Engineering topics
Shirron, Peter
Publications and source records attributed to Shirron, Peter.
Development of a Flight-Worthy 10 to 4 K Continuous Adiabatic Demagnetization Refrigerator
The cryogenics and fluids branch at NASA's Goddard Space Flight Center is currently developing a high-efficiency, vibration-free, flight-worthy Continuous Adiabatic Demagnetization Refrigerator (CADR) that consist of two modular units: one that lifts ~6 microW at 50 mK while rejecting its heat to a 4 K thermal sink, and another unit that provides a constant 4 K cooling stage while rejecting its heat to a thermal sink at 10 K. The two units are linked together via a 4 K common platform. This paper discusses the status report on the thermodynamic performance of the 4 -10 K ADR. This ADR utilizes an Nb3Sn superconducting magnet and Gadolinium Gallium Garnet (GGG) as its refrigerant. Results show that an idealized cycle, one where its hold time at 4 K is equal to the recycle time, can lift 13 mW at 4 K with a hold time of 132 seconds.
Vibration-Heating in ADR Kevlar Suspension Systems
The cryogenics group at NASA's Goddard Space Flight Center has a long-standing development and test program for laboratory and space-flight adiabatic demagnetization refrigerators (ADRs). These devices are used to cool components to temperatures as low as 0.05 K. At such low temperatures the ADR systems can provide a few micro-Watts of cooling power, so it is important to minimize the conduction of heat to these cold stages from the surroundings. The cold ADR elements are held in place by thin tensioned strings made of Kevlar, chosen for its high strength and stiffness and low thermal conductivity. During laboratory testing, we have observed that occasional significant additional heat loads on the coldest ADR stages correlate with unusually high vibration levels in the cryostat due to a noisy mechanical cryocooler. We theorized that this heat results from plastic deformation of the Kevlar fibers and frictional interactions among them, driven by the cryostat vibrations. We describe tests and calculations performed in attempt to confirm this source of the heating, and we discuss possible strategies to reduce this effect in future ADR suspension systems.
Development of a Space-Flight ADR Providing Continuous Cooling at 50 mK with Heat Rejection at 10 K
Future astronomical instruments will require sub-Kelvin detector temperatures to obtain high sensitivity. In many cases large arrays of detectors will be used, and the associated cooling systems will need performance surpassing the limits of present technologies. NASA is developing a compact cooling system that will lift heat continuously at temperatures below 50 mK and reject it at over 10 K. Based on Adiabatic Demagnetization Refrigerators (ADRs), it will have high thermodynamic efficiency and vibration-free operation with no moving parts. It will provide more than 10 times the current flight ADR cooling power at 50 mK and will also continuously cool a 4 K stage for instruments and optics. In addition, it will include an advanced magnetic shield resulting in external field variations below 5 µT. We describe the cooling system here and report on the progress in its development.
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.
The Primordial Inflation Polarization Explorer (PIPER): Current Status and Performance of the First Flight
The Primordial Inflation Polarization ExploreR (PIPER) is a balloon-borne instrument optimized to measure the polarization of the CMB at large angular scales. It will map 85% of the sky over a series of conventional balloon flights from the Northern and Southern hemispheres, measuring the B-mode polarization power spectrumover a range of multipoles from 2-300 covering both the reionization bump and the recombination peak, with sensitivity to measure the tensor-to-scalar ratio down to r = 0.007. PIPER will observe in four frequency bands centered at 200, 270, 350, and 600 GHz to characterize dust foregrounds. The instrument has background-limited sensitivity provided by fully cryogenic (1.7 K) optics focusing the sky signal onto kilo-pixel arrays of time-domain multiplexed Transition-Edge Sensor (TES) bolometers held at 100 mK. Polarization sensitivity and systematiccontrol are provided by front-end Variable-delay Polarization Modulators (VPMs). PIPER had its engineering flight in October 2017 from Fort Sumner, New Mexico. This papers outlines the major components in the PIPER system discussing the conceptual design as well as specific choices made for PIPER. We also report on the results of the engineering flight, looking at the functionality of the payload systems, particularly VPM, as well as pointing out areas of improvement.
PICO - the Probe of Inflation and Cosmic Origins
The Probe of Inflation and Cosmic Origins (PICO) is a NASA-funded study of a Probe-class mission concept. The top-level science objectives are to probe the physics of the Big Bang by measuring or constraining the energy scale of inflation, probe fundamental physics by measuring the number of light particles in the Universe and the sum of neutrino masses, to measure the reionization history of the Universe, and to understand the mechanisms driving the cosmic star formation history, and the physics of the galactic magnetic field. PICO would have multiple frequency bands between 21 and 799 GHz, and would survey the entire sky, producing maps of the polarization of the cosmic microwave background radiation, of galactic dust, of synchrotron radiation, and of various populations of point sources. Several instrument configurations, optical systems, cooling architectures, and detector and readout technologies have been and continue to be considered in the development of the mission concept. We will present a snapshot of the baseline mission concept currently under development.
Porous Plug Phase Separator and Superfluid Film Flow Suppression System for the Soft X-Ray Spectrometer Onboard Hitomi
When using superfluid helium in low gravity environments, porous plug phase separators are commonly used to vent boiloff gas while confining the bulk liquid to the tank. Invariably, there is a flow of superfluid film from the perimeter of the porous plug down the vent line. For the Soft X-ray Spectrometer onboard ASTRO-H (Hitomi), its approximately 30-liter helium supply has a lifetime requirement of more than 3 years. A nominal vent rate is estimated as ~ 30 ug/s, equivalent to ~ 0.7 mW heat load. It is therefore critical to suppress any film flow whose evaporation would not provide direct cooling of the remaining liquid helium. That is, the porous plug vent system must be designed to both minimize film flow and to ensure maximum extraction of latent heat from the film. The design goal for Hitomi is to reduce the film flow losses to <2 ug/s, corresponding to a loss of cooling capacity of <40 uW. The design adopts the same general design as implemented for Astro-E and E2, using a vent system composed of a porous plug, combined with an orifice, a heat exchanger, and knife-edge devices. In this paper, design, on-ground testing results and in-orbit performance are described.
Development of a Space-Flight ADR Providing Continuous Cooling at 50 Mk with Heat Rejection at 10 K
Future astronomical instruments will require sub-Kelvin detector temperatures to obtain high sensitivity. In many cases large arrays of detectors will be used, and the associated cooling systems will need performance surpassing the limits of present technologies. NASA is developing a compact cooling system that will lift heat continuously at temperatures below 50 mK and reject it at over 10 K. Based on Adiabatic Demagnetization Refrigerators (ADRs), it will have high thermodynamic efficiency and vibration-free operation with no moving parts. It will provide more than 10 times the current flight ADR cooling power at 50 mK and will also continuously cool a 4 K stage for instruments and optics. In addition, it will include an advanced magnetic shield resulting in external field variations below 5 T. We describe the cooling system here and report on the progress in its development.
Development of a Space-Flight ADR Providing Continuous Cooling at 50 mK with Heat Rejection at 10 K
Future astronomical instruments will require sub-Kelvin detector temperatures to obtain high sensitivity. In many cases large arrays of detectors will be used, and the associated cooling systems will need performance surpassing the limits of present technologies. NASA is developing a compact cooling system that will lift heat continuously at temperatures below 50 mK and reject it at over 10 K. Based on Adiabatic Demagnetization Refrigerators (ADRs), it will have high thermodynamic efficiency and vibration-free operation with no moving parts. It will provide more than 10 times the current flight ADR cooling power at 50 mK and will also continuously cool a 4 K stage for instruments and optics. In addition, it will include an advanced magnetic shield resulting in external field variations below 5 T. We describe the cooling system here and report on the progress in its development.
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.
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.
The 26th Space Cryogenic Workshop: Overview, Description of Presentations, and List of Abstracts
This is a summary of the 2015 Space Cryogenics Workshop that was held in Phoenix, Arizona, June 24 to 26, 2015. The workshop was organized by David Plachta and Jason Hartwig of the Cryogenics and Fluid Systems Branch at NASA Glenn Research Center, and continued the tradition of bringing together specialists in the field of space cryogenics to discuss upcoming and potential space missions, and the development of technologies that support or-more often-are enabling for the science and exploration goals of the world's space agencies. The workshop consisted of two days of talks and poster sessions, and provided ample opportunity for more informal discussions that foster collaborations and cooperation in the space cryogenics community. Selected papers from the workshop are published in a special issue of Cryogenics, which is expected to be published by the end of 2015.
Operating Modes and Cooling Capabilities of the Flight ADR for the SXS Instrument on Astro-H
The microcalorimeter array on the Soft X-ray Spectrometer instrument on Astro-H requires cooling to 50 mK, which will be accomplished by a 3-stage adiabatic demagnetization refrigerator (ADR). The ADR is surrounded 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 radiation shields within the cryostat. The unique ADR design allows the instrument to meet all of its science requirements using either the stored cryogen 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 in early 2014, and have since been extensively characterized and calibrated. At present, the four instruments are being integrated with the spacecraft in preparation for an early 2016 launch. This presentation summarizes the operation and performance of the ADR in all of its operating modes.
Thermodynamic Analysis of the 3-Stage ADR for the Astro-H Soft X-Ray Spectrometer Instrument
The Soft X-ray Spectrometer (SXS) instrument on Astro-H will use a 3-stage ADR to cool the microcalorimeter array to 50 mK. In the primary operating mode, two stages of the ADR cool the detectors using superfluid helium at 1.20 K as the heat sink. In the secondary mode, which is activated when the liquid helium is depleted, two of the stages continuously cool the (empty) helium tank using a 4.5 K Joule-Thomson cooler as the heat sink, and the third stage cools the detectors. In the design phase, a high-fidelity model of the ADR was developed in order to predict both the cooling capacity and heat rejection rates in both operating modes. The primary sources of heat flow are from the salt pills, hysteresis heat from the magnets and magnetic shields, and power dissipated by the heat switches. The flight instrument dewar, ADR, detectors and electronics were integrated in mid-2014 and have since undergone extensive performance testing, in part to validate the performance model. This paper will present the thermodynamic performance of the ADR, including cooling capacity, heat rejection to the heat sinks, and various measures of efficiency.
Sub-Kelvin Coolers for Space Missions: ADR Development at NASA/GSFC
Topics Covered: Science drivers for low temperature cooling; and Adiabatic Demagnetization Refrigerator (ADR). architectures and cooling capabilities (1) Single-stage ADR (2) Two-stage ADR (3) Astro-H 3-stage (4) Continuous ADR: 5-stage
Mechanical Tensile Testing of Titanium 15-3-3-3 and Kevlar 49 at Cryogenic Temperatures
Titanium 15-3-3-3 and Kevlar 49 are highly desired materials for structural components in cryogenic applications due to their low thennal conductivity at low temperatures. Previous tests have indicated that titanium 15-3-3-3 becomes increasingly brittle as the temperature decreases. Furthermore, little is known regarding the mechanical properties of Kevlar 49 at low temperatures, most specifically its Young's modulus. This testing investigates the mechanical properties of both materials at cryogenic temperatures through cryogenic mechanical tensile testing to failure. The elongation, ultimate tensile strength, yield strength, and break strength of both materials are provided and analyzed here.
Multi-Stage ADRs for Current and Future Astronomy Missions: Performance and Requirements for Cryogen-Free Operation
The cooling requirements for current (e.g. Astro-H) and future (e.g. IXO and ASP) astronomy missions pose significant challenges for the sub-Kelvin Cooler. In particular, the use of large detector arrays increases the cooling power needed, and the variety of cryocoolers that can be used for pre-cooling greatly expands the range of temperatures at which the sub-Kelvin cooler can be designed to reject heat. In most cases, there is also a need for a stable higher temperature stage for cooling amplifiers or telescope components. NASA/GSFC is currently building a 3-stage ADR for the Astro-H mission, and is developing a 5-stage ADR suitable for IXO and ASP, as well as many other missions in the early planning stages. The architecture of these ADRs allows them to be adapted rather easily for different cooling requirements and to accommodate different cryocooler capabilities (operating temperature and cooling power). This paper will discuss the performance of these ADRs, which operate in both continuous, and single-shot cooling modes, and the minimum cryocooler capabilities needed to meet the requirements of future missions.