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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Analysis of dewar and transfer line cooldown in Superfluid Helium On-Orbit Transfer Flight Experiment (SHOOT)

The Superfluid Helium On-Orbit Transfer Flight Experiment (SHOOT) is designed to demonstrate the techniques and components required for orbital superfluid (He II) replenishment of observatories and satellites. One of the tasks planned in the experiment is to cool a warm cryogen tank and a warm transfer line to liquid helium temperature. A math model, based on single-phase vapor flow heat transfer, has been developed to predict the cooldown time, component temperature histories, and helium consumption rate, for various initial conditions of the components and for the thermomechanical pump heater powers of 2 W and 0.5 W. This paper discusses the model and the analytical results, which can be used for planning the experiment operations and determining the pump heater power required for the cooldown operation.

Ng, Y. S.↗
NASA NTRS1991

A cosmic superfluid phase

The universe may have undergone a superfluid-like phase during its evolution, resulting from the injection of nontopological charge into the spontaneously broken vacuum. In the presence of vortices this charge is identified with angular momentum. This leads to turbulent domains on the scale of the correlation length. By restoring the symmetry at low temperatures, the vortices dissociate and push the charges to the boundaries of these domains. The model can be scaled (phenomenologically) to very low energies, it can be incorporated in a late time phase transition and form large scale structure in the boundary layers of the correlation volumes. The novel feature of the model lies in the fact that the dark matter is endowed with coherent motion. The possibilities of identifying this flow around superfluid vortices with the observed large scale bulk motion is discussed. If this identification is possible, then the definite prediction can be made that a more extended map of peculiar velocities would have to reveal large scale circulations in the flow pattern.

Gradwohl, Ben-Ami↗
NASA NTRS1990

Third-sound propagation in thick films of superfluid He-4

Atkins' (1959) basic theory of third sound in thick films of superfluid He-4 is extended here to include a heat source for exciting third sound. A one-dimensional model obeying periodic boundary conditions is developed which can represent a variety of experimentally important configurations. General solutions for the model equations are found which give a complete description of third-sound waves in terms of displacement of the film surface, superfluid velocity, and temperature change as functions of space and time. Algebraic expressions for quantities that occur in general formulas are found for special excitation signals. The structure of third sound is calculated for the first time and the results are found to be inconsistent with previous findings. A direct method for accurately measuring the vaporization coefficient is also presented.

Jackson, H. W.↗
NASA NTRS1989

Superfluid Helium On-Orbit Transfer (SHOOT) operations

The in-flight tests and the operational sequences of the Superfluid Helium On-Orbit Transfer (SHOOT) experiment are outlined. These tests include the transfer of superfluid helium at a variety of rates, the transfer into cold and warm receivers, the operation of an extravehicular activity coupling, and tests of a liquid acquisition device. A variety of different types of instrumentation will be required for these tests. These include pressure sensors and liquid flow meters that must operate in liquid helium, accurate thermometry, two types of quantity gauges, and liquid-vapor sensors.

Kittel, P.↗
NASA NTRS1991

Superfluid-like turbulence in cosmology

A network of vortices in a superfluid system exhibits turbulent behavior. It is argued that the universe may have experienced such a phase of superfluid-like turbulence due to the existence of a coherent state with non-topological charge and a network of global strings. The unique feature of a distribution of turbulent domains is that it can yield non-gravitationally induced large-scale coherent velocities. It may be difficult, however, to relate these velocities to the observed large-scale bulk motion.

Gradwohl, Ben-Ami↗
NASA NTRS1990

Superfluid helium on-orbit resupply

The requirements for superfluid helium (SFHe) resupply were investigated, and the results were used to develop a conceptual design for a superfluid helium tanker (SFHT) which is designed to meet a 50-mission requirement. The SFHT design uses a conventional dewar approach with multiple vapor cooled shields, and a porous-plug phase separator for on-orbit temperature control. An open loop refrigeration approach is used for ground conversion of normal He to SFHe, allowing near-total fill of the supply tank. Design diagrams of the SFHT concept and of various SFHT subsystems are presented.

Eberhardt, Ralph N.↗
NASA NTRS1990

A design and critical technology issues for on-orbit resupply of superfluid helium

The issues of and the solutions to the critical design and technology areas of the Superfluid Helium On-Orbit Transfer (SHOOT) experiment, presently under development at the NASA Goddard Spaceflight Center, are discussed. Special attention is given to the SHOOT design requirements for the 10,000-liter superfluid He resupply tanker system, the concept details of the system, and the resupply operations and their analysis. A block diagram of the SHOOT system is included along with fluid management schematic and configuration diagrams of the system and its subsystems. A summary of the dewar performance is also presented.

Hopkins, Richard A.↗
NASA NTRS1991

Welding of the superfluid helium on-orbit transfer (SHOOT) Flight Demonstration tanks and hardware

The SHOOT Flight Demonstration will provide the technology necessary to resupply superfluid helium in space. The helium dewars in SHOOT have unique requirements, including no detectable leaks, demonstrated structural integrity to allow flight aboard the Space Shuttle, and low parasitic heat leak. The requirements, materials, and processes used to fabricate the two superfluid helium dewars, particularly as they apply to welding, are presented.

Mcclure, Sidney↗
NASA NTRS1990

Superfluid helium needs and resupply on Space Station

Viewgraphs and discussion on superfluid helium needs and resupply on space station are presented. Topics covered include: uses of superfluid helium in space; space station He 2 technology issues; resupply - fluid management issues; liquid acquisition devices for on orbit transfer; and liquid acquisition devices for SHOOT.

Dipirro, Michael J.↗
NASA NTRS1993

Superfluid Helium On-Orbit Transfer (SHOOT) flight demonstration

The Superfluid Helium On-Orbit Transfer (SHOOT) Flight Demonstration was an attached Shuttle payload mounted on a Hitchhiker cross-bay carrier which flew on STS-57 in June of 1993. SHOOT successfully demonstrated the handling and transfer of superfluid helium between two containers, called dewars, in low gravity. SHOOT was a class C payload and for the STS-57 mission was termed a complex secondary payload. The primaries were the retrieval of the EURECA carrier and a collection of modular experiments contained in SPACEHAB. Because the liquid helium was continuously boiling off, SHOOT's activities were scheduled for the first three days of the mission, concurrent with some SPACEHAB experiments, but well before the EURECA retrieval. Control of the SHOOT experiment was highly interactive and originated primarily from the Goddard Payload Operations and Control Center (POCC). Transfer and calibration activities required continuous command windows of up to 50 minutes duration and up to 80 minutes out of each orbit. Occasionally the crew controlled the experiment using the Payload General Support Computer (PGSC) when near-real time control and monitoring was required. SHOOT also placed considerable demands on the orbiter, including a pitch rotation of 3 deg./sec for 15 minutes, and translational burns using both the aft and forward RCS jets to generate accelerations up to 7 milli-g. The basis for these and other requirements are discussed. Interacion with the crew and timing of crew activity during the mission will be detailed. The processing flow of SHOOT at KSC is described with emphasis on the tradeoffs for vertical, as opposed to horizontal, installation in the orbiter. Finally, some lessons learned are presented that are relevant to future cryogenic and Hitchhiker payloads.

Shirron, Peter↗
NASA NTRS2001

Dynamics and Morphology of Superfluid Helium Drops in a Microgravity Environment

We developed an apparatus that makes it possible to observe and study magnetically levitated drops of superfluid helium. The force on a diamagnetic substance in a magnetic field is proportional to the gradient of the square of the magnetic field B. For the magnetic force on helium to be equal to the gravitational force on Earth, it is necessary for the product of B with the field gradient dB/d z to be 21.5 T(exp 2)/cm. In addition, in order for the magnetic field to provide a stable trap, the value of B(exp 2) must increase in all directions in the horizontal plane that passes through the point where the field/field gradient product in the vertical direction has the critical value of 21.5 T(exp 2)/cm. A specially designed superconducting magnet that meets these specifications has been installed in a large helium dewar with optical access. Helium drops levitated by the magnet can be viewed along the axis of the solenoid. The sample chamber within the bore of the magnet is thermally isolated from the magnet and helium reservoir. Its temperature can be varied between 4 and 0.5 K, the lower part of the range being reached using a He-3 refrigerator. Liquid helium can be injected into the magnetic trap using a small capillary. Once a drop is contained in the trap it can be held there indefinitely. With this apparatus we have conducted a number of different types of experiments on helium drops so as to gain information necessary for performing experiments in space. With magnetically levitated drops we are limited to working with drops of 1 cm. or less in diameter. The shape of the drops larger than a few mm diameter can be distorted by the profile of the magnetic field. The study of phenomena such as the initial motion of the surfaces of two drops as they just make contact, requires the use large drops to resolve the behavior of interest. We have performed a detailed investigation of the shape oscillations of superfluid drops.

Seidel, George M.↗
NASA NTRS2001

Nucleation of Quantized Vortices from Rotating Superfluid Drops

The long-term goal of this project is to study the nucleation of quantized vortices in helium II by investigating the behavior of rotating droplets of helium II in a reduced gravity environment. The objective of this ground-based research grant was to develop new experimental techniques to aid in accomplishing that goal. The development of an electrostatic levitator for superfluid helium, described below, and the successful suspension of charged superfluid drops in modest electric fields was the primary focus of this work. Other key technologies of general low temperature use were developed and are also discussed.

Donnelly, Russell J.↗
NASA NTRS2003

Vortex Loops at the Superfluid Lambda Transition: An Exact Theory?

A vortex-loop theory of the superfluid lambda transition has been developed over the last decade, with many results in agreement with experiments. It is a very simple theory, consisting of just three basic equations. When it was first proposed the main uncertainty in the theory was the use Flory scaling to find the fractal dimension of the random-walking vortex loops. Recent developments in high-resolution Monte Carlo simulations have now made it possible to verify the accuracy of this Flory-scaling assumption. Although the loop theory is not yet rigorously proven to be exact, the Monte Carlo results show at the least that it is an extremely good approximation. Recent loop calculations of the critical Casimir effect in helium films in the superfluid phase T < Tc will be compared with similar perturbative RG calculations in the normal phase T > Tc; the two calculations are found to match very nicely right at Tc.

Williams, Gary A.↗
NASA NTRS2003

Thermal Conductivity of Liquid He-4 near the Superfluid Transition in Restricted Geometries

We present measurements of the thermal conductivity near the superfluid transition of He-4 in confined geometries. The confinements we have studied include: cylindrical geometries with radii L=.5 and 1.0 microns, and parallel plates with 5 micron spacing. For L=1.0 microns, measurements at six pressures were conducted, whereas only SVP measurements have been done for other geometries. For the 1-D confinement in cylinders, the data are consistent with a universal scaling for all pressures at and above T(sub lambda). There are indications of breakdown of scaling and universality below T(sub lambda). For the 2-D confinement between parallel plates, the preliminary results indicate that the thermal conductivity is finite at the bulk superfluid transition temperature. Further analyses are needed to compare the 2-D results with those in bulk and 1-D confinement.

Liu, Yuanming↗
NASA NTRS2003

Nonlinear Dynamics of the Superfluid Transition: What may We learn on orbit?

Linear response (specifically, Fourier's Law) in He-4 has been observed to fail in heat flow experiments near the superfluid transition. A detailed analysis of the data suggests that the hydrostatic pressure gradient across the helium column limits the divergence of the correlation length in our earth-based experiments. This is consistent with other observations, such as the surprising lack of mutual friction and hysteresis near the superfluid transition, and a 'rounding' of the transition that appears to be independent of heat flux in the low heat flux limit. I will discuss these unusual results from earth-based measurements, and will show predictions for the very different results that may result when we make our measurements on orbit as part of the M1 Mission of the Low- Temperature, Microgravity Physics Facility. This work has been funded by the Fundamental Physics Discipline within the Physical Sciences Research Office of NASA, and is conducted by the DYNAMX (UNM) and CQ (Caltech) Groups, with assistance from the Low Temperature Science and Quantum Sensors Group at JPL.

Duncan, Rob↗
NASA NTRS2005

Applied superconductivity and superfluidity for the exploration of the Moon and Mars

We discuss how superconductivity and superfluidity can be applied to solve the challenges in the exploration of the Moon and Mars. High sensitivity instruments using phenomena of superconductivity and superfluidity can potentially make significant contributions to the fields of navigation, automation, habitation, and resource location. Using the quantum nature of superconductivity, lightweight and very sensitive diagnostic tools can be made to monitor the health of astronauts. Moreover, the Moon and Mars offer a unique environment for scientific exploration. We also discuss how powerful superconducting instruments may enable scientists to seek answers to several profound questions about nature. These answers will not only deepen our appreciation of the universe, they may also open the door to paradigm-shifting technologies. c2005 COSPAR. Published by Elsevier Ltd. All rights reserved.

NASA Center JPL↗
NASA NTRS2004

Measurements of Thermal Conductivity of Superfluid Helium Near its Transition Temperature T(sub lambda) in a 2D Confinement

We report our recent experiments on thermal conductivity measurements of superfluid He-4 near its phase transition in a two-dimensional (2D) confinement under saturated vapor pressure. A 2D confinement is created by 2-mm- and 1-mm-thick glass capillary plates, consisting of densely populated parallel microchannels with cross-sections of 5 x 50 and 1 x 10 microns, correspondingly. A heat current (2 < Q < 400 nW/sq cm) was applied along the channels long direction. High-resolution measurements were provided by DC SQUID-based high-resolution paramagnetic salt thermometers (HRTs) with a nanokelvin resolution. We might find that thermal conductivity of confined helium is finite at the bulk superfluid transition temperature. Our 2D results will be compared with those in a bulk and 1D confinement.

Jerebets, Sergei↗
NASA NTRS2004

A Superfluid Clock

The performance of clocks is limited by the characteristics of the underlying oscillator. Both the quality factor of the oscillator and the signal-to-noise ratio for the resonator state measurement are important. A superfluid helium Helmholtz resonator operating at approx.100mK temperatures has the potential of maintaining frequency stability of 5x10(exp -15)/t(exp 1/2) on the time scale of a few months. The high dynamic range of lossless SQUID position displacement measurement, and low losses associated with the superfluid flow, combined with high mechanical stability of cryogenic assemblies, contribute to the projected stability. Low overall mass of the assembly allows for multiple stages of vibration isolation.

Penanen, Konstantin↗