Search NASA⌕ Search

SEARCH · Search NASA

Results for “vacuum systems”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Ionization Chamber Measures Extreme Ultraviolet

Ionization chamber operates in nearly total photon absorption as stable, self-calibrating detector of ionizing extreme ultraviolet radiation. Working gas of instrument is neon; photoionization properties well known and readily applicable to absolute measurements. Designed for measurements of solar ultraviolet flux aboard sounding rocket, instrument used on Earth to measure ultraviolet radiation in vacuum systems. Ionization chamber collects positive neon ions and electrons produced by irradiation of neon gas by ultraviolet photons. Approximately one ion produced by each photon; consequently, photoionization current nearly proportional to photon flux.

Carlson, Robert W.↗
NASA NTRS1987

Cascaded-Blackbody Heat Radiators

New class of heat radiators made of metal or other conductive fin stock, fins of which are textured or covered with smaller fins. Measured from outside, effective emissivity of projected radiator surface greater than, and somewhat independent of, emissivity of flat surface made of same material. Special coatings to enhance emissivity not required, and emissivity not degraded significantly in long term by environmental effects. Intended orginally to radiate excess heat away from spacecraft, new radiators also used on Earth to dissipate heat in vacuum systems.

Keddy, Michael D.↗
NASA NTRS1988

Portable Airflow Meter

Compact hand-held instrument measures airflow. Consists of hot-wire anemometer probe in flow-straightening tube that reduces swirling. Configuration developed empirically to reduce length of instrument to practical dimension for use and storage in confined space. Two versions of new straightener only 17 and 18 in. long. Weighs less than 8 lb. and readily stored on Space Shuttle, developed to measure airflow in waster-collection system during flight. Used on Earth to measure airflow in ventilation systems, vacuum cleaners, and the like.

Burgett, Frank A.↗
NASA NTRS1988

Organic molecules on meteoritic solid substrates

The production of C1-C3 monocarboxylic acids from carbonaceous meteorites was investigated by the radiolysis of air-free CO2 and alkane solutions, utilizing a Cs-137 gamma-ray source. Samples were first loaded on a vacuum system, irradiated, and then analyzed by the Hewlett Packard model 5890A gas chromatograph. Moreover, the samples were irradiated with and without added ferrous iron.

Sweeney, Michael A.↗
NASA NTRS1988

U.S. Laboratory Module - Its capabilities and accommodations to support user payloads

The U.S. Laboratory Module of the Space Station is discussed, focusing on user accommodations. The configuration and subsystems capabilities of the module are described, including the power, thermal, environmental control, and data management subsystems, the vacuum system, process materials management, and laboratory support equipment. The experimental facilities included in the laboratory are listed. The experiment operations planned for the laboratory are examined and compared with the experimental activities in other manned space laboratories.

Powell, Luther E.↗
NASA NTRS1990

Photon sputtering of H2O ices: A preliminary report

A preliminary measurement of the total yields of ejected ions and electrons from H2O ices has been carried out using the He I 584 A resonance line as the incident photon beam. The H2O ices were prepared at 77 K in an ultrahigh vacuum system. The total yield of the ejected ion species and electrons was determined to be 8.8x10(exp -5) and 4.2x10(exp -4), respectively.

Wu, C. Y. Robert↗
NASA NTRS1991

Sealing Out-Of-Round Tubes With O-Rings

Glass or ceramic tubes out-of-round sealed effectively by ordinary O-rings in caps of modified hydraulic fittings. In typical connection, O-ring squeezed between two surfaces having inward-opening slants of 5 degrees or 10 degrees. Slanted surfaces force ring inward, compressing it around tube. Connector metal fitting, tightened by hand around O-ring, seals O-ring against tube as much as 1/16 in. out of round. Modified connectors seal glass or ceramic tubes against gas or vacuum leakage in furnaces, vacuum systems, and tubes for glassblowing equipment.

Shlichta, Paul J.↗
NASA NTRS1990

Complete the development and construction of a spaceborne hydrogen maser clock

The objective, to complete the development of an engineering model of a spaceborne hydrogen maser, was successfully achieved. A layout of the maser and detail drawings of the physics package was completed during the first 7 months of the contract. A computer model was made for the maser's thermal design. Using numerical computations, heater resistances were established for 7 temperature controlled zones. The physics package includes: a vacuum manifold that houses four sorption pumps capable of scavenging hydrogen for 4 years, a titanium vacuum tank housing the cavity, metallic seals for all vacuum joints, an RF dissociator within the vacuum envelope, a two-layer printed circuit solenoid and four layers of moly-permalloy magnetic shields. Problems were encountered and overcome in the procurements of the PC solenoid and the magnetic shields. After completion of the fabrication of the maser's components, the maser was assembled using these parts and other components made available by SAO, NRL, and NASA from earlier development work. In March, 1990, the vacuum system was assembled, and by May the maser assembly was completed. The magnetic shielding was poor and the shields were removed, reannealed by a local vendor, and the maser was reassembled. The maser began tests in early June and has been oscillating since that time. The test results of the maser are very good and a life test of the maser is being conducted. It is anticipated that the development and construction of a maser to be tested in space under a new contract from NASA's Marshall Space Flight Center will continue.

Vessot, Robert F. C.↗
NASA NTRS1991

Near-term, 100-kW class ion engines

A design approach for large area, high power ion engines is presented. This approach conceptually divides a single engine into a combination of smaller discharge chambers (or segments) configured to operate as a single large area engine. This segmented ion thruster (SIT) approach is shown to enable the immediate development of 100-kW class argon ion engines for operation at a specific impulse of 10,000 s. A combination of six 30-cm diameter ion chambers operating as a single engine can process over 100 kW. Such a segmented ion engine could be built today and would operate from a single power processor unit. The segmented engine design approach may also enable the development of megawatt class ion engines. Potential benefits of the segmented ion thruster design include: mitigation of the span-to-gap problem central to the development of large area, high power ion engines; reduction in hollow cathode emission current requirements; improved fault tolerance; and reduced vacuum system pumping speed requirements for engine development testing.

Brophy, John R.↗
NASA NTRS1990

The JPL Molecular Contamination Investigation Facility

The Molecular Contamination Investigation Facility (MCIF) is discussed in terms of its use for improving the far-UV performance of a camera and its broader applications. The MCIF incorporates two independent vacuum systems with sample isolation chambers and regulated heat exchangers as well as three quartz-crystal microbalances (QCMs) and a residual gas analyzer. One cryogenic QCM is heat sunk into an LN2 heat exchanger, while the others are thermoelectrically controlled and are heat sunk into a regulated heat exchanger. Outgas accumulation can be measured at three surface temperatures between -180 and 80 C simultaneously, and results are presented for the testing of 34 samples in a large-chambered system and 22 samples in a system with a smaller chamber. The MCIF results provide a database for fabrication processes, material selection, maximum bakeout temperatures, and the development of an ultraclean bakeout chamber.

Taylor, Daniel M.↗
NASA NTRS1994

Hydrophobic Porous Material Adsorbs Small Organic Molecules

Composite molecular-sieve material has pore structure designed specifically for preferential adsorption of organic molecules for sizes ranging from 3 to 6 angstrom. Design based on principle that contaminant molecules become strongly bound to surface of adsorbent when size of contaminant molecules is nearly same as that of pores in adsorbent. Material used to remove small organic contaminant molecules from vacuum systems or from enclosed gaseous environments like closed-loop life-support systems.

Sharma, Pramod K.↗
NASA NTRS1995

Study of the space environmental effects on spacecraft engineering materials

The space environment in which the Space Station Freedom and other space platforms will orbit is truly a hostile environment. For example, the current estimates of the integral fluence for electrons above 1 Mev at 2000 nautical miles is above 2 x 10(exp 10) electrons/sq cm/day. and the proton integral fluence is above 1 x 109 protons/sq cm/day. At the 200 - 400 nautical miles, which is more representative of the altitude which will provide the environment for the Space Station, each of these fluences will be proportionately less; however, the data indicates that the radiation environment will obviously have an effect on structural materials exposed to the environment for long durations. The effects of this combined environment is the issue which needs to be understood for the long term exposure of structures in space. In order to better understand the effect of these hostile phenomena on spacecraft, several types of studies are worth performing in order to simulate at some level the effect of the environment. For example the effect of protons and electrons impacting structural materials are easily simulated through experiments using the Van de Graff and Pelletron accelerators currently housed in the Environmental Effects Facility at MSFC. Proton fluxes with energies of 700 Kev-2.5 Mev can be generated and used to impinge on sample targets to determine the effects of the particles. Also the Environmental Effects Facility has the capability to generate electron beams with energies from 700 Kev to 2.5 Mev. These facilities will be used in this research to simulate space environmental effects from energetic particles. Ultraviolet radiation, particularly in the ultraviolet (less than 400 nm wavelength) is less well characterized at this time. The Environmental Effects Facility has a vacuum system dedicated to studying the effects of ultraviolet radiation on specific surface materials. This particular system was assembled in a previous study (NAS8-38609) in order to perform a variety of experiments on materials proposed for the Space Station. That system has continued to function as planned and has been used in carrying out portions of the proposed study.

Obrien, Susan K.↗
NASA NTRS1995

Study of the space environmental effects on spacecraft engineering materials

The issue of the effects of the space environment on spacecraft needs to be understood for the long term exposure of structures in space. In order to better understand the effect of these hostile phenomena on spacecraft, several types of studies are worth performing in order to simulate at some level the effect of the environment. For example the effect of protons and electrons impacting structural materials are easily simulated through experiments using the Van de Graff and Pelletron accelerators currently housed at MSFC. Proton fluxes with energies of 700 KeV - 2.5 MeV can be generated and used to impinge on sample targets to determine the effects of the particles. Also the Environmental Effects Facility at MSFC has the capability to generate electron beams with energies from 700 KeV to 2.5 MeV. These facilities will be used in this research to simulate space environmental effects from energetic particles. Ultraviolet radiation, particularly less than 400 nm wavelength, is less well characterized at this time. The Environmental Effects Facility has a vacuum system dedicated to studying the effects of ultraviolet radiation on specific surface materials. This particular system was assembled in a previous study in order to perform a variety of experiments on materials proposed for the Space Station. That system has continued to function as planned and has been used in carrying out portions of the proposed study.

Obrien, Susan K.↗
NASA NTRS1995

Apparatus Measures Permeation Of Gases Through Coupons

Apparatus measures permeation of any variety of commercially available pure or mixed gases through polymeric or other material coupons of various thicknesses. Permeability measured at wide range of temperatures and pressures. Includes residual-gas-analyzer (RGA) sensor head and associated circuitry, and vacuum system. Also includes manifold with valves, through which gas of interest allowed to permeate through test coupon before traveling downstream to evacuated RGA sensor head. Temperature of test coupon monitored by thermocouple and maintained at specified value above ambient by use of electrical heating mantle or below ambient by use of bath of ethylene glycol, water, and dry ice.

Adam, Steven J.↗
NASA NTRS1995

Automated Positioner For A Specimen In A Vacuum Chamber

Custom-build apparatus positions specimen in vacuum system in three translational and one rotational degree of freedom. Operates under manual control, local microprocessor control, or remote computer control via general-purpose interface bus (GPIB), specific control option being selectable by technician. Used to position and orient specimen for secondary-ion mass spectroscopy (SIMS). Apparatus made from relatively inexpensive parts.

Bailey, Sheila G.↗
NASA NTRS1996

Atomic Oxygen Removes Varnish And Lacquer From Old Paintings

Dry and relatively nondestructive plasma process found effective in removing protective coats from old paintings. Process generates monatomic oxygen, which reacts with varnish, lacquer, polyurethane, acrylic, and other organic coating materials; reactions produce mostly carbon monoxide and water vapor, then simply pumped away by vacuum system in which plasma generated. Does not attack oxide-based pigments in underlying paint layers, and brush-stroke marks remain undisturbed.

Rutledge, Sharon K.↗
NASA NTRS1996

Space qualification of UV and IR reflecting coverslides for GaAs solar cells

As part of the space qualification effort for blue-red reflecting coverslides designed for use with GaAs solar cells, the first long-term (3000 hours) UV testing of unirradiated and 1 MeV electron-irradiated GaAs solar cells, with 4 types of multilayer-coated coverslides to reduce operating temperature, has produced some unexpected results. Important conclusions from this study, which includes two parallel tests, are as follows: (1) All of the GaAs solar cells with multilayer-coated coverslides display UV degradation. The laboratory data, extrapolated to 10 years in orbit, point to a significant loss mechanism from a combination of absorption and a reduction in optical match in such coatings from this portion of the space environment; (2) The effects of contamination in a vacuum system, on the measured degradation in solar-cell short-circuit current during a UV test, depend upon the type of coverslide coatings present on the coverslide surfaces. This has implications for both coated coverslides and optical solar reflectors (OSR's) in space; and (3) Because of the observed trends in this test and uncertainties in the extrapolation of data for multilayer coated coverslides, the use of any multilayer-coated coverslides for extended missions (greater than 1 year) cannot be recommended without prior flight testing.

Meulenberg, Andrew↗
NASA NTRS1998

Properties Data for Adhesion and Surface Chemistry of Aluminum: Sapphire-Aluminum, Single-Crystal Couple

An investigation was conducted to examine the adhesion and surface chemistry of single-crystal aluminum in contact with single-crystal sapphire (alumina). Pull-off force (adhesion) measurements were conducted under loads of 0. I to I mN in a vacuum of 10(exp -1) to 10(exp -9) Pa (approx. 10(exp -10) to 10(exp -11) torr) at room temperature. An Auger electron spectroscopy analyzer incorporated directly into an adhesion-measuring vacuum system was primarily used to define the chemical nature of the surfaces before and after adhesion measurements. The surfaces were cleaned by argon ion sputtering. With a clean aluminum-clean -sapphire couple the mean value and standard deviation of pull-off forces required to separate the surfaces were 3015 and 298 micro-N, respectively. With a contaminated aluminum-clean sapphire couple these values were 231 and 241 micro-N. The presence of a contaminant film on the aluminum surface reduced adhesion by a factor of 13. Therefore, surfaces cleanliness, particularly aluminum cleanliness, played an important role in the adhesion of the aluminum-sapphire couples. Pressures on the order of 10(exp -8) to 10(exp -9) Pa (approx. 10(exp -10) to 10(exp -11) torr) maintained a clean aluminum surface for only a short time (less then 1 hr) but maintained a clean sapphire surface, once it was achieved, for a much longer time.

Miyoshi, Kazuhisa↗