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Canavan, Edgar R.

Publications and source records attributed to Canavan, Edgar R..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

High Temperature Superconductor Lead Assemblies for XRISM

The RESOLVE instrument on the upcoming XRISM mission is a rebuild of the SXS instrument that successfully demonstrated high resolution X-ray spectroscopy on the Hitomi mission using a microcalorimeter array at 50 mK. As with SXS, the RESOLVE instrument requires High Temperature Superconductor (HTS) lead assemblies to carry high current to the Adiabatic Demagnetization Refrigerator (ADR) while meeting a very stringent heat conductance budget. For the RESOLVE HTS lead assemblies, we have used new materials and processes to improve the stability and consistency of solder joints to the HTS material. We have also designed a new thermal strap that eliminates stress concentrations on the HTS tapes. We present the results of testing on the engineering model and flight model units, as well as the results of long term testing on prototype solder joints.

Canavan, Edgar R.↗
NASA NTRS2019

Quick-Replacement High-Temperature Superconducting Current Leads for Use in a Research Cryostat

We report the use of a series of high-temperature superconducting leads in a cryostat that require no soldering to replace in the event of a failed lead. The temperature range spanned by the leads is 50 to 3 degrees Kelvin and they typically carry currents up to 4 amperes although they have a much higher capacity in this temperature range. The leads are integrated into the cryostat by clamping both ends to gold-plated copper pads. Support of the leads over the 25-centimeter length is provided by a simple G10 strong back. Details of the clamping interface, measurements of joint resistances, and other interesting observations will be discussed.

Superconductivity↗
NASA NTRS2018

Continuous Sub-Kelvin Cooling from an Adiabatic Demagnetization Refrigerator

We present the current state of development for a continuous magnetic refrigeration system capable of cooling a detector array or other payload to temperatures below 50 mK. This adiabatic demagnetization refrigerator contains four-stages that are cycling continuously yet present a constant ultra-low temperature heat sink at one physical location within the refrigerator. Two different configurations of essentially the same cooler will be presented where the difference is in the physical layout of the stages and the type of heat sink used for the refrigerator's heat rejection.

Magnetic Cooling↗
NASA NTRS2018

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↗
NASA NTRS2017

Development of Stable, Low Resistance Solder Joints for a Space-Flight HTS Lead Assemblies

The solder joints in spaceflight high temperature superconductor (HTS) lead assemblies for certain astrophysics missions have strict constraints on size and power dissipation. In addition, the joints must tolerate years of storage at room temperature, many thermal cycles, and several vibration tests between their manufacture and their final operation on orbit. As reported previously, solder joints between REBCO coated conductors and normal metal traces for the Astro-H mission showed low temperature joint resistance that grew approximately as log time over the course of months. Although the assemblies worked without issue in orbit, for the upcoming X-ray Astrophysics Recovery Mission we are attempting to improve our solder process to give lower, more stable, and more consistent joint resistance. We produce numerous sample joints and measure time- and thermal cycle-dependent resistance, and characterize the joints using x-ray and other analysis tools. For a subset of the joints, we use SEMEDS to try to understand the physical and chemical processes that effect joint behavior.

high temperature superconductivity↗
NASA NTRS2017

Cryogenic Thermal Emittance Measurements on Small-Diameter Stainless Steel Tubing

The Mid Infrared Instrument aboard the James Webb Space Telescope includes a mechanical cryocooler which cools its detectors to their 6 K operating temperature. The refrigerant flows through several meters of 2 mm diameter 304L stainless steel tubing, with some sections gold plated, and some not, which are exposed to their environment. An issue of water freezing onto the tube surfaces is mitigated by running a warm gas through the lines to sublimate the frozen water. To model the effect of this process on nearby instruments, an accurate measure of the tube emittance is needed. Previously we reported the absorptance of the gold plated stainless steel tubing as a function of source temperature (i.e. its environment). In this work the thermal emittance of the uncoated tubing is measured as a function of its temperature between 100 and 280 K. These values lead to an accurate prediction of the minimum length of time required to thermally recycle the system. We report the technique and present the results.

stainless steel↗
NASA NTRS2017

Passive Gas-Gap Heat Switches for Use in Low-Temperature Cryogenic Systems

We present the current state of development in passive gas-gap heat switches. This type of switch does not require a separate heater to activate heat transfer but, instead, relies upon the warming of one end due to an intrinsic step in a thermodynamic cycle to raise a getter above a threshold temperature. Above this temperature sequestered gas is released to couple both sides of the switch. This enhances the thermodynamic efficiency of the system and reduces the complexity of the control system. Various gas mixtures and getter configurations will be presented.

Gas-gap↗
NASA NTRS2017

PIPER Continuous Adiabatic Demagnetization Refrigerator

We report upon the development and testing of a 4-stage adiabatic demagnetization refrigerator (ADR) capable of continuous cooling at 0.100 Kelvin. This cooler is being built to cool the detector array aboard NASA's Primordial Inflation Polarization Explorer (PIPER) observatory. The goal of this balloon mission is to measure the primordial gravitational waves that should exist if the theory of cosmological inflation is correct. At altitude, the ADR will hold the array of transition-edge sensors at 100 mK continuously while periodically rejecting heat to a 1.2 K pumped helium bath. During testing on ground, the array is held at the same temperature but heat is rejected to a 4.2 K helium bath indicating the flexibility in this coolers design.

Magnetic Cooling Sub-Kelvin ADR↗
NASA NTRS2013

ADR salt pill design and crystal growth process for hydrated magnetic salts

A process is provided for producing a salt pill for use in very low temperature adiabatic demagnetization refrigerators (ADRs). The method can include providing a thermal bus in a housing. The thermal bus can include an array of thermally conductive metal conductors. A hydrated salt can be grown on the array of thermally conductive metal conductors. Thermal conductance can be provided to the hydrated salt.

Shirron, Peter J.↗
NASA NTRS2011

Improved Design and Fabrication of Hydrated-Salt Pills

A high-performance design, and fabrication and growth processes to implement the design, have been devised for encapsulating a hydrated salt in a container that both protects the salt and provides thermal conductance between the salt and the environment surrounding the container. The unitary salt/container structure is known in the art as a salt pill. In the original application of the present design and processes, the salt is, more specifically, a hydrated paramagnetic salt, for use as a refrigerant in a very-low-temperature adiabatic demagnetization refrigerator (ADR). The design and process can also be applied, with modifications, to other hydrated salts. Hydrated paramagnetic salts have long been used in ADRs because they have the desired magnetic properties at low temperatures. They also have some properties, disadvantageous for ADRs, that dictate the kind of enclosures in which they must be housed: Being hydrated, they lose water if exposed to less than 100-percent relative humidity. Because any dehydration compromises their magnetic properties, salts used in ADRs must be sealed in hermetic containers. Because they have relatively poor thermal conductivities in the temperature range of interest (<0.1 K), integral thermal buses are needed as means of efficiently transferring heat to and from the salts during refrigeration cycles. A thermal bus is typically made from a high-thermal-conductivity met al (such as copper or gold), and the salt is configured to make intimate thermal contact with the metal. Commonly in current practice (and in the present design), the thermal bus includes a matrix of wires or rods, and the salt is grown onto this matrix. The density and spacing of the conductors depend on the heat fluxes that must be accommodated during operation.

Shirron, Peter J.↗
NASA NTRS2011

Design of a 3-Stage ADR for the Soft X-Ray Spectrometer Instrument on the Astro-H Mission

The Japanese Astro-H mission will include the Soft X-ray Spectrometer (SXS) instrument, whose 36-pixel detector array of ultra-sensitive x-ray microcalorimeters requires cooling to 50 mK. This will be accomplished using a 3-stage adiabatic demagnetization refrigerator (ADR). The design is dictated by the need to operate with full redundancy with both a superfluid helium dewar at 1.3 K or below, and with a 4.5 K Joule-Thomson (JT) cooler. The ADR is configured as a 2-stage unit that is located in a well in the helium tank, and a third stage that is mounted to the top of the helium tank. The third stage is directly connected through two heat switches to the JT cooler and the helium tank, and manages heat flow between the two. When liquid helium is present, the 2-stage ADR operates in a single-shot manner using the superfluid helium as a heat sink. The third stage may be used independently to reduce the time-average heat load on the liquid to extend its lifetime. When the liquid is depleted, the 2nd and 3rd stages operate as a continuous ADR to maintain the helium tank at as low a temperature as possible - expected to be 1.2 K - and the 1st stage cools from that temperature as a single-stage, single-shot ADR. The ADR s design and operating modes are discussed, along with test results of the prototype 3-stage ADR.

Shirron, Peter J.↗
NASA NTRS2010

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.↗
NASA NTRS2008

Active Costorage of Cryogenic Propellants for Exploration

Long-term storage of cryogenic propellants is a critical requirement for NASA's effort to return to the moon. Liquid hydrogen and liquid oxygen provide the highest specific impulse of any practical chemical propulsion system, and thus provides the greatest payload mass per unit of launch mass. Future manned missions will require vehicles with the flexibility to remain in orbit for months, necessitating long-term storage of these cryogenic liquids. For decades cryogenic scientific satellites have used cryogens to cool instruments. In many cases, the lifetime of the primary cryogen tank has been extended by intercepting much of the heat incident on the tank at an intermediate-temperature shield cooled either by a second cryogen tank or a mechanical cryocooler. For an LH2/LO2 propellant system, a combination of these ideas can be used, in which the shield around the LO2 tank is attached to, and at the same temperature as, the LO2 tank, but is actively cooled so as to remove all heat impinging on the tank and shield. This configuration eliminates liquid oxygen boil-off and cuts the liquid hydrogen boil-off to a small fraction of the unshielded rate. This paper studies the concept of active costorage as a means of long-term cryogenic propellant storage. The paper describes the design impact of an active costorage system for the Crew Exploration Vehicle (CEV). This paper also compares the spacecraft level impact of the active costorage concept with a passive storage option in relation to two different scales of spacecraft that will be used for the lunar exploration effort, the CEV and the Earth Departure Stage (EDS). Spacecraft level studies are performed to investigate the impact of scaling of the costorage technologies for the different components of the Lunar Architecture and for different mission durations.

Canavan, Edgar R.↗
NASA NTRS2007

Optimized Heat Interception for Cryogen Tank Support

We consider means for using the cooling available in boil-off gas to intercept heat conducted through the support structure of a cryogen tank. A one-dimensional model of the structure coupled to a gas stream gives an analytical expression for heat leak in terms of flow rate for temperature independent-properties and laminar flow. A numerical model has been developed for heat transfer on a thin cylindrical tube with an attached vent line. The model is used to determine the vent path layout that will minimize heat flow into the cryogen tank. The results are useful for a number of applications, but the one of interest in this study is the minimization of the boil-off in large cryopropellant tanks in low Earth and low lunar orbit.

Canavan, Edgar R.↗
NASA NTRS2007

Cryogenic System for Interferometric Measurement of Dimensional Changes at 40 K: Design and Performance

This report describes the facility, experimental methods, characterizations, and uncertainty analysis of the Cryo Distortion Measurement Facility (CDMF) at the Goddard Space Flight Center (GSFC). This facility is designed to measure thermal distortions of structural elements as the temperature is lowered from 320K to below 40 K over multiple cycles, and is capable of unattended running and data logging. The first measurement is to be the change in length and any bending of composite tubes with Invar end-fittings. The CDMF includes a chamber that is efficiently cooled with two cryo-coolers (one single-stage and one two-stage) rather than with liquid cryogens. Five optical ports incorporate sapphire radiation shields - transparent to the interferometer - on each of two shrouds and a fused silica vacuum-port window. The change in length of composite tubes is monitored continuously with displacement-measuring interferometers; and the rotations, bending, and twisting are measured intermittently with theodolites and a surface-figure interferometer. Nickel-coated invar mirrors and attachment mechanisms were developed and qualified by test in the CDMF. The uncertainty in measurement of length change of 0.4 m tubes is currently estimated at 0.9 micrometers.

Blake, Peter↗
NASA NTRS2003

Continuous Cooling from 10 K to 4 K Using a Toroidal ADR

Future large infrared space telescopes will require cooling to 4K to achieve background limited performance for submillimeter wavelengths. These observatories will require lifetimes of many years and will have relatively large cooling requirements making stored helium dewars impractical. We have designed and are building an adiabatic demagnetization refrigerator (ADR) for use in cooling relatively large loads (10- 100 mW) at 4K and rejecting that heat to a cryocooler operating at 1 OK. Cryocoolers below 1 OK have poor thermodynamic efficiency and ADRs can operate in this temperature range with an efficiency of 75% of Carnot or better. Overall, this can save as much as 2/3 of the input power required to operate a 4K cryocooler. The ADR magnet consists of 8 short coils wired in series and arranged in a toroid to provide self shielding of its magnetic field. This will save mass (about 30% of the mass or about 1.5 kg in our small version, higher percentages in higher cooling power, larger versions) that would have been used for passive or active shields in an ordinary solenoid. The toroid has a 100 mm outer diameter and will produce an approximately 3T average field. In the initial demonstration model the toroid coils will be wound with ordinary NbTi wire and operated at 4K. A second version will then use Nb3Sn wire to provide complete 10K operation. As a refrigerant for this temperature range we will use either GdLiF4 or GdF3 crystals, pending tests of these crystals' cooling capacity per field and thermal conductance. Preliminary indications are that these materials are superior to GGG. We will use gas gap heat switches to alternately connect the toroid to the cold load and the warm heat sink. A small continuous stage will maintain the cold end at 4K while the main toroid is recycled.

DiPirro, Michael J.↗
NASA NTRS1999

Thermal Performance of the XRS Helium Insert

The X-Ray Spectrometer (XRS) is an instrument on the Japanese Astro-E satellite, scheduled for launch early in the year 2000. The XRS Helium Insert comprises a superfluid helium cryostat, an Adiabatic Demagnetization Refrigerator (ADR), and the XRS calorimeters with their cold electronics. The calorimeters are capable of detecting X-rays over the energy range 0.1 to 10 keV with a resolution of 12 eV. The Helium Insert completed its performance and verification testing at Goddard in January 1999. It was shipped to Japan, where it has been integrated with the neon dewar built by Sumitomo Heavy Industries. The Helium Insert was given a challenging lifetime requirement of 2.0 years with a goal of 2.5 years. Based on the results of the thermal performance tests, the predicted on-orbit lifetime is 2.6 years with a margin of 30%. This is the result of both higher efficiency in the ADR cycle and the low temperature top-off, more than compensating for an increase in the parasitic heat load. This paper presents a summary of the key design features and the results of the thermal testing of the XRS Helium Insert.

Breon, Susan R.↗