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At least 433 records · Page 24

On-Orbit Operation of the Adiabatic Demagnetization Refrigerator on the Astro-H/Hitomi Soft X-ray Spectrometer Instrument

The Soft X-ray Spectrometer instrument on the Astro-H observatory contains a 6x6 array of x-ray microcalorimeters, which is cooled to 50 mK by an adiabatic demagnetization refrigerator (ADR). The ADR consists of three stages in order to provide stable detector cooling using either a 1.2 K superfluid helium bath or a 4.5 K Joule-Thomson (JT) cryocooler as its heat sink. When liquid helium is present, two of the ADRs stages are used to single-shot cool the detectors while rejecting heat to the helium. After the helium is depleted, all three stages are used to cool both the helium tank (to about 1.5 K) and the detectors (to 50 mK) using the JT cryocooler as its heat sink. The Astro-H observatory, renamed Hitomi after its successful launch in February 2016, carried approximately 36 liters of helium into orbit. On day 5, the helium had cooled sufficiently (1.4 K) to allow operation of the ADR. This paper describes the design, operation and on-orbit performance of the ADR.

sub-kelvin refrigeration↗

Operating Modes and Cooling Capabilities of the 3-Stage ADR Developed for the Soft-X-Ray Spectrometer Instrument on Astro-H

A 3-stage adiabatic demagnetization refrigerator (ADR) is used on the Soft X-ray Spectrometer instrument on Astro-H to cool a 6x6 array of x-ray microcalorimeters to 50 mK. The ADR is supported by a cryogenic system consisting of a superfluid helium tank, a 4.5 K Joule-Thomson (JT) cryocooler, and additional 2-stage Stirling cryocoolers that pre-cool the JT cooler and cool radiation shields within the cryostat. The ADR is configured so that it can use either the liquid helium or the JT cryocooler as its heat sink, giving the instrument an unusual degree of tolerance for component failures or degradation in the cryogenic system. The flight detector assembly, ADR and dewar were integrated into the flight dewar in early 2014, and have since been extensively characterized and calibrated. This paper summarizes the operation and performance of the ADR in all of its operating modes

x-ray astronomy↗

Final Summary of On-Orbit ADR Operation on Hitomis Soft X-Ray Spectrometer Instrument

The Soft X-ray Spectrometer (SXS) on the Astro-H observatory contains a 6x6 array of x-ray microcalorimeters that are cooled to 50 mK by an adiabatic demagnetization refrigerator (ADR). The ADR consists of three stages in order to provide stable detector cooling using either a 1.2 K superfluid helium bath or a 4.5 K Joule-Thomson (JT) cryocooler as its heat sink. Astro-H was renamed Hitomi after it was successfully launched in February 2016. The SXS carried approximately 36 liters of helium into orbit, and by day 5 the helium had cooled sufficiently (1.4 K) to allow operation of the ADR. This paper summarizes the ADRs performance during the 38 days that the satellite was operational.

space astronomy↗

Orbital Gravity Gradiometry Beyond GOCE: Mission Concepts

Significant advances in the technologies needed for space-based cryogenic instruments have been made in the last decade, including cryocoolers, spacecraft architectures and cryogenic amplifiers. These enable considerably more complex instruments to be put into orbit for long-duration missions. One such instrument is the Superconducting Gravity Gradiometer (SGG) developed by Paik, et al. A magnetically levitated version is under consideration for a follow-on mission to GRACE (Gravity Recovery and Climate Experiment) and GOCE (Gravity field and steady-state Ocean Circulation Explorer). With its inherently greater rejection of common mode accelerations and ability to cancel the coupling of angular accelerations into the gradient signal, the SGG can achieve [an accuracy of] 0.01 milli-Eotvos (gravitational gradient of the Earth) divided by the square root of frequency in hertz, with requirements for attitude control that can be met with existing spacecraft. In addition, the use of a cryocooler for cooling the instrument will alleviate the previously severe constraint on mission lifetime imposed by the use of superfluid helium,. enabling mission durations in the 5-10 year range. Studies are underway to determine requirements for orbit (polar versus sun-synchronous), altitude (which affects spacecraft drag), instrument temperature and stability, cryocooler vibration control, and control and readout electronics. These will be used to determine the SGG's sensitivity and ultimate resolution for gravity recovery. This paper will discuss preliminary instrument and spacecraft design, and toplevel mission requirements.

Shirron, Peter J.↗

Design and Development of the Astro-H 3-Stage ADR

The Japanese Astro-H mission will include the Soft X-ray Spectrometer (SXS) instrument provided by NASA/GSFC. The SXS will perform imaging spectroscopy in the soft x-ray band using a 6x6 array of silicon microcalorimeters operated at 50 mK. The detectors will be cooled by a 3-stage adiabatic demagnetization refrigerator (ADR). The configuration allows the ADR to operate with both a 1.3 K superfluid helium bath and a 4.5 K cryocooler as its heat sink. Initially, when liquid helium is present, the two coldest stages of the ADR will operate in a single-shot mode to cool the detectors from 1.3 K. The 3rd stage may be used to transfer heat from the liquid to the cryocooler to extend its lifetime. When the liquid is depleted, the two warmest stages will operate in a continuous mode to establish a 1.3 K base temperature, from which the cold stage will operate in a single-shot mode to cool the detectors. This paper will describe the design and operating modes of the ADR, as well as details of individual components.

Shirron, Peter J.↗

Design and On-Orbit Operation of the Adiabatic Demagnetization Refrigerator on the Hitomi Soft X-Ray Spectrometer Instrument

The Soft X-ray Spectrometer instrument on the Astro-H observatory contains a 6x6 array of x-ray microcalorimeters that is cooled to 50 mK by an adiabatic demagnetization refrigerator (ADR). The ADR consists of three stages in order to provide stable detector cooling using either a 1.2 K superfluid helium bath or a 4.5 K Joule-Thomson (JT) cryocooler as its heat sink. When liquid helium is present, two of the ADR's stages are used to single-shot cool the detectors while rejecting heat to the helium. After the helium is depleted, all three stages are used to continuously cool the helium tank (to about 1.5 K) and single-shot cool the detectors (to 50 mK), using the JT cryocooler as its heat sink. The Astro-H observatory, renamed Hitomi after its successful launch in February 2016, carried approximately 36 liters of helium into orbit. On day 5, the helium had cooled sufficiently (<1.4 K) to allow operation of the ADR. This paper describes the design, operation and on-orbit performance of the ADR, and the use of the ADR's heat rejection as a tool for mass gauging the helium tank.

adiabatic demagnetization refrigerator↗

ADR Design and Operation for the X-Ray Imaging and Spectrometer Mission (XRISM)

Following the loss of the Hitomi x-ray astronomy satellite 38 days after its launch in early 2016, the US and Japanese space agencies (NASA and JAXA) agreed to fund a replacement mission, presently called XARM. XARM will include only the two soft x-ray instruments from Hitomi, the Soft X-ray Spectrometer (SXS), and the Soft X-ray Imager (SXI). For XARM, the spectrometer instrument named Resolve will be rebuilt to the original SXS design. It consists of a 6x6 array of silicon microcalorimeters cooled to 50 millikelvin by means of a 3-stage adiabatic demagnetization refrigerator (ADR) whose operation is supported by a 40 liter superfluid helium tank, a 4.5 K Joule-Thomson cryocooler and a number of 2-stage Stirling cryocoolers. These components were all successfully demonstrated on Hitomi before its failure. This talk will summarize the design of the XARM ADR and how it differs from the SXS version, and will briefly summarize on-orbit ADR performance during Hitomi's operational period.

adiabatic demagnetization refrigeration↗

3-Stage ADR for the X-Ray Imaging and Spectrometer Mission (XRISM)

Following the loss of the Hitomi x-ray astronomy satellite shortly after its launch in early 2016, the US and Japanese space agencies (NASA and JAXA) agreed to fund a replacement mission, presently called the X-Ray Imaging and Spectroscopy Mission (XRISM). XRISM will include only the two soft x-ray instruments from Hitomi, the Soft X-ray Spectrometer (SXS), and the Soft X-ray Imager (SXI). The spectrometer instrument, now named Resolve, will be similar to the original SXS design. It consists of a 6 by 6 array of silicon microcalorimeters cooled to 50 millikelvin by means of a 3-stage Adiabatic Demagnetization Refrigerator (ADR) whose operation is supported by a 40 liter superfluid helium tank, a 4.5-degrees-Kelvin Joule-Thomson cryocooler and a number of 2-stage Stirling cryocoolers. These components were all successfully demonstrated on Hitomi before its failure. This talk will summarize the design of the XRISM ADR and how it differs from the SXS version.

ADR (Adiabatic Demagnetization Refrigerator)↗