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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 1,549 records · Page 86
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

A solar simulator-pumped gas laser for the direct conversion of solar energy

Most proposed space power systems are comprised of three general stages, including the collection of the solar radiation, the conversion to a useful form, and the transmission to a receiver. The solar-pumped laser, however, effectively eliminates the middle stage and offers direct photon-to-photon conversion. The laser is especially suited for space-to-space power transmission and communication because of minimal beam spread, low power loss over large distances, and extreme energy densities. A description is presented of the first gas laser pumped by a solar simulator that is scalable to high power levels. The lasant is an iodide C3F7I that as a laser-fusion driver has produced terawatt peak power levels.

Weaver, W. R.↗
NASA NTRS1981

Hot-gas cold-dust pumping for water masers associated with H II regions

A collisional pump with an internal sink is proposed for the water masers associated with H II regions, where the population inversion occurs due to the absorption by cold ice-mantle grains in a highly dusty cloud of the far-infrared line radiation of hot water vapor. A new escape probability method is developed to calculate the transfer of line radiation in dusty medium. The pump mechanism explains the power of usual maser sources associated with H II regions and the enormous power of the sources associated with W49 N and external galaxies. Models of maser clouds have a radius of 5 x 10 to the 15th-10 to the 16th cm, an H2 number density of 4 x 10 to the 9th/cu cm, an expansion velocity of 10-30 km/s, a kinetic temperature of 350 K, and a grain temperature of 100 K. Giant maser sources require grains of the size about 1 micron. The apparent size of the emission spots (approximately 10 to the 13th cm) observed by VLBI is interpreted as due to a fluctuation in the cloud, and the assembly of the spots is spread within a size of 10 to the 16th cm. The temperature difference between the dust and gas is due to a relaxation process after an infrared burst accompanying protostar formation.

Deguchi, S.↗
NASA NTRS1983

Cryogenic Vacuum Pump

System provides high pumping capacity even for noble gases. First stage, removes water and CO2 from input gas. Second stage, removes noble gases except helium and some lighter gases not trapped by first stage. Third stage, traps all remaining gases. All three stages mounted inside liquid-nitrogen Dewar that cools first stage. Pump small enough for general laboratory use.

Zachman, C. A.↗
NASA NTRS1984

Estimating Pump Blockage

Blockage predicted for all components including inducers, impellers and diffusers. Pump performance predicted by semiempirical method shows excellent agreement with test results in Space Shuttle main-engine highpressure fuel turbopump. Comparisons of pump efficiency show equally good agreement of calculated values with experimental ones. Method improves current estimation methods based solely on subjective engineering judgment.

Chung, W.↗
NASA NTRS1982

A proposed optical pumping system requiring no electric power

A method for optically pumping a fluid without electrical power is described. The method is based on utilizing the radiation from a metal oxidant combustion reaction that is contained within a transparent tube that is immersed in the medium to be pumped. The reaction initiation and maintenance occurs by gas dynamically induced resonance within the transparent cavity. All that is required is a supply of high pressure oxidant and metallic powder. Materials that were successfully evaluated to date include aluminum, steel, magnesium, and titanium.

Phillips, B. R.↗
NASA NTRS1983

Solar-simulator-pumped atomic iodine laser kinetics

The literature contains broad ranges of disagreement in kinetic data for the atomic iodine laser. A kinetic model of a solar-simulator-pumped iodine laser is used to select those kinetic data consistent with recent laser experiments at the Langley Research Center. Analysis of the solar-simulator-pumped laser experiments resulted in the following estimates of rate coefficients: for alkyl radical (n-C3F7) and atomic iodine (I) recombination, 4.3 x 10 to the 11th power (1.9) + or - cu cm/s; for n-C3F7I stabilized atomic iodine recombination (I + I) 3.7 x 10 to the -32nd power (2.3) + or -1 cm to the 6th power/s; and for molecular iodine (I2) quenching, 3.1 x 10 to the -11th power (1.6) + or - 1 cu cm/s. These rates are consistent with the recent measurements.

Wilson, H. W.↗
NASA NTRS1983

Servo Controlled Variable Pressure Modification to Space Shuttle Hydraulic Pump

Engineering drawings show modifications made to the constant pressure control of the model AP27V-7 hydraulic pump to an electrically controlled variable pressure setting compensator. A hanger position indicator was included for continuously monitoring hanger angle. A simplex servo driver was furnished for controlling the pressure setting servovalve. Calibration of the rotary variable displacement transducer is described as well as pump performance and response characteristics.

Kouns, H. H.↗
NASA NTRS1982

Thermoelastohydrodynamic analysis of an oil pumping ring seal

The selection and evaluation of the numerical methods used in the thermoelastohydrodynamic analysis of an oil pumping ring seal are described, and the results from test problems used to demonstrate the validity of the implementing computer program are presented. A sampling of predicted pumping ring performance values is compared with existing experimental data. Agreement between prediction and test performance is obtained, yielding detailed information concerning fluid and solid parameters.

Smith, P. J.↗
NASA NTRS1982

Advances in NASA research on nuclear-pumped lasers

NASA has been primarily interested in nuclear-pumped lasers using the He-3 or U-235F6 reaction for lasant excitation. With He-3 excitation, a large volume, multiple-path He-3-Ar nuclear laser has produced an output of 1 kilowatt. Power deposition was shown to be homogeneous over this volume. The CO laser has been pumped for the first time using the He-3 reaction, producing approximately 200 Watts. Using a boron-10 coating to excite N2, nuclear lasing has been achieved in CO2 in a transfer laser configuration. Nuclear lasing of Ar-Xe has been demonstrated using fission fragment excitation from U-235F6. Research on the gas core reactor has resulted in a steady state operational power of 30 kilowatts with flowing U-235F6 in an argon vortex.

De Young, R. J.↗
NASA NTRS1983

Flashlamp-pumped iodine monobromide laser characteristics

The operating characteristics of a flashlamp-pumped IBr laser were investigated to evaluate its suitability for solar-pumped laser applications. A peak power of 350 W/sq cm at 2.7 microns was achieved at 12-torr IBr pressure. At 500-J flashlamp energy, the IBr output saturated; a gain of 0.17% per cm was measured for IBr. Neon was found to be effective for enhancing the recombination of the photodissociation products. With neon as a buffer gas, the laser pulse length was extended to 53 microsec. The termination of the laser pulse, within the flashlamp pulse, is thought to be due to the temperature rise in the gas. Increasing the IBr initial temperature decreased the lasing output. At 300 C, output dropped to approximately one-half the room temperature value. The dominant quencher is thought to be atomic iodine. IBr was found to couple better to the flashlamp energy than C3F7I.

Zapata, L. E.↗
NASA NTRS1985

Pump-Fed Versus Pressure-Fed Propulsion

Pumping system has lower mass. Equations worked out to compare masses of pump and pressure-fed bipropellant propulsion systems. Equations developed specifically for interplanetary spacecraft but technique adaptable to advanced automative energy-storage techniques.

Estey, P. N.↗
NASA NTRS1985

Adjustable Tuning Spring for Bellows Pump

Adjustable leaf spring increases maximum operating pressure of pump from 2 to over 60 psi (13 to over 400 kN/m2). Small commercial bellows pump using ac-powered electromagnet to vibrate bellows at mechanical resonance modified to operate over wider pressure range.

Green, G. L.↗
NASA NTRS1983

The Plasma Membrane Calcium Pump

Three aspect of cellular calcium metabolism in animal cells was discussed including the importance of the plasma membrane in calcium homeostasis, experiments dealing with the actual mechanism of the calcium pump, and the function of the pump in relationship to the mitochondria and to the function of calmodulin in the intact cell.

Rasmussen, H.↗
NASA NTRS1984

Analysis of a 10 megawatt space-based solar-pumped neodymium laser system

A ten megawatt solar-pumped continuous liquid laser system for space applications is examined. It is found that a single inflatable mirror of 434 m diameter used in conjunction with a conical secondary concentrator is sufficient to side pump a liquid neodymium lasant in an annular tube of 6 m length and 1 m outer and 0.8 m inner diameter. About one fourth of intercepted radiation converging on the laser tube is absorbed and one fifth of this radiation is effective in populating the upper levels. The liquid lasant is flowed through the annular laser cavity at 1.9 m/s and is cooled via a heat exchanger and a large radiator surface comparable in size to the concentrating mirror. The power density of incident light within the lasant of approximately 68 watt/cu cm required for cw operation is exceeded in the present annular configuration. Total system weight corresponds to 20,500 kg and is thus capable of being transported to near Earth orbit by a single shuttle flight.

Kurweg, U. H.↗
NASA NTRS1983

Measurement of heat pump processes induced by laser radiation

A series of experiments was performed in which a suitably tuned CO2 laser, frequency doubled by a Tl3AsSe37 crystal, was brought into resonance with a P-line or two R-lines in the fundamental vibration spectrum of CO. Cooling or heating produced by absorption in CO was measured in a gas-thermometer arrangement. P-line cooling and R-line heating could be demonstrated, measured, and compared. The experiments were continued with CO mixed with N2 added in partial pressures from 9 to 200 Torr. It was found that an efficient collisional resonance energy transfer from CO to N2 existed which increased the cooling effects by one to two orders of magnitude over those in pure CO. Temperature reductions in the order of tens of degrees Kelvin were obtained by a single pulse in the core of the irradiated volume. These measurements followed predicted values rather closely, and it is expected that increase of pulse energies and durations will enhance the heat pump effects. The experiments confirm the feasibility of quasi-isentropic engines which convert laser power into work without the need for heat rejection. Of more immediate potential interest is the possibility of remotely powered heat pumps for cryogenic use, such applications are discussed to the extent possible at the present stage.

Garbuny, M.↗
NASA NTRS1984

Intensity and absorbed-power distribution in a cylindrical solar-pumped dye laser

The internal intensity and absorbed-power distribution of a simplified hypothetical dye laser of cylindrical geometry is calculated. Total absorbed power is also calculated and compared with laboratory measurements of lasing-threshold energy deposition in a dye cell to determine the suitability of solar radiation as a pump source or, alternatively, what modifications, if any, are necessary to the hypothetical system for solar pumping.

Williams, M. D.↗
NASA NTRS1984

Theoretcial studies of solar-pumped lasers

A method of pumping a COhZ laser by a hot cavity was demonstrated. The cavity, heated by solar radiation, should increase the efficiency of solar pumped lasers used for energy conversion. Kinetic modeling is used to examine the behavior of such a COhZ laser. The kinetic equations are solved numerically vs. time and, in addition, steady state solutions are obtained analytically. The effect of gas heating filling the lower laser level is included. The output power and laser efficiency are obtained as functions of black body temperature and gas ratios (COhZ-He-Ar) and pressures. The values are compared with experimental results.

Harries, W. L.↗
NASA NTRS1983

Broad-band gain in optically pumped S2

The broad fluorescence spectrum and Franck-Condon shift of the B-X system of S2 are exploited in broad-band-gain experiments using the absorption of 308-nm XeCl excimer radiation to pump the level (upsilon-prime = 4) in an S2 vapor with and without Ar. The fluorescence spectra are examined to determine the effects of gas collisions, and the intense near-UV and visible bands are attributed to the redistribution of the population among the upsilon-prime levels resulting from S2-Ar collisions. Broad-band gain is observed on the rare-gas relaxation bands (2,17) (about 475 nm) and (3,18) (480 nm), while absorption is found in the (0,6), (0,7), and (0,8) near-UV (about 360-380-nm) bands where a transient population cascading down the X-state manifold fills the lower levels. It is inferred from the achievement of gain over much of the S2 fluorescence bandwidth that nonselective pumping mechanisms like discharges, solar energy, or flashlamps can be used with S2 as the tunable, chemically stable 'dye'.

Epler, J. E.↗