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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Superconducting properties of evaporated copper molybdenum sulfide films

Films of copper molybdenum sulfide were produced by coevaporation. Those that were superconducting contained only the ternary compound and free molybdenum. The range of copper content in the ternary compound was as large as that in polycrystalline material, that is, it includes either phase alone, or a mixture of the two phases of this material. This is in contrast with sputtered materials where copper concentration has been limited to a narrower range. The upper critical field and the critical current were measured as functions of external magnetic field, and found to be similar to those of sputtered copper molybdenum sulfide, when the comparison was made for samples having the same amount of copper.

Woollam, J. A.↗
NASA NTRS1981

Superconducting gyrocon would be very efficient

Cryogenic operation of gyrocon increases gain by more than 35 dB and efficiency by 90 percent. Device consists of electron gun, deflection cavity output cavity, collector, and output coupler. Inout and output cavities are made of superconducting lead or niobium. Gyrocon operates at frquencies up to 50 GHz.

Yen, H. C.↗
NASA NTRS1982

First results from a superconductive detector for moving magnetic monopoles

A velocity- and mass-independent search for moving magnetic monopoles is being performed by continuously monitoring the current in a 20-sq cm area superconducting loop. A single candidate event, consistent with one Dirac unit of magnetic charge, has been detected during five runs totaling 151 days. These data set an upper limit of 6.1 x

Cabrera, B.↗
NASA NTRS1982

Fabrication techniques for superconducting readout loops

Procedures for the fabrication of superconducting readout loops out of niobium on glass substrates were developed. A computer program for an existing fabrication system was developed. Both positive and negative resist procedures for the production of the readout loops were investigated. Methods used to produce satisfactory loops are described and the various parameters affecting the performance of the loops are analyzed.

Payne, J. E.↗
NASA NTRS1982

Superconducting gravimeter

The superconducting gravimeter was developed and applied to field measurements. The stability of the instrument yielded the highest precision measurements of the Earth tides ever attained. It revealed unprecedented details about the effect of the atmosphere on gravity. Secular variations in gravity and the stability of the instruments were measured by comparing records from co-located instruments. These efforts have resulted in substantial reductions in the noise level at very low frequencies so that the peak differences between two instruments at the same location can be reduced to 0.1 micron gal.

Goodkind, J. M.↗
NASA NTRS1983

Critical fields of liquid superconducting metallic hydrogen

Liquid metallic hydrogen, in a fully dissociated state, is predicted at certain densities to pass from dirty to clean and from type II to type I superconducting behavior as temperature is lowered. Previously announced in STAR as N82-29374

Jaffe, J.↗
NASA NTRS1983

Low-noise 115-GHz receiver using superconducting tunnel junctions

A 110-118-GHz receiver based on a superconducting quasiparticle tunnel junction mixer is described. The single-sideband noise temperature is as low as 68 + or - 3 K. This is nearly twice the sensitivity of any other receiver at this frequency. The receiver was designed using a low-frequency scale model in conjunction with the quantum mixer theory. A scaled version of the receiver for operation at 46 GHz has a single-sideband noise temperature of 55 K. The factors leading to the success of this design are discussed.

Pan, S.-K.↗
NASA NTRS1984

Superconducting Nbti and Pb(cu) Bandpass Filters

Superconducting Nb0.45Ti0.55 and Pb electroplated on Cu bandpass microwave filtes were constructed to investigate their low loss properties at 4.7 K. An interdigital stripline filter configuration was selected as the optimum structure for future applications. The filter was designed to operate at 8.45 GHz with an equal ripple bandwidth of 0.15 GHz. The insertion loss and the noise temperature contribution were measured at 4.7 K. In addition, the insertion loss was studied as a function of out of band power (up to 1 watt) and temperature (4.7 K up to T(c)). Results of an oxygen free high conductivity Cu filter are included for comparison.

Bautista, J. J.↗
NASA NTRS1984

A flying superconducting magnet and cryostat for magnetic suspension of wind-tunnel models

The engineering practicality of a persistent high-field superconducting solenoid cryostat as a magnetic suspension and balance system (MSBS) for wind-tunnel testing of aircraft and missile models is examined. The test apparatus is a simple solenoid of filamentary NbTi superconductor with a cupronickel matrix. The apparatus, with a length-to-diameter ratio of 6 to 1 and a radius of 32 mm, used a 0.25 mm wire with a critical current of 27 A in an external field of 6 T. The total heat inleak of 150 mW was achieved. Helium boiloff rates were tested over a range of operating conditions, including pitch attitudes from 10 deg nose down to 90 deg nose up; the rate was estimated as low, but the aerodynamic acceptability of venting gaseous helium has not been determined. It is shown that the effectiveness of the concept increases with increasing scale, and performance in excess of that of conventional ferromagnets is achievable with reduction in size and costs, and with aptness to transonic wind-tunnel testing. Detailed specifications and schematics are included.

Britcher, C.↗
NASA NTRS1985

Superconducting electromagnetic actuators for astronomical Fabry-Perot interferometers

Two types of superconducting electromagnetic actuators linear and angular - for precise control of Fabry-Perot spectrometer etalons at liquid helium temperature were manufactured and tested successfully. The linear displacement unit (45 Newtons/Amp) has maximum travel of + or - 44 microns with off-axis deviation of less than 1.5 arcseconds for 15 microns path. The angular unit has maximum tilt of + or - 8 arcminutes and can maintain parallelism of two etalons to better than 0.3 arcsecond of angle by compensating the differential contraction upon cooling and off-axis deviation of the linear displacement unit. These actuators are proving especially useful in low temperature infrared instrumentation where other choices, such as piezoelectric crystals, fail and where essentially zero power dissipation permits low infrared backgrounds to be maintained along with long cryogenic lifetimes.

Nishimura, T.↗
NASA NTRS1985

Superconducting NbTi and Pb(Cu) bandpass filters

Superconducting NbO.45Ti0.55 and Pb electroplated on Cu bandpass microwave filters were constructed to investigate their low loss properties at 4.7 K. An interdigital stripline filter configuration was selected as the optimum structure for future applications. The filter was designed to operate at 8.45 GHz with an equal ripple bandwidth of 0.15 GHz. The insertion loss and the noise temperature contribution were measured at 4.7 K. In addition, the insertion loss was studied as a function of out of band power (up to 1 watt) and temperature (4.7 K up to Tc). Results of an oxygen free high conductivity Cu filter are included for comparison.

Bautista, J. J.↗
NASA NTRS1985

A rotating superconducting solenoid for 100 kWh energy storage

Two concentric superconducting solenoids, one rotating, the other stationary are analyzed for energy storage in space. Energy is transferred from the rotating mass through a shaft coupled to a motor-generator. The inner windings interact with the magnetic field of the outer solenoid to cancel the centrifugal and self-field forces of the flywheel rim. Current is induced in the inner solenoid thus requiring no separate power supply, while the current in the outer solenoid must vary with the angular velocity of the flywheel. The effect of the gap and scaling laws are developed. The efficiency in energy per unit mass is marginally attractive.

Waynert, J.↗
NASA NTRS1986

Room-Temperature Deposition of NbN Superconducting Films

Films with high superconducting transition temperatures deposited by reactive magnetron sputtering. Since deposition process does not involve significantly high substrate temperatures, employed to deposit counter electrode in superconductor/insulator/superconductor junction without causing any thermal or mechanical degradation of underlying delicate tunneling barrier. Substrates for room-temperature deposition of NbN polymeric or coated with photoresist, making films accessible to conventional lithographic patterning techniques. Further refinements in deposition technique yield films with smaller transition widths, Tc of which might approach predicted value of 18 K.

Thakoor, S.↗
NASA NTRS1985

High T(c) superconducting NbN films deposited at room temperature

The dc reactive magnetron sputtering process yields stoichiometric NbN films with superconducting transition temperature T(c) as high as 15.7 K on substrates as varied as glass, glazed ceramic, fused quartz, and sapphire. These films posses fcc (B1) structure and (111) texture. The most dominant factors governing the formation of the transition metal nitrides are the relative metal and nitrogen fluxes incident on the substrate and the background argon pressure (which dictates the overall reactive sites and residence times for nitrogen).

Thakoor, S.↗
NASA NTRS1986

A lead-on-sapphire superconducting cavity of superior quality

A cavity consisting of a superconducting lead film on a sapphire substrate has been fabricated to obtain the enhanced frequency stability possible with this configuration. The cavity exhibits a quality value Q exceeding 2 x 10 to the 9th in its TE011 mode with a resonant frequency of 2.689 GHz. Methods of fabrication and testing of the cavity are presented. Since the interface between the film and substrate is exposed ot the full value of the resonant magnetic field, the present experiment is the most sensitive test to date for enhanced losses at the interface itself. No evidence of such losses is used. In fact, the measured values of the surface resistance match very well predictions for RF losses based on the BCS theory.

Thakoor, S.↗