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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Performance of all-metal demountable cryogenic seals at superfluid helium temperatures

Two all-metal demountable cryogenic seals with an outside diameter of 36.6 mm, inside diameter of 27.2 mm, and thickness of 0.51 mm were leak-tested at room temperature (300 K), liquid nitrogen temperature (21 cycles at 77 K), liquid helium temperature (9 cycles at 4.2 K), and susperfluid helium temperature (4 cycles at 1.6 K). Each seal was mounted and demounted for 13 cycles. Thickness measurements at 90 deg intervals along the circumference showed a maximum seal compression of 0.038 mm. Leak-rate measurements at all temperatures showed no detectable leak above the helium background level, typically 0.1 x 10(-9) std-cc/sec, during testing.

Salerno, Louis J.↗
NASA NTRS1988

Dewar to dewar model for superfluid helium transfer

A model has been developed to predict the flow of He II between a source and a receiving dewar. The model uses a finite difference aproximation to integrate the describing equations. The transfer path may contain porous plugs or mechanical pumps, heater sections, heat leaks, constrictions due to valves, and bends. These line elements may occur in any order and in any quantity. The line elements are easily reconfigured by changing the input data. The input consists of the number of finite element cells, the pressure in each dewar, the heat input to each section and the dimensions of each section. The output is the temperature, pressure, flow rate, velocities and heat flux in each section. An internal reference table provides the properties of He II. The model is programmed for a LOTUS work sheet. It converges rapidly and usually requires 10 to 15 iterations. For most applications an iteration takes 30 s on an AT. The predictions agree well with experimental data.

Snyder, H. A.↗
NASA NTRS1989

Aerodynamic testing in cryogenic nitrogen gas - A precursor to testing in superfluid helium

Testing techniques for transonic cryogenic tunnels using nitrogen as the test fluid are presented. The measurement of static aerodynamic coefficients used to determine component efficiency is discussed, focusing on tests of two-dimensional airfoils at transonic Mach numbers. Also, three-dimensional tests of complete configurations and sidewall mounted wings are examined. Consideration is given to time-dependent phenomena, fluid mechanics, nonintrusive laser techniques, the detection of transition and separation, and testing for flutter, buffet, and oscillating airfoil characteristics.

Lawing, Pierce L.↗
NASA NTRS1990

Pressure drop in the SHOOT superfluid helium acquisition system

Central to the upcoming Superfield Helium On-Orbit Transfer (SHOOT) demonstration is the fluid acquisition system. The main component of the system is a rectangular cross-section gallery area with one side fabricated from a fine mesh screen. He II enters through the screen and is delivered to a fountain effect pump. A model is proposed to predict the pressure drop as fluid flows through the screen and an expression is derived for the required gallery arm length as a function of flow rate demand. The model is compared with measurement of pressure drop in a full scale SHOOT gallery arm operated with flow rates of up to 850 cu dm/hr. The tests were conducted in the University of Wisconsin horizontal liquid helium flow facility to minimize gravitational effects.

Nissen, J. A.↗
NASA NTRS1990

Superfluid helium dynamics

Two papers on cryogenics are presented. The first is entitled, Characterizing He II Flow Through Porous Materials Using Counterflow Data. The second paper is entitled, Thermal Behavior of the SHOOT Gallery Arm. Both papers were presented at the Cryogenic Engineering Conference in Huntsville, AL.

Vansciver, Steven W.↗
NASA NTRS1976

Method and apparatus for generating coherent radiation in the ultra-violet region and above by use of distributed feedback

Helium in the superfluid state emits copious amounts of radiation in the ultraviolet region when excited by an electron stream. Conventional laser action using mirrors is impossible in superfluid helium because there are no mirrors that will reflect VUV radiation. By utilizing the distributed feedback method, the superfluid helium can be made to lase. By setting up a standing wave in superfluid helium that has a wavelength equal to, or harmonically related to, half the wavelength of the photon radiation chosen to be emitted as laser radiation by the superfluid helium, the need for end mirrors to produce reflection of the laser radiation is eliminated and reflection occurs instead at the wavefronts of the standing wave. The photons leave the superfluid helium at right angles to the standing wave as coherent radiation having a very high intensity. The standing wave established in the superfluid helium may be an acoustical standing wave, a thermal standing wave (second sound), or an electric standing wave.

Saffren, M. M.↗
NASA NTRS1988

Pump performance requirement for the liquid helium orbital resupply tanker

The Liquid Helium Orbital Resupply Tanker (currently renamed to Superfluid Helium Tanker) will greatly enhance the lifetime of the space missions which require superfluid helium. The Superfluid Helium Tanker pump performance requirement is driven by the superfluid helium replenishment needs of the Space Infrared Telescope Facility (SIRTF). SIRTF is one of the space missions which will require on-orbit superfluid helium resupply in the 1990s. The Superfluid Helium Tanker will carry at least 10,000 L of superfluid helium and provide a minimum pump head of 170 torr (0 to 200 L/h) to cool SIRTF from 150 to 2 K. When the SIRTF tank starts to collect liquid, a minimum flow rate of 300 L/h with a pump head of 60 torr is required to fill the 4000-liter tank.

Lee, J. H.↗
NASA NTRS1988

Space Cryogenics Workshop, University of Wisconsin, Madison, June 22, 23, 1987

Papers are presented on liquid helium servicing from the Space Station, performance estimates in the Superfluid Helium On-Orbit Transfer Flight Experiment, an analytical study of He II flow characteristics in the SHOOT transfer line, a Dewar to Dewar model for superfluid helium transfer, and mechanical pumps for superfluid helium transfer in space. Attention is also given to the cavitation characteristics of a small centrifugal pump in He I and He II, turbulent flow pressure drop in various He II transfer system components, slip effects associated with Knudsen transport phenomena in porous media, and an integrated fountain effect pump device for fluid management at low gravity. Other papers are on liquid/vapor phase separation in He-4 using electric fields, an enclosed capillary device for low-gravity management of He II, cavitation in flowing superfluid helium, the long-term performance of the passive thermal control systems of the IRAS spacecraft, and a novel approach to supercritical helium flight cryostat support structures.

Source record↗
NASA NTRS1990

The fountain effect in aerospace cryogenics

The theory of the fountain effect, also known as the thermomechanical effect, exhibited by superfluid helium is presented, and the application of this effect in space projects is described. Future uses of superfluid He in space are also discussed. These include the use of the fountain effect for liquid-vapor phase separation; for pumping superfluid helium from a storage vessel to a payload (as in the Superfluid Helium On-Orbit Transfer Flight Demonstration and the Superfluid Helium Tanker); for actuating a low-temperature refrigerator; and for circulating liquid helium within a cryostat (as in the Astromag dewar).

Castles, S. H.↗
NASA NTRS1982

Superfluid-supercritical helium tradeoff analysis for the Shuttle Infrared Telescope Facility (SIRTF)

A comparative study is made of three methods for obtaining the required cooling of the SIRTF. The first is a supercritical helium system in which the 2 K temperatures are obtained by a Joule-Thomson expander; the second is a superfluid (He II) helium system; and the third is a hybrid system in which supercritical helium provides the major cooling and small He II reservoirs supply specific detector cooling. The superfluid helium system is found to offer superior performance; it would be the system to use if funding were available. The comparative study gives equal weight to performance, operations, and cost. From this point of view, the hybrid system is selected as the best compromise to obtain an operational SIRTF.

Gier, H. L.↗
NASA NTRS1992

Blow-down analysis of helium from a cryogenic dewar

NASA is currently developing Space Shuttle-based refilling of helium using superfluid helium on-orbit transfer (SHOOT). All the critical components of SHOOT need to be developed through ground-based tests. The helium dewar is one of these components. The Dewar consists of a vacuum vessel enclosing a superinsulated tank. The space between the vacuum vessel and the liquid tank is considered a common vacuum space. In the event that the vacuum is lost, the heat transfers to the dewar and the pressure inside the dewar increases rapidly, resulting in rupture of the dewar due to excessive pressure. Therefore, an emergency vent line is required for release of helium to prevent the dewar from rupturing. The study describes a numerical model for blow-down analysis in an emergency. This qualifies the design of the emergency vent line to be adequate for the assumed heat loads to the helium dewar.

Khan, H. J.↗
NASA NTRS1978

Cryogenic helium 2 systems for space applications

Two cryogenic systems are described which will provide cooling for experiments to be flown on Spacelab 2 in the early 1980's. The first system cools a scanning infrared telescope by the transfer of cold helium gas from a separate superfluid helium storage dewar. The flexible design permits the helium storage dewar and transfer assembly to be designed independent of the infrared experiment. Where possible, modified commerical apparatus is used. The second cryogenic system utilizes a specially designed superfluid dewar in which a superfluid helium experiment chamber is immersed. Each dewar system employs a porous plug as a phase separator to hold the liquid helium within the dewar and provide cold gas to a vent line. To maintain the low vapor pressure of the superfluid, each system requires nearly continuous prelaunch vacuum pump service, and each will vent to space during the Spacelab 2 flight.

Urban, E.↗
NASA NTRSDate not supplied

Finding and Fixing a Small Low Temperature Leak - A Case Study on XRISM/Resolve

The Resolve instrument on the X-Ray Imaging and Spectroscopy Mission (XRISM) uses an Adiabatic Demagnetization Refrigerator (ADR) to cool extremely sensitive x-ray microcalorimeters to 50 mK. A 40-liter superfluid helium dewar and a 4.5 K Joule Thomson (JT)/Stirling cryocooler serve as heat sinks for the ADR and staged cooling for the dewar. The superfluid helium lifetime is required to last at least 3 years on orbit with margin. The superfluid helium dewar developed a small leak (~5e-7 Pa m^3/s) at low temperature which compromised the dewar vacuum in two days of ground testing. It turns out that this leak disappears completely at room temperature (<5e-13 Pa m^3/s). This presentation describes the lengthy process of characterizing, isolating, and ultimately, repairing this leak.

Michael DiPirro↗
NASA NTRS1989

Cryogenic techniques for large superconducting magnets in space

A large superconducting magnet is proposed for use in a particle astrophysics experiment, ASTROMAG, which is to be mounted on the United States Space Station. This experiment will have a two-coil superconducting magnet with coils which are 1.3 to 1.7 meters in diameter. The two-coil magnet will have zero net magnetic dipole moment. The field 15 meters from the magnet will approach earth's field in low earth orbit. The issue of high Tc superconductor will be discussed in the paper. The reasons for using conventional niobium-titanium superconductor cooled with superfluid helium will be presented. Since the purpose of the magnet is to do particle astrophysics, the superconducting coils must be located close to the charged particle detectors. The trade off between the particle physics possible and the cryogenic insulation around the coils is discussed. As a result, the ASTROMAG magnet coils will be operated outside of the superfluid helium storage tank. The fountain effect pumping system which will be used to cool the coil is described in the report. Two methods for extending the operating life of the superfluid helium dewar are discussed. These include: operation with a third shield cooled to 90 K with a sterling cycle cryocooler, and a hybrid cryogenic system where there are three hydrogen-cooled shields and cryostat support heat intercept points.

Green, M. A.↗
NASA NTRS1990

Science and applications of He-II in space

Applications of He II in space environment are described, with special attention given to application of He II as a cryogen in several completed and planned space mission. Major applications of He II include the completed Infrared Astronomical Satellite and the Spacelab 2 Infrared Telescope missions, and planned missions that include the NASA Cosmic Background Experiment, the Space IR Telescope, the Large Deployable Reflector, and the ESA's Infrared Space Observatory. Science experiments include the completed Superfluid Helium in Zero Gravity Experiment and the planned Superfluid Helium On-Orbit Transfer and Lambda Point experiments.

Mason, Peter V.↗
NASA NTRS1984

Cryogenic and thermal design for the Space Infrared Telescope Facility (SIRTF)

The 1-meter class cryogenically cooled Space Infrared Telescope Facility (SIRTF) planned by NASA, is scheduled for a 1992 launch. SIRTF would be deployed from the Shuttle, and placed into a sun synchronous polar orbit of 700 km. The facility has been defined for a mission with a minimum initial lifetime of one year in orbit with mission extension that could be made possible through in-orbit servicing of the superfluid helium cryogenic system, and use of a thermal control system. The superfluid dewar would use an orbital disconnect system for the tank supports, and vapor cooling of the barrel baffle. The transient analysis of the design shows that the superfluid helium tank with no active feedback comes within temperature requirements for the nominal orbital aperture heat load, quiescent instrument, and chopper conditions.

Lee, J. H.↗