Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “atom optics”

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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Optical Injection Locking of a VCSEL in an OEO

Optical injection locking has been demonstrated to be effective as a means of stabilizing the wavelength of light emitted by a vertical-cavity surface- emitting laser (VCSEL) that is an active element in the frequency-control loop of an opto-electronic oscillator (OEO) designed to implement an atomic clock based on an electromagnetically- induced-transparency resonance. This particular optical-injection- locking scheme is expected to enable the development of small, low-power, high-stability atomic clocks that would be suitable for use in applications involving precise navigation and/or communication. In one essential aspect of operation of an OEO of the type described above, a microwave modulation signal is coupled into the VCSEL. Heretofore, it has been well known that the wavelength of light emitted by a VCSEL depends on its temperature and drive current, necessitating thorough stabilization of these operational parameters. Recently, it was discovered that the wavelength also depends on the microwave power coupled into the VCSEL. Inasmuch as the microwave power circulating in the frequency-control loop is a dynamic frequency-control variable (and, hence, cannot be stabilized), there arises a need for another means of stabilizing the wavelength. The present optical-injection-locking scheme satisfies the need for a means to stabilize the wavelength against microwave- power fluctuations. It is also expected to afford stabilization against temperature and current fluctuations. In an experiment performed to demonstrate this scheme, wavelength locking was observed when about 200 W of the output power of a commercial tunable diode laser was injected into a commercial VCSEL, designed to operate in the wavelength range of 795+/-3 nm, that was generating about 200 microW of optical power. (The use of relatively high injection power levels is a usual practice in injection locking of VCSELs.)

Strekalov, Dmitry↗
NASA NTRS1984

Diode laser 87Rb optical pumping in an evacuated wall-coated cell

The evacuated wall coated sealed cell coupled with diode laser optical pumping offers a number of attractive potential advantages for use in Rb or Cs atomic frequency standards. An investigation of systematic effects is required to explore possible limitations of the technique. The use of diode laser optical pumping of 87 Rb in an evacuated wall coated sealed cell is presented. Experimental results/discussion to be presented include the signal strength and line broadening of the 0 - 0 hyperfine resonance as a function of light intensity for the D1 optical transitions (F - F prime) - (2 1 prime) and (2 - 2 prime), shift of the 0 - 0 hyperfine frequency as a function of laser intensity and de-tuning from optical resonance, and diode laser frequency stabilization techniques.

Lee, W. K.↗
NASA NTRS1973

High modulus high temperature glass fibers

The search for a new high-modulus, high-temperature glass fiber involved the preparation of 500 glass compositions lying in 12 glass fields. These systems consisted primarily of low atomic number oxides and rare-earth oxides. Direct optical measurements of the kinetics of crystallization of the cordierite-rare earth system, for example, showed that the addition of rare-earth oxides decreased the rate of formation of cordierite crystals. Glass samples prepared from these systems proved that the rare-earth oxides made large specific contributions to the Young's modulus of the glasses. The best glasses have moduli greater than 21 million psi, the best glass fibers have moduli greater than 18 million psi, and the best glass fiber-epoxy resin composites have tensile strengths of 298,000 psi, compressive strengths of at least 220,000 psi, flexural strengths of 290,000 psi, and short-beam shear strengths of almost 17,000 psi.

Bacon, J. F.↗
NASA NTRS1980

The effect of zirconium on the isothermal oxidation of nominal Ni-14Cr-24Al alloys

The isothermal oxidation of Ni-14Cr-24Al-xZr-type alloys was performed in still air at 1100, 1150, and 1200 C for times up to 200 hr. The zirconium content of the alloys varied from 0-0.63 atom percent (a/o). The oxidized surfaces were studied by optical microscopy, X-ray diffraction, and scanning electron microscopy. The base alloy was an alumina former with the zirconium-containing alloys also developing some ZrO2. The addition of zirconium above 0.066 a/o increased the rate of weight gain relative to the base alloy. Due to oxide penetratio, the weight gain increased with Zr content; however, the scale thickness did not increase. The Zr did increase the adherence of the oxide, particularly at 1200 C. The delta W/A vs. time data fit the parabolic model of oxidation. The specific diffusion mechanism operative could not be identified by analysis of the calculated activation energies. Measurements of the Al2O3 scale lattice constants yielded the same values for all alloys.

Kahn, A. S.↗
NASA NTRS1980

The excitation and collisional deactivation of metastable N/2P/ atoms in auroras

The concentration and altitude distribution of metastable N(2P) atoms was measured in a diffuse IBC II(+) auroral arc. The dominant N(2P) source is shown to be the dissociative excitation of N2 by electron impact with a minor contribution from the dissociative recombination of N2(+) ions. The possibility that an ion-molecule process involving atomic oxygen and vibrationally excited N2(+) ions is a significant N(2P) source is examined. Values for the proportional yield of N(+), N(2P), N(2D), and N(4S) atoms from electron-impact dissociation of N2 under optically thick conditions are given.

Zipf, E. C.↗
NASA NTRS1985

Examination of returned solar-max surfaces for impacting orbital debris and meteoroids

The thermal insulation of the Solar Maximum Mission launched on 14 February 1980 which consisted of 17 layers of alumized Kapton offers an excellent opportunity to obtain chemistry of impacting particles. To date, approximately 0.7 sq. met. of the insulation and 0.05 sq. met. of the aluminum louvers have been mapped by optical microscope for crater diameters larger than 40 microns. Atomic oxygen has eroded up to 20 microns of the exposed Kapton surfaces removing the older and smaller craters. The crater size distribution found on 3 different Kapton surfaces is shown. About 250 chemical spectra were recorded of particles observed in or around impact pits or in the debris pattern found on the second layer beneath impact holes in the outer layer. The debris populations are listed and discussed.

Kessler, D. J.↗
NASA NTRS1986

Degenerate four-wave mixing in a mercury-argon discharge

Phase conjugation has been obtained with pump powers as low as 0.5 mW on the 546.1-nm line of atomic mercury. Collisional processes that oppose the effects of optical pumping sustain the signal. Line splittings observed in the Doppler regime are compared with theory. Reflectivities agree with those obtained from a model that includes pump absorption.

Richardson, W.↗
NASA NTRS1991

Thermal control materials

The LDEF M0003-5 Thermal Control Materials Experiment contains numerous thermal control coatings, metallized and nonmetallized polymeric films, adhesives, OSR's, and metallic foils. The materials were located on the leading and trailing edges of the satellite, therefore exposed to two different low earth orbital environments. Many specimens received a total exposure of 5.75 years and other received a limited exposure of 0.9 years to the complete environment. On-orbit and post flight photographic records are presented. The material's physical and optical performance are discussed as a function of location and duration of exposure. Data concerning specimen condition, degradation, contamination, optical reflectance and transmittance are discussed. The effect of atomic oxygen erosion on specific materials is also presented, The performance of adhesive bonds with polymeric films is reviewed.

Hurley, C.↗
NASA NTRS1992

Short-cavity squeezing in barium

Broadband phase sensitive noise and squeezing were experimentally observed in a system of barium atoms interacting with a single mode of a short optical cavity. Squeezing of 13 +/- 3 percent was observed. A maximum possible squeezing of 45 +/- 8 percent could be inferred for out experimental conditions, after correction for measured loss factors. Noise reductions below the quantum limit were found over a range of detection frequencies 60-170 MHz and were best for high cavity transmission and large optical depths. The amount of squeezing observed is consistent with theoretical predictions from a full quantum statistical model of the system.

Hope, D. M.↗
NASA NTRS1992

The preliminary Long Duration Exposure Facility (LDEF) materials data base

A preliminary Long Duration Exposure Facility (LDEF) Materials Data Base was developed by the LDEF Materials Special Investigation Group (MSIG). The LDEF Materials Data Base is envisioned to eventually contain the wide variety and vast quantity of materials data generated for LDEF. The data is searchable by optical, thermal, and mechanical properties, exposure parameters (such as atomic oxygen flux), and author(s) or principal investigator(s). The LDEF Materials Data Base was incorporated into the Materials and Processes Technical Information System (MAPTIS). MAPTIS is a collection of materials data which was computerized and is available to engineers, designers, and researchers in the aerospace community involved in the design and development of spacecraft and related hardware. This paper describes the LDEF Materials Data Base and includes step-by-step example searches using the data base. Information on how to become an authorized user of the system is included.

Funk, Joan G.↗
NASA NTRS1991

The 1.083 micron tunable CW semiconductor laser

A tunable CW laser is desired to produce light equivalent to the helium spectral line at 1.08 microns. This laser will serve as an optical pumping source for He-3 and He-4 atoms used in space magnetometers. This light source can be fabricated either as a semiconductor laser diode or a pumped solid state laser. Continuous output power of greater than 10 mW is desired. Semiconductor lasers can be thermally tuned, but must be capable of locking onto the helium resonance lines. Solid state lasers must have efficient pumping sources suitable for space configuration. Additional requirements are as follows: space magnetometer applications will include low mass (less than 0.5 kg), low power consumption (less than 0.75 W), and high stability/reliability for long missions (5-10 years).

Wang, C. S.↗
NASA NTRS1993

Materials And Processes Technical Information System (MAPTIS) LDEF materials data base

A preliminary Long Duration Exposure Facility (LDEF) Materials Data Base was developed by the LDEF Materials Special Investigation Group (MSIG). The LDEF Materials Data Base is envisioned to eventually contain the wide variety and vast quantity of materials data generated from LDEF. The data is searchable by optical, thermal, and mechanical properties, exposure parameters (such as atomic oxygen flux) and author(s) or principal investigator(s). Tne LDEF Materials Data Base was incorporated into the Materials and Processes Technical Information System (MAPTIS). MAPTIS is a collection of materials data which has been computerized and is available to engineers, designers, and researchers in the aerospace community involved in the design and development of spacecraft and related hardware. The LDEF Materials Data Base is described and step-by-step example searches using the data base are included. Information on how to become an authorized user of the system is included.

Funk, Joan G.↗
NASA NTRS1992

Mid-infrared rotational line emission from interstellar molecular hydrogen

The line emission from the v = 0-0 S(0), S(2), and S(3), and the v = 1-0 and v = 2-1 S(1) transitions of molecular hydrogen in clouds exposed to high FUV fluxes and in shocks is modeled. Particular attention is given to the lowest pure rotational H2 transitions at 20 and 17 microns, respectively. It is found that, in photodissociation regions (PDRs), the emission comes from warm (greater than about 100 k) molecular gas, situated at optical depths greater than about 1, beyond the hot atomic surface layer of the clouds. For FUV fields, G0 = 1000 to 100,000 times the average interstellar field densities n = 10 exp 3 - 10 exp 7/cu cm, the typical line intensities are in the range 10 exp -6 to 10 exp -4 ergs/s sq cm sr. The predictions for the line intensities from both C-type and J-type shock models are compared. The results are applied to recent observations of the 0-0 S(1) transition in both the PDR and the shocked gas in Orion.

Burton, Michael G.↗
NASA NTRS1999

MSFC Investigations of Beta Cloth Darkening Due to Ultraviolet Radiation Interactions

A common component of multi-layer insulation blankets is beta cloth, a woven fiberglass cloth impregnated with Teflon. It is planned for extensive use on the International Space Station (ISS). The Environmental Effects Group of the Marshall Space Flight Center Materials, Processing and Manufacturing Department has investigated the impact of atomic oxygen (AO) and ultraviolet (UV) radiation on the optical properties of plain and aluminized beta cloth, both in the laboratory and as part of long-duration flight experiments. These investigations indicate that beta cloth was susceptible to darkening in the presence of UV radiation, dependent on the additives used. The presence of AO countered some, if not all, of the UV degradation.

Kamenetzky, Rachel R.↗
NASA NTRS1999

Comparison of Observed Beta Cloth Interactions with Simulated and Actual Space Environment

A common component of multilayer insulation blankets is beta cloth, a woven fiberglass cloth impregnated with Teflon(TM). It is planned for extensive use on the International Space Station. The Environmental Etl'ects Group of the Marshall Space Flight Center Materials, Processing, and Manufacturing Department has investigated the impact of atomic oxygen (AO) and ultraviolet (UV) radiation on the optical properties of plain and aluminized beta cloth. both in the laboratory and as part of long-duration flight experiments. These investigations indicate that beta cloth is susceptible to darkening in the presence of UV radiation, dependent on the additives used. AO interactions resulted in bleaching of the beta cloth.

Kamenetzy, R. R.↗
NASA NTRS2010

MSFC Thermal Protection System Materials on MISSE-6

The Lightweight Nonmetallic Thermal Protection Materials Technology (LNTPMT) program studied a number of ceramic matrix composites, ablator materials, and tile materials for durability in simulated space environment. Materials that indicated low atomic oxygen reactivity and negligible change in thermo-optical properties in ground testing were selected to fly on the Materials on International Space Station Experiment (MISSE)-6. These samples were exposed for 17 months to the low Earth orbit environment on both the ram and wake sides of MISSE-6B. Thermo-optical properties are discussed, along with any changes in mass.

Finckenor, Miria M.↗
NASA NTRS1991

Evaluation of thermal control coatings for use on solar dynamic radiators in low Earth orbit

Thermal control coatings with high thermal emittance and low solar absorptance are needed for Space Station Freedom (SSF) solar dynamic power module radiator (SDR) surfaces for efficient heat rejection. Additionally, these coatings must be durable to low earth orbital (LEO) environmental effects of atomic oxygen, ultraviolet radiation and deep thermal cycles which occur as a result of start-up and shut-down of the solar dynamic power system. Eleven candidate coatings were characterized for their solar absorptance and emittance before and after exposure to ultraviolet (UV) radiation (200 to 400 nm), vacuum UV (VUV) radiation (100 to 200 nm) and atomic oxygen. Results indicated that the most durable and best performing coatings were white paint thermal control coatings Z-93, zinc oxide pigment in potassium silicate binder, and YB-71, zinc orthotitanate pigment in potassium silicate binder. Optical micrographs of these materials exposed to the individual environmental effects of atomic oxygen and vacuum thermal cycling showed that no surface cracking occurred.

Dever, Joyce A.↗