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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 505 records · Page 28

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NASA NTRS1976

Thermal-environment testing of a 30-cm engineering model thruster

An experimental test program was carried out to document all 30-cm electron bombardment Hg ion bombardment thruster functions and characteristics over the thermal environment of several proposed missions. An engineering model thruster was placed in a thermal test facility equipped with -196 C walls and solar simulation. The thruster was cold soaked and exposed to simulated eclipses lasting in duration from 17 to 72 minutes. The thruster was operated at quarter, to full beam power in various thermal configurations which simulated multiple thruster operation, and was also exposed to 1 and 2 suns solar simulation. Thruster control characteristics and constraints; performance, including thrust magnitude and direction; and structural integrity were evaluated over the range of thermal environments tested.

Mirtich, M. J.↗

NASA NTRS1976

Thermal-environmental testing of a 30-cm engineering model thruster

Mirtich, M. J.↗

NASA NTRS1976

Performance and heat transfer characteristics of the laser-heated rocket - A future space transportation system

The application of advanced liquid-bipropellant rocket engine analysis techniques has been utilized for prediction of the potential delivered performance and the design of thruster wall cooling schemes for laser-heated rocket thrusters. Delivered specific impulse values greater than 1000 lbf-sec/lbm are potentially achievable based on calculations for thrusters designed for 10-kW and 5000-kW laser beam power levels. A thruster wall-cooling technique utilizing a combination of regenerative cooling and a carbon-seeded hydrogen boundary layer is presented. The flowing carbon-seeded hydrogen boundary layer provides radiation absorption of the heat radiated from the high-temperature plasma. Also described is a forced convection thruster wall cooling design for an experimental test thruster.

Shoji, J. M.↗

NASA NTRS1978

Ion beam sputtering of fluoropolymers

Ion beam sputter processing rates as well as pertinent characteristics of etched targets and films are described. An argon ion beam source was used to sputter etch and deposit the fluoropolymers PTFE, FEP, and CTFE. Ion beam energy, current density, and target temperature were varied to examine effects on etch and deposition rates. The ion etched fluoropolymers yield cone or spire-like surface structures which vary depending upon the type of polymer, ion beam power density, etch time, and target temperature. Sputter target and film characteristics documented by spectral transmittance measurements, X-ray diffraction, ESCA, and SEM photomicrographs are included.

Sovey, J. S.↗

NASA NTRS1978

Ion beam sputtering of fluoropolymers

Etching and deposition of fluoropolymers are of considerable industrial interest for applications dealing with adhesion, chemical inertness, hydrophobicity, and dielectric properties. This paper describes ion beam sputter processing rates as well as pertinent characteristics of etched targets and films. An argon ion beam source was used to sputter etch and deposit the fluoropolymers PTFE, FEP, and CTFE. Ion beam energy, current density, and target temperature were varied to examine effects on etch and deposition rates. The ion etched fluoropolymers yield cone or spire-like surface structures which vary depending upon the type of polymer, ion beam power density, etch time, and target temperature. Also presented are sputter target and film characteristics which were documented by spectral transmittance measurements, X-ray diffraction, ESCA, and SEM photomicrographs.

Sovey, J. S.↗

NASA NTRS1979

Power combining in an array of microwave power rectifiers

This work analyzes the resultant efficiency degradation when identical rectifiers operate at different RF power levels as caused by the power beam taper. Both a closed-form analytical circuit model and a detailed computer-simulation model are used to obtain the output dc load line of the rectifier. The efficiency degradation is nearly identical with series and parallel combining, and the closed-form analytical model provides results which are similar to the detailed computer-simulation model.

Gutmann, R. J.↗

NASA NTRS1979

Geostationary Platforms Mission and Payload Requirements Study. Volume 1: Executive summary

Time-phased missions and payloads for potential accommodation on geostationary platforms and the engineering requirements placed upon the platform housekeeping elements by selected payloads are identified. Optimum locations for geostationary platforms, potential missions and their characteristics, and potential user requirements were determined as well as the interface requirements between the missions and h the geostationary platform. A payload data book was prepared and antenna tradeoff studies were conducted. Payload missions are defined in terms of frequencies, power, beam patterns, interconnections, support requirements, and other characteristics.

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NASA NTRS1981

Radio maps of Jupiter's radiation belts and planetary disk at lambda 6 cm

Two-dimensional maps of Jupiter's radio emission were made in April 1978 at a frequency of 4885 MHz (6 cm) using the Westerbork telescope in the Netherlands. Pictures in the Stokes parameters I, Q and U have been obtained every 15 deg in longitude, each smeared over 20 deg of the planet's rotation. The half power beam width was approximately 1/6 of the disk diameter in right ascension and approximately 1/2 in declination. The planetary disk shows little or no limb darkening at this wavelength and has a temperature of 220 + or - 8 K. The radiation belts clearly show a kind of plateau or flattening in intensity in the outer part of the belt. A comparison with 21 and 50 cm maps indicate no difference in the width and form of the emission regions with wavelength.

De Pater, I.↗

NASA NTRS1982

A study to survey NASA laser applications and identify suitable lasers for specific NASA needs

All potential applications of high power lasers which might, in particular, use the JPL copper-halide laser under development were considered for study. A wide range of applications were identified with strong emphasis on remote sensing applications. Power beaming and laser propulsion were also identified as major areas of interest to NASA.

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NASA NTRS1980

Microwave heating of the lower ionosphere

Changes in the properties of the lower ionosphere due to ohmic heating of the plasma by the solar power satellite (SPS) microwave power beam are considered. The development of a predictive model of the underdense interaction of an electromagnetic beam and the lower ionosphere is described. The extent to which the Platteville and Arecibo experiments simulate SPS conditions is considered.

Meltz, G.↗

NASA NTRS1984

Aeronautical technology 2000 - A projection of advanced vehicle concepts

At the request of NASA and under the aegis of the National Research Council, representatives from industry, academic institutions and government have participated in a workshop to consider opportunities for the exploitation of aircraft technology in such fields as aerodynamics, materials, structures, guidance, navigation and control, human factors, propulsion, computers and data processing, and systems integration. Attention is given to the advanced vehicle concepts that have emerged for possible year-2000 implementation, which encompass such diverse aircraft types as supersonic transports, hypersonic airliners, missiles, and interceptors, transatmospheric vehicles, next-generation space shuttles, subsonic transports and attack aircraft, advanced helicopter, tilt-rotor VTOL configurations, and solar- and microwave beam-powered extremely high altitude aircraft.

Rosen, C. C., III↗

NASA NTRS1985

Vibrational excitation of CO by blackbody radiation

Lasers excited by blackbody radiation are of interest for power beaming applications in space. In such a system sunlight is collected and focused into a blackbody cavity, heating it to approximately 2000 K. An appropriate absorbing molecule is vibrationally heated but not translationally heated when passed through the blackbody cavity. The vibrationally excited gas is then mixed with a lasant resulting in laser emission. The number density of CO molecules within a blackbody radiation field of a given temperature and pressure is calculated. Such calculations show the degree of excitation achievable, under ideal conditions, from blackbody pumping.

Arriola, L.↗

NASA NTRS1986

Polar-cap and coronal-hole-associated brightenings of the Sun at millimeter wavelengths

Mapping observations of the Sun at millimeter wavelengths were made on 16 to 22 July 1984 with the 45-m telescope of the Nobeyama Radio Observatory. Seven 36-GHz (8.3-mm) maps and five 98-GHz (3.1-mm) maps were taken with half-power beam widths of 46 arc sec and 17 arc sec, respectively. Instead of the conventional rastering technique, a radial-scan method was adopted in which every scan passes through the disk center. Accordingly, the variation of the atmosphere attenuation due to changes in the weather conditions can be easily estimated and removed by using the brightness values at the disk center as calibration data. Also, the pointing errors of the telescope due to the high-speed scans can be corrected by using the solar limbs as position references. The rms residual errors in relative brightness and position after the corrections were estimated to be approx. 2% and approx. 5 arc sec respectively. To further reduce these errors, enabled us to make high-quality maps with with or approx. 1% uncertainty in brightness. Here and in the following, brightness is expressed in terms of the average brightness of the solar disk as a unit. Note that the brightness temperature of the quiet Sun is approx. 8000 K and approx. 6000 K at 36 GHz and 98 GHz, respectively.

Kosugi, T.↗

NASA NTRS1986

Antimatter propulsion, status and prospects

The use of advanced propulsion techniques must be considered if the currently envisioned launch date of the manned Mars mission were delayed until 2020 or later. Within the next thirty years, technological advances may allow such methods as beaming power to the ship, inertial-confinement fusion, or mass-conversion of antiprotons to become feasible. A propulsion system with an ISP of around 5000 s would allow the currently envisioned mission module to fly to Mars in 3 months and would require about one million pounds to be assembled in Earth orbit. Of the possible methods to achieve this, the antiproton mass-conversion reaction offers the highest potential, the greatest problems, and the most fascination. Increasing the production rates of antiprotons is a high priority task at facilities around the world. The application of antiprotons to propulsion requires the coupling of the energy released in the mass-conversion reaction to thrust-producing mechanisms. Recent proposals entail using the antiprotons to produce inertial confinement fusion or to produce negative muons which can catalyze fusion. By increasing the energy released per antiproton, the effective cost, (dollars/joule) can be reduced. These proposals and other areas of research can be investigated now. These short term results will be important in assessing the long range feasibility of an antiproton powered engine.

Howe, Steven D.↗

NASA NTRS1988

High-speed assembly language (80386/80387) programming for laser spectra scan control and data acquisition providing improved resolution water vapor spectroscopy

An assembly language program using the Intel 80386 CPU and 80387 math co-processor chips was written to increase the speed of data gathering and processing, and provide control of a scanning CW ring dye laser system. This laser system is used in high resolution (better than 0.001 cm-1) water vapor spectroscopy experiments. Laser beam power is sensed at the input and output of white cells and the output of a Fabry-Perot. The assembly language subroutine is called from Basic, acquires the data and performs various calculations at rates greater than 150 faster than could be performed by the higher level language. The width of output control pulses generated in assembly language are 3 to 4 microsecs as compared to 2 to 3.7 millisecs for those generated in Basic (about 500 to 1000 times faster). Included are a block diagram and brief description of the spectroscopy experiment, a flow diagram of the Basic and assembly language programs, listing of the programs, scope photographs of the computer generated 5-volt pulses used for control and timing analysis, and representative water spectrum curves obtained using these programs.

Allen, Robert J.↗

NASA NTRS1987

Apollo Lightcraft project

The detailed design of a beam-powered transatmospheric vehicle, the Apollo Lightcraft, was selected as the project for the design course. The principal goal is to reduce the LEO payload delivery cost by at least three orders of magnitude below the Space Shuttle Orbiter in the post 2020 era. The completely reusable, single-stage-to-orbit shuttlecraft will take off and land vertically, and have a reentry heat shield integrated with its lower surface. At appropriate points along the launch trajectory, the combined cycle propulsion system will transition through three or four airbreathing modes, and finally use a pure rocket mode for orbital insertion. The objective for the Spring semester propulsion source was to design and perform a detailed theoretical analysis on an advanced combined-cycle engine suitable for the Apollo Lightcraft. The preliminary theoretical analysis of this combined-cycle engine is now completed, and the acceleration performance along representative orbital trajectories was simulated. The total round trip cost is $3430 or $686 per person. This represents a payload delivery cost of $3.11/lb, which is a factor of 1000 below the STS. The Apollo Lightcraft concept is now ready for a more detailed investigation during the Fall semester Transatmosphere Vehicle Design course.

Myrabo, Leik N.↗

NASA NTRS1988

Electrothermal propulsion of spacecraft with millimeter and submillimeter electromagnetic energy

The concept of millimeter and submillimeter wave electrothermal propulsion is considered. State-of-the-art radiation sources from 30-1000 GHz are examined to determine their applicability to electrothermal propulsion systems. The problem of energy conversion and power conditioning in this frequency range is also addressed. The potential advantage of utilizing power beaming with millimeter and submillimeter systems is examined. Finally, areas of future research and development are indicated.

Frasch, L. L.↗

NASA NTRS1989

Electron/Ion-Scattering Apparatus

In new apparatus, most of electrons scattered inelastically over wide range of angles measured simultaneously, with consequent increase in signal-to-noise ratio by factor of about 10 to 4th power. Beam of electrons and beam of ions aimed along low-intensity magnetic field between pair of electric-field plates. Crossed electric and magnetic fields hardly affect ions but cause electrons to drift toward ions by trochoidal motion. With modifications, apparatus used for measurements of excitation cross sections in neutral atoms, molecules, radicals, and excited states of atoms and molecules.

Chutjian, Ara↗