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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Characteristics and performance of a superconducting bumpy-torus magnet facility for plasma research

The NASA Lewis bumpy-torus facility consists of 12 superconducting coils, each 19 cm i.d. and capable of 3.0 T on its axis. The coils are equally spaced around a toroidal array with a major diameter of 1.52 m; they are mounted with the major axis of the torus vertical in a single vacuum tank 2.6 m in diameter. Tests of the facility mapped out its magnetic, cryogenic, vacuum, mechanical, and electrical performance. The design value of the maximum magnetic field on the magnetic axis, 3.0 T, was reached and exceeded. A maximum magnetic field of 3.23 T was held for a period of 60 minutes. When the coils were charged to a maximum magnetic field of 3.35 T, the coil system went normal without apparent damage or degradation of performance.

Roth, J. R.↗
NASA NTRS1972

Performance of a 12-coil superconducting bumpy torus magnet facility

The bumpy torus facility consists of 12 superconducting coils, each 19 cm i.d. and capable of 3.0 teslas on their axes. The coils are equally spaced around a toroidal array with a major diameter of 1.52 m, and are mounted with the major axis of the torus vertical in a single vacuum tank 2.6 m in diameter. Final shakedown tests of the facility mapped out its magnetic, cryogenic, vacuum, mechanical, and electrical performance. The facility is now ready for use as a plasma physics research facility. A maximum magnetic field on the magnetic axis of 3.23 teslas was held for a period of more than sixty minutes without a coil normalcy. The design field was 3.00 teslas. The steady-state liquid helium boil-off rate was 87 liters per hour of liquid helium without the coils charged. The coil array was stable when subjected to an impulsive loading, even with the magnets fully charged. When the coils were charged to a maximum magnetic field of 3.35 teslas, the system was driven normal without damage.

Roth, J. R.↗
NASA NTRS1972

Performance of a 12-coil superconducting 'bumpy torus' magnet facility.

The NASA-Lewis 'bumpy torus' facility consists of 12 superconducting coils, each 19 cm ID and capable of 3.0 tesla on their axes. The coils are equally spaced around a toroidal array with a major diameter of 1.52 m, and are mounted with the major axis of the torus vertical in a single vacuum tank 2.6 m in diameter. Final shakedown tests of the facility mapped out its magnetic, cryogenic, vacuum, mechanical, and electrical performance. The facility is now ready for use as a plasma physics research facility. A maximum magnetic field on the magnetic axis of 3.23 teslas has been held for a period of more than sixty minutes without a coil normalcy.

Roth, J. R.↗
NASA NTRS1990

The NASA-Lewis program on fusion energy for space power and propulsion, 1958-1978

An historical synopsis is provided of the NASA-Lewis research program on fusion energy for space power and propulsion systems. It was initiated to explore the potential applications of fusion energy to space power and propulsion systems. Some fusion related accomplishments and program areas covered include: basic research on the Electric Field Bumpy Torus (EFBT) magnetoelectric fusion containment concept, including identification of its radial transport mechanism and confinement time scaling; operation of the Pilot Rig mirror machine, the first superconducting magnet facility to be used in plasma physics or fusion research; operation of the Superconducting Bumpy Torus magnet facility, first used to generate a toroidal magnetic field; steady state production of neutrons from DD reactions; studies of the direct conversion of plasma enthalpy to thrust by a direct fusion rocket via propellant addition and magnetic nozzles; power and propulsion system studies, including D(3)He power balance, neutron shielding, and refrigeration requirements; and development of large volume, high field superconducting and cryogenic magnet technology.

Schulze, Norman R.↗
DOE OSTI2025

A Spectrochemical Series for Electron Spin Relaxation

Controlling the rate of electron spin relaxation in paramagnetic molecules is essential for contemporary applications in molecular magnetism and quantum information science. However, the physical mechanisms of spin relaxation remain incompletely understood, and new spectroscopic observables play an important role in evaluating spin dynamics mechanisms and structure–property relationships. Here, we use cryogenic magnetic circular dichroism (MCD) spectroscopy and pulse electron paramagnetic resonance (EPR) in tandem to examine the impact of ligand field (d–d) excited states on spin relaxation rates. We employ a broad scope of square-planar Cu(II) compounds with varying ligand field strength, including CuS 4 , CuN 4 , CuN 2 O 2 , and CuO 4 first coordination spheres. An unexpectedly strong correlation exists between spin relaxation rates and the average d–d excitation energy (R 2 = 0.97). The relaxation rate trends as the inverse 11th power of the excited-state energies, whereas simplified theoretical models predict only an inverse second power dependence. These experimental results directly implicate ligand field excited states as playing a critical role in the ground-state spin relaxation mechanism. Furthermore, ligand field strength is revealed to be a particularly powerful design principle for spin dynamics, enabling formation of a spectrochemical series for spin relaxation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1984

Temperature stability limits for an isothermal demagnetization refrigerator

It is pointed out that magnetic refrigeration can provide additional cooling for infrared detectors on space missions, taking into account the Shuttle Infrared Telescope Facility (SIRTF) and the Large Deployable Reflector (LDR). From a temperature of 2 K provided by the primary cryogens, magnetic refrigerators could cool bolometers or pumped photoconductors to 0.1 K or below. Such a reduction in operating temperature would increase the sensitivity for bolometers, while the response at longer wavelengths for pumped photoconductors would be improved. Two types of magnetic refrigeration cycles have been proposed. One type uses a complete demagnetization. The present investigation is concerned with the second type, which uses a feedback-controlled isothermal demagnetization, taking into account the temperature stability limits. Attention is given to control system resolution, thermometer noise, reaction time, and thermal time constants.

Kittel, P.↗
DOE OSTI2025

Off-state magnetoresistance in long-channel germanium Schottky-barrier MOSFETs

An increasing magnetic field perpendicular to an undoped semiconductor surface at low temperature is known to strengthen the binding of localized electrons to stationary ions, as the wavefunction's tails evolve from exponential to Gaussian. It is also known that application of a high bias voltage to a depleted semiconductor can liberate bound charge and induce a large drop in electrical resistance. We connect these established results to experimental electrical transport measurements on off-state germanium Schottky-barrier metal–oxide–semiconductor field-effect transistor (MOSFETs) with an aluminum oxide insulating dielectric and platinum germanide contacts. We make measurements at the three distinct orientations of the magnetic field with respect to the substrate and the current. At 6 K, we observe sharp attenuation of current by more than 2 orders of magnitude, within 60 mT, at a crossover magnetic field perpendicular to the substrate. A 1 T magnetic field attenuates the current by more than 4 orders of magnitude. The strength of the attenuation and the value of the crossover field are controlled by both the gate–source and drain–source voltages. The attenuation is much weaker when the magnetic field is parallel to the current. Finally, we orient the magnetic field parallel to the substrate, but perpendicular to the current, allowing us to distinguish charge hopping at the oxide interface from charge hopping in the bulk. In conclusion, this large off-state magnetoresistance can be exploited for cryogenic magnetic- and photo-detection, and for high-bias, low-leakage MOSFETs.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2026

Machine Protection Studies of Fast Instability-Driven Beam Losses in the EIC Electron Storage Ring

Fast transverse beam instabilities represent one of the most challenging protection scenarios for the Electron-Ion Collider (EIC) electron storage ring (ESR). Coherent betatron oscillations driven by collective effects can grow rapidly and lead to substantial beam losses within only a few tens of turns, posing a threat to collimators, superconducting (SC) magnets, cryogenic systems, and detector components. A dedicated simulation framework based on distributed transverse excitations was developed to evaluate instability-driven beam losses in the ESR. A conservative instability rise time on the order of 10 turns was used to define a bounding protection scenario. Simulations show that the original two-collimator configuration is insufficient to localize losses under all operating conditions, whereas an optimized four-collimator configuration reduces loss leakage into protected regions by more than two orders of magnitude. Nevertheless, the most severe instability scenarios produce catastrophic beam impacts, with nearly half of the stored beam being intercepted by the collimators within a single turn, exceeding the preliminary estimated survivability limits of the baseline collimator design. The results demonstrate that collimation alone is insufficient to guarantee safe ESR operation and must be complemented by a fast machine-protection system. Dedicated turn-by-turn beam-position monitors and fast beam-loss monitors provide sufficient advance warning to detect instability growth and initiate a beam abort before equipment-damaging loss levels are reached. These findings establish quantitative requirements for the ESR machine-protection architecture and support the implementation of a multilayer protection strategy for both accelerator and detector systems.

43 PARTICLE ACCELERATORS↗
NASA NTRS2012

Measuring Segmented Primary Mirror WFE in the Presence of Vibration and Thermal Drift on the Light-Weighted JWST

The light-weighted design of the Optical Telescope Element (OTE) of the James Webb Telescope (JWST) leads to additional sensitivity to vibration from the ground - an important consideration to the measurement uncertainty of the wavefront error (WFE) in the primary mirror. Furthermore, segmentation of the primary mirror leads to rigid-body movements of segment areas in the WFE. The ground vibrations are minimized with modifications to the test facility, and by the architecture of the equipment supporting the load. Additional special test equipment (including strategically placed isolators, tunable mass dampers, and cryogenic magnetic dampers) mitigates the vibration and the response sensitivity before reaching the telescope. A multi-wavelength interferometer is designed and operated to accommodate the predicted residual vibration. Thermal drift also adds to the measurement variation. Test results of test equipment components, measurement theory, and finite element analysis combine to predict the test uncertainty in the future measurement of the primary mirror. The vibration input to the finite element model comes from accelerometer measurements of the facility with the environmental control pumps operating. One of the isolators have been built and tested to validate the dynamic performance. A preliminary model of the load support equipment and the OTE with the Integrated Science Instrument Module (ISIM) is complete. The performance of the add-on dampers have been established in previous applications. And operation of the multi-wavelength interferometer was demonstrated on a scaled hardware version of the JWST in an environment with vibration and thermal drift.

Whitman, Tony L.↗
NASA NTRS2023

Low-Cost Testing in Representative Lunar Regolith Environment

Rapid prototyping and testing are key enablers of iterative designs common in early technology research and development. Testing in a dusty environment is critical to prepare the Cryogenic Magnetic Coupler for lunar operations. To enable early and iterative testing of dust mitigation concepts, a low-cost, low-fidelity representative lunar regolith environment was developed at the National Aeronautics and Space Administration (NASA) Armstrong Flight Research Center (Edwards, California). Based on preliminary testing with this test setup, a similar setup may be of interest to universities and other entities looking to develop the capability to safely test relatively small-scale components with lunar regolith simulant. The development of this lunar regolith test chamber and results from preliminary testing are presented in this paper. Also discussed are further development strategies for the potential improvement of this setup.

Scott Stebbins↗
NASA NTRS1994

Tests Of A Magnetic Bearing For Cryogenic Applications

Report describes experiments performed in test rig on hybrid magnetic bearing for possible use in turbopumps at low temperature. Results of tests indicate feasible to use bearing in cryogenic environments and bearing damps bending-mode vibrations of flexible rotor as rotor accelerates or decelerates through speeds at which bending-mode oscillations excited.

Dirusso, Eliseo↗
NASA NTRS1982

Magnetically suspended Stirling cryogenic space refrigerator Status report

At the 1979 Cryogenic Engineering Conference, attention was given to conceptual designs of spaceborne cryogenic refrigeration systems which can provide long-term, unattended operation. Since that time, efforts have continued to translate one of those concepts into an engineering model. The present investigation is concerned with a refrigerator which was designed to generate 5 W of cooling power at a temperature of 65 K. The compression heat of the refrigerator is dissipated at a temperature of 300 K, and the output of the system is to be maintained reliably for a period of five years or longer. The refrigerator design is based on the Stirling cycle, which has an ideal efficiency equal to that of the Carnot cycle. Attention is given to some background information concerning a cryogenic refrigerator, the design of the refrigerator components, and the development status. The magnetic bearings and the linear motors have been tested at the component level.

Daniels, A.↗
NASA NTRS1978

Ultra-low magnetic field apparatus for a cryogenic gyroscope

An ultralow magnetic field apparatus for earth-based testing of a cryogenic gyroscope system designed for a satellite test of general relativity is described. The magnetic field apparatus makes use of a superconducting lead shield while also maintaining sufficient mechanical stability to obtain a gyroscope readout sensitivity of one arcsec over a limited range. A gyroscope environment of 2.3 times 10 to the minus seventh power gauss has been attained with the magnetic field shielding technique. The magnetic field apparatus is to be used with a three-axis London moment readout system.

Cabrera, B.↗