consists of a hermetic experiment volume coupled to the ADR's salt pills and heat switches. The magnet insert remains in the dewar at all times, while the ADR insert may be inserted and removed even when the dewar is cold. The cooldown from room temperature takes less than 1.5 hours, and cycling of the ADR as little as 30 minutes. Future tests will investigate the use of neon exchange gas to accelerate cooling of the ADR and more thermally isolated components such as wiring and structural supports. Design and operation of the system are discussed.

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“…This capability is being retained for SXS. Various helium containment shells have been used in flight and laboratory ADRs, including machined Ti15333 [6], Vespel with an outer Ti15333 foil [4], and gamma-alumina with an inner Ti15333 foil [7]. Below 1 K, the gamma-alumina composite appears to have the best thermal performance, but we are also investigating T300 carbon composite instead of gamma-alumina.…”

Section: Recycling Sequencementioning

confidence: 99%

Optimization of a Two-Stage Adr for the Soft X-Ray Spectrometer (Sxs) Instrument on the Astro-H Mission

Shirron¹,

Kimball²,

Wegel³

et al. 2010

AIP Conference Proceedings

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NASA/Goddard Space Flight Center has begun developing the Soft X-ray Spectrometer (SXS) instrument that will be flown on the Japanese Astro-H mission. The SXS's 36-pixel detector array will be cooled to 50 mK using a two-stage adiabatic demagnetization refrigerator (ADR). A complicating factor for its design is that the ADR will be integrated into a superfluid helium dewar at 1.3 K that will be coupled to a 1.8 K Joule-Thomson (JT) stage through a heat switch. When liquid helium is present, the coupling will be weak, and the JT stage will act primarily as a shield to reduce parasitic heat loads. When the liquid is depleted, the heat switch will couple more strongly so that the ADR can continue to operate using the JT stage as its heat sink. A two-stage ADR is the most mass efficient option and it has the operational flexibility to work well with a stored cryogen and a cryocooler. The stages are operated independently, and this opens up a very large parameter space for optimizing the design. This paper discusses the optimization process and most relevant trades considered in the design of the SXS ADR, and its expected performance.

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Passive gas-gap heat switches for use in adiabatic demagnetization refrigerators

Cited by 23 publications

References 3 publications

A miniature continuous adiabatic demagnetization refrigerator with compact shielded superconducting magnets

A miniature continuous adiabatic demagnetization refrigerator with compact shielded superconducting magnets

A Rapid Turnaround Two-Stage Adiabatic Demagnetization Refrigerator for Cooling to 50 mK

Optimization of a Two-Stage Adr for the Soft X-Ray Spectrometer (Sxs) Instrument on the Astro-H Mission

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