Multi-stage Adiabatic Demagnetization Refrigerator Research Articles

Performance test results of a helium Dewar for the Resolve instrument onboard the XRISM

The X-ray imaging and spectroscopy mission (XRISM) is an X-ray astronomy satellite developed by the Japan Aerospace Exploration Agency (JAXA) and the National Aeronautics and Space Administration (NASA) to explore the evolution of the universe and its physical phenomena as the replacement for ASTRO-H. One of the primary scientific instruments of the XRISM is the Resolve, which utilizes an X-ray microcalorimeter array. This detector array is required to be cooled down to 50 mK using a complex cryogenic system with a multistage adiabatic demagnetization refrigerator (ADR) developed by NASA and a cryogenic system developed by Sumitomo Heavy Industries, Ltd. (SHI). The cryogenic system is required to cool the heat sink of the ADR to a temperature below 1.5 K in orbit for at least 3 years. To meet the specific requirements, we developed a hybrid cryogenic system consisting of a liquid helium tank, a 4K Joule–Thomson cooler, and two two-stage Stirling coolers. As a result, the specific requirements were verified by ground tests. This paper describes the design, including the major changes from ASTRO-H, fabrication, and results of the ground tests of the helium Dewar of the Resolve instrument.

Requirement of the on/off ratio of superconducting heat switch used for the continuous stage of cADR

As an important component of the adiabatic demagnetization refrigerator (ADR), the superconducting heat switch uses the different thermal conductivities of a metal in the normal state and the superconducting state to turn the heat switch on / off for the continuous stage. Switch ratio is an important parameter to evaluate the performance of a heat switch, which is related to many factors. Peter Kittel calculated the different switch ratio requirements in the single-stage and multi-stage ADR. Based on that, this paper focuses on the relationship between the required switch ratio and operating parameters of the ADR system, especially the ratio of the heat leak to the effective cooling power.

Experimental results of ADR cooling tuned for operation at 50 mK or higher temperature

Several astrophysics missions are currently planned, with significant European participations. To reach their targeted performances, cooling down to temperature of 50 or 100 mK, depending on the instrument design is required. Multi stage Adiabatic Demagnetization Refrigerator (ADR) cooling can provide such performances and is well adapted for space. At the early stage of the mission definition various cryogenics design are considered implying different cooling requirements. A 3-stage ADR cooler demonstration model for space has been used to demonstrate and validate several operation modes. Results will be presented for a 100 mK cooling including a continuous 400 mK stage as well as for 300 mK continuous cooler. A specific focus has also been put on 50 mK temperature measurements demonstrating the tight thermal stability, well below 1 μk that can be reached with this technology.

LiteBIRD Cryogenic Chain: 100 mK Cooling with Mechanical Coolers and ADRs

LiteBIRD is a JAXA-led L-Class mission aimed at the study of B-mode polarization of the cosmic microwave background. Measurements on 15 bandwidth from 34 to 448 GHz are made on two instruments, low-frequency telescope and medium- and high-frequency telescope. To reach the desired sensitivities, more than 4500 transition edge sensors detectors, used on both instruments, will be continuously cooled to 100 mK. The cryogenic design based on shield cooling and mechanical coolers is presented in this paper. Shield cooling will be done with passive cooling and 15 K pulse tube coolers. A single cryogenic chain will cool both instruments. A 4 K stage is cooled by a 4He Joule–Thomson cooler from Japanese Aerospace Exploration Agency, pre-cooled by Stirling coolers. Multistage adiabatic demagnetization refrigerator will be optimized to provide continuous cooling at 1.75 K, 300 mK and 100 mK with 2.2 µW of cooling power on the latter stage. Seven ADR stages provided by NASA (USA) and CEA (France) are required. Details on the thermal design, preliminary sizing and expected performance are presented.

In-orbit performance of a helium dewar for the soft X-ray spectrometer onboard ASTRO-H

ASTRO-H was an X-ray astronomy satellite that the Japan Aerospace Exploration Agency (JAXA) developed to study the evolution of the universe and physical phenomena yet to be discovered. The primary scientific instrument of ASTRO-H was the Soft X-ray Spectrometer (SXS). Its detectors were to be cooled to 50 m K using a complex cryogenic system with a multistage adiabatic demagnetization refrigerator (ADR) developed by the National Aeronautics and Space Administration (NASA), and a cryogenic system developed by Sumitomo Heavy Industries, Ltd. (SHI). SHI’s cryogenic system was required to cool the ADR’s heatsink to 1.3 K or less in orbit for three years or longer. To meet these requirements, SHI developed a hybrid cryogenic system consisting of a liquid helium tank, a 4 K Joule-Thomson cooler, and two two-stage Stirling coolers.ASTRO-H was launched from Tanegashima Space Center on February 17, 2016. The initial operation of the SXS cryogenic system in orbit was completed successfully. The cooling performance was as expected and could have exceeded the lifetime requirement of three years.This paper describes results of ground tests, results of top-off filling of superfluid liquid helium just before launch, and cooling performance in orbit.

Cryogen free cooling of ASTRO-H SXS Helium Dewar from 300 K to 4 K

Soft X-ray Spectrometer instrument (SXS) is one of the primary scientific instruments of ASTRO-H. SXS has a cold detector that is cooled to 50 mK by using a multi-stage Adiabatic Demagnetization Refrigerator (ADR). SXS Dewar containing ADR provides 1.3 K heat sink by using liquid helium in nominal operation. After liquid helium is dried up, 4 K heat sink is provided by using mechanical coolers. Both nominal operation and cryogen free operation were successfully demonstrated. This paper describes the test result of cryogen free operation and cool-down performance from room temperature by using only mechanical coolers without liquid helium. The coolers on the Dewar cooled down cold mass from around 300 K to 4 K with 260 W electric power in 40 days. Cold mass is 35 kg in 4 K area including the helium tank, ADR and detector assembly.

The Astro-H high temperature superconductor lead assemblies

The Soft X-ray Spectrometer (SXS) instrument, one of several instruments on JAXA’s Astro-H mission, will observe diffuse X-ray sources with unparalleled spectral resolution using a microcalorimeter array operating at 50mK. The array is cooled with a multi-stage Adiabatic Demagnetization Refrigerator mounted on a 40l helium tank. The tank is at the center of a typical “shell in shell” cryostat, with the innermost shield cooled by a JT cryocooler, and successive outer shields cooled by stirling-cycle cryocoolers. To achieve a multi-year liquid helium lifetime and to avoid exceeding the limited capacity of the JT cooler, very strict requirements are placed on every source of heat leak into these surfaces from the higher temperature shields. However, each ADR stage draws a maximum of 2A, and the Wiedemann–Franz Law precludes even an optimized set of normal-metal leads capable of such high current from achieving the required low thermal conductance. Instead, a set of lead assemblies have been developed based on narrow high temperature superconductor (HTS) tapes derived from commercially available coated conductors.Although the HTS tapes are flexible and have high tensile strength, they are extremely sensitive to damage through a number of mechanisms. A robust set of assemblies have been developed that provide mechanical support to the tapes, provide appropriate interfaces at either end, and yet still meet the challenging thermal requirements. An Engineering Model (EM) set of HTS lead assemblies have survived environmental testing, both as individual units and as part of the EM cryostat, and have performed without problem in recent operation of the EM instrument. The Flight Model (FM) HTS lead assemblies are currently nearing completion.

Optimization strategies for single-stage, multi-stage and continuous ADRs

Adiabatic Demagnetization Refrigerators (ADR) have many advantages that are prompting a resurgence in their use in spaceflight and laboratory applications. They are solid-state coolers capable of very high efficiency and very wide operating range. However, their low energy storage density translates to larger mass for a given cooling capacity than is possible with other refrigeration techniques. The interplay between refrigerant mass and other parameters such as magnetic field and heat transfer points in multi-stage ADRs gives rise to a wide parameter space for optimization. This paper first presents optimization strategies for single ADR stages, focusing primarily on obtaining the largest cooling capacity per stage mass, then discusses the optimization of multi-stage and continuous ADRs in the context of the coordinated heat transfer that must occur between stages. The goal for the latter is usually to obtain the largest cooling power per mass or volume, but there can also be many secondary objectives, such as limiting instantaneous heat rejection rates and producing intermediate temperatures for cooling of other instrument components.