Note: a novel vacuum ultraviolet light source assembly with aluminum-coated electrodes for enhancing the ionization efficiency of photoionization mass spectrometry.

PubMed

Zhu, Zhixiang; Wang, Jian; Qiu, Keqing; Liu, Chengyuan; Qi, Fei; Pan, Yang

2014-04-01

A novel vacuum ultraviolet (VUV) light source assembly (VUVLSA) for enhancing the ionization efficiency of photoionization mass spectrometer has been described. The VUVLSA composes of a Krypton lamp and a pair of disk electrodes with circular center cavities. The two interior surfaces that face the photoionization region were aluminum-coated. VUV light can be reflected back and forth in the photoionization region between the electrodes, thus the photoionization efficiency can be greatly enhanced. The performances of two different shaped electrodes, the coated double flat electrodes (DFE), and double conical electrodes, were studied. We showed that the signal amplification of coated DFE is around 4 times higher than that of uncoated electrodes without VUV light reflection. The relationship between the pressure of ionization chamber and mass signal enhancement has also been studied.

The generation of a tunable laser emission in the vacuum ultraviolet and its application to supersonic jet/multiphoton ionization mass spectrometry

NASA Astrophysics Data System (ADS)

Uchimura, Tomohiro; Onoda, Takayuki; Lin, Cheng-Huang; Imasaka, Totaro

1999-08-01

An optical parametric oscillator and a Ti:sapphire laser are used as a pump source for the generation of high-order vibrational stimulated Raman emission in the vacuum ultraviolet region. This tunable laser is employed as an excitation/ionization source in a supersonic jet/multiphoton ionization/time-of-flight mass spectrometric study of benzene. The merits and potential advantages of this approach are discussed in this study.

In situ measurements of scattering from contaminated optics in the Vacuum Ultraviolet

NASA Astrophysics Data System (ADS)

Herren, Kenneth A.; Linton, Roger C.; Whitaker, Ann F.

1990-07-01

NASA's In Situ Contamination Effects Facility has been used to measure the time dependence of the angular reflectance from molecularly contaminated optical surfaces in the vacuum ultraviolet. The light scattering measurements are accomplished in situ on optical surfaces in real time during deposition of molecular contaminants. The measurements are taken using noncoherent VUV sources with the predominant wavelengths being the krypton resonance lines at 1236 and 1600 angstroms. Detection of the scattered light is accomplished using a set of three solar blind VUV photomultipliers. An in-plane VUV BRDF (bidirectional reflectance distribution function) experiment is described and details of the on-going program to characterize optical materials exposed to the space environment is reported.

In situ measurements of scattering from contaminated optics in the Vacuum Ultraviolet

NASA Technical Reports Server (NTRS)

Herren, Kenneth A.; Linton, Roger C.; Whitaker, Ann F.

1990-01-01

NASA's In Situ Contamination Effects Facility has been used to measure the time dependence of the angular reflectance from molecularly contaminated optical surfaces in the vacuum ultraviolet. The light scattering measurements are accomplished in situ on optical surfaces in real time during deposition of molecular contaminants. The measurements are taken using noncoherent VUV sources with the predominant wavelengths being the krypton resonance lines at 1236 and 1600 angstroms. Detection of the scattered light is accomplished using a set of three solar blind VUV photomultipliers. An in-plane VUV BRDF (bidirectional reflectance distribution function) experiment is described and details of the on-going program to characterize optical materials exposed to the space environment is reported.

Resolution of isomeric new designer stimulants using gas chromatography - Vacuum ultraviolet spectroscopy and theoretical computations.

PubMed

Skultety, Ludovit; Frycak, Petr; Qiu, Changling; Smuts, Jonathan; Shear-Laude, Lindsey; Lemr, Karel; Mao, James X; Kroll, Peter; Schug, Kevin A; Szewczak, Angelica; Vaught, Cory; Lurie, Ira; Havlicek, Vladimir

2017-06-08

Distinguishing isomeric representatives of "bath salts", "plant food", "spice", or "legal high" remains a challenge for analytical chemistry. In this work, we used vacuum ultraviolet spectroscopy combined with gas chromatography to address this issue on a set of forty-three designer drugs. All compounds, including many isomers, returned differentiable vacuum ultraviolet/ultraviolet spectra. The pair of 3- and 4-fluoromethcathinones (m/z 181.0903), as well as the methoxetamine/meperidine/ethylphenidate (m/z 247.1572) triad, provided very distinctive vacuum ultraviolet spectral features. On the contrary, spectra of 4-methylethcathinone, 4-ethylmethcathinone, 3,4-dimethylmethcathinone triad (m/z 191.1310) displayed much higher similarities. Their resolution was possible only if pure standards were probed. A similar situation occurred with the ethylone and butylone pair (m/z 221.1052). On the other hand, majority of forty-three drugs was successfully separated by gas chromatography. The detection limits for all the drug standards were in the 2-4 ng range (on-column amount), which is sufficient for determinations of seized drugs during forensics analysis. Further, state-of-the-art time-dependent density functional theory was evaluated for computation of theoretical absorption spectra in the 125-240 nm range as a complementary tool. Copyright © 2017 Elsevier B.V. All rights reserved.

Corona And Ultraviolet Equipment For Testing Materials

NASA Technical Reports Server (NTRS)

Laue, Eric G.

1993-01-01

Two assemblies of laboratory equipment developed for use in testing abilities of polymers, paints, and other materials to withstand ultraviolet radiation and charged particles. One is vacuum ultraviolet source built around commercial deuterium lamp. Other exposes specimen in partial vacuum to both ultraviolet radiation and brush corona discharge. Either or both assemblies used separately or together to simulate approximately combination of solar radiation and charged particles encountered by materials aboard spacecraft in orbit around Earth. Also used to provide rigorous environmental tests of materials exposed to artificial ultraviolet radiation and charged particles in industrial and scientific settings or to natural ultraviolet radiation and charged particles aboard aircraft at high altitudes.

Single photon ionization and chemical ionization combined ion source based on a vacuum ultraviolet lamp for orthogonal acceleration time-of-flight mass spectrometry.

PubMed

Hua, Lei; Wu, Qinghao; Hou, Keyong; Cui, Huapeng; Chen, Ping; Wang, Weiguo; Li, Jinghua; Li, Haiyang

2011-07-01

A novel combined ion source based on a vacuum ultraviolet (VUV) lamp with both single photon ionization (SPI) and chemical ionization (CI) capabilities has been developed for an orthogonal acceleration time-of-flight mass spectrometer (oaTOFMS). The SPI was accomplished using a commercial 10.6 eV krypton discharge lamp with a photon flux of about 10(11) photons s(-1), while the CI was achieved through ion-molecule reactions with O(2)(+) reactant ions generated by photoelectron ionization at medium vacuum pressure (MVP). To achieve high ionization efficiency, the ion source pressure was elevated to 0.3 mbar and the photoionization length was extended to 36 mm. As a result, limits of detection (LODs) down to 3, 4, and 6 ppbv were obtained for benzene, toluene, and p-xylene in MVP-SPI mode, and values of 8 and 10 ppbv were obtained for toluene and chloroform, respectively, in SPI-CI mode. As it is feasible to switch between MVP-SPI mode and SPI-CI mode rapidly, this system is capable of monitoring complex organic mixtures with a wide range of ionization energies (IEs). The analytical capacity of this system was demonstrated by measuring dehydrogenation products of long-chain paraffins to olefins through direct capillary sampling and drinking water disinfection byproducts from chlorine through a membrane interface.

Vacuum-Ultraviolet Photovoltaic Detector.

PubMed

Zheng, Wei; Lin, Richeng; Ran, Junxue; Zhang, Zhaojun; Ji, Xu; Huang, Feng

2018-01-23

Over the past two decades, solar- and astrophysicists and material scientists have been researching and developing new-generation semiconductor-based vacuum ultraviolet (VUV) detectors with low power consumption and small size for replacing traditional heavy and high-energy-consuming microchannel-detection systems, to study the formation and evolution of stars. However, the most desirable semiconductor-based VUV photovoltaic detector capable of achieving zero power consumption has not yet been achieved. With high-crystallinity multistep epitaxial grown AlN as a VUV-absorbing layer for photogenerated carriers and p-type graphene (with unexpected VUV transmittance >96%) as a transparent electrode to collect excited holes, we constructed a heterojunction device with photovoltaic detection for VUV light. The device exhibits an encouraging VUV photoresponse, high external quantum efficiency (EQE) and extremely fast tempera response (80 ns, 10 4 -10 6 times faster than that of the currently reported VUV photoconductive devices). This work has provided an idea for developing zero power consumption and integrated VUV photovoltaic detectors with ultrafast and high-sensitivity VUV detection capability, which not only allows future spacecraft to operate with longer service time and lower launching cost but also ensures an ultrafast evolution of interstellar objects.

Simulated Space Vacuum Ultraviolet (VUV) Exposure Testing for Polymer Films

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Pietromica, Anthony J.; Stueber, Thomas J.; Sechkar, Edward A.; Messer, Russell K.

2002-01-01

Vacuum ultraviolet (VUV) radiation of wavelengths between 115 and 200 nm produced by the sun in the space environment can cause degradation to polymer films producing changes in optical, mechanical, and chemical properties. These effects are particularly important for thin polymer films being considered for ultra-lightweight space structures, because, for most polymers, VUV radiation is absorbed in a thin surface layer. NASA Glenn Research Center has developed facilities and methods for long-term ground testing of polymer films to evaluate space environmental VUV radiation effects. VUV exposure can also be used as part of sequential simulated space environmental exposures to determine combined damaging effects. This paper will describe the effects of VUV on polymer films and the necessity for ground testing. Testing practices used at Glenn Research Center for VUV exposure testing will be described including characterization of the VUV radiation source used, calibration procedures traceable to the National Institute of Standards and Technology (NIST), and testing techniques for VUV exposure of polymer surfaces.

Absolute photon-flux measurements in the vacuum ultraviolet

NASA Technical Reports Server (NTRS)

Samson, J. A. R.; Haddad, G. N.

1974-01-01

Absolute photon-flux measurements in the vacuum ultraviolet have extended to short wavelengths by use of rare-gas ionization chambers. The technique involves the measurement of the ion current as a function of the gas pressure in the ion chamber. The true value of the ion current, and hence the absolute photon flux, is obtained by extrapolating the ion current to zero gas pressure. Examples are given at 162 and 266 A. The short-wavelength limit is determined only by the sensitivity of the current-measuring apparatus and by present knowledge of the photoionization processes that occur in the rate gases.

Effects of space vacuum and solar ultraviolet irradiation (254 nanometers) on the colony forming ability of Bacillus subtilis spores

NASA Technical Reports Server (NTRS)

Buecker, H.; Horneck, G.; Wollenhaupt, H.

1973-01-01

Bacillus subtilis spores are highly resistant to harsh environments. Therefore, in the Apollo 16 Microbial Response to Space Environment Experiment (M191), these spores were exposed to space vacuum or solar ultraviolet irradiation, or both, to estimate the change of survival for terrestrial organisms in space. The survival of the spores was determined in terms of colony-forming ability. Comparison of the flight results with results of simulation experiments on earth applying high vacuum or ultraviolet irradiation, or both, revealed no remarkable difference. Simultaneous exposure to both these space factors resulted in a synergistic effect (that is, an ultraviolet supersensitivity). Therefore, the change of survival in space is assumed to depend on the degree of protection against solar ultraviolet irradiation.

Generation of multicolor vacuum ultraviolet pulses through four-wave sum-frequency mixing in argon

NASA Astrophysics Data System (ADS)

Shi, Liping; Li, Wenxue; Zhou, Hui; Wang, Di; Ding, Liang'en; Zeng, Heping

2013-11-01

We demonstrate efficient generation of multicolor vacuum ultraviolet pulses with excellent mode quality through χ(3)-based four-wave sum-frequency mixing and third-order harmonic generation of 400- and 267-nm femtosecond laser pulses in argon gas. The χ(3)-based nonlinear optical processes were optimized with appropriate control of gas pressure and group velocity delay between the driving pulses. Furthermore, the pulse breakup effects were observed for tightly focused ultraviolet pulses.

Vacuum ultraviolet images of the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

Smith, Andrew M.; Cornett, Robert H.; Hill, Robert S.

1987-09-01

Images with 50arcsec resolution of the Large Magellanic Cloud (LMC), obtained with sounding-rocket instrumentation in two vacuum ultraviolet (VUV) bandpasses, are presented. The bandpasses are each ≡200 Å wide and are centered, for hot stars, near 1500 Å and 1900 Å. Photometry was done on the digitized images for all associations in the list of Lucke and Hodge. The authors discuss the results and their relationship to the overall characteristics of star formation in the LMC. They present a simple model for propagating star formation in the LMC whose results closely resemble the distribution of associations as revealed by VUV images.

Effects of ultraviolet (UV) irradiation in air and under vacuum on low-k dielectrics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhury, F. A.; Nguyen, H. M.; Shohet, J. L., E-mail: shohet@engr.wisc.edu

This work addresses the effect of ultraviolet radiation of wavelengths longer than 250 nm on Si-CH{sub 3} bonds in porous low-k dielectrics. Porous low-k films (k = 2.3) were exposed to 4.9 eV (254 nm) ultraviolet (UV) radiation in both air and vacuum for one hour. Using Fourier Transform Infrared (FTIR) spectroscopy, the chemical structures of the dielectric films were analyzed before and after the UV exposure. UV irradiation in air led to Si-CH{sub 3} bond depletion in the low-k material and made the films hydrophilic. However, no change in Si-CH{sub 3} bond concentration was observed when the same samplesmore » were exposed to UV under vacuum with a similar fluence. These results indicate that UV exposures in vacuum with wavelengths longer than ∼250 nm do not result in Si-CH{sub 3} depletion in low-k films. However, if the irradiation takes place in air, the UV irradiation removes Si-CH{sub 3} although direct photolysis of air species does not occur above ∼242 nm. We propose that photons along with molecular oxygen and, water, synergistically demethylate the low-k films.« less

Vacuum ultraviolet spectra of uranium hexafluoride/argon mixtures

NASA Technical Reports Server (NTRS)

Krascella, N. L.

1976-01-01

The transmission properties of room temperature helium at pressures up to 20 atmospheres were determined in the wavelength range from 80 to 300 nm. Similarly, the transmission properties of uranium hexafluoride at 393 K (pressures less than 1.0 mm) were determined in the wavelength range from 80 to about 120 nm. The results show that high pressure helium is sufficiently transparent in the vacuum ultraviolet region (provided trace contaminants are removed) to be utilized as a transparent purge gas in future fissioning gaseous uranium plasma reactor experiments. Absorption cross sections for uranium hexafluoride were calculated from the data between 80 and 120 nm and were of the order of 10 to the -17 power sq cm.

Extreme Ultraviolet Explorer Bright Source List

NASA Technical Reports Server (NTRS)

Malina, Roger F.; Marshall, Herman L.; Antia, Behram; Christian, Carol A.; Dobson, Carl A.; Finley, David S.; Fruscione, Antonella; Girouard, Forrest R.; Hawkins, Isabel; Jelinsky, Patrick

1994-01-01

Initial results from the analysis of the Extreme Ultraviolet Explorer (EUVE) all-sky survey (58-740 A) and deep survey (67-364 A) are presented through the EUVE Bright Source List (BSL). The BSL contains 356 confirmed extreme ultraviolet (EUV) point sources with supporting information, including positions, observed EUV count rates, and the identification of possible optical counterparts. One-hundred twenty-six sources have been detected longward of 200 A.

CIV Polarization Measurements using a Vacuum Ultraviolet Fabry-Perot Interferometer

NASA Technical Reports Server (NTRS)

West, Edward; Gary, G. Allen; Cirtain, Jonathan; David, John; Kobayashi, Ken; Pietraszewski, Chris

2009-01-01

Marshall Space Flight Center's (MSFC) is developing a Vacuum Ultraviolet (VUV) Fabry-P rot Interferometer that will be launched on a sounding rocket for high throughput, high-cadence, extended field of view CIV (155nm) measurements. These measurements will provide (i) Dopplergrams for studies of waves, oscillations, explosive events, and mass motions through the transition region, and, (ii), polarization measurements to study the magnetic field in the transition region. This paper will describe the scientific goals of the instrument, a brief description of the optics and the polarization characteristics of the VUV Fabry P rot.

Bidirectional Reflectance Function Measurement of Molecular Contaminant Scattering in the Vacuum Ultraviolet

NASA Technical Reports Server (NTRS)

Herren, Kenneth A.; Gregory, Don A.

2006-01-01

Bi-directional reflectance distribution function (BRDF) measurements of optical surfaces both before and after molecular contamination were done using UV, VUV and visible light. Molecular contamination of optical surfaces from outgassed material has been shown in many cases to proceed from acclimation centers, and to produce many roughly hemispherical "islands" of contamination on the surface. Vacuum Ultraviolet (VW) wavelengths are used here to measure angularly scattered light from optical surfaces.

Intensity and Energy Level Analysis of the Vacuum Ultraviolet Spectrum of Four Times Ionize Nickel (Ni V)

NASA Astrophysics Data System (ADS)

Ward, Jacob Wolfgang; Nave, Gillian

2016-01-01

Recent measurements of four times ionized iron and nickel (Fe V & Ni V) wavelengths in the vacuum ultraviolet (VUV) have been taken using the National Institute for Standards and Technology (NIST) Normal Incidence Vacuum Spectrograph (NIVS) with a sliding spark light source with invar electrodes. The wavelengths observed in those measurements make use of high resolution photographic plates with the majority of observed lines having uncertainties of approximately 3mÅ. In addition to observations made with photographic plates, the same wavelength region was observed with phosphor image plates, which have been demonstrated to be accurate as a method of intensity calibration when used with a deuterium light source. This work will evaluate the use of phosphor image plates and deuterium lamps as an intensity calibration method for the Ni V spectrum in the 1200-1600Å region of the VUV. Additionally, by pairing the observed wavelengths of Ni V with accurate line intensities, it is possible to create an energy level optimization for Ni V providing high accuracy Ritz wavelengths. This process has previously been applied to Fe V and produced Ritz wavelengths that agreed with the above experimental observations.

Examination of Laser Microprobe Vacuum Ultraviolet Ionization Mass Spectrometry with Application to Mapping Mars Returned Samples

NASA Astrophysics Data System (ADS)

Burton, A. S.; Berger, E. L.; Locke, D. R.; Lewis, E. K.; Moore, J. F.

2018-04-01

Laser microprobe of surfaces utilizing a two laser setup whereby the desorption laser threshold is lowered below ionization, and the resulting neutral plume is examined using 157nm Vacuum Ultraviolet laser light for mass spec surface mapping.

Interplanetary survival probability of Aspergillus terreus spores under simulated solar vacuum ultraviolet irradiation

NASA Astrophysics Data System (ADS)

Sarantopoulou, E.; Gomoiu, I.; Kollia, Z.; Cefalas, A. C.

2011-01-01

This work is a part of ESA/EU SURE project aiming to quantify the survival probability of fungal spores in space under solar irradiation in the vacuum ultraviolet (VUV) (110-180 nm) spectral region. The contribution and impact of VUV photons, vacuum, low temperature and their synergies on the survival probability of Aspergillus terreus spores is measured at simulated space conditions on Earth. To simulate the solar VUV irradiation, the spores are irradiated with a continuous discharge VUV hydrogen photon source and a molecular fluorine laser, at low and high photon intensities at 10 15 photon m -2 s -1 and 3.9×10 27 photons pulse -1 m -2 s -1, respectively. The survival probability of spores is independent from the intensity and the fluence of photons, within certain limits, in agreement with previous studies. The spores are shielded from a thin carbon layer, which is formed quickly on the external surface of the proteinaceous membrane at higher photon intensities at the start of the VUV irradiation. Extrapolating the results in space conditions, for an interplanetary direct transfer orbit from Mars to Earth, the spores will be irradiated with 3.3×10 21 solar VUV photons m -2. This photon fluence is equivalent to the irradiation of spores on Earth with 54 laser pulses with an experimental ˜92% survival probability, disregarding the contribution of space vacuum and low temperature, or to continuous solar VUV irradiation for 38 days in space near the Earth with an extrapolated ˜61% survival probability. The experimental results indicate that the damage of spores is mainly from the dehydration stress in vacuum. The high survival probability after 4 days in vacuum (˜34%) is due to the exudation of proteins on the external membrane, thus preventing further dehydration of spores. In addition, the survival probability is increasing to ˜54% at 10 K with 0.12 K/s cooling and heating rates.

Source replenishment device for vacuum deposition

DOEpatents

Hill, Ronald A.

1988-01-01

A material source replenishment device for use with a vacuum deposition apparatus. The source replenishment device comprises an intermittent motion producing gear arrangement disposed within the vacuum deposition chamber. An elongated rod having one end operably connected to the gearing arrangement is provided with a multiarmed head at the opposite end disposed adjacent the heating element of the vacuum deposition apparatus. An inverted U-shaped source material element is releasably attached to the outer end of each arm member whereby said multiarmed head is moved to locate a first of said material elements above said heating element, whereupon said multiarmed head is lowered to engage said material element with the heating element and further lowered to release said material element on the heating element. After vaporization of said material element, second and subsequent material elements may be provided to the heating element without the need for opening the vacuum deposition apparatus to the atmosphere.

Source replenishment device for vacuum deposition

DOEpatents

Hill, R.A.

1986-05-15

A material source replenishment device for use with a vacuum deposition apparatus is described. The source replenishment device comprises an intermittent motion producing gear arrangement disposed within the vacuum deposition chamber. An elongated rod having one end operably connected to the gearing arrangement is provided with a multiarmed head at the opposite end disposed adjacent the heating element of the vacuum deposition apparatus. An inverted U-shaped source material element is releasably attached to the outer end of each arm member whereby said multiarmed head is moved to locate a first of said material elements above said heating element, whereupon said multiarmed head is lowered to engage said material element with the heating element and further lowered to release said material element on the heating element. After vaporization of said material element, second and subsequent material elements may be provided to the heating element without the need for opening the vacuum deposition apparatus to the atmosphere.

Vacuum Ultraviolet Photoionization of Complex Chemical Systems

DOE PAGES

Kostko, Oleg; Bandyopadhyay, Biswajit; Ahmed, Musahid

2016-02-24

Tunable vacuum ultraviolet (VUV) radiation coupled to mass spectrometry is applied to the study of complex chemical systems in this paper. The identification of novel reactive intermediates and radicals is revealed in flame, pulsed photolysis, and pyrolysis reactors, leading to the elucidation of spectroscopy, reaction mechanisms, and kinetics. Mass-resolved threshold photoelectron photoion coincidence measurements provide unprecedented access to vibrationally resolved spectra of free radicals present in high-temperature reactors. Photoionization measurements in water clusters, nucleic acid base dimers, and their complexes with water provide signatures of proton transfer in hydrogen-bonded and π-stacked systems. Experimental and theoretical methods to track ion–molecule reactionsmore » and fragmentation pathways in intermolecular and intramolecular hydrogen-bonded systems in sugars and alcohols are described. Photoionization of laser-ablated molecules, clusters, and their reaction products inform thermodynamics and spectroscopy that are relevant to astrochemistry and catalysis. Finally, new directions in coupling VUV radiation to interrogate complex chemical systems are discussed.« less

Effect of vacuum-ultraviolet irradiation on the dielectric constant of low-k organosilicate dielectrics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, H.; Shohet, J. L.; Ryan, E. T.

2014-11-17

Vacuum ultraviolet (VUV) irradiation is generated during plasma processing in semiconductor fabrications, while the effect of VUV irradiation on the dielectric constant (k value) of low-k materials is still an open question. To clarify this problem, VUV photons with a range of energies were exposed on low-k organosilicate dielectrics (SiCOH) samples at room temperature. Photon energies equal to or larger than 6.0 eV were found to decrease the k value of SiCOH films. VUV photons with lower energies do not have this effect. This shows the need for thermal heating in traditional ultraviolet (UV) curing since UV light sources do notmore » have sufficient energy to change the dielectric constant of SiCOH and additional energy is required from thermal heating. In addition, 6.2 eV photon irradiation was found to be the most effective in decreasing the dielectric constant of low-k organosilicate films. Fourier Transform Infra-red Spectroscopy shows that these 6.2 eV VUV exposures removed organic porogens. This contributes to the decrease of the dielectric constant. This information provides the range of VUV photon energies that could decrease the dielectric constant of low-k materials most effectively.« less

Microwave-driven ultraviolet light sources

DOEpatents

Manos, Dennis M.; Diggs, Jessie; Ametepe, Joseph D.

2002-01-29

A microwave-driven ultraviolet (UV) light source is provided. The light source comprises an over-moded microwave cavity having at least one discharge bulb disposed within the microwave cavity. At least one magnetron probe is coupled directly to the microwave cavity.

Space-time resolving vacuum ultraviolet spectrometer based on a rotating polyhedral mirror

NASA Astrophysics Data System (ADS)

Lin, Xiaodong; Xie, Jikang

2000-05-01

Using a rotating polyhedral mirror and a vacuum ultraviolet (VUV) monochromater, a space-time resolving VUV diagnostic system is developed. Measurement of the O VI (103.2 nm) radiation on the HT-6M tokamak shows that the time resolution of the system is better than 4 ms and the space resolution is better than 2 cm. Compared with traditional instruments, this system has improved measurement efficiency, and error from shot-to-shot discharge variations is avoided.

Vacuum ultraviolet photoionization cross section of the hydroxyl radical.

PubMed

Dodson, Leah G; Savee, John D; Gozem, Samer; Shen, Linhan; Krylov, Anna I; Taatjes, Craig A; Osborn, David L; Okumura, Mitchio

2018-05-14

The absolute photoionization spectrum of the hydroxyl (OH) radical from 12.513 to 14.213 eV was measured by multiplexed photoionization mass spectrometry with time-resolved radical kinetics. Tunable vacuum ultraviolet (VUV) synchrotron radiation was generated at the Advanced Light Source. OH radicals were generated from the reaction of O( 1 D) + H 2 O in a flow reactor in He at 8 Torr. The initial O( 1 D) concentration, where the atom was formed by pulsed laser photolysis of ozone, was determined from the measured depletion of a known concentration of ozone. Concentrations of OH and O( 3 P) were obtained by fitting observed time traces with a kinetics model constructed with literature rate coefficients. The absolute cross section of OH was determined to be σ(13.436 eV) = 3.2 ± 1.0 Mb and σ(14.193 eV) = 4.7 ± 1.6 Mb relative to the known cross section for O( 3 P) at 14.193 eV. The absolute photoionization spectrum was obtained by recording a spectrum at a resolution of 8 meV (50 meV steps) and scaling to the single-energy cross sections. We computed the absolute VUV photoionization spectrum of OH and O( 3 P) using equation-of-motion coupled-cluster Dyson orbitals and a Coulomb photoelectron wave function and found good agreement with the observed absolute photoionization spectra.

Vacuum ultraviolet photoionization cross section of the hydroxyl radical

NASA Astrophysics Data System (ADS)

Dodson, Leah G.; Savee, John D.; Gozem, Samer; Shen, Linhan; Krylov, Anna I.; Taatjes, Craig A.; Osborn, David L.; Okumura, Mitchio

2018-05-01

The absolute photoionization spectrum of the hydroxyl (OH) radical from 12.513 to 14.213 eV was measured by multiplexed photoionization mass spectrometry with time-resolved radical kinetics. Tunable vacuum ultraviolet (VUV) synchrotron radiation was generated at the Advanced Light Source. OH radicals were generated from the reaction of O(1D) + H2O in a flow reactor in He at 8 Torr. The initial O(1D) concentration, where the atom was formed by pulsed laser photolysis of ozone, was determined from the measured depletion of a known concentration of ozone. Concentrations of OH and O(3P) were obtained by fitting observed time traces with a kinetics model constructed with literature rate coefficients. The absolute cross section of OH was determined to be σ(13.436 eV) = 3.2 ± 1.0 Mb and σ(14.193 eV) = 4.7 ± 1.6 Mb relative to the known cross section for O(3P) at 14.193 eV. The absolute photoionization spectrum was obtained by recording a spectrum at a resolution of 8 meV (50 meV steps) and scaling to the single-energy cross sections. We computed the absolute VUV photoionization spectrum of OH and O(3P) using equation-of-motion coupled-cluster Dyson orbitals and a Coulomb photoelectron wave function and found good agreement with the observed absolute photoionization spectra.

Vacuum ultraviolet photon fluxes in argon-containing inductively coupled plasmas

NASA Astrophysics Data System (ADS)

Radovanov, S. B.; Persing, H. M.; Wang, S.; Culver, C. L.; Boffard, J. B.; Lin, C. C.; Wendt, A. E.

2013-09-01

Vacuum ultraviolet (VUV) photons emitted from excited atomic states are ubiquitous in material processing plasmas. Damage of materials is induced by energy transfer from the VUV photons to the surface, causing disorder in the surface region, surface reactions, and affecting bonds in the material bulk. Monitoring of the surface flux of VUV photons from inductively coupled plasmas (ICP) and its dependence on discharge parameters is thus highly desirable. Results of non-invasive, direct windowless VUV detection using a photosensitive diode will be presented. Relative VUV fluxes were also obtained using a sodium salicylate coating on the inside of a vacuum window, converting VUV into visible light detected through the vacuum window. The coating is sensitive to wavelengths in the range 80-300 nm, while the photodiode is only sensitive to wavelengths below 120 nm. In argon the VUV emissions are primarily produced by spontaneous decay from 3p5 4 s resonance levels (1s2,1s4) and may be reabsorbed by ground state atoms. Real-time resonance level concentrations were measured and used to predict the VUV photon flux at the detector for a range of different ICP pressures, powers, and for various admixtures of Ar with N2, and H2. This work was supported in part by NSF grant PHY-1068670.

Vacuum ultraviolet imagery of the Virgo Cluster region. II - Total far-ultraviolet flux of galaxies

NASA Astrophysics Data System (ADS)

Kodaira, K.; Watanabe, T.; Onaka, T.; Tanaka, W.

1990-11-01

The total flux in the far-ultraviolet region around 150 nm was measured for more than 40 galaxies in the central region of the Virgo Cluster, using two imaging telescopes on board a sounding rocket. The observed far-ultraviolet flux shows positive correlations with the H I 21 cm flux and the far-infrared flux for spiral galaxies, and with the X-ray flux and the radio continuum flux for elliptical galaxies. The former correlations of spiral galaxies are interpreted in terms of star formation activity, which indicates substantial depletion in the Virgo galaxies in accordance with the H I stripping. The latter correlations of elliptical galaxies indicate possible far-ultraviolet sources of young population, in addition to evolved hot stars. Far-ultraviolet fluxes from two dwarf elliptical galaxies were obtained tentatively, indicating star formation activity in elliptical galaxies. A high-resolution UV imagery by HST would be effective to distinguish the young population and the old population in elliptical galaxies.

The first Extreme Ultraviolet Explorer source catalog

NASA Technical Reports Server (NTRS)

Bowyer, S.; Lieu, R.; Lampton, M.; Lewis, J.; Wu, X.; Drake, J. J.; Malina, R. F.

1994-01-01

The Extreme Ultraviolet Explorer (EUVE) has conducted an all-sky survey to locate and identify point sources of emission in four extreme ultraviolet wavelength bands centered at approximately 100, 200, 400, and 600 A. A companion deep survey of a strip along half the ecliptic plane was simultaneously conducted. In this catalog we report the sources found in these surveys using rigorously defined criteria uniformly applied to the data set. These are the first surveys to be made in the three longer wavelength bands, and a substantial number of sources were detected in these bands. We present a number of statistical diagnostics of the surveys, including their source counts, their sensitivites, and their positional error distributions. We provide a separate list of those sources reported in the EUVE Bright Source List which did not meet our criteria for inclusion in our primary list. We also provide improved count rate and position estimates for a majority of these sources based on the improved methodology used in this paper. In total, this catalog lists a total of 410 point sources, of which 372 have plausible optical ultraviolet, or X-ray identifications, which are also listed.

Polarized vacuum ultraviolet and X-radiation

NASA Technical Reports Server (NTRS)

Samson, J. A. R.

1978-01-01

The most intense source of polarized vacuum UV and X radiation is synchrotron radiation, which exhibits a degree of partially polarized light between about 80-100%. However, the radiation transmitted by vacuum UV monochromators can also be highly polarized. The Seya-Namioka type of monochromator can produce partially polarized radiation between 50-80%. For certain experiments it is necessary to know the degree of polarization of the radiation being used. Also, when synchrotron radiation and a monochromator are combined the polarization characteristic of both should be known in order to make full use of these polarization properties. The polarizing effect of monochromators (i.e., diffraction gratings) have been measured at the Seya angle and at grazing angles for various spectral orders. Experimental evidence is presented which shows that the reciprocity law holds for polarization by reflection where the angle of incidence and diffraction are unequal. These results are reviewed along with the techniques for measuring the degree of polarization.

Synchrotron Vacuum Ultraviolet Light and Soft X-Ray Radiation Effects on Aluminized Teflon FEP Investigated

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Townsend, Jacqueline A.; Gaier, James R.; Jalics, Alice I.

1999-01-01

Since the Hubble Space Telescope (HST) was deployed in low Earth orbit in April 1990, two servicing missions have been conducted to upgrade its scientific capabilities. Minor cracking of second-surface metalized Teflon FEP (DuPont; fluorinated ethylene propylene) surfaces from multilayer insulation (MLI) was first observed upon close examination of samples with high solar exposure retrieved during the first servicing mission, which was conducted 3.6 years after deployment. During the second HST servicing mission, 6.8 years after deployment, astronaut observations and photographic documentation revealed significant cracks in the Teflon FEP layer of the MLI on both the solar- and anti-solar-facing surfaces of the telescope. NASA Goddard Space Flight Center directed the efforts of the Hubble Space Telescope MLI Failure Review Board, whose goals included identifying the low-Earth-orbit environmental constituent(s) responsible for the cracking and embrittling of Teflon FEP which was observed during the second servicing mission. The NASA Lewis Research Center provided significant support to this effort. Because soft x-ray radiation from solar flares had been considered as a possible cause for the degradation of the mechanical properties of Teflon FEP (ref. 1), the effects of soft xray radiation and vacuum ultraviolet light on Teflon FEP were investigated. In this Lewisled effort, samples of Teflon FEP with a 100-nm layer of vapor-deposited aluminum (VDA) on the backside were exposed to synchrotron radiation of various vacuum ultraviolet and soft x-ray wavelengths between 18 nm (69 eV) and 0.65 nm (1900 eV). Synchrotron radiation exposures were conducted using the National Synchrotron Light Source at Brookhaven National Laboratory. Samples of FEP/VDA were exposed with the FEP surface facing the synchrotron beam. Doses and fluences were compared with those estimated for the 20-yr Hubble Space Telescope mission.

Vacuum ultraviolet and infrared spectra of condensed methyl acetate on cold astrochemical dust analogs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sivaraman, B.; Nair, B. G.; Mason, N. J.

2013-12-01

Following the recent report of the first identification of methyl acetate (CH{sub 3}COOCH{sub 3}) in the interstellar medium (ISM), we have carried out vacuum ultraviolet (VUV) and infrared (IR) spectroscopy studies on methyl acetate from 10 K until sublimation in an ultrahigh vacuum chamber simulating astrochemical conditions. We present the first VUV and IR spectra of methyl acetate relevant to ISM conditions. Spectral signatures clearly showed molecular reorientation to have started in the ice by annealing the amorphous ice formed at 10 K. An irreversible phase change from amorphous to crystalline methyl acetate ice was found to occur between 110more » K and 120 K.« less

Development of two-channel prototype ITER vacuum ultraviolet spectrometer with back-illuminated charge-coupled device and microchannel plate detectors.

PubMed

Seon, C R; Choi, S H; Cheon, M S; Pak, S; Lee, H G; Biel, W; Barnsley, R

2010-10-01

A vacuum ultraviolet (VUV) spectrometer of a five-channel spectral system is designed for ITER main plasma impurity measurement. To develop and verify the system design, a two-channel prototype system is fabricated with No. 3 (14.4-31.8 nm) and No. 4 (29.0-60.0 nm) among the five channels. The optical system consists of a collimating mirror to collect the light from source to slit, two holographic diffraction gratings with toroidal geometry, and two different electronic detectors. For the test of the prototype system, a hollow cathode lamp is used as a light source. To find the appropriate detector for ITER VUV system, two kinds of detectors of the back-illuminated charge-coupled device and the microchannel plate electron multiplier are tested, and their performance has been investigated.

Electron impact excitation of argon in the extreme vacuum ultraviolet

NASA Technical Reports Server (NTRS)

Mentall, J. E.; Morgan, H. D.

1976-01-01

Polarization-free excitation cross sections in the extreme vacuum ultraviolet have been measured for electron impact on Ar. Observed spectral features were those lines of Ar I and Ar II which lie between 700 and 1100 A. Excitation functions were measured for the Ar I resonance line at 1048 A and the Ar II resonance line at 920 A. Peak cross sections for these two lines were found to be (39.4 plus or minus 7.9) x 10 to the -18th and (6.9 plus or minus 1.4) x 10 to the -18th, respectively. At low energies, excitation of the Ar II resonance line is dominated by an electron exchange transition.

Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakeman, M. S.; Lawrence Berkeley National Laboratory, Berkeley, California 94720; Tilborg, J. van

We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placementmore » of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range.« less

Vacuum ultraviolet spectropolarimeter design for precise polarization measurements.

PubMed

Narukage, Noriyuki; Auchère, Frédéric; Ishikawa, Ryohko; Kano, Ryouhei; Tsuneta, Saku; Winebarger, Amy R; Kobayashi, Ken

2015-03-10

Precise polarization measurements in the vacuum ultraviolet (VUV) region provide a new means for inferring weak magnetic fields in the upper atmosphere of the Sun and stars. We propose a VUV spectropolarimeter design ideally suited for this purpose. This design is proposed and adopted for the NASA-JAXA chromospheric lyman-alpha spectropolarimeter (CLASP), which will record the linear polarization (Stokes Q and U) of the hydrogen Lyman-α line (121.567 nm) profile. The expected degree of polarization is on the order of 0.1%. Our spectropolarimeter has two optically symmetric channels to simultaneously measure orthogonal linear polarization states with a single concave diffraction grating that serves both as the spectral dispersion element and beam splitter. This design has a minimal number of reflective components with a high VUV throughput. Consequently, these design features allow us to minimize the polarization errors caused by possible time variation of the VUV flux during the polarization modulation and by statistical photon noise.

Surface assessment of CaF2 deep-ultraviolet and vacuum-ultraviolet optical components by the quasi-Brewster angle technique.

PubMed

Wang, Jue; Maier, Robert L

2006-08-01

The requirements for optical components have drastically increased for the deep-ultraviolet and vacuum-ultraviolet spectral regions. Low optical loss, high laser damage threshold, and long lifetime fluoride optics are required for microlithographic applications. A nondestructive quasi-Brewster angle technique (qBAT) has been developed for evaluating the quality of optical surfaces including both top surface and subsurface information. By using effective medium approximation, the negative quasi-Brewster angle shift at wavelengths longer than 200 nm has been used to model the distribution of subsurface damage, whereas the positive quasi-Brewster angle shift for wavelengths shorter than 200 nm has been explained by subsurface contamination. The top surface roughness depicted by the qBAT is consistent with atomic force microscopy measurements. The depth and the microporous structure of the subsurface damage measured by the qBAT has been confirmed by magnetorheological finishing. The technique has been extended to evaluate both polished and antireflection-coated CaF(2) components.

Laser Desorption Postionization Mass Spectrometry of Antibiotic-Treated Bacterial Biofilms using Tunable Vacuum Ultraviolet Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gasper, Gerald L; Takahashi, Lynelle K; Zhou, Jia

2010-08-04

Laser desorption postionization mass spectrometry (LDPI-MS) with 8.0 ? 12.5 eV vacuum ultraviolet synchrotron radiation is used to single photon ionize antibiotics andextracellular neutrals that are laser desorbed both neat and from intact bacterial biofilms. Neat antibiotics are optimally detected using 10.5 eV LDPI-MS, but can be ionized using 8.0 eV radiation, in agreement with prior work using 7.87 eV LDPI-MS. Tunable vacuum ultraviolet radiation also postionizes laser desorbed neutrals of antibiotics and extracellular material from within intact bacterial biofilms. Different extracellular material is observed by LDPI-MS in response to rifampicin or trimethoprim antibiotic treatment. Once again, 10.5 eV LDPI-MSmore » displays the optimum trade-off between improved sensitivity and minimum fragmentation. Higher energy photons at 12.5 eV produce significant parent ion signal, but fragment intensity and other low mass ions are also enhanced. No matrix is added to enhance desorption, which is performed at peak power densities insufficient to directly produce ions, thus allowing observation of true VUV postionization mass spectra of antibiotic treated biofilms.« less

Simultaneous removal of NO and SO2 using vacuum ultraviolet light (VUV)/heat/peroxymonosulfate (PMS).

PubMed

Liu, Yangxian; Wang, Yan; Wang, Qian; Pan, Jianfeng; Zhang, Jun

2018-01-01

Simultaneous removal process of SO 2 and NO from flue gas using vacuum ultraviolet light (VUV)/heat/peroxymonosulfate (PMS) in a VUV spraying reactor was proposed. The key influencing factors, active species, reaction products and mechanism of SO 2 and NO simultaneous removal were investigated. The results show that vacuum ultraviolet light (185 nm) achieves the highest NO removal efficiency and yield of and under the same test conditions. NO removal is enhanced at higher PMS concentration, light intensity and oxygen concentration, and is inhibited at higher NO concentration, SO 2 concentration and solution pH. Solution temperature has a double impact on NO removal. CO 2 concentration has no obvious effect on NO removal. and produced from VUV-activation of PMS play a leading role in NO removal. O 3 and ·O produced from VUV-activation of O 2 also play an important role in NO removal. SO 2 achieves complete removal under all experimental conditions due to its very high solubility in water and good reactivity. The highest simultaneous removal efficiency of SO 2 and NO reaches 100% and 91.3%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dynamic photolytical actinometry of the vacuum-ultraviolet radiation produced by multichannel surface discharges of submicrosecond duration.

PubMed

Tcheremiskine, V I; Uteza, O P; Sentis, M L; Mikheev, L D

2007-06-01

Absolute measurements of the vacuum-ultraviolet (VUV) radiation power produced by a planar broadband optical source of submicrosecond light pulse duration are carried out in the transient regime of formation of a photodissociation (bleaching) wave in a photodecomposing absorptive medium. The source is based on a multichannel surface discharge initiated in ArN(2) gas mixtures on the area of approximately 0.1 m(2). The energetic characteristics of the produced VUV radiation are determined on the basis of spatially and temporally resolved observations of the pulsed photolysis of XeF(2) vapors. It is shown that the photon flux intensity produced by the source within the spectral range of 120-200 nm reaches 1.1 x 10(23) photonscm(2) s corresponding to the effective brightness temperature of discharge plasma of 20 kK and to the intrinsic efficiency of the discharge VUV emission of 3.2%. Numerical simulations of the photolysis process show a rather weak sensitivity of the results to the fraction of discharge radiation emitted into the line spectrum, as well as to the angular distribution of emitted radiation. The spectral band of measurements can be selected according to the choice of parent photodecomposing particles.

Vacuum Ultraviolet Radiation Desorption of Molecular Contaminants Deposited on Quartz Crystal Microbalances

NASA Technical Reports Server (NTRS)

Albyn, Keith; Burns, Dewitt

2006-01-01

Recent quartz crystal microbalance measurements made in the Marshall Space Flight Center, Photo-Deposition Facility, for several materials, recorded a significant loss of deposited contaminants when the deposition surface of the microbalance was illuminated by a deuterium lamp. These measurements differ from observations made by other investigators in which the rate of deposition increased significantly when the deposition surface was illuminated with vacuum ultraviolet radiation. These observations suggest that the accelerated deposition of molecular contaminants on optically sensitive surfaces is dependant upon the contaminant being deposited and must be addressed during the materials selection process by common material screening techniques.

Vacuum ultraviolet detector for gas chromatography.

PubMed

Schug, Kevin A; Sawicki, Ian; Carlton, Doug D; Fan, Hui; McNair, Harold M; Nimmo, John P; Kroll, Peter; Smuts, Jonathan; Walsh, Phillip; Harrison, Dale

2014-08-19

Analytical performance characteristics of a new vacuum ultraviolet (VUV) detector for gas chromatography (GC) are reported. GC-VUV was applied to hydrocarbons, fixed gases, polyaromatic hydrocarbons, fatty acids, pesticides, drugs, and estrogens. Applications were chosen to feature the sensitivity and universal detection capabilities of the VUV detector, especially for cases where mass spectrometry performance has been limited. Virtually all chemical species absorb and have unique gas phase absorption cross sections in the approximately 120-240 nm wavelength range monitored. Spectra are presented, along with the ability to use software for deconvolution of overlapping signals. Some comparisons with experimental synchrotron data and computed theoretical spectra show good agreement, although more work is needed on appropriate computational methods to match the simultaneous broadband electronic and vibronic excitation initiated by the deuterium lamp. Quantitative analysis is governed by Beer-Lambert Law relationships. Mass on-column detection limits reported for representatives of different classes of analytes ranged from 15 (benzene) to 246 pg (water). Linear range measured at peak absorption for benzene was 3-4 orders of magnitude. Importantly, where absorption cross sections are known for analytes, the VUV detector is capable of absolute determination (without calibration) of the number of molecules present in the flow cell in the absence of chemical interferences. This study sets the stage for application of GC-VUV technology across a wide breadth of research areas.

Vacuum ultraviolet photofragmentation of octadecane: photoionization mass spectrometric and theoretical investigation.

PubMed

Xu, Jing; Sang, Pengpeng; Zhao, Lianming; Guo, Wenyue; Qi, Fei; Xing, Wei; Yan, Zifeng

The photoionization and fragmentation of octadecane were investigated with infrared laser desorption/tunable synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (IRLD/VUV PIMS) and theoretical calculations. Mass spectra of octadecane were measured at various photon energies. The fragment ions were gradually detected with the increase of photon energy. The main fragment ions were assigned to radical ions (C n H 2 n +1 + , n  = 4-11) and alkene ions (C n H 2 n + , n  = 5-10). The ionization energy of the precursor and appearance energy of ionic fragments were obtained by measuring the photoionization efficiency spectrum. Possible formation pathways of the fragment ions were discussed with the help of density functional theory calculations.

A synchrotron-radiation-based variable angle ellipsometer for the visible to vacuum ultraviolet spectral range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neumann, M. D., E-mail: maciej.neumann@isas.de; Cobet, C.; Esser, N.

2014-05-15

A rotating analyzer spectroscopic polarimeter and ellipsometer with a wide-range θ-2θ goniometer installed at the Insertion Device Beamline of the Metrology Light Source in Berlin is presented. With a combination of transmission- and reflection-based polarizing elements and the inherent degree of polarization of the undulator radiation, this ellipsometer is able to cover photon energies from about 2 eV up to 40 eV. Additionally, a new compensator design based on a CaF{sub 2} Fresnel rhomb is presented. This compensator allows ellipsometric measurements with circular polarization in the vacuum ultraviolet spectral range and thus, for example, the characterization of depolarizing samples. The new instrumentmore » was initially used for the characterization of the polarization of the beamline. The technical capabilities of the ellipsometer are demonstrated by a cohesive wide-range measurement of the dielectric function of epitaxially grown ZnO.« less

Effects of plasma and vacuum-ultraviolet exposure on the mechanical properties of low-k porous organosilicate glass

Treesearch

X. Guo; J.E. Jakes; S. Banna; Y. Nishi; J.L. Shohet

2014-01-01

The effects of plasma exposure and vacuum-ultraviolet (VUV) irradiation on the mechanical properties of low-k porous organosilicate glass (SiCOH) dielectric films were investigated. Nanoindentation measurements were made on SiCOH films before and after exposure to an electron-cyclotron-resonance plasma or a monochromatic synchrotron VUV beam, to determine the changes...

Development of a liquid tin microjet target for an efficient laser-produced plasma extreme ultraviolet source.

PubMed

Higashiguchi, Takeshi; Hamada, Masaya; Kubodera, Shoichi

2007-03-01

A regenerative tin liquid microjet target was developed for a high average power extreme ultraviolet (EUV) source. The diameter of the target was smaller than 160 microm and good vacuum lower than 0.5 Pa was maintained during the operation. A maximum EUV conversion efficiency of 1.8% at the Nd:yttrium-aluminum-garnet laser intensity of around 2 x 10(11) Wcm(2) with a spot diameter of 175 microm (full width at half maximum) was observed. The angular distribution of the EUV emission remained almost isotropic, whereas suprathermal ions mainly emerged toward the target normal.

Development of a liquid tin microjet target for an efficient laser-produced plasma extreme ultraviolet source

NASA Astrophysics Data System (ADS)

Higashiguchi, Takeshi; Hamada, Masaya; Kubodera, Shoichi

2007-03-01

A regenerative tin liquid microjet target was developed for a high average power extreme ultraviolet (EUV) source. The diameter of the target was smaller than 160 μm and good vacuum lower than 0.5 Pa was maintained during the operation. A maximum EUV conversion efficiency of 1.8% at the Nd:yttrium-aluminum-garnet laser intensity of around 2×1011 W/cm2 with a spot diameter of 175 μm (full width at half maximum) was observed. The angular distribution of the EUV emission remained almost isotropic, whereas suprathermal ions mainly emerged toward the target normal.

Facility and Methods Developed for Simulated Space Vacuum Ultraviolet Exposure Testing of Polymer Films

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Pietromica, Anthony J.; Stueber, Thomas J.; Sechkar, Edward A.; Messer, Russell K.

2002-01-01

Vacuum ultraviolet (VUV) radiation of wavelengths between 115 and 200 nm produced by the Sun in the space environment can degrade polymer films, producing changes in their optical, mechanical, and chemical properties. These effects are particularly important for thin polymer films being considered for ultralightweight space structures, because, for most polymers, VUV radiation is absorbed in a thin surface layer. The NASA Glenn Research Center has developed facilities and methods for long-term ground testing of polymer films to evaluate space environmental VUV radiation effects. VUV exposure can also be used as part of combined or sequential simulated space environmental exposures to determine combined damaging effects with other aspects of the space environment, which include solar ultraviolet radiation, solar flare x-rays, electron and proton radiation, atomic oxygen (for low-Earth-orbit missions), and temperature effects. Because the wavelength sensitivity of VUV damage is not well known for most materials, Glenn's VUV facility uses a broad-spectrum deuterium lamp with a magnesium fluoride window that provides output between 115 and 200 nm. Deuterium lamps of this type were characterized by the National Institute of Standards and Technology and through measurements at Glenn. Spectral irradiance measurements show that from approximately 115 to 160 nm, deuterium lamp irradiance can be many times that of air mass zero solar irradiance, and as wavelength increases above approximately 160 nm, deuterium lamp irradiance decreases in comparison to the Sun. The facility is a cryopumped vacuum chamber that achieves a system pressure of approximately 5310(exp -6) torr. It contains four individual VUV-exposure compartments in vacuum, separated by water-cooled copper walls to minimize VUV radiation and any sample contamination cross interactions between compartments. Each VUV-exposure compartment contains a VUV deuterium lamp, a motor-controlled sample stage coupled with a

Is vacuum ultraviolet detector a concentration or a mass dependent detector?

PubMed

Liu, Huian; Raffin, Guy; Trutt, Guillaume; Randon, Jérôme

2017-12-29

The vacuum ultraviolet detector (VUV) is a very effective tool for chromatogram deconvolution and peak identification, and can also be used for quantification. To avoid quantitative issues in relation to time drift, such as variation of peak area or peak height, the detector response type has to be well defined. Due to the make-up flow and pressure regulation of make-up, the detector response (height of the peak) and peak area appeared to be dependent on experimental conditions such as inlet pressure and make-up pressure. Even if for some experimental conditions, VUV looks like mass-flow sensitive detector, it has been demonstrated that VUV is a concentration sensitive detector. Copyright © 2017 Elsevier B.V. All rights reserved.

Measurements of the intrinsic quantum efficiency and absorption length of tetraphenyl butadiene thin films in the vacuum ultraviolet regime

NASA Astrophysics Data System (ADS)

Benson, Christopher; Gann, Gabriel Orebi; Gehman, Victor

2018-04-01

A key enabling technology for many liquid noble gas (LNG) detectors is the use of the common wavelength shifting medium tetraphenyl butadiene (TPB). TPB thin films are used to shift ultraviolet scintillation light into the visible spectrum for detection and event reconstruction. Understanding the wavelength shifting efficiency and optical properties of these films are critical aspects in detector performance and modeling and hence in the ultimate physics sensitivity of such experiments. This article presents the first measurements of the room-temperature microphysical quantum efficiency for vacuum-deposited TPB thin films - a result that is independent of the optics of the TPB or substrate. Also presented are measurements of the absorption length in the vacuum ultraviolet regime, the secondary re-emission efficiency, and more precise results for the "black-box" efficiency across a broader spectrum of wavelengths than previous results. The low-wavelength sensitivity, in particular, would allow construction of LNG scintillator detectors with lighter elements (Ne, He) to target light mass WIMPs.

A review of vacuum ARC ion source research at ANSTO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, P.J.; Noorman, J.T.; Watt, G.C.

1996-08-01

The authors talk briefly describes the history and current status of vacuum arc ion source research at the Australian Nuclear Science and Technology Organization (ANSTO). In addition, the author makes some mention of the important role of previous Vacuum Arc Ion Source Workshops in fostering the development of this research field internationally. During the period 1986 - 89, a type of plasma centrifuge known as a vacuum arc centrifuge was developed at ANSTO as part of a research project on stable isotope separation. In this device, a high current vacuum arc discharge was used to produce a metal plasma whichmore » was subsequently rotated in an axial magnetic field. The high rotational speeds (10{sup 5} - 10{sup 6} rad sec{sup {minus}1}) achievable with this method produce centrifugal separation of ions with different mass:charge ratios such as isotopic species. The first portent of things to come occurred in 1985 when Dr. Ian Brown visited ANSTO`s Lucas Heights Research Laboratories and presented a talk on the metal vapour vacuum arc (MEVVA) ion source which had only recently been invented by Brown and co-workers, J. Galvin and R. MacGill, at Lawrence Berkeley Laboratory. For those of us involved in vacuum arc centrifuge research, this was an exciting development primarily because the metal vapour vacuum arc plasma source was common to both devices. Thus, a type of arc, which had since the 1930`s been extensively investigated as a means of switching high current loads, had found wider application as a useful plasma source.« less

Vacuum ultraviolet photoabsorption of prime ice analogues of Pluto and Charon

NASA Astrophysics Data System (ADS)

Pavithraa, S.; Lo, J.-I.; Rahul, K.; Raja Sekhar, B. N.; Cheng, B.-M.; Mason, N. J.; Sivaraman, B.

2018-02-01

Here we present the first Vacuum UltraViolet (VUV) photoabsorption spectra of ice analogues of Pluto and Charon ice mixtures. For Pluto the ice analogue is an icy mixture containing nitrogen (N2), carbon monoxide (CO), methane (CH4) and water (H2O) prepared with a 100:1:1:3 ratio, respectively. Photoabsorption of icy mixtures with and without H2O were recorded and no significant changes in the spectra due to presence of H2O were observed. For Charon a VUV photoabsorption spectra of an ice analogue containing ammonia (NH3) and H2O prepared with a 1:1 ratio was recorded, a spectrum of ammonium hydroxide (NH4OH) was also recorded. These spectra may help to interpret the P-Alice data from New Horizons.

Extreme ultraviolet (EUV) and FUV calibration facility for special sensor ultraviolet limb imager (SSULI)

NASA Astrophysics Data System (ADS)

Boyer, Craig N.; Osterman, Steven N.; Thonnard, Stefan E.; McCoy, Robert P.; Williams, J. Z.; Parker, S. E.

1994-09-01

A facility for calibrating far ultraviolet and extreme ultraviolet instruments has recently been completed at the Naval Research Laboratory. Our vacuum calibration vessel is 2-m in length, 1.67-m in diameter, and can accommodate optical test benches up to 1.2-m wide by 1.5-m in length. A kinematically positioned frame with four axis precision pointing capability of 10 microns for linear translation and .01 degrees for rotation is presently used during vacuum optical calibration of SSULI. The chamber was fabricated from 304 stainless steel and polished internally to reduce surface outgassing. A dust-free environment is maintained at the rear of the vacuum chamber by enclosing the 2-m hinged vacuum access door in an 8 ft. by 8 ft. class 100 clean room. Every effort was made to obtain an oil-free environment within the vacuum vessel. Outgassing products are continually monitored with a 1 - 200 amu residual gas analyzer. An oil-free claw and vane pump evacuates the chamber to 10-2 torr through 4 in. diameter stainless steel roughing lines. High vacuum is achieved and maintained with a magnetically levitated 480 l/s turbo pump and a 3000 l/s He4 cryopump. Either of two vacuum monochrometers, a 1-m f/10.4 or a 0.2-m f/4.5 are coaxially aligned with the optical axis of the chamber and are used to select single UV atomic resonance lines from a windowless capillary or penning discharge UV light source. A calibrated channeltron detector is coaxially mounted with the SSULI detector during calibration. All vacuum valves, the cooling system for the cryopump compressor, and the roughing pump are controlled through optical fibers which are interfaced to a computer through a VME board. Optical fibers were chosen to ensure that complete electrical isolation is maintained between the computer and the vacuum system valves-solenoids and relays.

Vacuum ultraviolet photoionization of carbohydrates and nucleotides

NASA Astrophysics Data System (ADS)

Shin, Joong-Won; Bernstein, Elliot R.

2014-01-01

Carbohydrates (2-deoxyribose, ribose, and xylose) and nucleotides (adenosine-, cytidine-, guanosine-, and uridine-5'-monophosphate) are generated in the gas phase, and ionized with vacuum ultraviolet photons (VUV, 118.2 nm). The observed time of flight mass spectra of the carbohydrate fragmentation are similar to those observed [J.-W. Shin, F. Dong, M. Grisham, J. J. Rocca, and E. R. Bernstein, Chem. Phys. Lett. 506, 161 (2011)] for 46.9 nm photon ionization, but with more intensity in higher mass fragment ions. The tendency of carbohydrate ions to fragment extensively following ionization seemingly suggests that nucleic acids might undergo radiation damage as a result of carbohydrate, rather than nucleobase fragmentation. VUV photoionization of nucleotides (monophosphate-carbohydrate-nucleobase), however, shows that the carbohydrate-nucleobase bond is the primary fragmentation site for these species. Density functional theory (DFT) calculations indicate that the removed carbohydrate electrons by the 118.2 nm photons are associated with endocyclic C-C and C-O ring centered orbitals: loss of electron density in the ring bonds of the nascent ion can thus account for the observed fragmentation patterns following carbohydrate ionization. DFT calculations also indicate that electrons removed from nucleotides under these same conditions are associated with orbitals involved with the nucleobase-saccharide linkage electron density. The calculations give a general mechanism and explanation of the experimental results.

Vacuum ultraviolet photoionization of carbohydrates and nucleotides.

PubMed

Shin, Joong-Won; Bernstein, Elliot R

2014-01-28

Carbohydrates (2-deoxyribose, ribose, and xylose) and nucleotides (adenosine-, cytidine-, guanosine-, and uridine-5(')-monophosphate) are generated in the gas phase, and ionized with vacuum ultraviolet photons (VUV, 118.2 nm). The observed time of flight mass spectra of the carbohydrate fragmentation are similar to those observed [J.-W. Shin, F. Dong, M. Grisham, J. J. Rocca, and E. R. Bernstein, Chem. Phys. Lett. 506, 161 (2011)] for 46.9 nm photon ionization, but with more intensity in higher mass fragment ions. The tendency of carbohydrate ions to fragment extensively following ionization seemingly suggests that nucleic acids might undergo radiation damage as a result of carbohydrate, rather than nucleobase fragmentation. VUV photoionization of nucleotides (monophosphate-carbohydrate-nucleobase), however, shows that the carbohydrate-nucleobase bond is the primary fragmentation site for these species. Density functional theory (DFT) calculations indicate that the removed carbohydrate electrons by the 118.2 nm photons are associated with endocyclic C-C and C-O ring centered orbitals: loss of electron density in the ring bonds of the nascent ion can thus account for the observed fragmentation patterns following carbohydrate ionization. DFT calculations also indicate that electrons removed from nucleotides under these same conditions are associated with orbitals involved with the nucleobase-saccharide linkage electron density. The calculations give a general mechanism and explanation of the experimental results.

Vacuum ultraviolet photoionization of carbohydrates and nucleotides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shin, Joong-Won, E-mail: jshin@govst.edu; Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872; Bernstein, Elliot R., E-mail: erb@lamar.colostate.edu

Carbohydrates (2-deoxyribose, ribose, and xylose) and nucleotides (adenosine-, cytidine-, guanosine-, and uridine-5{sup ′}-monophosphate) are generated in the gas phase, and ionized with vacuum ultraviolet photons (VUV, 118.2 nm). The observed time of flight mass spectra of the carbohydrate fragmentation are similar to those observed [J.-W. Shin, F. Dong, M. Grisham, J. J. Rocca, and E. R. Bernstein, Chem. Phys. Lett. 506, 161 (2011)] for 46.9 nm photon ionization, but with more intensity in higher mass fragment ions. The tendency of carbohydrate ions to fragment extensively following ionization seemingly suggests that nucleic acids might undergo radiation damage as a result of carbohydrate,more » rather than nucleobase fragmentation. VUV photoionization of nucleotides (monophosphate-carbohydrate-nucleobase), however, shows that the carbohydrate-nucleobase bond is the primary fragmentation site for these species. Density functional theory (DFT) calculations indicate that the removed carbohydrate electrons by the 118.2 nm photons are associated with endocyclic C–C and C–O ring centered orbitals: loss of electron density in the ring bonds of the nascent ion can thus account for the observed fragmentation patterns following carbohydrate ionization. DFT calculations also indicate that electrons removed from nucleotides under these same conditions are associated with orbitals involved with the nucleobase-saccharide linkage electron density. The calculations give a general mechanism and explanation of the experimental results.« less

Steady-State Vacuum Ultraviolet Exposure Facility With Automated Lamp Calibration and Sample Positioning Fabricated

NASA Technical Reports Server (NTRS)

Sechkar, Edward A.; Steuber, Thomas J.; Banks, Bruce A.; Dever, Joyce A.

2000-01-01

The Next Generation Space Telescope (NGST) will be placed in an orbit that will subject it to constant solar radiation during its planned 10-year mission. A sunshield will be necessary to passively cool the telescope, protecting it from the Sun s energy and assuring proper operating temperatures for the telescope s instruments. This sunshield will be composed of metalized polymer multilayer insulation with an outer polymer membrane (12 to 25 mm in thickness) that will be metalized on the back to assure maximum reflectance of sunlight. The sunshield must maintain mechanical integrity and optical properties for the full 10 years. This durability requirement is most challenging for the outermost, constantly solar-facing polymer membrane of the sunshield. One of the potential threats to the membrane material s durability is from vacuum ultraviolet (VUV) radiation in wavelengths below 200 nm. Such radiation can be absorbed in the bulk of these thin polymer membrane materials and degrade the polymer s optical and mechanical properties. So that a suitable membrane material can be selected that demonstrates durability to solar VUV radiation, ground-based testing of candidate materials must be conducted to simulate the total 10- year VUV exposure expected during the Next Generation Space Telescope mission. The Steady State Vacuum Ultraviolet exposure facility was designed and fabricated at the NASA Glenn Research Center at Lewis Field to provide unattended 24-hr exposure of candidate materials to VUV radiation of 3 to 5 times the Sun s intensity in the wavelength range of 115 to 200 nm. The facility s chamber, which maintains a pressure of approximately 5 10(exp -6) torr, is divided into three individual exposure cells, each with a separate VUV source and sample-positioning mechanism. The three test cells are separated by a water-cooled copper shield plate assembly to minimize thermal effects from adjacent test cells. Part of the interior sample positioning mechanism of one

Solar CIV Vacuum-Ultraviolet Fabry-Perot Interferometers

NASA Technical Reports Server (NTRS)

Gary, G. Allen; West, Edward A.; Rees, David; McKay, Jack A.; Zukic, Maumer; Herman, Peter

2006-01-01

Aims: A tunable, high spectral resolution, high effective finesse, vacuum ultraviolet (VUV) Fabry-Perot interferometer (PPI) is designed for obtaining narrow-passband images, magnetograms, and Dopplergrams of the transition region emission line of CIV (155 nm). Methods: The integral part of the CIV narrow passband filter package (with a 2-10 pm FWHM) consists of a multiple etalon system composed of a tunable interferometer that provides high-spectral resolution and a static low-spectral resolution interferometer that allows a large effective free spectral range. The prefilter for the interferometers is provided by a set of four mirrors with dielectric high-reflective coatings. A tunable interferometer, a VUV piezoelectric-control etalon, has undergone testing using the surrogate F2 eximer laser line at 157 nm for the CIV line. We present the results of the tests with a description of the overall concept for a complete narrow-band CIV spectral filter. The static interferometer of the filter is envisioned as being hudt using a set of fixed MgF2 plates. The four-mirror prefilter is designed to have dielectric multilayer n-stacks employing the design concept used in the Ultraviolet Imager of NASA's Polar Spacecraft. A dual etalon system allows the effective free spectral range to be commensurate with the prefilter profile. With an additional etalon, a triple etalon system would allow a spectrographic resolution of 2 pm. The basic strategy has been to combine the expertise of spaceflight etalon manufacturing with VUV coating technology to build a VUV FPI which combines the best attributes of imagers and spectrographs into a single compact instrument. Results. Spectro-polarimetry observations of the transition region CIV emission can be performed to increase the understanding of the magnetic forces, mass motion, evolution, and energy release within the solar atmosphere at the base of the corona where most of the magnetic field is approximately force-free. The 2D imaging

Devices useful for vacuum ultraviolet beam characterization including a movable stage with a transmission grating and image detector

DOEpatents

Gessner, Oliver; Kornilov, Oleg A; Wilcox, Russell B

2013-10-29

The invention provides for a device comprising an apparatus comprising (a) a transmission grating capable of diffracting a photon beam into a diffracted photon output, and (b) an image detector capable of detecting the diffracted photon output. The device is useful for measuring the spatial profile and diffraction pattern of a photon beam, such as a vacuum ultraviolet (VUV) beam.

Luminescence from Vacuum-Ultraviolet-Irradiated Cosmic Ice Analogs and Residue

NASA Technical Reports Server (NTRS)

Gudipati, Murthy S.; Dworkin, Jason P.; Chillier, Xavier D. F.; Allamandola, Louis J.

2003-01-01

Here we report a study of the optical luminescent properties for a variety of vacuum-ultraviolet (VUV)-irradiated cosmic ice analogs and the complex organic residues produced. Detailed results are presented for the irradiated, mixed molecular ice: H2O: CH3OH:NH3:CO(100:50:1:1), a realistic representation for an interstellar/precometary ice that reproduces all the salient infrared spectral features associated with interstellar ices. The irradiated ices and the room-temperature residues resulting from this energetic processing have remarkable photoluminescent properties in the visible (520-570 nm). The luminescence dependence on temperature, thermal cycling, and VUV exposure is described. It is suggested that this type of luminescent behavior might be applicable to solar system and interstellar observations and processes for various astronomical objects with an ice heritage. Some examples include grain temperature determination and vaporization rates, nebula radiation balance, albedo values, color analysis, and biomarker identification.

Luminescence from Vacuum-Ultraviolet-Irradiated Cosmic Ice Analogs and Residues

NASA Technical Reports Server (NTRS)

Gudipati, Murthy S.; Dworkin, Jason P.; Chillier, Xavier D. F.; Allamandola, Louis J.

2003-01-01

Here we report a study of the optical luminescent properties for a variety of vacuum-ultraviolet (VUV)- irradiated cosmic ice analogs and the complex organic residues produced. Detailed results are presented for the irradiated, mixed molecular ice: H2O:CH3OH:NH3:CO (100:50:1:1), a realistic representation for an interstellar/precometary ice that reproduces all the salient infrared spectral features associated with interstellar ices. The irradiated ices and the room-temperature residues resulting from this energetic processing have remarkable photoluminescent properties in the visible (520-570 nm). The luminescence dependence on temperature, thermal cycling, and VUV exposure is described. It is suggested that this type of luminescent behavior might be applicable to solar system and interstellar observations and processes for various astronomical objects with an ice heritage. Some examples include grain temperature determination and vaporization rates, nebula radiation balance, albedo values, color analysis, and biomarker identification.

Vacuum ultraviolet photoabsorption of prime ice analogues of Pluto and Charon.

PubMed

Pavithraa, S; Lo, J-I; Rahul, K; Raja Sekhar, B N; Cheng, B-M; Mason, N J; Sivaraman, B

2018-02-05

Here we present the first Vacuum UltraViolet (VUV) photoabsorption spectra of ice analogues of Pluto and Charon ice mixtures. For Pluto the ice analogue is an icy mixture containing nitrogen (N 2 ), carbon monoxide (CO), methane (CH 4 ) and water (H 2 O) prepared with a 100:1:1:3 ratio, respectively. Photoabsorption of icy mixtures with and without H 2 O were recorded and no significant changes in the spectra due to presence of H 2 O were observed. For Charon a VUV photoabsorption spectra of an ice analogue containing ammonia (NH 3 ) and H 2 O prepared with a 1:1 ratio was recorded, a spectrum of ammonium hydroxide (NH 4 OH) was also recorded. These spectra may help to interpret the P-Alice data from New Horizons. Copyright © 2017 Elsevier B.V. All rights reserved.

Exploiting single photon vacuum ultraviolet photoionization to unravel the synthesis of complex organic molecules in interstellar ices

NASA Astrophysics Data System (ADS)

Abplanalp, Matthew J.; Förstel, Marko; Kaiser, Ralf I.

2016-01-01

Complex organic molecules (COM) such as aldehydes, ketones, carboxylic acids, esters, and amides are ubiquitous in the interstellar medium, but traditional gas phase astrochemical models cannot explain their formation routes. By systematically exploiting on line and in situ vacuum ultraviolet photoionization coupled with reflectron time of flight mass spectrometry (PI-ReTOF-MS) and combining these data with infrared spectroscopy (FTIR), we reveal that complex organic molecules can be synthesized within interstellar ices that are condensed on interstellar grains via non-equilibrium reactions involving suprathermal hydrogen atoms at temperatures as low as 5 K. By probing for the first time specific structural isomers without their degradation (fragment-free), the incorporation of tunable vacuum ultraviolet photoionization allows for a much greater understanding of reaction mechanisms that exist in interstellar ices compared to traditional methods, thus eliminating the significant gap between observational and laboratory data that existed for the last decades. With the commission of the Atacama Large Millimeter/Submillimeter Array (ALMA), the number of detections of more complex organic molecules in space will continue to grow ⿿ including biorelevant molecules connected to the Origins of Life theme ⿿ and an understanding of these data will rely on future advances in sophisticated physical chemistry laboratory experiments.

Evaluation of miniature vacuum ultraviolet lamps for stability and operating characteristics, Lyman-Alpha task

NASA Technical Reports Server (NTRS)

Hurd, W. A.

1985-01-01

Modifications required to change the near ultraviolet source in the Optical Contamination Monitor to a source with output at or near the Lyman-Alpha hydrogen line are discussed. The effort consisted of selecting, acquiring and testing candidate miniature ultraviolet lamps with significant output in or near 121.6 nm. The effort also included selection of a miniature dc high-voltage power supply capable of operating the lamp. The power supply was required to operate from available primary power supplied by the Optical Effect Module (DEM) and it should be flight qualified or have the ability to be qualified by the user.

Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

NASA Technical Reports Server (NTRS)

Meyer, Scott Andrew

1995-01-01

The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3 x 10(exp 17) and 9 x 10(exp 17)/cu cm. The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

NASA Technical Reports Server (NTRS)

Meyer, Scott Andrew

1995-01-01

The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3x10(exp 17) and 9x10(exp 17) cm(exp -3). The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

NASA Technical Reports Server (NTRS)

Meyer, Scott Andrew

1995-01-01

The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3 x 10(exp 17) and 9 x 10(exp 17) cm(exp -3). The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

International Test Program for Synergistic Atomic Oxygen and Vacuum Ultraviolet Radiation Exposure of Spacecraft Materials

NASA Technical Reports Server (NTRS)

Miller, Sharon K.

2001-01-01

The components and materials of spacecraft in low Earth orbit can degrade in thermal and optical performance through interaction with atomic oxygen and vacuum ultraviolet (VUV) radiation, which are predominant in low Earth orbit. Because of the importance of low Earth orbit durability and performance to manufacturers and users, an international test program for assessing the durability of spacecraft materials and components was initiated. Initial tests at the NASA Glenn Research Center consisted of exposure of samples representing a variety of thermal control paints, multilayer insulation materials, and Sun sensors that have been used in space. Materials donated from various international sources were tested alongside materials whose performance is well known, such as Teflon FEP, Kapton H, or Z-93-P white paint. The optical, thermal, or mass loss data generated during the tests were then provided to the participating material suppliers. Data were not published unless the participant donating the material consented to publication. The test program is intended to give spacecraft builders and users a better understanding of degradation processes and effects so that they can improve their predictions of spacecraft performance.

Polarization selection rules and optical transitions in terbium activated yttrium tantalate phosphor under x-ray, vacuum-ultraviolet, and ultraviolet excitations.

PubMed

Nazarov, Mihail; Tsukerblat, Boris; Byeon, Clare Chisu; Arellano, Ivan; Popovici, Elisabeth-Jeanne; Noh, Do Young

2009-01-01

The terbium-activated yttrium tantalite (YTaO(4):Tb(3+)) phosphor is of great interest due to the interesting spectroscopic properties of rare earth ions in crystals and also practical use in x-ray imaging. Using the group-theoretical approach, we analyze the selection rules for the transition between Stark components of Tb(3+) in symmetry of the actual crystal field and the polarization for the allowed transitions. The luminescence upon UV, vacuum-ultraviolet (VUV), and x-ray excitation is presented and discussed. The YTaO(4):Tb(3+) phosphors are found to be efficient VUV-excited luminescent materials that could be used not only in x-ray intensifying screens, but also in mercury-free fluorescent lamps or plasma display panels.

A squeezed light source operated under high vacuum

PubMed Central

Wade, Andrew R.; Mansell, Georgia L.; Chua, Sheon S. Y.; Ward, Robert L.; Slagmolen, Bram J. J.; Shaddock, Daniel A.; McClelland, David E.

2015-01-01

Non-classical squeezed states of light are becoming increasingly important to a range of metrology and other quantum optics applications in cryptography, quantum computation and biophysics. Applications such as improving the sensitivity of advanced gravitational wave detectors and the development of space-based metrology and quantum networks will require robust deployable vacuum-compatible sources. To date non-linear photonics devices operated under high vacuum have been simple single pass systems, testing harmonic generation and the production of classically correlated photon pairs for space-based applications. Here we demonstrate the production under high-vacuum conditions of non-classical squeezed light with an observed 8.6 dB of quantum noise reduction down to 10 Hz. Demonstration of a resonant non-linear optical device, for the generation of squeezed light under vacuum, paves the way to fully exploit the advantages of in-vacuum operations, adapting this technology for deployment into new extreme environments. PMID:26657616

A squeezed light source operated under high vacuum

NASA Astrophysics Data System (ADS)

Wade, Andrew R.; Mansell, Georgia L.; Chua, Sheon S. Y.; Ward, Robert L.; Slagmolen, Bram J. J.; Shaddock, Daniel A.; McClelland, David E.

2015-12-01

Non-classical squeezed states of light are becoming increasingly important to a range of metrology and other quantum optics applications in cryptography, quantum computation and biophysics. Applications such as improving the sensitivity of advanced gravitational wave detectors and the development of space-based metrology and quantum networks will require robust deployable vacuum-compatible sources. To date non-linear photonics devices operated under high vacuum have been simple single pass systems, testing harmonic generation and the production of classically correlated photon pairs for space-based applications. Here we demonstrate the production under high-vacuum conditions of non-classical squeezed light with an observed 8.6 dB of quantum noise reduction down to 10 Hz. Demonstration of a resonant non-linear optical device, for the generation of squeezed light under vacuum, paves the way to fully exploit the advantages of in-vacuum operations, adapting this technology for deployment into new extreme environments.

High-Reflectivity Coatings for a Vacuum Ultraviolet Spectropolarimeter

NASA Astrophysics Data System (ADS)

Narukage, Noriyuki; Kubo, Masahito; Ishikawa, Ryohko; Ishikawa, Shin-nosuke; Katsukawa, Yukio; Kobiki, Toshihiko; Giono, Gabriel; Kano, Ryouhei; Bando, Takamasa; Tsuneta, Saku; Auchère, Frédéric; Kobayashi, Ken; Winebarger, Amy; McCandless, Jim; Chen, Jianrong; Choi, Joanne

2017-03-01

Precise polarization measurements in the vacuum ultraviolet (VUV) region are expected to be a new tool for inferring the magnetic fields in the upper atmosphere of the Sun. High-reflectivity coatings are key elements to achieving high-throughput optics for precise polarization measurements. We fabricated three types of high-reflectivity coatings for a solar spectropolarimeter in the hydrogen Lyman-α (Lyα; 121.567 nm) region and evaluated their performance. The first high-reflectivity mirror coating offers a reflectivity of more than 80 % in Lyα optics. The second is a reflective narrow-band filter coating that has a peak reflectivity of 57 % in Lyα, whereas its reflectivity in the visible light range is lower than 1/10 of the peak reflectivity (˜ 5 % on average). This coating can be used to easily realize a visible light rejection system, which is indispensable for a solar telescope, while maintaining high throughput in the Lyα line. The third is a high-efficiency reflective polarizing coating that almost exclusively reflects an s-polarized beam at its Brewster angle of 68° with a reflectivity of 55 %. This coating achieves both high polarizing power and high throughput. These coatings contributed to the high-throughput solar VUV spectropolarimeter called the Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP), which was launched on 3 September, 2015.

Dissociative excitation of vacuum ultraviolet emission features by electron impact on molecular gases. 3: CO2

NASA Technical Reports Server (NTRS)

Mumma, M. J.; Borst, W. L.; Zipf, E. C.

1972-01-01

Vacuum ultraviolet multiplets of C I, C II, and O I were produced by electron impact of CO2. Absolute emission cross sections for these multiplets were measured from threshold to 350 eV. The electrostatically focussed electron gun used in this series of experiments is described in detail. The atomic multiplets which were produced by dissociative excitation of CO2 and the cross sections at 100 eV are given. The dependence of the excitation functions on electron energy shows that these multiplets are produced by electric-dipole-allowed transitions in CO2.

Vacuum simulation and characterization for the Linac4 H- source

NASA Astrophysics Data System (ADS)

Pasquino, C.; Chiggiato, P.; Michet, A.; Hansen, J.; Lettry, J.

2013-02-01

At CERN, the 160 MeV H- Linac4 will soon replace the 50 MeV proton Linac2. In the H- source two major sources of gas are identified. The first is the pulsed injection at about 0.1 mbar in the plasma chamber. The second is the constant H2 injection up to 10-5 mbar in the LEBT for beam space charge compensation. In addition, the outgassing of materials exposed to vacuum can play an important role in contamination control and global gas balance. To evaluate the time dependent partial pressure profiles in the H- ion source and the RFQ, electrical network - vacuum analogy and test particle Monte Carlo simulation have been used. The simulation outcome indicates that the pressure requirements are in the reach of the proposed vacuum pumping system. Preliminary results show good agreement between the experimental and the simulated pressure profiles; a calibration campaign is in progress to fully benchmark the implemented calculations. Systematic outgassing rate measurements are on-going for critical components in the ion source and RFQ. Amongst them those for the Cu-coated SmCo magnet located in the vacuum system of the biased electron dump electrode, show results lower to stainless steel at room temperature.

Two-dimensional vacuum ultraviolet images in different MHD events on the EAST tokamak

NASA Astrophysics Data System (ADS)

Zhijun, WANG; Xiang, GAO; Tingfeng, MING; Yumin, WANG; Fan, ZHOU; Feifei, LONG; Qing, ZHUANG; EAST Team

2018-02-01

A high-speed vacuum ultraviolet (VUV) imaging telescope system has been developed to measure the edge plasma emission (including the pedestal region) in the Experimental Advanced Superconducting Tokamak (EAST). The key optics of the high-speed VUV imaging system consists of three parts: an inverse Schwarzschild-type telescope, a micro-channel plate (MCP) and a visible imaging high-speed camera. The VUV imaging system has been operated routinely in the 2016 EAST experiment campaign. The dynamics of the two-dimensional (2D) images of magnetohydrodynamic (MHD) instabilities, such as edge localized modes (ELMs), tearing-like modes and disruptions, have been observed using this system. The related VUV images are presented in this paper, and it indicates the VUV imaging system is a potential tool which can be applied successfully in various plasma conditions.

Gage measures total radiation, including vacuum UV, from ionized high-temperature gases

NASA Technical Reports Server (NTRS)

Wood, A. D.

1969-01-01

Transient-heat transfer gage measures the total radiation intensity from vacuum ultraviolet and ionized high temperature gases. The gage includes a sensitive piezoelectric crystal that is completely isolated from any ionized flow and vacuum ultraviolet irradiation.

Vacuum Ultraviolet Radiation and Atomic Oxygen Durability Evaluation of HST Bi-Stem Thermal Shield Materials

NASA Technical Reports Server (NTRS)

Dever, Joyce; deGroh, Kim K.

2002-01-01

Bellows-type thermal shields were used on the bi-stems of replacement solar arrays installed on the Hubble Space Telescope (HST) during the first HST servicing mission (SMI) in December 1993. These thermal shields helped reduce the problem of thermal gradient- induced jitter observed with the original HST solar arrays during orbital thermal cycling and have been in use on HST for eight years. This paper describes ground testing of the candidate solar array bi-stem thermal shield materials including backside aluminized Teflon(R)FEP (fluorinated ethylene propylene) with and without atomic oxygen (AO) and ultraviolet radiation protective surface coatings for durability to AO and combined AO and vacuum ultraviolet (VOV) radiation. NASA Glenn Research Center (GRC) conducted VUV and AO exposures of samples of candidate thermal shield materials at HST operational temperatures and pre- and post-exposure analyses as part of an overall program coordinated by NASA Goddard Space Flight Center (GSFC) to determine the on-orbit durability of these materials. Coating adhesion problems were observed for samples having the AO- and combined AO/UV-protective coatings. Coating lamination occurred with rapid thermal cycling testing which simulated orbital thermal cycling. This lack of adhesion caused production of coating flakes from the material that would have posed a serious risk to HST optics if the coated materials were used for the bi-stem thermal shields. No serious degradation was observed for the uncoated aluminized Teflon(R) as evaluated by optical microscopy, although atomic force microscopy (AFM) microhardness testing revealed that an embrittled surface layer formed on the uncoated Teflon(R) surface due to vacuum ultraviolet radiation exposure. This embrittled layer was not completely removed by AO erosion, No cracks or particle flakes were produced for the embrittled uncoated material upon exposure to VUV and AO at operational temperatures to an equivalent exposure of

Test of prototype ITER vacuum ultraviolet spectrometer and its application to impurity study in KSTAR plasmas.

PubMed

Seon, C R; Hong, J H; Jang, J; Lee, S H; Choe, W; Lee, H H; Cheon, M S; Pak, S; Lee, H G; Biel, W; Barnsley, R

2014-11-01

To optimize the design of ITER vacuum ultraviolet (VUV) spectrometer, a prototype VUV spectrometer was developed. The sensitivity calibration curve of the spectrometer was calculated from the mirror reflectivity, the grating efficiency, and the detector efficiency. The calibration curve was consistent with the calibration points derived in the experiment using the calibrated hollow cathode lamp. For the application of the prototype ITER VUV spectrometer, the prototype spectrometer was installed at KSTAR, and various impurity emission lines could be measured. By analyzing about 100 shots, strong positive correlation between the O VI and the C IV emission intensities could be found.

A vacuum spark ion source: High charge state metal ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yushkov, G. Yu., E-mail: gyushkov@mail.ru; Nikolaev, A. G.; Frolova, V. P.

2016-02-15

High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less thanmore » 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.« less

Resonantly enhanced method for generation of tunable, coherent vacuum ultraviolet radiation

DOEpatents

Glownia, James H.; Sander, Robert K.

1985-01-01

Carbon Monoxide vapor is used to generate coherent, tunable vacuum ultraviolet radiation by third-harmonic generation using a single tunable dye laser. The presence of a nearby electronic level resonantly enhances the nonlinear susceptibility of this molecule allowing efficient generation of the vuv light at modest pump laser intensities, thereby reducing the importance of a six-photon multiple-photon ionization process which is also resonantly enhanced by the same electronic level but to higher order. By choosing the pump radiation wavelength to be of shorter wavelength than individual vibronic levels used to extend tunability stepwise from 154.4 to 124.6 nm, and the intensity to be low enough, multiple-photon ionization can be eliminated. Excitation spectra of the third-harmonic emission output exhibit shifts to shorter wavelength and broadening with increasing CO pressure due to phase matching effects. Increasing the carbon monoxide pressure, therefore, allows the substantial filling in of gaps arising from the stepwise tuning thereby providing almost continuous tunability over the quoted range of wavelength emitted.

Resonantly enhanced method for generation of tunable, coherent vacuum-ultraviolet radiation

DOEpatents

Glownia, J.H.; Sander, R.K.

1982-06-29

Carbon Monoxide vapor is used to generate coherent, tunable vacuum ultraviolet radiation by third-harmonic generation using a single tunable dye laser. The presence of a nearby electronic level resonantly enhances the nonlinear susceptibility of this molecule allowing efficient generation of the vuv light at modest pump laser intensities, thereby reducing the importance of a six-photon multiple-photon ionization process which is also resonantly enhanced by the same electronic level but no higher order. By choosing the pump radiation wavelength to be of shorter wavelength than individual vibronic levels used to extend tunability stepwise from 154.4 to 124.6 nm, and the intensity to be low enough, multiple-photon ionization can be eliminated. Excitation spectra of the third-harmonic emission output exhibit shifts to shorter wavelength and broadening with increasing CO pressure due to phase matching effects. Increasing the carbon monoxide pressure, therefore, allows the substantial filling in of gaps arising from the stepwise tuning thereby providing almost continuous tunability over the quoted range of wavelength emitted.

Ultra-fast switching of light by absorption saturation in vacuum ultra-violet region.

PubMed

Yoneda, Hitoki; Inubushi, Yuichi; Tanaka, Toshihiro; Yamaguchi, Yuta; Sato, Fumiya; Morimoto, Shunsuke; Kumagai, Taisuke; Nagasono, Mitsuru; Higashiya, Atsushi; Yabashi, Makina; Ishikawa, Tetsuya; Ohashi, Haruhiko; Kimura, Hiroaki; Kitamura, Hikaru; Kodama, Ryosuke

2009-12-21

Advances in free electron lasers producing high energy photons [Nat. Photonics 2(9), 555-559 (2008)] are expected to open up a new science of nonlinear optics of high energy photons. Specifically, lasers of photon energy higher than the plasma frequency of a metal can show new interaction features because they can penetrate deeply into metals without strong reflection. Here we show the observation of ultra-fast switching of vacuum ultra-violet (VUV) light caused by saturable absorption of a solid metal target. A strong gating is observed at energy fluences above 6J/cm2 at wavelength of 51 nm with tin metal thin layers. The ratio of the transmission at high intensity to low intensity is typically greater than 100:1. This means we can design new nonlinear photonic devices such as auto-correlator and pulse slicer for the VUV region.

National Synchrotron Light Source II storage ring vacuum systems

DOE PAGES

Hseuh, Hsiao-Chaun; Hetzel, Charles; Leng, Shuwei; ...

2016-04-05

The National Synchrotron Light Source II, completed in 2014, is a 3-GeV synchrotron radiation (SR) facility at Brookhaven National Laboratory and has been in steady operation since. With a design electron current of 500 mA and subnanometer radians horizontal emittance, this 792-m circumference storage ring is providing the highest flux and brightness x-ray beam for SR users. Also, the majority of the storage ring vacuum chambers are made of extruded aluminium. Chamber sections are interconnected using low-impedance radiofrequency shielded bellows. SR from the bending magnets is intercepted by water-cooled compact photon absorbers resided in the storage ring chambers. Finally, thismore » paper presents the design of the storage ring vacuum system, the fabrication of vacuum chambers and other hardware, the installation, the commissioning, and the continuing beam conditioning of the vacuum systems.« less

National Synchrotron Light Source II storage ring vacuum systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hseuh, Hsiao-Chaun, E-mail: hseuh@bnl.gov; Hetzel, Charles; Leng, Shuwei

2016-05-15

The National Synchrotron Light Source II, completed in 2014, is a 3-GeV synchrotron radiation (SR) facility at Brookhaven National Laboratory and has been in steady operation since. With a design electron current of 500 mA and subnanometer radians horizontal emittance, this 792-m circumference storage ring is providing the highest flux and brightness x-ray beam for SR users. The majority of the storage ring vacuum chambers are made of extruded aluminium. Chamber sections are interconnected using low-impedance radiofrequency shielded bellows. SR from the bending magnets is intercepted by water-cooled compact photon absorbers resided in the storage ring chambers. This paper presents themore » design of the storage ring vacuum system, the fabrication of vacuum chambers and other hardware, the installation, the commissioning, and the continuing beam conditioning of the vacuum systems.« less

Photodissociation dynamics of H2O at 111.5 nm by a vacuum ultraviolet free electron laser

NASA Astrophysics Data System (ADS)

Wang, Heilong; Yu, Yong; Chang, Yao; Su, Shu; Yu, Shengrui; Li, Qinming; Tao, Kai; Ding, Hongli; Yang, Jaiyue; Wang, Guanglei; Che, Li; He, Zhigang; Chen, Zhichao; Wang, Xingan; Zhang, Weiqing; Dai, Dongxu; Wu, Guorong; Yuan, Kaijun; Yang, Xueming

2018-03-01

Photodissociation dynamics of H2O via the F ˜ state at 111.5 nm were investigated using the high resolution H-atom Rydberg "tagging" time-of-flight (TOF) technique, in combination with the tunable vacuum ultraviolet free electron laser at the Dalian Coherent Light Source. The product translational energy distributions and angular distributions in both parallel and perpendicular directions were derived from the recorded TOF spectra. Based on these distributions, the quantum state distributions and angular anisotropy parameters of OH (X) and OH (A) products have been determined. For the OH (A) + H channel, highly rotationally excited OH (A) products have been observed. These products are ascribed to a fast direct dissociation on the B ˜ 1A1 state surface after multi-step internal conversions from the initial excited F ˜ state to the B ˜ state. While for the OH (X) + H channel, very highly rotationally excited OH (X) products with moderate vibrational excitation are revealed and attributed to the dissociation via a nonadiabatic pathway through the well-known two conical intersections between the B ˜ -state and the X ˜ -state surfaces.

Vacuum ultraviolet photoionization mass spectrometric study of cyclohexene.

PubMed

Chen, Jun; Cao, Maoqi; Wei, Bin; Ding, Mengmeng; Shan, Xiaobin; Liu, Fuyi; Sheng, Liusi

2016-02-01

In this work, photoionization and dissociation of cyclohexene have been studied by means of coupling a reflectron time-of-flight mass spectrometer with the tunable vacuum ultraviolet (VUV) synchrotron radiation. The adiabatic ionization energy of cyclohexene as well as the appearance energies of its fragment ions C6 H9 (+) , C6 H7 (+) , C5 H7 (+) , C5 H5 (+) , C4 H6 (+) , C4 H5 (+) , C3 H5 (+) and C3 H3 (+) were derived from the onset of the photoionization efficiency (PIE) curves. The optimized structures for the transition states and intermediates on the ground state potential energy surfaces related to photodissociation of cyclohexene were characterized at the ωB97X-D/6-31+g(d,p) level. The coupled cluster method, CCSD(T)/cc-pVTZ, was employed to calculate the corresponding energies with the zero-point energy corrections by the ωB97X-D/6-31+g(d,p) approach. Combining experimental and theoretical results, possible formation pathways of the fragment ions were proposed and discussed in detail. The retro-Cope rearrangement was found to play a crucial role in the formation of C4 H6 (+) , C4 H5 (+) and C3 H5 (+) . Intramolecular hydrogen migrations were observed as dominant processes in most of the fragmentation pathways of cyclohexene. The present research provides a clear picture of the photoionization and dissociation processes of cyclohexene in the 8- to 15.5-eV photon energy region. Copyright © 2016 John Wiley & Sons, Ltd.

Generation of vacuum ultraviolet radiation by intracavity high-harmonic generation toward state detection of single trapped ions

NASA Astrophysics Data System (ADS)

Wakui, Kentaro; Hayasaka, Kazuhiro; Ido, Tetsuya

2014-12-01

Vacuum ultraviolet (VUV) radiation around 159 nm is obtained toward direct excitation of a single trapped ion. An efficient fluoride-based VUV output coupler is employed for intracavity high-harmonic generation of a Ti:S oscillator. Using this coupler, where we measured its reflectance to be about 90 %, an average power reaching 6.4 W is coupled out from a modest fundamental power of 650 mW. When a single comb component out of 1.9 10 teeth is resonant to the atomic transition, 100s of fluorescence photons per second will be detectable under a realistic condition.

Measurement system to determine the total and angle-resolved light scattering of optical components in the deep-ultraviolet and vacuum-ultraviolet spectral regions

NASA Astrophysics Data System (ADS)

Schröder, Sven; Gliech, Stefan; Duparré, Angela

2005-10-01

An instrumentation for total and angle-resolved scattering (ARS) at 193 and 157 nm has been developed at the Fraunhofer Institute in Jena to meet the severe requirements for scattering analysis of deep- and vacuum-ultraviolet optical components. Extremely low backscattering levels of 10^-6 for the total scattering measurements and more than 9 orders of magnitude dynamic range for ARS have been accomplished. Examples of application extend from the control of at-wavelength scattering losses of superpolished substrates with rms roughness as small as 0.1 nm to the detection of volume material scattering and the study into the scattering of multilayer coatings. In addition, software programs were developed to model the roughness-induced light scattering of substrates and thin-film coatings.

Effects of Various Wavelength Ranges of Vacuum Ultraviolet Radiation on Teflon FEP Film Investigated

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; McCracken, Cara A.

2004-01-01

Teflon Fluorinated Ethylene Propylene (FTP) films (DuPont) have been widely used for spacecraft thermal control and have been observed to become embrittled and cracked upon exposure to the space environment. This degradation has been attributed to a synergistic combination of radiation and thermal effects. A research study was undertaken at the NASA Glenn Research Center to examine the effects of different wavelength ranges of vacuum ultraviolet (VUV) radiation on the degradation of the mechanical properties of FEP. This will contribute to an overall understanding of space radiation effects on Teflon FEP, and will provide information necessary to determine appropriate techniques for using laboratory tests to estimate space VUV degradation. Research was conducted using inhouse facilities at Glenn and was carried out, in part, through a grant with the Cleveland State University. Samples of Teflon FEP film of 50.8 microns thickness were exposed to radiation from a VUV lamp from beneath different cover windows to provide different exposure wavelength ranges: MgF2 (115 to 400 nm), crystalline quartz (140 to 400 nm), and fused silica (FS, 155 to 400 nm). Following exposure, FEP film specimens were tensile tested to determine the ultimate tensile strength and elongation at failure as a function of the exposure duration for each wavelength range. The graphs show the effect of ultraviolet exposure on the mechanical properties of the FEP samples.

Improved Thermal-Vacuum Compatible Flat Plate Radiometric Source For System-Level Testing Of Optical Sensors

NASA Technical Reports Server (NTRS)

Schwarz, Mark A.; Kent, Craig J.; Bousquet, Robert; Brown, Steven W.

2016-01-01

In this work, we describe an improved thermal-vacuum compatible flat plate radiometric source which has been developed and utilized for the characterization and calibration of remote optical sensors. This source is unique in that it can be used in situ, in both ambient and thermal-vacuum environments, allowing it to follow the sensor throughout its testing cycle. The performance of the original flat plate radiometric source was presented at the 2009 SPIE1. Following the original efforts, design upgrades were incorporated into the source to improve both radiometric throughput and uniformity. The pre-thermal-vacuum (pre-TVAC) testing results of a spacecraft-level optical sensor with the improved flat plate illumination source, both in ambient and vacuum environments, are presented. We also briefly discuss potential FPI configuration changes in order to improve its radiometric performance.

Birefringence of magnesium fluoride in the vacuum ultraviolet and application to a half-waveplate.

PubMed

Ishikawa, Ryohko; Kano, Ryouhei; Bando, Takamasa; Suematsu, Yoshinori; Ishikawa, Shin-nosuke; Kubo, Masahito; Narukage, Noriyuki; Hara, Hirohisa; Tsuneta, Saku; Watanabe, Hiroko; Ichimoto, Kiyoshi; Aoki, Kunichika; Miyagawa, Kenta

2013-12-01

Spectro-polarimeteric observations in the vacuum-ultraviolet (VUV) region are expected to be developed as a new astrophysics diagnostic tool for investigating space plasmas with temperatures of >10(4)  K. Precise measurements of the difference in the extraordinary and ordinary refractive indices are required for developing accurate polarimeters, but reliable information on the birefringence in the VUV range is difficult to obtain. We have measured the birefringence of magnesium fluoride (MgF2) with an accuracy of better than ±4×10(-5) around the hydrogen Lyman-α line (121.57 nm). We show that MgF2 can be applied practically as a half-waveplate for the chromospheric Lyman-alpha spectro-polarimeter (CLASP) sounding rocket experiment and that the developed measurement method can be easily applied to other VUV birefringent materials at other wavelengths.

Gas chromatography-vacuum ultraviolet spectroscopy for analysis of fatty acid methyl esters.

PubMed

Fan, Hui; Smuts, Jonathan; Bai, Ling; Walsh, Phillip; Armstrong, Daniel W; Schug, Kevin A

2016-03-01

A new vacuum ultraviolet (VUV) detector for gas chromatography was recently developed and applied to fatty acid methyl ester (FAME) analysis. VUV detection features full spectral acquisition in a wavelength range of 115-240nm, where virtually all chemical species absorb. VUV absorption spectra of 37 FAMEs, including saturated, monounsaturated, and polyunsaturated types were recorded. Unsaturated FAMEs show significantly different gas phase absorption profiles than saturated ones, and these classes can be easily distinguished with the VUV detector. Another advantage includes differentiating cis/trans-isomeric FAMEs (e.g. oleic acid methyl ester and linoleic acid methyl ester isomers) and the ability to use VUV data analysis software for deconvolution of co-eluting signals. As a universal detector, VUV also provides high specificity, sensitivity, and a fast data acquisition rate, making it a powerful tool for fatty acid screening when combined with gas chromatography. The fatty acid profile of several food oil samples (olive, canola, vegetable, corn, sunflower and peanut oils) were analyzed in this study to demonstrate applicability to real world samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV

PubMed Central

Wang, He; Xu, Yiming; Ulonska, Stefan; Robinson, Joseph S.; Ranitovic, Predrag; Kaindl, Robert A.

2015-01-01

Novel table-top sources of extreme-ultraviolet light based on high-harmonic generation yield unique insight into the fundamental properties of molecules, nanomaterials or correlated solids, and enable advanced applications in imaging or metrology. Extending high-harmonic generation to high repetition rates portends great experimental benefits, yet efficient extreme-ultraviolet conversion of correspondingly weak driving pulses is challenging. Here, we demonstrate a highly-efficient source of femtosecond extreme-ultraviolet pulses at 50-kHz repetition rate, utilizing the ultraviolet second-harmonic focused tightly into Kr gas. In this cascaded scheme, a photon flux beyond ≈3 × 1013 s−1 is generated at 22.3 eV, with 5 × 10−5 conversion efficiency that surpasses similar harmonics directly driven by the fundamental by two orders-of-magnitude. The enhancement arises from both wavelength scaling of the atomic dipole and improved spatio-temporal phase matching, confirmed by simulations. Spectral isolation of a single 72-meV-wide harmonic renders this bright, 50-kHz extreme-ultraviolet source a powerful tool for ultrafast photoemission, nanoscale imaging and other applications. PMID:26067922

Ultraviolet Communication for Medical Applications

DTIC Science & Technology

2015-06-01

DEI procured several UVC phosphors and tested them with vacuum UV (VUV) excitation. Available emission peaks include: 226 nm, 230 nm, 234 nm, 242...SUPPLEMENTARY NOTES Report contains color. 14. ABSTRACT Under this Phase II SBIR effort, Directed Energy Inc.’s (DEI) proprietary ultraviolet ( UV ...15. SUBJECT TERMS Non-line-of-sight (NLOS), networking, optical communication, plasma-shells, short range, ultraviolet ( UV ) light 16. SECURITY

Carrier Conduction and Light Emission by Modification of Poly(alkylfluorene) Interface under Vacuum Ultraviolet Light Irradiation

NASA Astrophysics Data System (ADS)

Ohmori, Yutaka; Kajii, Hirotake; Terashima, Daiki; Kusumoto, Yusuke

2013-03-01

Organic field effect transistors (OFETs) have been extensively studied for flexible electronics. The characteristics of poly(9,9-dioctylfluorenyl-2,7-dyl) (F8) modified by thermal or light are strongly dependent on the carrier transport and optical characteristics. We investigate all solution-processed OFETs with Ag nano-ink as gate electrodes patterned by Vacuum Ultraviolet (VUV) (172 nm). Bi-layer gate insulators of amorphous fluoro-polymer CYTOP (Asahi Glass Corp.) and poly(methylmethacrylate) (PMMA) were used. Top-gate-type OFETs with ITO source/drain electrode utilizing F8 or poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) as an active layer were fabricated, and investigated the carrier conduction and emission characteristic. Without VUV irradiation, both OFETs showed the ambipolar and light-emitting characteristics. On the other hand, F8 devices with VUV exhibited only p-type conduction. The quenching centers were generated in F8 layer by VUV irradiation, which are related to the electron trap sites at the interface. OFETs with F8BT showed both p- and n-type conduction even after VUV. F8BT suffers less damage by VUV and maintain light emission. Light emitting transistors were realized utilizing F8BT patterned by VUV irradiation. This research was partially supported financially by MEXT. The authors thank Harima Chemicals Inc. for providing Ag nano-ink.

Quantitative analysis of vacuum-ultraviolet radiation from nanosecond laser-zinc interaction

NASA Astrophysics Data System (ADS)

Parchamy, Homaira; Szilagyi, John; Masnavi, Majid; Richardson, Martin

2018-07-01

The paper reports measurements of the vacuum-ultraviolet spectral irradiances of a flat zinc target over a wavelength region of 124-164 nm generated by 10 and 60 ns duration low-intensities, 5 ×109 - 3 ×1010 W cm-2, 1.06 μm wavelength laser pulses. Maximum radiation conversion efficiencies of 2.5%/2πsr and 0.8%/2πsr were measured for 60 and 10 ns laser pulses at the intensities of 5 ×109 and 1.4 ×1010 W cm-2, respectively. Atomic structure calculations using a relativistic configuration-interaction, flexible atomic code and a developed non-local thermodynamic equilibrium population kinetics model in comparison to the experimental spectra detected by the Seya-Namioka type monochromator reveal the strong broadband experimental emission originates mainly from 3d94p-3d94s, 3d94d-3d94p and 3d84p-3d84s, 3d84d-3d84p unresolved-transition arrays of double and triple ionized zinc, respectively. Two-dimensional radiation-hydrodynamics code is used to investigate time-space plasma evolution and spectral radiation of a 10 ns full-width-at-half-maximum Gaussian laser pulse-zinc interaction.

Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

NASA Astrophysics Data System (ADS)

Jablonowski, H.; Bussiahn, R.; Hammer, M. U.; Weltmann, K.-D.; von Woedtke, Th.; Reuter, S.

2015-12-01

Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100-400 nm) and, in particular, vacuum ultraviolet (VUV, 10-200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH2O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H2O2) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O2•-) and hydroxyl radicals (•OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

Spectral lines and characteristic of temporal variations in photoionized plasmas induced with laser-produced plasma extreme ultraviolet source

NASA Astrophysics Data System (ADS)

Saber, I.; Bartnik, A.; Wachulak, P.; Skrzeczanowski, W.; Jarocki, R.; Fiedorowicz, H.

2017-11-01

Spectral lines for Kr/Ne/H2 photoionized plasma in the ultraviolet and visible (UV/Vis) wavelength ranges have been created using a laser-produced plasma (LPP) EUV source. The source is based on a double-stream gas puff target irradiated with a commercial Nd:YAG laser. The laser pulses were focused onto a gas stream, injected into a vacuum chamber synchronously with the EUV pulses. Spectral lines from photoionization in neutral Kr/Ne/H2 and up to few charged states were observed. The intense emission lines were associated with the Kr transition lines. Experimental and theoretical investigations on intensity variations for some ionic lines are presented. A decrease in the intensity with the delay time between the laser pulse and the spectrum acquisition was revealed. Electron temperature and electron density in the photoionized plasma have been estimated from the characteristic emission lines. Temperature was obtained using Boltzmann plot method, assuming that the population density of atoms and ions are considered in a local thermodynamic equilibrium (LTE). Electron density was calculated from the Stark broadening profile. The temporal evaluation of the plasma and the way of optimizing the radiation intensity of LPP EUV sources is discussed.

Vacuum energy from noncommutative models

NASA Astrophysics Data System (ADS)

Mignemi, S.; Samsarov, A.

2018-04-01

The vacuum energy is computed for a scalar field in a noncommutative background in several models of noncommutative geometry. One may expect that the noncommutativity introduces a natural cutoff on the ultraviolet divergences of field theory. Our calculations show however that this depends on the particular model considered: in some cases the divergences are suppressed and the vacuum energy is only logarithmically divergent, in other cases they are stronger than in the commutative theory.

Exciplex vacuum ultraviolet emission spectra of KrAr: Temperature dependence and potentials

NASA Astrophysics Data System (ADS)

Subtil, J.-L.; Jonin, C.; Laporte, P.; Reininger, R.; Spiegelmann, F.; Gürtler, P.

1996-11-01

The temperature dependence of the emissions from the 0+(3P1)and 1(3P2) Kr*Ar exciplex states in the range 85-350 K was studied using time resolved techniques, vacuum ultraviolet synchrotron radiation, and argon samples doped with minimal amounts of krypton. As the temperature is increased, the emission shifts to the blue, its width increases by almost a factor of 2, and the line shape becomes asymmetrical. The experimental line shapes have been simulated by means of Franck-Condon density calculations using the available ground state potential of Aziz and Slaman [Mol. Phys. 58, 679 (1986)] and by modeling the exciplex potentials as Morse curves. The potential parameters for the 0+ and 1 states are re=5.05±0.01 and 5.07±0.01 a0, respectively; De=1150±200 cm-1 and β=1.4±0.1 a0-1 for both states. The latter two values yield ωe=140 cm-1 and ωexe=4.3 cm-1. The energy positions of the exciplexes's wells and their depths are compared with published results.

Vacuum ultraviolet spectroscopy of the lowest-lying electronic state in subcritical and supercritical water

NASA Astrophysics Data System (ADS)

Marin, Timothy W.; Janik, Ireneusz; Bartels, David M.; Chipman, Daniel M.

2017-05-01

The nature and extent of hydrogen bonding in water has been scrutinized for decades, including how it manifests in optical properties. Here we report vacuum ultraviolet absorption spectra for the lowest-lying electronic state of subcritical and supercritical water. For subcritical water, the spectrum redshifts considerably with increasing temperature, demonstrating the gradual breakdown of the hydrogen-bond network. Tuning the density at 381 °C gives insight into the extent of hydrogen bonding in supercritical water. The known gas-phase spectrum, including its vibronic structure, is duplicated in the low-density limit. With increasing density, the spectrum blueshifts and the vibronic structure is quenched as the water monomer becomes electronically perturbed. Fits to the supercritical water spectra demonstrate consistency with dimer/trimer fractions calculated from the water virial equation of state and equilibrium constants. Using the known water dimer interaction potential, we estimate the critical distance between molecules (ca. 4.5 Å) needed to explain the vibronic structure quenching.

Vacuum ultraviolet spectroscopy of the lowest-lying electronic state in subcritical and supercritical water

DOE PAGES

Marin, Timothy W.; Janik, Ireneusz; Bartels, David M.; ...

2017-05-17

The nature and extent of hydrogen bonding in water has been scrutinized for decades, including how it manifests in optical properties. Here we report vacuum ultraviolet absorption spectra for the lowest-lying electronic state of subcritical and supercritical water. For subcritical water, the spectrum redshifts considerably with increasing temperature, demonstrating the gradual breakdown of the hydrogen-bond network. Tuning the density at 381°C gives insight into the extent of hydrogen bonding in supercritical water. The known gas-phase spectrum, including its vibronic structure, is duplicated in the low-density limit. With increasing density, the spectrum blueshifts and the vibronic structure is quenched as themore » water monomer becomes electronically perturbed. Fits to the supercritical water spectra demonstrate consistency with dimer/trimer fractions calculated from the water virial equation of state and equilibrium constants. As a result, using the known water dimer interaction potential, we estimate the critical distance between molecules (ca. 4.5 Å) needed to explain the vibronic structure quenching.« less

Scintillation screen applications in a vacuum arc ion source with composite hydride cathode

NASA Astrophysics Data System (ADS)

Wang, X. H.; Tuo, X. G.; Yang, Z.; Peng, Y. F.; Li, J.; Lv, H. Y.; Li, J. H.; Long, J. D.

2018-05-01

Vacuum arc ion source with composite hydride cathode was developed to produce intense ion beams which can be applied in particle accelerator injections. Beam profile and beam composition are two fundamental parameters of the beam for the vacuum arc ion source in such specific applications. An aluminum-coated scintillation screen with an ICCD camera readout was used to show the space-time distribution of the beam directly. A simple magnetic analysis assembly with the scintillation screen shows the beam composition information of this kind ion source. Some physical and technical issues are discussed and analyzed in the text.

Comparison of direct and alternating current vacuum ultraviolet lamps in atmospheric pressure photoionization.

PubMed

Vaikkinen, Anu; Haapala, Markus; Kersten, Hendrik; Benter, Thorsten; Kostiainen, Risto; Kauppila, Tiina J

2012-02-07

A direct current induced vacuum ultraviolet (dc-VUV) krypton discharge lamp and an alternating current, radio frequency (rf) induced VUV lamp that are essentially similar to lamps in commercial atmospheric pressure photoionization (APPI) ion sources were compared. The emission distributions along the diameter of the lamp exit window were measured, and they showed that the beam of the rf lamp is much wider than that of the dc lamp. Thus, the rf lamp has larger efficient ionization area, and it also emits more photons than the dc lamp. The ionization efficiencies of the lamps were compared using identical spray geometries with both lamps in microchip APPI mass spectrometry (μAPPI-MS) and desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS). A comprehensive view on the ionization was gained by studying six different μAPPI solvent compositions, five DAPPI spray solvents, and completely solvent-free DAPPI. The observed reactant ions for each solvent composition were very similar with both lamps except for toluene, which showed a higher amount of solvent originating oxidation products with the rf lamp than with the dc lamp in μAPPI. Moreover, the same analyte ions were detected with both lamps, and thus, the ionization mechanisms with both lamps are similar. The rf lamp showed a higher ionization efficiency than the dc lamp in all experiments. The difference between the lamp ionization efficiencies was greatest when high ionization energy (IE) solvent compositions (IEs above 10 eV), i.e., hexane, methanol, and methanol/water, (1:1 v:v) were used. The higher ionization efficiency of the rf lamp is likely due to the larger area of high intensity light emission, and the resulting larger efficient ionization area and higher amount of photons emitted. These result in higher solvent reactant ion production, which in turn enables more efficient analyte ion production. © 2012 American Chemical Society

A Penning discharge source for extreme ultraviolet calibration

NASA Technical Reports Server (NTRS)

Finley, David S.; Jelinsky, Patrick; Bowyer, Stuart; Malina, Roger F.

1986-01-01

A Penning discharge lamp for use in the calibration of instruments and components for the extreme ultraviolet has been developed. This source is sufficiently light and compact to make it suitable for mounting on the movable slit assembly of a grazing incidence Rowland circle monochromator. Because this is a continuous discharge source, it is suitable for use with photon counting detectors. Line radiation is provided both by the gas and by atoms sputtered off the interchangeable metal cathodes. Usable lines are produced by species as highly ionized as Ne IV and Al V. The wavelength coverage provided is such that a good density of emission lines is available down to wavelengths as short as 100A. This source fills the gap between 100 and 300A, which is inadequately covered by the other available compact continuous radiation sources.

Oxygen isotope fractionation in the vacuum ultraviolet photodissociation of carbon monoxide: Wavelength, pressure and temperature dependency.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, Subrata; Davis, Ryan; Ahmed, Musahid

Several absorption bands exist in the VUV region of Carbon monoxide (CO). Emission spectra indicate that these bands are all predissociative. An experimental investigation of CO photodissociation by vacuum ultraviolet photons (90 to 108 nm; ~13 to 11 eV) from the Advanced Light Source Synchrotron and direct measurement of the associated oxygen isotopic composition of the products are presented here. A wavelength dependency of the oxygen isotopic composition in the photodissociation product was observed. Slope values (δ'{sup 18}O/ δ'{sup 17}O) ranging from 0.76 to 1.32 were observed in oxygen three-isotope space (δ'{sup 18}O vs. δ'{sup 17}O) which correlated with increasingmore » synchrotron photon energy, and indicate a dependency of the upper electronic state specific dissociation dynamics (e.g., perturbation and coupling associated with a particular state). An unprecedented magnitude in isotope separation was observed for photodissociation at the 105 and 107 nm synchrotron bands and are found to be associated with accidental predissociation of the vibrational states ({nu} = 0 and 1) of the upper electronic state E{sup 1}Π. For each synchrotron band, a large (few hundred per mil) extent of isotopic fractionation was observed and the range of fractionation is a combination of column density and exposure time. A significant temperature dependency in oxygen isotopic fractionation was observed, indicating a rotational level dependency in the predissociation process.« less

Simulation of the synergistic low Earth orbit effects of vacuum thermal cycling, vacuum UV radiation, and atomic oxygen

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Degroh, Kim K.; Stidham, Curtis R.; Stueber, Thomas J.; Dever, Therese M.; Rodriguez, Elvin; Terlep, Judith A.

1992-01-01

In order to assess the low Earth orbit (LEO) durability of candidate space materials, it is necessary to use ground laboratory facilities which provide LEO environmental effects. A facility combining vacuum thermal cycling and vacuum ultraviolet (VUV) radiation has been designed and constructed at NASA Lewis Research Center for this purpose. This facility can also be operated without the VUV lamps. An additional facility can be used to provide VUV exposure only. By utilizing these facilities, followed by atomic oxygen exposure in an RF plasma asher, the effects of the individual vacuum thermal cycling and VUV environments can be compared to the effect of the combined vacuum thermal cycling/VUV environment on the atomic oxygen durability of materials. The synergistic effects of simulated LEO environmental conditions on materials were evaluated by first exposing materials to vacuum thermal cycling, VUV, and vacuum thermal cycling/VUV environments followed by exposure to atomic oxygen in an RP plasma asher. Candidate space power materials such as atomic oxygen protected polyimides and solar concentrator mirrors were evaluated using these facilities. Characteristics of the Vacuum Thermal Cycling/VUV Exposure Facility which simulates the temperature sequences and solar ultraviolet radiation exposure that would be experienced by a spacecraft surface in LEO are discussed. Results of durability evaluations of some candidate space power materials to the simulated LEO environmental conditions will also be discussed. Such results have indicated that for some materials, atomic oxygen durability is affected by previous exposure to thermal cycling and/or VUV exposure.

Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jablonowski, H.; Hammer, M. U.; Reuter, S.

Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100–400 nm) and, in particular, vacuum ultraviolet (VUV, 10–200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH{sub 2}O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stablemore » reactive oxygen species, hydrogen peroxide (H{sub 2}O{sub 2}) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O{sub 2}{sup •−}) and hydroxyl radicals ({sup •}OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.« less

Ultraviolet source for rocket measurements of nitric oxide in the upper atmosphere. [D region

NASA Technical Reports Server (NTRS)

Siddiqui, J. M. H.

1974-01-01

An ultraviolet source suitable for balloon and rocket payloads for measurements of nitric oxide in the lower D-region of the ionosphere was developed. The source primarily emits 1236 A and 1165 A photons obtained from an R.F.-excited krypton discharge in a resonator of coaxial geometry. Ultraviolet flux output greater than 10 to the 14th power photons/sec can be obtained from this source. A systematic design philosophy is developed which enables the photon output to be optimized with respect to photon wavelength, gas pressure, R.F., resonator geometry, and gas to be used. Critical factors in the design are discussed in detail.

Probing the infrared counterparts of diffuse far-ultraviolet sources in the Galaxy

NASA Astrophysics Data System (ADS)

Saikia, Gautam; Shalima, P.; Gogoi, Rupjyoti; Pathak, Amit

2017-12-01

Recent availability of high quality infrared (IR) data for diffuse regions in the Galaxy and external galaxies have added to our understanding of interstellar dust. A comparison of ultraviolet (UV) and IR observations may be used to estimate absorption, scattering and thermal emission from interstellar dust. In this paper, we report IR and UV observations for selective diffuse sources in the Galaxy. Using archival mid-infrared (MIR) and far-infrared (FIR) observations from Spitzer Space Telescope, we look for counterparts of diffuse far-ultraviolet (FUV) sources observed by the Voyager, Far Ultraviolet Spectroscopic Explorer (FUSE) and Galaxy Evolution Explorer (GALEX) telescopes in the Galaxy. IR emission features at 8 μm are generally attributed to Polycyclic Aromatic Hydrocarbon (PAH) molecules, while emission at 24 μm are attributed to Very Small Grains (VSGs). The data presented here is unique and our study tries to establish a relation between various dust populations. By studying the FUV-IR correlations separately at low and high latitude locations, we have identified the grain component responsible for the diffuse FUV emission.

VUV dissociative excitation cross sections of H2O, NH3, and CH4 by electron impact. [Vacuum Ultra-Violet

NASA Technical Reports Server (NTRS)

Morgan, H. D.; Mentall, J. E.

1974-01-01

Absolute excitation functions for excited fragments resulting from electron bombardment of H2O, NH3, and CH4 by low-energy electrons (0 to 300 eV) have been measured in the vacuum ultraviolet (1100 to 1950 A). The predominant emission for each molecule was the H Lyman-alpha line, while the O I, N I, C I, and C II emissions were at least an order of magnitude weaker. Absolute cross sections at 100 eV are given along with the appearance potential of the various processes and the possible dissociative-excitation channels through which such processes proceed.

Electroweak vacuum instability and renormalized Higgs field vacuum fluctuations in the inflationary universe

NASA Astrophysics Data System (ADS)

Kohri, Kazunori; Matsui, Hiroki

2017-08-01

In this work, we investigated the electroweak vacuum instability during or after inflation. In the inflationary Universe, i.e., de Sitter space, the vacuum field fluctuations < δ phi 2 > enlarge in proportion to the Hubble scale H2. Therefore, the large inflationary vacuum fluctuations of the Higgs field < δ phi 2 > are potentially catastrophic to trigger the vacuum transition to the negative-energy Planck-scale vacuum state and cause an immediate collapse of the Universe. However, the vacuum field fluctuations < δ phi 2 >, i.e., the vacuum expectation values have an ultraviolet divergence, and therefore a renormalization is necessary to estimate the physical effects of the vacuum transition. Thus, in this paper, we revisit the electroweak vacuum instability from the perspective of quantum field theory (QFT) in curved space-time, and discuss the dynamical behavior of the homogeneous Higgs field phi determined by the effective potential V eff( phi ) in curved space-time and the renormalized vacuum fluctuations < δ phi 2 >ren via adiabatic regularization and point-splitting regularization. We simply suppose that the Higgs field only couples the gravity via the non-minimal Higgs-gravity coupling ξ(μ). In this scenario, the electroweak vacuum stability is inevitably threatened by the dynamical behavior of the homogeneous Higgs field phi, or the formations of AdS domains or bubbles unless the Hubble scale is small enough H< ΛI .

Numerical Study on Natural Vacuum Solar Desalination System with Varying Heat Source Temperature

NASA Astrophysics Data System (ADS)

Ambarita, H.

2017-03-01

A natural vacuum desalination unit with varying low grade heat source temperature is investigated numerically. The objective is to explore the effects of the variable temperature of the low grade heat source on performances and characteristics of the desalination unit. The specifications of the desalination unit are naturally vacuumed with surface area of seawater in evaporator and heating coil are 0.2 m2 and 0.188 m2, respectively. Temperature of the heating coil is simulated based on the solar radiation in the Medan city. A program to solve the governing equations in forward time step marching technique is developed. Temperature of the evaporator, fresh water production rate, and thermal efficiency of the desalination unit are analysed. Simulation is performed for 9 hours, it starts from 8.00 and finishes at 17.00 of local time. The results show that, the desalination unit with operation time of 9 hours can produce 5.705 L of freshwater and thermal efficiency is 81.8 %. This reveals that varying temperature of the heat source of natural vacuum desalination unit shows better performance in comparison with constant temperature of the heat source.

Coupling a versatile aerosol apparatus to a synchrotron: Vacuum ultraviolet light scattering, photoelectron imaging, and fragment free mass spectrometry

NASA Astrophysics Data System (ADS)

Shu, Jinian; Wilson, Kevin R.; Ahmed, Musahid; Leone, Stephen R.

2006-04-01

An aerosol apparatus has been coupled to the Chemical Dynamics Beamline of the Advanced Light Source at Lawrence Berkeley National Laboratory. This apparatus has multiple capabilities for aerosol studies, including vacuum ultraviolet (VUV) light scattering, photoelectron imaging, and mass spectroscopy of aerosols. By utilizing an inlet system consisting of a 200μm orifice nozzle and aerodynamic lenses, aerosol particles of ˜50nm-˜1μm in diameter can be sampled directly from atmospheric pressure. The machine is versatile and can probe carbonaceous aerosols generated by a laboratory flame, nebulized solutions of biological molecules, hydrocarbon aerosol reaction products, and synthesized inorganic nanoparticles. The sensitivity of this apparatus is demonstrated by the detection of nanoparticles with VUV light scattering, photoelectron imaging, and charged particle detection. In addition to the detection of nanoparticles, the thermal vaporization of aerosols on a heater tip leads to the generation of intact gas phase molecules. This phenomenon coupled to threshold single photon ionization, accessible with tunable VUV light, allows for fragment-free mass spectrometry of complex molecules. The initial experiments with light scattering, photoelectron imaging, and aerosol mass spectrometry reported here serve as a demonstration of the design philosophy and multiple capabilities of the apparatus.

High-resolution vacuum-ultraviolet photoabsorption spectra of 1-butyne and 2-butyne

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacovella, U.; Holland, D. M. P.; Boyé-Péronne, S.

2015-07-21

The absolute photoabsorption cross sections of 1- and 2-butyne have been recorded at high resolution by using the vacuum-ultraviolet Fourier-Transform spectrometer at the SOLEIL Synchrotron. Both spectra show more resolved structure than previously observed, especially in the case of 2-butyne. In this work, we assess the potential importance of Rydberg states with higher values of orbital angular momentum, l, than are typically observed in photoabsorption experiments from ground state molecules. We show how the character of the highest occupied molecular orbitals in 1- and 2-butyne suggests the potential importance of transitions to such high-l (l = 3 and 4) Rydbergmore » states. Furthermore, we use theoretical calculations of the partial wave composition of the absorption cross section just above the ionization threshold and the principle of continuity of oscillator strength through an ionization threshold to support this conclusion. The new absolute photoabsorption cross sections are discussed in light of these arguments, and the results are consistent with the expectations. This type of argument should be valuable for assessing the potential importance of different Rydberg series when sufficiently accurate direct quantum chemical calculations are difficult, for example, in the n ≥ 5 manifolds of excited states of larger molecules.« less

Control of the polarization of a vacuum-ultraviolet, high-gain, free-electron laser

DOE PAGES

Allaria, Enrico; Diviacco, Bruno; Callegari, Carlo; ...

2014-12-02

The two single-pass, externally seeded free-electron lasers (FELs) of the FERMI user facility are designed around Apple-II-type undulators that can operate at arbitrary polarization in the vacuum ultraviolet-to-soft x-ray spectral range. Furthermore, within each FEL tuning range, any output wavelength and polarization can be set in less than a minute of routine operations. We report the first demonstration of the full output polarization capabilities of FERMI FEL-1 in a campaign of experiments where the wavelength and nominal polarization are set to a series of representative values, and the polarization of the emitted intense pulses is thoroughly characterized by three independentmore » instruments and methods, expressly developed for the task. The measured radiation polarization is consistently >90% and is not significantly spoiled by the transport optics; differing, relative transport losses for horizontal and vertical polarization become more prominent at longer wavelengths and lead to a non-negligible ellipticity for an originally circularly polarized state. The results from the different polarimeter setups validate each other, allow a cross-calibration of the instruments, and constitute a benchmark for user experiments.« less

Vacuum ultraviolet radiation effects on two-dimensional MoS2 field-effect transistors

NASA Astrophysics Data System (ADS)

McMorrow, Julian J.; Cress, Cory D.; Arnold, Heather N.; Sangwan, Vinod K.; Jariwala, Deep; Schmucker, Scott W.; Marks, Tobin J.; Hersam, Mark C.

2017-02-01

Atomically thin MoS2 has generated intense interest for emerging electronics applications. Its two-dimensional nature and potential for low-power electronics are particularly appealing for space-bound electronics, motivating the need for a fundamental understanding of MoS2 electronic device response to the space radiation environment. In this letter, we quantify the response of MoS2 field-effect transistors (FETs) to vacuum ultraviolet (VUV) total ionizing dose radiation. Single-layer (SL) and multilayer (ML) MoS2 FETs are compared to identify differences that arise from thickness and band structure variations. The measured evolution of the FET transport properties is leveraged to identify the nature of VUV-induced trapped charge, isolating the effects of the interface and bulk oxide dielectric. In both the SL and ML cases, oxide trapped holes compete with interface trapped electrons, exhibiting an overall shift toward negative gate bias. Raman spectroscopy shows no variation in the MoS2 signatures as a result of VUV exposure, eliminating significant crystalline damage or oxidation as possible radiation degradation mechanisms. Overall, this work presents avenues for achieving radiation-hard MoS2 devices through dielectric engineering that reduces oxide and interface trapped charge.

Flow-Tube Investigations of Hypergolic Reactions of a Dicyanamide Ionic Liquid Via Tunable Vacuum Ultraviolet Aerosol Mass Spectrometry.

PubMed

Chambreau, Steven D; Koh, Christine J; Popolan-Vaida, Denisia M; Gallegos, Christopher J; Hooper, Justin B; Bedrov, Dmitry; Vaghjiani, Ghanshyam L; Leone, Stephen R

2016-10-07

The unusually high heats of vaporization of room-temperature ionic liquids (RTILs) complicate the utilization of thermal evaporation to study ionic liquid reactivity. Although effusion of RTILs into a reaction flow-tube or mass spectrometer is possible, competition between vaporization and thermal decomposition of the RTIL can greatly increase the complexity of the observed reaction products. In order to investigate the reaction kinetics of a hypergolic RTIL, 1-butyl-3-methylimidazolium dicyanamide (BMIM + DCA - ) was aerosolized and reacted with gaseous nitric acid, and the products were monitored via tunable vacuum ultraviolet photoionization time-of-flight mass spectrometry at the Chemical Dynamics Beamline 9.0.2 at the Advanced Light Source. Reaction product formation at m/z 42, 43, 44, 67, 85, 126, and higher masses was observed as a function of HNO 3 exposure. The identities of the product species were assigned to the masses on the basis of their ionization energies. The observed exposure profile of the m/z 67 signal suggests that the excess gaseous HNO 3 initiates rapid reactions near the surface of the RTIL aerosol. Nonreactive molecular dynamics simulations support this observation, suggesting that diffusion within the particle may be a limiting step. The mechanism is consistent with previous reports that nitric acid forms protonated dicyanamide species in the first step of the reaction.

Research on vacuum utraviolet calibration technology

NASA Astrophysics Data System (ADS)

Wang, Jiapeng; Gao, Shumin; Sun, Hongsheng; Chen, Yinghang; Wei, Jianqiang

2014-11-01

Importance of extreme ultraviolet (EUV) and far ultraviolet (FUV) calibration is growing fast as vacuum ultraviolet payloads are wildly used in national space plan. A calibration device is established especially for the requirement of EUV and FUV metrology and measurement. Spectral radiation and detector relative spectral response at EUV and FUV wavelengths can be calibrated with accuracy of 26% and 20%, respectively. The setup of the device, theoretical model and value retroactive method are introduced and measurement of detector relative spectral response from 30 nm to 200 nm is presented in this paper. The calibration device plays an important role in national space research.

Vacuum insulation of the high energy negative ion source for fusion application.

PubMed

Kojima, A; Hanada, M; Hilmi, A; Inoue, T; Watanabe, K; Taniguchi, M; Kashiwagi, M; Umeda, N; Tobari, H; Kobayashi, S; Yamano, Y; Grisham, L R

2012-02-01

Vacuum insulation on a large size negative ion accelerator with multiple extraction apertures and acceleration grids for fusion application was experimentally examined and designed. In the experiment, vacuum insulation characteristics were investigated in the JT-60 negative ion source with >1000 apertures on the grid with the surface area of ∼2 m(2). The sustainable voltages varied with a square root of the gap lengths between the grids, and decreased with number of the apertures and with the surface area of the grids. Based on the obtained results, the JT-60SA (super advanced) negative ion source is designed to produce 22 A, 500 keV D(-) ion beams for 100 s.

Electroweak vacuum instability and renormalized Higgs field vacuum fluctuations in the inflationary universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohri, Kazunori; Matsui, Hiroki, E-mail: kohri@post.kek.jp, E-mail: matshiro@post.kek.jp

In this work, we investigated the electroweak vacuum instability during or after inflation. In the inflationary Universe, i.e., de Sitter space, the vacuum field fluctuations < δ φ {sup 2} > enlarge in proportion to the Hubble scale H {sup 2}. Therefore, the large inflationary vacuum fluctuations of the Higgs field < δ φ {sup 2} > are potentially catastrophic to trigger the vacuum transition to the negative-energy Planck-scale vacuum state and cause an immediate collapse of the Universe. However, the vacuum field fluctuations < δ φ {sup 2} >, i.e., the vacuum expectation values have an ultraviolet divergence, andmore » therefore a renormalization is necessary to estimate the physical effects of the vacuum transition. Thus, in this paper, we revisit the electroweak vacuum instability from the perspective of quantum field theory (QFT) in curved space-time, and discuss the dynamical behavior of the homogeneous Higgs field φ determined by the effective potential V {sub eff}( φ ) in curved space-time and the renormalized vacuum fluctuations < δ φ {sup 2} >{sub ren} via adiabatic regularization and point-splitting regularization. We simply suppose that the Higgs field only couples the gravity via the non-minimal Higgs-gravity coupling ξ(μ). In this scenario, the electroweak vacuum stability is inevitably threatened by the dynamical behavior of the homogeneous Higgs field φ, or the formations of AdS domains or bubbles unless the Hubble scale is small enough H < Λ {sub I} .« less

Vacuum Ultraviolet (VUV) radiation-induced degradation of Fluorinated Ethylene Propylene (FEP) Teflon aboard the Long Duration Exposure Facility (LDEF)

NASA Technical Reports Server (NTRS)

Brinza, David E.; Stiegman, A. E.; Staszak, Paul R.; Laue, Eric G.; Liang, Ranty H.

1992-01-01

Examination of fluorinated ethylene propylene (FEP) copolymer specimens recovered from the Long Duration Exposure Facility (LDEF) provides evidence for degradation attributed to extended solar vacuum ultraviolet (VUV) irradiation. Scanning electron microscope (SEM) images of sheared FEP film edges reveal the presence of a highly embrittled layer on the exposed surface of specimens obtained from the trailing edge of the LDEF. Similar images obtained for leading edge and control FEP films do not exhibit evidence for such an embrittled layer. Laboratory VUV irradiation of FEP films is found to produce a damage layer similar to that witnessed in the LDEF trailing edge films. Spectroscopic analyses of irradiated films provide data to advance a photochemical mechanism for degradation.

Identification and deconvolution of carbohydrates with gas chromatography-vacuum ultraviolet spectroscopy.

PubMed

Schenk, Jamie; Nagy, Gabe; Pohl, Nicola L B; Leghissa, Allegra; Smuts, Jonathan; Schug, Kevin A

2017-09-01

Methodology for qualitative and quantitative determination of carbohydrates with gas chromatography coupled to vacuum ultraviolet detection (GC-VUV) is presented. Saccharides have been intently studied and are commonly analyzed by gas chromatography-mass spectrometry (GC-MS), but not always effectively. This can be attributed to their high degree of structural complexity: α/β anomers from their axial/equatorial hydroxyl group positioning at the C1-OH and flexible ring structures that lead to the open chain, five-membered ring furanose, and six-membered ring pyranose configurations. This complexity can result in convoluted chromatograms, ambiguous fragmentation patterns and, ultimately, analyte misidentification. In this study, mono-, di, and tri-saccharides were derivatized by two different methods-permethylation and oximation/pertrimethylsilylation-and analyzed by GC-VUV. These two derivatization methods were then compared for their efficiency, ease of use, and robustness. Permethylation proved to be a useful technique for the analysis of ketopentoses and pharmaceuticals soluble in dimethyl sulfoxide (DMSO), while the oximation/pertrimethylsilylation method prevailed as the more promising, overall, derivatization method. VUV spectra have been shown to be distinct and allow for efficient differentiation of isomeric species such as ketopentoses and reducing versus non-reducing sugars. In addition to identification, pharmaceutical samples containing several compounds were derivatized and analyzed for their sugar content with the GC-VUV technique to provide data for qualitative analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Synergistic damage effects of vacuum ultraviolet photons and O2 in SiCOH ultra-low-k dielectric films

NASA Astrophysics Data System (ADS)

Lee, J.; Graves, D. B.

2010-10-01

Damage incurred during plasma processing, leading to increases in dielectric constant k, is a persistent problem with porous ultra-low-k dielectric films, such as SiCOH. Although most of the proposed mechanisms of plasma-induced damage focus on the role of ion bombardment and radical attack, we show that plasma-generated vacuum ultraviolet (VUV) photons can play a role in creating damage leading to increases in the dielectric constant of this material. Using a vacuum beam apparatus with a calibrated VUV lamp, we show that 147 nm VUV photons impacting SiCOH results in post-exposure adsorption and reaction with water vapour from the atmosphere to form silanol bonds, thereby raising the dielectric constant. Furthermore, the level of damage increases synergistically under simultaneous exposure to VUV photons and O2. The vacuum beam photon fluences are representative of typical plasma processes, as measured in a separate plasma tool. Fourier-transform infrared (FTIR) spectroscopy (ex situ) and mass spectrometry (in situ) imply that O2 reacts with methyl radicals formed from scissioned Si-C bonds to create CO2 and H2O, the latter combining with Si dangling bonds to generate more SiOH groups than with photon exposure alone. In addition, sample near-surface diffusivity, manipulated through ion bombardment and sample heating, can be seen to affect this process. These results demonstrate that VUV photo-generated surface reactions can be potent contributors to ultra-low-k dielectric SiCOH film plasma-induced damage, and suggest that they could play analogous roles in other plasma-surface interactions.

Vacuum insulation of the high energy negative ion source for fusion application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kojima, A.; Hanada, M.; Inoue, T.

2012-02-15

Vacuum insulation on a large size negative ion accelerator with multiple extraction apertures and acceleration grids for fusion application was experimentally examined and designed. In the experiment, vacuum insulation characteristics were investigated in the JT-60 negative ion source with >1000 apertures on the grid with the surface area of {approx}2 m{sup 2}. The sustainable voltages varied with a square root of the gap lengths between the grids, and decreased with number of the apertures and with the surface area of the grids. Based on the obtained results, the JT-60SA (super advanced) negative ion source is designed to produce 22 A,more » 500 keV D{sup -} ion beams for 100 s.« less

Ultraviolet irradiation at elevated temperatures and thermal cycling in vacuum of FEP-A covered silicon solar cells

NASA Technical Reports Server (NTRS)

Broder, J. D.; Marsik, S. J.

1978-01-01

Experiments were designed and performed on silicon solar cells covered with heat-bonded FEP-A in an effort to explain the rapid degeneration of open-circuit voltage and maximum power observered on cells of this type included in an experiment on the ATS-6 spacecraft. Solar cells were exposed to ultraviolet light in vacuum at temperatures ranging from 30 to 105 C. The samples were then subjected to thermal cycling from 130 to -130 C. Inspection following irradiation indicated that all the covers remained physically intact. However, during the temperature cycling heat-bonded covers showed cracking. The test showed that heat-bonded FEP-A covers embrittle during UV exposure and the embrittlement is dependent upon sample temperature during irradiation. The results of the experiment suggest a probable mechanism for the degradation of the FEP-A cells on ATS-6.

Vacuum ultraviolet trimming of oxygenated functional groups from oxidized self-assembled hexadecyl monolayers in an evacuated environment

NASA Astrophysics Data System (ADS)

Soliman, Ahmed I. A.; Utsunomiya, Toru; Ichii, Takashi; Sugimura, Hiroyuki

2017-09-01

Vacuum ultraviolet light irradiation in dry air generates active oxygen species, which have powerful oxidation abilities. These active oxygen species (O) can oxidize the alkyl moieties of polymers, and generate new oxygenated groups such as OH, CHO and COOH groups. Reducing the oxygen content in the exposure environment decreases the rate of oxidation processes. In this study, we examined the influences of the 172 nm VUV irradiation in a high vacuum (HV, < 10-3 Pa) environment on the chemical constituents, surface properties and morphological structure of well-defined VUV/(O)-modified hexadecyl (HD-) self-assembled monolayer (SAM) prepared on hydrogen-terminated silicon (H-Si) substrate. After VUV light irradiation in a HV environment (HV-VUV), the chemical constituents and surface properties were changed in two distinct stages. At short irradiation time (the first stage), the Csbnd O and COO groups decreased rapidly, while the Cdbnd O groups slightly changed. The dissociation of nonderivatizable groups (such as ether (Csbnd Osbnd C) and ester (Csbnd COOsbnd C) groups) compensated the dissociated OH, CHO, Csbnd COsbnd C and COOH groups. With further irradiation (the second stage), the quantities of the oxygenated groups slightly decreased. The carbon skeleton (Csbnd C) of SAM was scarcely dissociated during the HV-VUV treatment. These chemical changes affected the surface properties, such as wettability and morphology.

Combined ultraviolet studies of astronomical source

NASA Technical Reports Server (NTRS)

Dupress, A. K.; Baliunas, S. L.; Blair, W. P.; Hartmann, L. W.; Huchra, J. P.; Raymond, J. C.; Smith, G. H.; Soderblom, D. R.

1985-01-01

As part of its Ultraviolet Studies of Astronomical Sources the Smithsonian Astrophysical Observatory for the period 1 Feb. 1985 to 31 July 1985 observed the following: the Cygnus Loop; oxygen-rich supernova remnants in 1E0102-72; the Large Magellanic Cloud supernova remnants; P Cygni profiles in dwarf novae; soft X-ray photoionization of interstellar gas; spectral variations in AM Her stars; the mass of Feige 24; atmospheric inhomogeneities in Lambda Andromedae and FF Aquarii; photometric and spectroscopic observation of Capella; Alpha Orionis; metal deficient giant stars; M 67 giants; high-velocity winds from giant stars; accretion disk parameters in cataclysmic variables; chromospheric emission of late-type dwarfs in visual binaries; chromospheres and transient regions of stars in the Ursa Major group; and low-metallicity blue galaxies.

The development of a tunable, single-frequency ultraviolet laser source for UV filtered Rayleigh scattering

NASA Technical Reports Server (NTRS)

Finkelstein, N.; Gambogi, J.; Lempert, Walter R.; Miles, Richard B.; Rines, G. A.; Finch, A.; Schwarz, R. A.

1995-01-01

We present the development of a flexible, high power, narrow line width, tunable ultraviolet source for diagnostic application. By frequency tripling the output of a pulsed titanium-sapphire laser, we achieve broadly tunable (227-360 nm) ultraviolet light with high quality spatial and spectral resolution. We also present the characterization of a mercury vapor cell which provides a narrow band, sharp edge absorption filter at 253.7 nm. These two components form the basis for the extension of the Filtered Rayleigh Scattering technique into the ultraviolet. The UV-FRS system is comprised of four pieces: a single frequency, cw tunable Ti:Sapphire seeding source; a high-powered pulsed Ti:Sapphire oscillator; a third harmonic generator system; and an atomic mercury vapor filter. In this paper we discuss the development and characterization of each of these elements.

Outgassing Measurements for Three Materials, Combined with Vacuum Ultraviolet Radiation Illumination of the Volatile Condensable Materials

NASA Technical Reports Server (NTRS)

Albyn, Keith

2005-01-01

The photolysis of three organic materials, by vacuum ultraviolet (VUV) radiation, has been quantified using 15-MHz temperature-controlled quartz microbalances (TQCM's). The rate at which molecular species, released from the individual samples, condensed on two TQCM s was measured for periods of up to 139.9-hours. The individual samples were heated in an effusion cell and the emitted molecular species collected on a pair of TQCM's which were maintained at -40 degrees Celsius. At several points during the deposition measurement, the deposition surface of one TQCM was illuminated by a 30 Watt deuterium lamp, and the loss of material from that surface was observed. V W illumination of the TQCM, concurrent with condensation, reduced the rate that material was lost from the deposition surface. These measurements present a contrasting picture of molecular deposition, in the presence of VUV, to that presented by other investigators who observed an enhanced rate of molecular deposition, when the deposition surface was illuminated by VUV.

Measurement of the vacuum-ultraviolet absorption spectrum of low-k dielectrics using X-ray reflectivity

NASA Astrophysics Data System (ADS)

Choudhury, F. A.; Nguyen, H. M.; King, S. W.; Lee, C. H.; Lin, Y. H.; Fung, H. S.; Chen, C. C.; Li, W.; Benjamin, D.; Blatz, J. M.; Nishi, Y.; Shohet, J. L.

2018-02-01

During plasma processing, low-k dielectrics are exposed to high levels of vacuum ultraviolet (VUV) radiation that can cause severe damage to dielectric materials. The degree and nature of VUV-induced damage depend on the VUV photon energies and fluence. In this work, we examine the VUV-absorption spectrum of low-k organosilicate glass using specular X-ray reflectivity (XRR). Low-k SiCOH films were exposed to synchrotron VUV radiation with energies ranging from 7 to 21 eV, and the density vs. depth profile of the VUV-irradiated films was extracted from fitting the XRR experimental data. The results show that the depth of the VUV-induced damage layer is a function of the photon energy. Between 7 and 11 eV, the depth of the damaged layer decreases sharply from 110 nm to 60 nm and then gradually increases to 85 nm at 21 eV. The maximum VUV absorption in low-k films occurs between 11 and 15 eV. The depth of the damaged layer was found to increase with film porosity.

Broadband reflectance coatings for vacuum ultraviolet application

NASA Technical Reports Server (NTRS)

Herzig, Howard; Fleetwood, C. M., Jr.; Flint, B. K.

1987-01-01

An experimental investigation has obtained results indicating that neither LaF3 nor LiYF4 are acceptable alternatives to MgF2 as coatings for vacuum-deposited aluminum mirrors from which high UV reflectance down to 1150 A is required. Nevertheless, LaF3 may prove useful in those specialized applications in which the suppression of lower wavelength emissions, such as the 1216-A hydrogen line, is desirable.

A technique for synergistic atomic oxygen and vacuum ultraviolet radiation durability evaluation of materials for use in LEO

NASA Technical Reports Server (NTRS)

Rutledge, Sharon K.; Banks, Bruce A.

1996-01-01

Material erosion data collected during flight experiments such as the Environmental Oxygen Interaction with Materials (EOIM)-3 and the Long Duration Exposure Facility (LDEF) have raised questions as to the sensitivity of material erosion to levels of atomic oxygen exposure and vacuum ultraviolet (VUV) radiation. The erosion sensitivity of some materials such as FEP Teflon used as a thermal control material on satellites in low Earth orbit (LEO), is particularly important but difficult to determine. This is in large part due to the inability to hold all but one exposure parameter constant during a flight experiment. This is also difficult to perform in a ground based facility, because often the variation of the level of atomic oxygen or VUV radiation also results in a change in the level of the other parameter. A facility has been developed which allows each parameter to be changed almost independently and offer broad area exposure. The resulting samples can be made large enough for mechanical testing. The facility uses an electron cyclotron resonance plasma source to provide the atomic oxygen. A series of glass plates is used to focus the atomic oxygen while filtering the VUV radiation from the plasma source. After filtering, atomic oxygen effective flux levels can still be measured which are as high as 7 x 10(exp 15) atoms/cm(exp 2)-sec which is adequate for accelerated testing. VUV radiation levels after filtering can be as low as 0.3 suns. Additional VUV suns can be added with the use of deuterium lamps which allow the VUV level to be changed while keeping the flux of atomic oxygen constant. This paper discusses the facility, and results from exposure of Kapton and FEP at pre-determined atomic oxygen flux and VUV sun levels.

Quantification of isomerically summed hydrocarbon contributions to crude oil by carbon number, double bond equivalent, and aromaticity using gas chromatography with tunable vacuum ultraviolet ionization.

PubMed

Nowak, Jeremy A; Weber, Robert J; Goldstein, Allen H

2018-03-12

The ability to structurally characterize and isomerically quantify crude oil hydrocarbons relevant to refined fuels such as motor oil, diesel, and gasoline represents an extreme challenge for chromatographic and mass spectrometric techniques. This work incorporates two-dimensional gas chromatography coupled to a tunable vacuum ultraviolet soft photoionization source, the Chemical Dynamics Beamline 9.0.2 of the Advanced Light Source at the Lawrence Berkeley National Laboratory, with a time-of-flight mass spectrometer (GC × GC-VUV-TOF) to directly characterize and isomerically sum the contributions of aromatic and aliphatic species to hydrocarbon classes of four crude oils. When the VUV beam is tuned to 10.5 ± 0.2 eV, both aromatic and aliphatic crude oil hydrocarbons are ionized to reveal the complete chemical abundance of C 9 -C 30 hydrocarbons. When the VUV beam is tuned to 9.0 ± 0.2 eV only aromatic hydrocarbons are ionized, allowing separation of the aliphatic and aromatic fractions of the crude oil hydrocarbon chemical classes in an efficient manner while maintaining isomeric quantification. This technique provides an effective tool to determine the isomerically summed aromatic and aliphatic hydrocarbon compositions of crude oil, providing information that goes beyond typical GC × GC separations of the most dominant hydrocarbon isomers.

Internal motion in high vacuum systems

NASA Astrophysics Data System (ADS)

Frank, J. M.

Three transfer and positioning mechanisms have been developed for the non-air exposed, multistep processing of components in vacuum chambers. The functions to be performed in all of the systems include ultraviolet/ozone cleaning, vacuum baking, deposition of thin films, and thermocompression sealing of the enclosures. Precise positioning of the components is required during the evaporation and sealing processes. The three methods of transporting and positioning the components were developed to accommodate the design criteria and goals of each individual system. The design philosophy, goals, and operation of the three mechanisms are discussed.

Far Ultraviolet Spectroscopy of Saturn's Icy Moon Rhea

NASA Astrophysics Data System (ADS)

Elowitz, Mark; Hendrix, Amanda; Mason, Nigel J.; Sivaraman, Bhalamurugan

2018-01-01

We present an analysis of spatially resolved, far-UV reflectance spectra of Saturn’s icy satellite Rhea, collected by the Cassini Ultraviolet Imaging Spectrograph (UVIS). In recent years ultraviolet spectroscopy has become an important tool for analysing the icy satellites of the outer solar system (1Hendrix & Hansen, 2008). Far-UV spectroscopy provides unique information about the molecular structure and electronic transitions of chemical species. Many molecules that are suspected to be present in the icy surfaces of moons in the outer solar system have broad absorption features due to electronic transitions that occur in the far-UV portion of the spectrum. The studies show that Rhea, like the other icy satellites of the Saturnian system are dominated by water-ice as evident by the 165-nm absorption edge, with minor UV absorbing contaminants. Far-UV spectra of several Saturnian icy satellites, including Rhea and Dione, show an unexplained weak absorption feature centered near 184 nm. To carry out the geochemical survey of Rhea’s surface, the UVIS observations are compared with vacuum-UV spectra of thin-ice samples measured in laboratory experiments. Thin film laboratory spectra of water-ice and other molecular compounds in the solid phase were collected at near-vacuum conditions and temperatures identical to those at the surface of Rhea. Comparison between the observed far-UV spectra of Rhea’s surface ice and modelled spectra based on laboratory absorption measurements of different non-water-ice compounds show that two possible chemical compounds could explain the 184-nm absorption feature. The two molecular compounds include simple chlorine molecules and hydrazine monohydrate. Attempts to explain the source(s) of these compounds on Rhea and the scientific implications of their possible discovery will be summarized.[1] Hendrix, A. R. & Hansen, C. J. (2008). Icarus, 193, pp. 323-333.

Advanced Photon Source accelerator ultrahigh vacuum guide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, C.; Noonan, J.

1994-03-01

In this document the authors summarize the following: (1) an overview of basic concepts of ultrahigh vacuum needed for the APS project, (2) a description of vacuum design and calculations for major parts of APS, including linac, linac waveguide, low energy undulator test line, positron accumulator ring (PAR), booster synchrotron ring, storage ring, and insertion devices, and (3) cleaning procedures of ultrahigh vacuum (UHV) components presently used at APS.

A new endstation at the Swiss Light Source for ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy measurements of liquid solutions.

PubMed

Brown, Matthew A; Redondo, Amaia Beloqui; Jordan, Inga; Duyckaerts, Nicolas; Lee, Ming-Tao; Ammann, Markus; Nolting, Frithjof; Kleibert, Armin; Huthwelker, Thomas; Müächler, Jean-Pierre; Birrer, Mario; Honegger, Juri; Wetter, Reto; Wörner, Hans Jakob; van Bokhoven, Jeroen A

2013-07-01

A new liquid microjet endstation designed for ultraviolet (UPS) and X-ray (XPS) photoelectron, and partial electron yield X-ray absorption (XAS) spectroscopies at the Swiss Light Source is presented. The new endstation, which is based on a Scienta HiPP-2 R4000 electron spectrometer, is the first liquid microjet endstation capable of operating in vacuum and in ambient pressures up to the equilibrium vapor pressure of liquid water at room temperature. In addition, the Scienta HiPP-2 R4000 energy analyzer of this new endstation allows for XPS measurements up to 7000 eV electron kinetic energy that will enable electronic structure measurements of bulk solutions and buried interfaces from liquid microjet samples. The endstation is designed to operate at the soft X-ray SIM beamline and at the tender X-ray Phoenix beamline. The endstation can also be operated using a Scienta 5 K ultraviolet helium lamp for dedicated UPS measurements at the vapor-liquid interface using either He I or He II α lines. The design concept, first results from UPS, soft X-ray XPS, and partial electron yield XAS measurements, and an outlook to the potential of this endstation are presented.

Vacuum system for room temperature X-ray lithography source (XLS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schuchman, J.C.

1988-09-30

A prototype room-temperature X-Ray Lithography Source (XLS)was proposed to be built at Brookhaven National Laboratory as part of a technology-transfer- to-American-industry program. The overall machine comprises a full energy linac, a 170 meter long transport line, and a 39 meter circumference storage ring. The scope of this paper will be limited to describing the storage ring vacuum system. (AIP)

Vacuum system for room temperature X-ray lithography source (XLS)

NASA Astrophysics Data System (ADS)

Schuchman, J. C.

1988-09-01

A prototype room-temperature X-Ray Lithography Source (XLS)was proposed to be built at Brookhaven National Laboratory as part of a technology-transfer- to-American-industry program. The overall machine comprises a full energy linac, a 170 meter long transport line, and a 39 meter circumference storage ring. The scope of this paper will be limited to describing the storage ring vacuum system. (AIP)

Solid state direct bonding of polymers by vacuum ultraviolet light below 160 nm

NASA Astrophysics Data System (ADS)

Hashimoto, Yuki; Yamamoto, Takatoki

2017-10-01

This work investigated the application of vacuum ultraviolet (VUV) irradiation to the bonding of various substrates, including glass, polycarbonate (PC), cyclic olefin polymer (COP), polydimethylsiloxane (PDMS) and polymethyl methacrylate (PMMA). This method has the advantage of being able to bond various substrates without the application of heat or adhesives, and therefore may be very useful in the fabrication of micro/nanoscale structures composed of polymers. In contrast to previous applications of this technique, the present study used VUV radiation at wavelengths at and below 160 nm so as to take advantage of the higher energy in this range. Bonding was assessed based on measuring the shear stress of various test specimens subjected to VUV irradiation and then pressed together, and a number of analytical methods were also employed to examine the irradiated surfaces in order to elucidate the morphological and chemical changes following VUV treatment. These analyses included water contact angle measurements, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), time of flight secondary ion mass spectrometry (TOF-SIMS) and atomic force microscopy (AFM). Poor bonding was identified between combinations consisting of PMMA/PC, PMMA/COP, PMMA/PMMA, PMMA/glass, and PC/COP, whereas all other combinations resulted in successful bonding with the bonding stress values such as PC/PC = 2.0 MPa, PC/glass = 10.7 MPa and COP/COP = 1.7 MPa, respectively.

Vacuum cleaner emissions as a source of indoor exposure to airborne particles and bacteria.

PubMed

Knibbs, Luke D; He, Congrong; Duchaine, Caroline; Morawska, Lidia

2012-01-03

Vacuuming can be a source of indoor exposure to biological and nonbiological aerosols, although there are few data that describe the magnitude of emissions from the vacuum cleaner itself. We therefore sought to quantify emission rates of particles and bacteria from a large group of vacuum cleaners and investigate their potential determinants, including temperature, dust bags, exhaust filters, price, and age. Emissions of particles between 0.009 and 20 μm and bacteria were measured from 21 vacuums. Ultrafine (<100 nm) particle emission rates ranged from 4.0 × 10(6) to 1.1 × 10(11) particles min(-1). Emission of 0.54-20 μm particles ranged from 4.0 × 10(4) to 1.2 × 10(9) particles min(-1). PM(2.5) emissions were between 2.4 × 10(-1) and 5.4 × 10(3) μg min(-1). Bacteria emissions ranged from 0 to 7.4 × 10(5) bacteria min(-1) and were poorly correlated with dust bag bacteria content and particle emissions. Large variability in emission of all parameters was observed across the 21 vacuums, which was largely not attributable to the range of determinant factors we assessed. Vacuum cleaner emissions contribute to indoor exposure to nonbiological and biological aerosols when vacuuming, and this may vary markedly depending on the vacuum used.

Highly coherent vacuum ultraviolet radiation at the 15th harmonic with echo-enabled harmonic generation technique

NASA Astrophysics Data System (ADS)

Hemsing, E.; Dunning, M.; Hast, C.; Raubenheimer, T. O.; Weathersby, S.; Xiang, D.

2014-07-01

X-ray free-electron lasers are enabling access to new science by producing ultrafast and intense x rays that give researchers unparalleled power and precision in examining the fundamental nature of matter. In the quest for fully coherent x rays, the echo-enabled harmonic generation technique is one of the most promising methods. In this technique, coherent radiation at the high harmonic frequencies of two seed lasers is generated from the recoherence of electron beam phase space memory. Here we report on the generation of highly coherent and stable vacuum ultraviolet radiation at the 15th harmonic of an infrared seed laser with this technique. The experiment demonstrates two distinct advantages that are intrinsic to the highly nonlinear phase space gymnastics of echo-enabled harmonic generation in a new regime, i.e., high frequency up-conversion efficiency and insensitivity to electron beam phase space imperfections. Our results allow comparison and confirmation of predictive models and scaling laws, and mark a significant step towards fully coherent x-ray free-electron lasers that will open new scientific research.

Preparation of Mirror Coatings for the Vacuum Ultraviolet in a 2-m Evaporator.

PubMed

Bradford, A P; Hass, G; Osantowski, J F; Toft, A R

1969-06-01

The design and features of a 2-m evaporator suitable for coating large mirrors uniformly with Al + MgF(2) and Al + LiF films of high reflectance in the vacuum uv are described. The techniques used for monitoring film thicknesses during the film deposition and for producing films of uniform thicknesses over large areas are discussed. It is shown that the Al films for MgF(2)_ and LiF-protected mirrors of highest reflectance in the vacuum uv down to 1000 A should be 700-800 A thick. Data on the vacuum uv reflectance of Al coated with MgF(2) films of various thicknesses are presented. It was found that mirror coatings prepared in a large evaporator have a higher reflectance in the vacuum uv than those deposited under the same vacuum and deposition conditions in a small vacuum unit. At lambda = 1216 A, the reflectance of Al overcoated with 250 A of MgF(2) was measured to be about 85%.

Reflection polarizers for the vacuum ultraviolet using Al + MgF2 mirrors and an MgF2 plate

NASA Technical Reports Server (NTRS)

Hass, G.; Hunter, W. R.

1978-01-01

Consideration is given to the design and operation of a three-mirror reflecting polarizer where one of the reflecting surfaces is an MgF2 plate, the other surfaces are Al + MgF2 coatings, and one reflection occurs at or near the true Brewster angle. It is found that the polarizer is most efficient in the 1200-2000 A wavelength region, and that by optimum selection of the angle of incidence on the MgF2 plate, polarization values of 100 and over are yielded from 900 to 3000 A. The polarizer may be used at wavelengths as short as 500 A, although it is observed that at such wavelengths the polarization value decreases to about 10. It is noted that all reflecting polarizers operating in the vacuum ultraviolet wavelength may manifest changing characteristics as their mirrors become contaminated, and that polarization must therefore be occasionally remeasured.

Optimizing laser produced plasmas for efficient extreme ultraviolet and soft X-ray light sources

NASA Astrophysics Data System (ADS)

Sizyuk, Tatyana; Hassanein, Ahmed

2014-08-01

Photon sources produced by laser beams with moderate laser intensities, up to 1014 W/cm2, are being developed for many industrial applications. The performance requirements for high volume manufacture devices necessitate extensive experimental research supported by theoretical plasma analysis and modeling predictions. We simulated laser produced plasma sources currently being developed for several applications such as extreme ultraviolet lithography using 13.5% ± 1% nm bandwidth, possibly beyond extreme ultraviolet lithography using 6.× nm wavelengths, and water-window microscopy utilizing 2.48 nm (La-α) and 2.88 nm (He-α) emission. We comprehensively modeled plasma evolution from solid/liquid tin, gadolinium, and nitrogen targets as three promising materials for the above described sources, respectively. Results of our analysis for plasma characteristics during the entire course of plasma evolution showed the dependence of source conversion efficiency (CE), i.e., laser energy to photons at the desired wavelength, on plasma electron density gradient. Our results showed that utilizing laser intensities which produce hotter plasma than the optimum emission temperatures allows increasing CE for all considered sources that, however, restricted by the reabsorption processes around the main emission region and this restriction is especially actual for the 6.× nm sources.

Sources and measurement of ultraviolet radiation.

PubMed

Diffey, Brian L

2002-09-01

Ultraviolet (UV) radiation is part of the electromagnetic spectrum. The biological effects of UV radiation vary enormously with wavelength and for this reason the UV spectrum is further subdivided into three regions: UVA, UVB, and UVC. Quantities of UV radiation are expressed using radiometric terminology. A particularly important term in clinical photobiology is the standard erythema dose (SED), which is a measure of the erythemal effectiveness of a UV exposure. UV radiation is produced either by heating a body to an incandescent temperature, as is the case with solar UV, or by passing an electric current through a gas, usually vaporized mercury. The latter process is the mechanism whereby UV radiation is produced artificially. Both the quality (spectrum) and quantity (intensity) of terrestrial UV radiation vary with factors including the elevation of the sun above the horizon and absorption and scattering by molecules in the atmosphere, notably ozone, and by clouds. For many experimental studies in photobiology it is simply not practicable to use natural sunlight and so artificial sources of UV radiation designed to simulate the UV component of sunlight are employed; these are based on either optically filtered xenon arc lamps or fluorescent lamps. The complete way to characterize an UV source is by spectroradiometry, although for most practical purposes a detector optically filtered to respond to a limited portion of the UV spectrum normally suffices.

Deep ultraviolet semiconductor light sources for sensing and security

NASA Astrophysics Data System (ADS)

Shatalov, Max; Bilenko, Yuri; Yang, Jinwei; Gaska, Remis

2009-09-01

III-Nitride based deep ultraviolet (DUV) light emitting diodes (LEDs) rapidly penetrate into sensing market owing to several advantages over traditional UV sources (i.e. mercury, xenon and deuterium lamps). Small size, a wide choice of peak emission wavelengths, lower power consumption and reduced cost offer flexibility to system integrators. Short emission wavelength offer advantages for gas detection and optical sensing systems based on UV induced fluorescence. Large modulation bandwidth for these devices makes them attractive for frequency-domain spectroscopy. We will review present status of DUV LED technology and discuss recent advances in short wavelength emitters and high power LED lamps.

Radiometric calibration of the vacuum-ultraviolet spectrograph SUMER on the SOHO spacecraft with the B detector.

PubMed

Schühle, U; Curdt, W; Hollandt, J; Feldman, U; Lemaire, P; Wilhelm, K

2000-01-20

The Solar Ultraviolet Measurement of Emitted Radiation (SUMER) vacuum-ultraviolet spectrograph was calibrated in the laboratory before the integration of the instrument on the Solar and Heliospheric Observatory (SOHO) spacecraft in 1995. During the scientific operation of the SOHO it has been possible to track the radiometric calibration of the SUMER spectrograph since March 1996 by a strategy that employs various methods to update the calibration status and improve the coverage of the spectral calibration curve. The results for the A Detector were published previously [Appl. Opt. 36, 6416 (1997)]. During three years of operation in space, the B detector was used for two and one-half years. We describe the characteristics of the B detector and present results of the tracking and refinement of the spectral calibration curves with it. Observations of the spectra of the stars alpha and rho Leonis permit an extrapolation of the calibration curves in the range from 125 to 149.0 nm. Using a solar coronal spectrum observed above the solar disk, we can extrapolate the calibration curves by measuring emission line pairs with well-known intensity ratios. The sensitivity ratio of the two photocathode areas can be obtained by registration of many emission lines in the entire spectral range on both KBr-coated and bare parts of the detector's active surface. The results are found to be consistent with the published calibration performed in the laboratory in the wavelength range from 53 to 124 nm. We can extrapolate the calibration outside this range to 147 nm with a relative uncertainty of ?30% (1varsigma) for wavelengths longer than 125 nm and to 46.5 nm with 50% uncertainty for the short-wavelength range below 53 nm.

Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.

Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicatemore » the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. Finally, an intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.« less

Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

NASA Astrophysics Data System (ADS)

Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.; Leone, Stephen R.

2016-01-01

Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicate the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. An intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.

Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

DOE PAGES

Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.; ...

2016-01-18

Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicatemore » the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. Finally, an intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.« less

Comparison of surface vacuum ultraviolet emissions with resonance level number densities. II. Rare-gas plasmas and Ar-molecular gas mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boffard, John B., E-mail: jboffard@wisc.edu; Lin, Chun C.; Wang, Shicong

2015-03-15

Vacuum ultraviolet (VUV) emissions from excited plasma species can play a variety of roles in processing plasmas, including damaging the surface properties of materials used in semiconductor processing. Depending on their wavelength, VUV photons can easily transmit thin upper dielectric layers and affect the electrical characteristics of the devices. Despite their importance, measuring VUV fluxes is complicated by the fact that few materials transmit at VUV wavelengths, and both detectors and windows are easily damaged by plasma exposure. The authors have previously reported on measuring VUV fluxes in pure argon plasmas by monitoring the concentrations of Ar(3p{sup 5}4s) resonance atomsmore » that produce the VUV emissions using noninvasive optical emission spectroscopy in the visible/near-infrared wavelength range [Boffard et al., J. Vac. Sci. Technol., A 32, 021304 (2014)]. Here, the authors extend this technique to other rare-gases (Ne, Kr, and Xe) and argon-molecular gas plasmas (Ar/H{sub 2}, Ar/O{sub 2}, and Ar/N{sub 2}). Results of a model for VUV emissions that couples radiation trapping and the measured rare-gas resonance level densities are compared to measurements made with both a calibrated VUV photodiode and a sodium salicylate fluorescence detection scheme. In these more complicated gas mixtures, VUV emissions from a variety of sources beyond the principal resonance levels of the rare gases are found to contribute to the total VUV flux.« less

Vacuum and ultraviolet radiation effects on binders and pigments for spacecraft thermal control coatings

NASA Technical Reports Server (NTRS)

Progar, D. J.; Wade, W. R.

1971-01-01

An evaluation of several silicone resin binders and powdered inorganic pigments for potential use in spacecraft thermal-control paint formulations is presented. The pigments were selected on the basis of a hypothesis relating the heat of formation of a compound to the compound's resistance to ultra-radiation-induced degradation. Reflectance measurements were made in situ to determine degradation rates due to ultraviolet radiation. The tested polydimethylsiloxane resins were not significantly affected by long exposures to ultraviolet radiation. All the pigments, which were dispersed in a polydimethylsiloxane resin, were degraded by ultraviolet radiation as determined by an increase of solar absorptance. For the materials evaluated in this study, no evidence was found to indicate that pigments with high heats of formation were resistant to ultraviolet degradation.

Vacuum ultra-violet damage and damage mitigation for plasma processing of highly porous organosilicate glass dielectrics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marneffe, J.-F. de, E-mail: marneffe@imec.be; Lukaszewicz, M.; Porter, S. B.

2015-10-07

Porous organosilicate glass thin films, with k-value 2.0, were exposed to 147 nm vacuum ultra-violet (VUV) photons emitted in a Xenon capacitive coupled plasma discharge. Strong methyl bond depletion was observed, concomitant with a significant increase of the bulk dielectric constant. This indicates that, besides reactive radical diffusion, photons emitted during plasma processing do impede dielectric properties and therefore need to be tackled appropriately during patterning and integration. The detrimental effect of VUV irradiation can be partly suppressed by stuffing the low-k porous matrix with proper sacrificial polymers showing high VUV absorption together with good thermal and VUV stability. In addition,more » the choice of an appropriate hard-mask, showing high VUV absorption, can minimize VUV damage. Particular processing conditions allow to minimize the fluence of photons to the substrate and lead to negligible VUV damage. For patterned structures, in order to reduce VUV damage in the bulk and on feature sidewalls, the combination of both pore stuffing/material densification and absorbing hard-mask is recommended, and/or the use of low VUV-emitting plasma discharge.« less

The efficacy of post porosity plasma protection against vacuum-ultraviolet damage in porous low-k materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lionti, K.; Volksen, W.; Darnon, M.

2015-03-21

As of today, plasma damage remains as one of the main challenges to the reliable integration of porous low-k materials into microelectronic devices at the most aggressive node. One promising strategy to limit damage of porous low-k materials during plasma processing is an approach we refer to as post porosity plasma protection (P4). In this approach, the pores of the low-k material are filled with a sacrificial agent prior to any plasma treatment, greatly minimizing the total damage by limiting the physical interactions between plasma species and the low-k material. Interestingly, the contribution of the individual plasma species to themore » total plasma damage is not fully understood. In this study, we investigated the specific damaging effect of vacuum-ultraviolet (v-UV) photons on a highly porous, k = 2.0 low-k material and we assessed the P4 protective effect against them. It was found that the impact of the v-UV radiation varied depending upon the v-UV emission lines of the plasma. More importantly, we successfully demonstrated that the P4 process provides excellent protection against v-UV damage.« less

Degradation of organic pollutants by Vacuum-Ultraviolet (VUV): Kinetic model and efficiency.

PubMed

Xie, Pengchao; Yue, Siyang; Ding, Jiaqi; Wan, Ying; Li, Xuchun; Ma, Jun; Wang, Zongping

2018-04-15

Vacuum-Ultraviolet (VUV), an efficient and green method to produce hydroxyl radical (•OH), is effective in degrading numerous organic contaminants in aqueous solution. Here, we proposed an effective and simple kinetic model to describe the degradation of organic pollutants in VUV system, by taking the •OH scavenging effects of formed organic intermediates as co-existing organic matter in whole. Using benzoic acid (BA) as a •OH probe, •OH was regarded vital for pollutant degradation in VUV system, and the thus developed model successfully predicted its degradation kinetics under different conditions. Effects of typical influencing factors such as BA concentrations and UV intensity were investigated quantitatively by the model. Temperature was found to be an important influencing factor in the VUV system, and the quantum yield of •OH showed a positive linear dependence on temperature. Impacts of humic acid (HA), alkalinity, chloride, and water matrices (realistic waters) on the oxidation efficiency were also examined. BA degradation was significantly inhibited by HA due to its scavenging of •OH, but was influenced much less by the alkalinity and chloride; high oxidation efficiency was still obtained in the realistic water. The degradation kinetics of three other typical micropollutants including bisphenol A (BPA), nitrobenzene (NB) and dimethyl phthalate (DMP), and the mixture of co-existing BA, BPA and DMP were further studied, and the developed model predicted the experimental data well, especially in realistic water. It is expected that this study will provide an effective approach to predict the degradation of organic micropollutants by the promising VUV system, and broaden the application of VUV system in water treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow

NASA Technical Reports Server (NTRS)

Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

1993-01-01

A NASA sounding rocket experiment was developed to study the solar extreme ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far ultraviolet (FUV) were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University (Supriya Chakrabarti), but only the National Center for Atmospheric Research (NCAR)/University of Colorado (CU) four solar instruments and one airglow instrument are discussed here. The primary solar EUV instrument is a 1/4 meter Rowland circle EUV spectrograph which has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2 nm resolution. Another solar irradiance instrument is an array of six silicon XUV photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with about 15 nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc-seconds. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2 nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates. The one-dimensional and two-dimensional CODACON detectors were developed at CU by Dr. George Lawrence. The pre-flight and post-flight photometric calibrations were performed at our calibration laboratory and at the Synchrotron Ultraviolet

Electronic state spectroscopy by high-resolution vacuum ultraviolet photoabsorption, He(I) photoelectron spectroscopy and ab initio calculations of ethyl acetate

NASA Astrophysics Data System (ADS)

Śmialek, Malgorzata A.; Łabuda, Marta; Guthmuller, Julien; Hubin-Franskin, Marie-Jeanne; Delwiche, Jacques; Hoffmann, Søren Vrønning; Jones, Nykola C.; Mason, Nigel J.; Limão-Vieira, Paulo

2016-06-01

The high-resolution vacuum ultraviolet photoabsorption spectrum of ethyl acetate, C4H8O2, is presented over the energy range 4.5-10.7 eV (275.5-116.0 nm). Valence and Rydberg transitions and their associated vibronic series observed in the photoabsorption spectrum, have been assigned in accordance with new ab initio calculations of the vertical excitation energies and oscillator strengths. Also, the photoabsorption cross sections have been used to calculate the photolysis lifetime of this ester in the upper stratosphere (20-50 km). Calculations have also been carried out to determine the ionisation energies and fine structure of the lowest ionic state of ethyl acetate and are compared with a newly recorded photoelectron spectrum (from 9.5 to 16.7 eV). Vibrational structure is observed in the first photoelectron band of this molecule for the first time.

21 CFR 884.4340 - Fetal vacuum extractor.

Code of Federal Regulations, 2011 CFR

2011-04-01

... means of a suction cup attached to the scalp and is powered by an external vacuum source. This generic type of device may include the cup, hosing, vacuum source, and vacuum control. (b) Classification...

21 CFR 884.4340 - Fetal vacuum extractor.

Code of Federal Regulations, 2010 CFR

2010-04-01

... means of a suction cup attached to the scalp and is powered by an external vacuum source. This generic type of device may include the cup, hosing, vacuum source, and vacuum control. (b) Classification...

Ultraviolet radiation induced discharge laser

DOEpatents

Gilson, Verle A.; Schriever, Richard L.; Shearer, James W.

1978-01-01

An ultraviolet radiation source associated with a suitable cathode-anode electrode structure, disposed in a gas-filled cavity of a high pressure pulsed laser, such as a transverse electric atmosphere (TEA) laser, to achieve free electron production in the gas by photoelectric interaction between ultraviolet radiation and the cathode prior to the gas-exciting cathode-to-anode electrical discharge, thereby providing volume ionization of the gas. The ultraviolet radiation is produced by a light source or by a spark discharge.

Ultraviolet Changes of the Central Source and the Very Nearby Ejecta

NASA Technical Reports Server (NTRS)

Gull, Theodore R.; Nielsen, Krister; Vierira, Gladys; Hillier, John; Walborn, Nolan; Davidson, Kris

2004-01-01

We utilized the high spatial and high spectral resolution of the HST/STIS MAMA echelle modes in the ultraviolet (0.025 inch spatial resolution and 30,000 to 120,000 spectral resolving power) to view changes in and around Eta Carinae before and after the X-Ray drop which occurred on June 29, 2003 (M. Corcoran, IAUC 8160). Major changes in the spectra of the Central Source and nearby nebulosities occurred between June 22 and July 5. Visibility of the Central Source dropped, especially between 1175 and 1350 Angstroms, but not uniformly throughout the ultraviolet. This fading is likely due to multiple line absorptions both in the source and in the intervening ejecta. Nebular emission of Si III] and Fe III, located 0.09 sec. to the west, disappeared. By July 29, a bright feature extending up to 0.071 sec. east of the Central Source became prominent in broad emission lines near 2500 Angstroms, but was not noticeable longward of 2900 Angstroms. ACS/HRC imagery and STIS CCD spectra taken concurrently are being examined for larger scale changes. Numerous narrow velocity components between -146 and -585 kilometers per second were identified in spectra before the minimum. New components appeared primarily in Fe II absorption lines with velocities between -170 and -380 kilometers per second. While the lines of the -513 kilometers per second component did not change, most lines of the -146 kilometers per second component changed considerably. Lines originating from high energy levels diminished or disappeared, while lines originating from lower energy levels strengthened. Strong absorption lines of Ti II, not present before the X-Ray drop, appeared within seven days, but disappeared by July 29. Further analysis of these unprecedented data will provide significant new information about the structure of Eta Carinae and its periodic variations.

Engineering support for an ultraviolet imager for the ISTP mission

NASA Technical Reports Server (NTRS)

Torr, Douglas G.

1991-01-01

Design and development activities were carried out for the Ultraviolet Imager (UVI) to be flown on the Polar Spacecraft of the INternational Solar Terrestrial Physics (ISTP) Mission. The following tasks were performed: (1) design and fabrication of prototype/engineering model of the UVI imager; (2) preliminary design review; (3) vacuum ultraviolet filter design; (4) auroral energy deposition code; (5) model of LBH vehicle glow; (6) laboratory measurement program of collision cross-sections; and (7) support of ISTP meetings.

Vacuum polarization in Coulomb field revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zamastil, J., E-mail: zamastil@karlov.mff.cuni.cz; Šimsa, D.

2017-04-15

Simplified derivation of Wichmann–Kroll term is presented. The derivation uses two formulas for hypergeometric functions, but otherwise is elementary. It is found that Laplace transform of the vacuum charge density diverges at zero momentum transfer. This divergence has nothing to do with known ultraviolet divergence. The latter is related to the large momentum behavior of the pertinent integral, while the former to the small momentum behavior. When these divergences are removed, the energy shift caused by vacuum polarization for an ordinary hydrogen obtained here is in an exact agreement with the result obtained by Wichmann and Kroll. Also, for muonicmore » hydrogen the result obtained here reasonably agrees with that given in literature.« less

Ultraviolet Source For Testing Hydrogen-Fire Detectors

NASA Technical Reports Server (NTRS)

Hall, Gregory A.; Larson, William E.; Youngquist, Robert C.; Moerk, John S.; Haskell, William D.; Cox, Robert B.; Polk, Jimmy D.; Stout, Stephen J.; Strobel, James P.

1995-01-01

Hand-held portable unit emits ultraviolet light similar to that emitted by hydrogen burning in air. Developed for use in testing optoelectronic hydrogen-fire detectors, which respond to ultraviolet light at wavelengths from 180 to 240 nanometers. Wavelength range unique in that within it, hydrogen fires emit small but detectable amounts of radiation, light from incandescent lamps and Sun almost completely absent, and air sufficiently transmissive to enable detection of hydrogen fire from distance. Consequently, this spectral region favorable for detecting hydrogen fires while minimizing false alarms.

21 CFR 872.6350 - Ultraviolet detector.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultraviolet detector. 872.6350 Section 872.6350...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6350 Ultraviolet detector. (a) Identification. An ultraviolet detector is a device intended to provide a source of ultraviolet light which is used...

21 CFR 872.6350 - Ultraviolet detector.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ultraviolet detector. 872.6350 Section 872.6350...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6350 Ultraviolet detector. (a) Identification. An ultraviolet detector is a device intended to provide a source of ultraviolet light which is used...

21 CFR 872.6350 - Ultraviolet detector.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ultraviolet detector. 872.6350 Section 872.6350...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6350 Ultraviolet detector. (a) Identification. An ultraviolet detector is a device intended to provide a source of ultraviolet light which is used...

21 CFR 872.6350 - Ultraviolet detector.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ultraviolet detector. 872.6350 Section 872.6350...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6350 Ultraviolet detector. (a) Identification. An ultraviolet detector is a device intended to provide a source of ultraviolet light which is used...

21 CFR 872.6350 - Ultraviolet detector.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ultraviolet detector. 872.6350 Section 872.6350...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6350 Ultraviolet detector. (a) Identification. An ultraviolet detector is a device intended to provide a source of ultraviolet light which is used...

Vacuum ultraviolet emission spectrum measurement of a microwave-discharge hydrogen-flow lamp in several configurations: Application to photodesorption of CO ice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Y.-J.; Wu, C.-Y. R.; Chuang, K.-J.

2014-01-20

We report measurements of the vacuum ultraviolet (VUV) emission spectra of a microwave-discharge hydrogen-flow lamp (MDHL), a common tool in astrochemistry laboratories working on ice VUV photoprocessing. The MDHL provides hydrogen Ly-α (121.6 nm) and H{sub 2} molecular emission in the 110-180 nm range. We show that the spectral characteristics of the VUV light emitted in this range, in particular the relative proportion of Ly-α to molecular emission bands, strongly depend on the pressure of H{sub 2} inside the lamp, the lamp geometry (F type versus T type), the gas used (pure H{sub 2} versus H{sub 2} seeded in He),more » and the optical properties of the window used (MgF{sub 2} versus CaF{sub 2}). These different configurations are used to study the VUV irradiation of CO ice at 14 K. In contrast to the majority of studies dedicated to the VUV irradiation of astrophysical ice analogs, which have not taken into consideration the emission spectrum of the MDHL, our results show that the processes induced by photons in CO ice from a broad energy range are different and more complex than the sum of individual processes induced by monochromatic sources spanning the same energy range, as a result of the existence of multistate electronic transitions and discrepancy in absorption cross sections between parent molecules and products in the Ly-α and H{sub 2} molecular emission ranges.« less

Isobutyl acetate: electronic state spectroscopy by high-resolution vacuum ultraviolet photoabsorption, He(I) photoelectron spectroscopy and ab initio calculations

NASA Astrophysics Data System (ADS)

Śmiałek, Malgorzata A.; Łabuda, Marta; Hubin-Franskin, Marie-Jeanne; Delwiche, Jacques; Hoffmann, Søren Vrønning; Jones, Nykola C.; Mason, Nigel J.; Limão-Vieira, Paulo

2017-05-01

The high-resolution vacuum ultraviolet photoabsorption spectrum of isobutyl acetate, C6H12O2, is presented here and was measured over the energy range 4.3-10.8 eV (290-115 nm). Valence and Rydberg transitions with their associated vibronic series have been observed in the photoabsorption spectrum and are assigned in accordance with new ab initio calculations of the vertical excitation energies and oscillator strengths. The measured photoabsorption cross sections have been used to calculate the photolysis lifetime of this ester in the Earth's upper atmosphere (20-50 km). Calculations have also been carried out to determine the ionization energies and fine structure of the lowest ionic state of isobutyl acetate and are compared with a photoelectron spectrum (from 9.5 to 16.7 eV), recorded for the first time. Vibrational structure is observed in the first photoelectron band of this molecule. Contribution to the Topical Issue: "Dynamics of Systems at the Nanoscale", edited by Andrey Solov'yov and Andrei Korol.

Vacuum ultraviolet spectra of the late twilight airglow.

NASA Technical Reports Server (NTRS)

Buckley, J. L.; Moos, H. W.

1971-01-01

Evaluation of sounding rocket spectra of the late twilight (solar-zenith angle of 120 deg) ultraviolet airglow between 1260 and 1900 A. The only observed features are O I 1304 and 1356. When the instrument looked at an elevation of 17 deg above the western horizon, the brightnesses were 70 and 33 rayleighs, respectively. The upper limits on the total intensity of the Lyman-Birge-Hopfield and Vegard-Kaplan systems of N2 were 26 plus or minus 26 and 55 plus or minus 55 rayleighs, respectively. An estimate shows that a large part of the O I emissions may be due to excitation by conjugate-point electrons.

A thermal vacuum-UV solar simulator test system for assessing microbiological viability

NASA Technical Reports Server (NTRS)

Ross, D. S.; Wardle, M. D.; Taylor, D. M.

1975-01-01

Microorganisms were exposed to a simulated space environment in order to assess the photobiological effect of broad spectrum, nonionizing solar electromagnetic radiation in terms of viability. A thermal vacuum chamber capable of maintaining a vacuum of 0.000133n/sq m and an ultraviolet rich solar simulator were the main ingredients of the test system. Results to date indicate the system to be capable of providing reliable microbiological data.

Fourier-transform spectroscopy of HD in the vacuum ultraviolet at λ = 87-112 nm

NASA Astrophysics Data System (ADS)

Ivanov, T. I.; Dickenson, G. D.; Roudjane, M.; de Oliveira, N.; Joyeux, D.; Nahon, L.; Tchang-Brillet, W.-Ü. L.; Ubachs, W.

2010-03-01

Absorption spectroscopy in the vacuum ultraviolet (VUV) domain was performed on the hydrogen-deuteride molecule with a novel Fourier-transform spectrometer based upon wavefront division interferometry. This unique instrument, which is a permanent endstation of the undulator-based beamline DESIRS on the synchrotron SOLEIL facility, opens the way to Fourier-transform spectroscopy in the VUV range. The HD spectral lines in the Lyman and Werner bands were recorded in the 87-112 nm range from a quasi-static gas sample in a windowless configuration and with a Doppler-limited resolution. Line positions of some 268 transitions in the ? Lyman bands and 141 transitions in the ? Werner bands were deduced with uncertainties of 0.04 cm-1 (1σ) which correspond to Δλ/λ ∼ 4 × 10-7. This extensive laboratory database is of relevance for comparison with astronomical observations of H2 and HD spectra from highly redshifted objects, with the goal of extracting a possible variation of the proton-to-electron mass ratio (μ = m p /m e ) on a cosmological time scale. For this reason also calculations of the so-called sensitivity coefficients K i were performed in order to allow for deducing constraints on Δμ/μ. The K i coefficients, associated with the line shift that each spectral line undergoes as a result of a varying value for μ, were derived from calculations as a function of μ solving the Schrödinger equation using ab initio potentials.

Determination of ionization energies of CnN (n=4-12): Vacuum-ultraviolet (VUV) photoionization experiments and theoretical calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostko, Oleg; Zhou, Jia; Sun, Bian Jian

2010-06-10

Results from single photon vacuum ultraviolet photoionization of astrophysically relevant CnN clusters, n = 4 - 12, in the photon energy range of 8.0 eV to 12.8 eV are presented. The experimental photoionization efficiency curves, combined with electronic structure calculations, provide improved ionization energies of the CnN species. A search through numerous nitrogen-terminated CnN isomers for n=4-9 indicates that the linear isomer has the lowest energy, and therefore should be the most abundant isomer in the molecular beam. Comparison with calculated results also shed light on the energetics of the linear CnN clusters, particularly in the trends of the even-carbonmore » and the odd-carbon series. These results can help guide the search of potential astronomical observations of these neutral molecules together with their cations in highly ionized regions or regions with a high UV/VUV photon flux (ranging from the visible to VUV with flux maxima in the Lyman- region) in the interstellar medium.« less

Determination of ionization energies of CnN (n=4-12): Vacuum-ultraviolet (VUV) photoionization experiments and theoretical calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostko, Oleg; Zhou, Jia; Sun, Bian Jian

2010-03-02

Results from single photon vacuum ultraviolet photoionization of astrophysically relevant CnN clusters, n = 4 - 12, in the photon energy range of 8.0 eV to 12.8 eV are presented. The experimental photoionization efficiency curves, combined with electronic structure calculations, provide improved ionization energies of the CnN species. A search through numerous nitrogen-terminated CnN isomers for n=4-9 indicates that the linear isomer has the lowest energy, and therefore should be the most abundant isomer in the molecular beam. Comparison with calculated results also shed light on the energetics of the linear CnN clusters, particularly in the trends of the even-carbonmore » and the odd-carbon series. These results can help guide the search of potential astronomical observations of these neutral molecules together with their cations in highly ionized regions or regions with a high UV/VUV photon flux (ranging from the visible to VUV with flux maxima in the Lyman-a region) in the interstellar medium.« less

Evaluation of Thermal Control Coatings and Polymeric Materials Exposed to Ground Simulated Atomic Oxygen and Vacuum Ultraviolet Radiation

NASA Technical Reports Server (NTRS)

Kamenetzky, R. R.; Vaughn, J. A.; Finckenor, M. M.; Linton, R. C.

1995-01-01

Numerous thermal control and polymeric samples with potential International Space Station applications were evaluated for atomic oxygen and vacuum ultraviolet radiation effects in the Princeton Plasma Physics Laboratory 5 eV Neutral Atomic Oxygen Facility and in the MSFC Atomic Oxygen Drift Tube System. Included in this study were samples of various anodized aluminum samples, ceramic paints, polymeric materials, and beta cloth, a Teflon-impregnated fiberglass cloth. Aluminum anodizations tested were black duranodic, chromic acid anodize, and sulfuric acid anodize. Paint samples consisted of an inorganic glassy black paint and Z-93 white paint made with the original PS7 binder and the new K2130 binder. Polymeric samples evaluated included bulk Halar, bulk PEEK, and silverized FEP Teflon. Aluminized and nonaluminized Chemfab 250 beta cloth were also exposed. Samples were evaluated for changes in mass, thickness, solar absorptance, and infrared emittance. In addition to material effects, an investigation was made comparing diffuse reflectance/solar absorptance measurements made using a Beckman DK2 spectroreflectometer and like measurements made using an AZ Technology-developed laboratory portable spectroreflectometer.

Progress on the Design of the Storage Ring Vacuum System for the Advanced Photon Source Upgrade Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stillwell, B.; Billett, B.; Brajuskovic, B.

2017-06-20

Recent work on the design of the storage ring vacuum system for the Advanced Photon Source Upgrade project (APS-U) includes: revising the vacuum system design to accommodate a new lattice with reverse bend magnets, modifying the designs of vacuum chambers in the FODO sections for more intense incident synchrotron radiation power, modifying the design of rf-shielding bellows liners for better performance and reliability, modifying photon absorber designs to make better use of available space, and integrated planning of components needed in the injection, extraction and rf cavity straight sections. An overview of progress in these areas is presented.

A new membrane inlet interface of a vacuum ultraviolet lamp ionization miniature mass spectrometer for on-line rapid measurement of volatile organic compounds in air.

PubMed

Hou, Keyong; Wang, Junde; Li, Haiyang

2007-01-01

A novel membrane inlet interface coupled to a single-photon ionization (SPI) miniature time-of-flight mass spectrometer has been developed for on-line rapid measurement of volatile organic compounds (VOCs). The vacuum ultraviolet (VUV) light source for SPI was a commercial krypton discharge lamp with photon energy of 10.6 eV and photon flux of 10(10) photons/s. The experimental results showed that the sensitivity was 5 times as high as obtained with the traditional membrane inlet. The enrichment efficiency could be adjusted in the range of 10 to 20 times for different VOCs when a buffer cell was added to the inlet interface, and the memory effect was effectively eliminated. A detection limit as low as 25 parts-per-billion by volume (ppbv) for benzene has been achieved, with a linear dynamic range of three orders of magnitude. The rise times were 6 s, 10 s and 15 s for benzene, toluene and p-xylene, respectively, and the fall time was only 6 s for all of these compounds. The analytical capacity of this system was demonstrated by the on-line analysis of VOCs in single puff mainstream cigarette smoke, in which more than 50 compounds were detected in 2 s. Copyright 2007 John Wiley & Sons, Ltd.

Secondary Structure Prediction of Protein Constructs Using Random Incremental Truncation and Vacuum-Ultraviolet CD Spectroscopy

PubMed Central

Pukáncsik, Mária; Orbán, Ágnes; Nagy, Kinga; Matsuo, Koichi; Gekko, Kunihiko; Maurin, Damien; Hart, Darren; Kézsmárki, István; Vertessy, Beata G.

2016-01-01

A novel uracil-DNA degrading protein factor (termed UDE) was identified in Drosophila melanogaster with no significant structural and functional homology to other uracil-DNA binding or processing factors. Determination of the 3D structure of UDE is excepted to provide key information on the description of the molecular mechanism of action of UDE catalysis, as well as in general uracil-recognition and nuclease action. Towards this long-term aim, the random library ESPRIT technology was applied to the novel protein UDE to overcome problems in identifying soluble expressing constructs given the absence of precise information on domain content and arrangement. Nine constructs of UDE were chosen to decipher structural and functional relationships. Vacuum ultraviolet circular dichroism (VUVCD) spectroscopy was performed to define the secondary structure content and location within UDE and its truncated variants. The quantitative analysis demonstrated exclusive α-helical content for the full-length protein, which is preserved in the truncated constructs. Arrangement of α-helical bundles within the truncated protein segments suggested new domain boundaries which differ from the conserved motifs determined by sequence-based alignment of UDE homologues. Here we demonstrate that the combination of ESPRIT and VUVCD spectroscopy provides a new structural description of UDE and confirms that the truncated constructs are useful for further detailed functional studies. PMID:27273007

Real-time radiative divertor feedback control development for the NSTX-U tokamak using a vacuum ultraviolet spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soukhanovskii, V. A., E-mail: vlad@llnl.gov; Kaita, R.; Stratton, B.

2016-11-15

A radiative divertor technique is planned for the NSTX-U tokamak to prevent excessive erosion and thermal damage of divertor plasma-facing components in H-mode plasma discharges with auxiliary heating up to 12 MW. In the radiative (partially detached) divertor, extrinsically seeded deuterium or impurity gases are used to increase plasma volumetric power and momentum losses. A real-time feedback control of the gas seeding rate is planned for discharges of up to 5 s duration. The outer divertor leg plasma electron temperature T{sub e} estimated spectroscopically in real time will be used as a control parameter. A vacuum ultraviolet spectrometer McPherson Modelmore » 251 with a fast charged-coupled device detector is developed for temperature monitoring between 5 and 30 eV, based on the Δn = 0, 1 line intensity ratios of carbon, nitrogen, or neon ion lines in the spectral range 300–1600 Å. A collisional-radiative model-based line intensity ratio will be used for relative calibration. A real-time T{sub e}-dependent signal within a characteristic divertor detachment equilibration time of ∼10–15 ms is expected.« less

Real-time radiative divertor feedback control development for the NSTX-U tokamak using a vacuum ultraviolet spectrometer

DOE PAGES

Soukhanovskii, V. A.; Kaita, R.; Stratton, B.

2016-08-04

Here, a radiative divertor technique is planned for the NSTX-U tokamak to prevent excessive erosion and thermal damage of divertor plasma-facing components in H-mode plasma discharges with auxiliary heating up to 12 MW. In the radiative (partially detached) divertor, extrinsically seeded deuterium or impurity gases are used to increase plasma volumetric power and momentum losses. A real-time feedback control of the gas seeding rate is planned for discharges of up to 5 s duration. The outer divertor leg plasma electron temperature T e estimated spectroscopically in real time will be used as a control parameter. A vacuum ultraviolet spectrometer McPhersonmore » Model 251 with a fast charged-coupled device detector is developed for temperature monitoring between 5 and 30 eV, based on the Δn = 0, 1 line intensity ratios of carbon, nitrogen, or neon ion lines in the spectral range 300–1600 Å. A collisional-radiative model-based line intensity ratio will be used for relative calibration. A real-time T e-dependent signal within a characteristic divertor detachment equilibration time of ~10–15 ms is expected.« less

Ultraviolet absorption hygrometer

DOEpatents

Gersh, M.E.; Bien, F.; Bernstein, L.S.

1986-12-09

An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

IMPEDANCE MEASUREMENT OF VACUUM CHAMBER COMPONENTS FOR THE ADVANCE PHOTON SOURCE (APS) UPGRADE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sangroula, M.; Lindberg, R.; Lill, R.

2017-06-16

The proposed Advance Photon Source Upgrade (APS-U) employs a multi-bend achromat (MBA) lattice to increase the photon brightness by two to three orders of magnitude. One of the main design challenges of the upgrade is to minimize rf heating and collective instabilities associated with the impedance of small-aperture vacuum components. As part of this effort, my research focuses on impedance measurement and simulation of various MBA vacuum components. Here, we present the summary of the impedance contributions for the APS-U and describe our planned impedance measurement technique, including some measurement results for the non-evaporative getter (NEG)-coated copper chamber and simulationmore » results for other critical components using a novel Goubau line (G-line) set up.« less

Impedance measurement of vacuum chamber components for the Advance Photon Source(APS) Upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sangroula, M.; Lindberg, R.; Lill, R.

2017-01-01

The proposed Advance Photon Source Upgrade (APS-U) employs a multi-bend achromat (MBA) lattice to increase the photon brightness by two to three orders of magnitude. One of the main design challenges of the upgrade is to minimize rf heating and collective instabilities associated with the impedance of small-aperture vacuum components. As part of this effort, my research focuses on impedance measurement and simulation of various MBA vacuum components. Here, we present the summary of the impedance contributions for the APS-U and describe our planned impedance measurement technique, including some measurement results for the non-evaporative getter (NEG)-coated copper chamber and simulationmore » results for other critical components using a novel Goubau line (G-line) set up.« less

High current multicharged metal ion source using high power gyrotron heating of vacuum arc plasma.

PubMed

Vodopyanov, A V; Golubev, S V; Khizhnyak, V I; Mansfeld, D A; Nikolaev, A G; Oks, E M; Savkin, K P; Vizir, A V; Yushkov, G Yu

2008-02-01

A high current, multi charged, metal ion source using electron heating of vacuum arc plasma by high power gyrotron radiation has been developed. The plasma is confined in a simple mirror trap with peak magnetic field in the plug up to 2.5 T, mirror ratio of 3-5, and length variable from 15 to 20 cm. Plasma formed by a cathodic vacuum arc is injected into the trap either (i) axially using a compact vacuum arc plasma gun located on axis outside the mirror trap region or (ii) radially using four plasma guns surrounding the trap at midplane. Microwave heating of the mirror-confined, vacuum arc plasma is accomplished by gyrotron microwave radiation of frequency 75 GHz, power up to 200 kW, and pulse duration up to 150 micros, leading to additional stripping of metal ions by electron impact. Pulsed beams of platinum ions with charge state up to 10+, a mean charge state over 6+, and total (all charge states) beam current of a few hundred milliamperes have been formed.

Printable Top-Gate-Type Polymer Light-Emitting Transistors with Surfaces of Amorphous Fluoropolymer Insulators Modified by Vacuum Ultraviolet Light Treatment

NASA Astrophysics Data System (ADS)

Kajii, Hirotake; Terashima, Daiki; Kusumoto, Yusuke; Ikezoe, Ikuya; Ohmori, Yutaka

2013-04-01

We investigated the fabrication and electrical and optical properties of top-gate-type polymer light-emitting transistors with the surfaces of amorphous fluoropolymer insulators, CYTOP (Asahi Glass) modified by vacuum ultraviolet light (VUV) treatment. The surface energy of CYTOP, which has a good solution barrier property was increased by VUV irradiation, and the gate electrode was fabricated by solution processing on the CYTOP film using the Ag nano-ink. The influence of VUV irradiation on the optical properties of poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) films with various gate insulators was investigated to clarify the passivation effect of gate insulators. It was found that the poly(methyl methacrylate) (PMMA) film prevented the degradation of the F8BT layer under VUV irradiation because the PMMA film can absorb VUV. The solution-processed F8BT device with multilayer PMMA/CYTOP insulators utilizing a gate electrode fabricated using the Ag nano-ink exhibited both the ambipolar characteristics and yellow-green emission.

Water Treatment Using Advanced Ultraviolet Light Sources Final Report CRADA No. TC02089.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoppes, W.; Oster, S.

This was a collaborative effort between Lawrence Livermore National Security, LLC as manager and operator of Lawrence Livermore National Laboratory (LLNL) and Teknichal Services, LLC (TkS), to develop water treatment systems using advanced ultraviolet light sources. The Russian institutes involved with this project were The High Current Electronics Institute (HCEI) and Russian Institute of Technical Physics-Institute of Experimental Physics (VNIIEF). HCEI and VNIIEF developed and demonstrated the potential commercial viability of short-wavelength ultraviolet excimer lamps under a Thrust 1 Initiatives for Proliferation Prevention (IPP) Program. The goals of this collaboration were to demonstrate both the commercial viability of excilampbased watermore » disinfection and achieve further substantial operational improvement in the lamps themselves; particularly in the area of energy efficiency.« less

Line spectrum and ion temperature measurements from tungsten ions at low ionization stages in large helical device based on vacuum ultraviolet spectroscopy in wavelength range of 500-2200 Å.

PubMed

Oishi, T; Morita, S; Huang, X L; Zhang, H M; Goto, M

2014-11-01

Vacuum ultraviolet spectra of emissions released from tungsten ions at lower ionization stages were measured in the Large Helical Device (LHD) in the wavelength range of 500-2200 Å using a 3 m normal incidence spectrometer. Tungsten ions were distributed in the LHD plasma by injecting a pellet consisting of a small piece of tungsten metal and polyethylene tube. Many lines having different wavelengths from intrinsic impurity ions were observed just after the tungsten pellet injection. Doppler broadening of a tungsten candidate line was successfully measured and the ion temperature was obtained.

Ultraviolet spectrophotometry of three LINERs

NASA Technical Reports Server (NTRS)

Goodrich, R. W.; Keel, W. C.

1986-01-01

Three galaxies known to be LINERs were observed spectroscopically in the ultraviolet in an attempt to detect the presumed nonthermal continuum source thought to be the source of photoionization in the nuclei. NGC 4501 was found to be too faint for study with the IUE spectrographs, while NGC 5005 had an extended ultraviolet light profile. Comparison with the optical light profile of NGC 5005 indicates that the ultraviolet source is distributed spatially in the same manner as the optical starlight, probably indicating that the ultraviolet excess is due to a component of hot stars in the nucleus. These stars contribute detectable absorption features longward of 2500 A; together with optical data, the IUE spectra suggest a burst of star formation about 1 billion yr ago, with a lower rate continuing to produce a few OB stars. In NGC 4579, a point source contributing most of the ultraviolet excess is found that is much different than the optical light distribution. Furthermore, the ultraviolet to X-ray spectral index in NGC 4579 is 1.4, compatible with the UV to X-ray indices found for samples of Seyfert galaxies. This provides compelling evidence for the detection of the photoionizing continuum in NGC 4579 and draws the research fields of normal galaxies and active galactic nuclei closer together. The emission-line spectrum of NGC 4579 is compared with calculations from a photoionization code, CLOUDY, and several shock models. The photoionization code is found to give superior results, adding to the increasing weight of evidence that the LINER phenomenon is essentially a scaled-down version of the Seyfert phenomenon.

Fundamental investigation of ultraviolet radiation effects in polymeric film-forming materials

NASA Technical Reports Server (NTRS)

Giori, C.; Yamauchi, T.; Llewellen, P.; Gilligan, J.

1974-01-01

A literature search from 1958 to present was conducted on the effect of ultraviolet radiation on polymeric materials, with particular emphasis on vacuum photolysis, mechanisms of degradation, and energy transfer phenomena. The literature from 1958 to 1968 was searched manually, while the literature from 1968 to present was searched by using a computerized keyword system. The primary objective was to provide the necessary background information for the design of new or modified materials with improved stability to the vacuum-radiation environment of space.

Evidence for a New Class of Extreme Ultraviolet Sources

NASA Technical Reports Server (NTRS)

Maoz, Dan; Ofek, Eran O.; Shemi, Amotz

1997-01-01

Most of the sources detected in the extreme ultraviolet (EUV; 100-600 A) by the ROSAT/WFC and EUVE all-sky surveys have been identified with active late-type stars and hot white dwarfs that are near enough to the Earth to escape absorption by interstellar gas. However, about 15 per cent of EUV sources are as yet unidentified with any optical counterparts. We examine whether the unidentified EUV sources may consist of the same population of late-type stars and white dwarfs. We present B and R photometry of stars in the fields of seven of the unidentified EUV sources. We detect in the optical the entire main-sequence and white dwarf population out to the greatest distances where they could still avoid absorption. We use color-magnitude diagrams to demonstrate that, in most of the fields, none of the observed stars has the colours and magnitudes of late-type dwarfs at distances less than 100 pc. Similarly, none of the observed stars is a white dwarf within 500 pc that is hot enough to be a EUV emitter. The unidentified EUV sources we study are not detected in X-rays, while cataclysmic variables, X-ray binaries, and active galactic nuclei generally are. We conclude that some of the EUV sources may be a new class of nearby objects, which are either very faint at optical bands or which mimic the colours and magnitudes of distant late-type stars or cool white dwarfs. One candidate for optically faint objects is isolated old neutron stars, slowly accreting interstellar matter. Such neutron stars are expected to be abundant in the Galaxy, and have not been unambiguously detected.

Powerful model for the point source sky: Far-ultraviolet and enhanced midinfrared performance

NASA Technical Reports Server (NTRS)

Cohen, Martin

1994-01-01

I report further developments of the Wainscoat et al. (1992) model originally created for the point source infrared sky. The already detailed and realistic representation of the Galaxy (disk, spiral arms and local spur, molecular ring, bulge, spheroid) has been improved, guided by CO surveys of local molecular clouds, and by the inclusion of a component to represent Gould's Belt. The newest version of the model is very well validated by Infrared Astronomy Satellite (IRAS) source counts. A major new aspect is the extension of the same model down to the far ultraviolet. I compare predicted and observed far-utraviolet source counts from the Apollo 16 'S201' experiment (1400 A) and the TD1 satellite (for the 1565 A band).

Note: Triggering behavior of a vacuum arc plasma source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lan, C. H., E-mail: lanchaohui@163.com; Long, J. D.; Zheng, L.

2016-08-15

Axial symmetry of discharge is very important for application of vacuum arc plasma. It is discovered that the triggering method is a significant factor that would influence the symmetry of arc discharge at the final stable stage. Using high-speed multiframe photography, the transition processes from cathode-trigger discharge to cathode-anode discharge were observed. It is shown that the performances of the two triggering methods investigated are quite different. Arc discharge triggered by independent electric source can be stabilized at the center of anode grid, but it is difficult to achieve such good symmetry through resistance triggering. It is also found thatmore » the triggering process is highly correlated to the behavior of emitted electrons.« less

Vacuum-deposited polymer/silver reflector material

NASA Astrophysics Data System (ADS)

Affinito, John D.; Martin, Peter M.; Gross, Mark E.; Bennett, Wendy D.

1994-09-01

Weatherable, low cost, front surface, solar reflectors on flexible substrates would be highly desirable for lamination to solar concentrator panels. The method to be described in this paper may permit such reflector material to be fabricated for less the 50$CNT per square foot. Vacuum deposited Polymer/Silver/Polymer reflectors and Fabry-Perot interference filters were fabricated in a vacuum web coating operation on polyester substrates. Reflectivities were measured in the wavelength range from .4 micrometers to .8 micrometers . It is hoped that a low cost substrate can be used with the substrate laminated to the concentrator and the weatherable acrylic polymer coating facing the sun. This technique should be capable of deposition line speeds approaching 1500 linear feet/minute2. Central to this technique is a new vacuum deposition process for the high rate deposition of polymer films. This polymer process involves the flash evaporation of an acrylic monomer onto a moving substrate. The monomer is subsequently cured by an electron beam or ultraviolet light. This high speed polymer film deposition process has been named the PML process- for Polymer Multi- Layer.

The three-dimensional steady radial expansion of a viscous gas from a sonic source into a vacuum.

NASA Technical Reports Server (NTRS)

Bush, W. B.; Rosen, R.

1971-01-01

The three-dimensional steady radial expansion of a viscous, heat-conducting, compressible fluid from a spherical sonic source into a vacuum is analyzed using the Navier-Stokes equations as a basis. It is assumed that the model fluid is a perfect gas having constant specific heats, a constant Prandtl number of order unity, and viscosity coefficients varying as a power of the absolute temperature. Limiting forms for the flow variable solutions are studied for the Reynolds number based on the sonic source conditions, going to infinity and the Newtonian parameter both fixed and going to zero. For the case of the viscosity-temperature exponent between .5 and 1, it is shown that the velocity as well as the pressure approach zero as the radial distance goes to infinity. The formulations of the distinct regions that span the domain extending from the sonic source to the vacuum are presented.

Solid-State Laser Source of Tunable Narrow-Bandwidth Ultraviolet Radiation

NASA Technical Reports Server (NTRS)

Goldberg, Lew; Kliner, Dahv A.; Koplow, Jeffrey P.

1998-01-01

A solid-state laser source of tunable and narrow-bandwidth UV light is disclosed. The system relies on light from a diode laser that preferably generates light at infrared frequencies. The light from the seed diode laser is pulse amplified in a light amplifier, and converted into the ultraviolet by frequency tripling, quadrupling, or quintupling the infrared light. The narrow bandwidth, or relatively pure light, of the seed laser is preserved, and the pulse amplifier generates high peak light powers to increase the efficiency of the nonlinear crystals in the frequency conversion stage. Higher output powers may be obtained by adding a fiber amplifier to power amplify the pulsed laser light prior to conversion.

Vacuum ultraviolet imagery of the Virgo cluster region

NASA Astrophysics Data System (ADS)

Onaka, T.; Tanaka, W.; Watanabe, T.; Watanabe, J.; Yamaguchi, A.; Nakagiri, M.; Kodaira, K.; Nakano, M.; Sasaki, M.; Tsujimura, T.; Yamashita, K.

1989-07-01

The results are reported of an experiment using the UV imager aboard an attitude-controlled S520 type sounding rocket. The total UV fluxes of galaxies in the Virgo Cluster as well as the flux level of the diffuse UV background around the cluster were measured. The data on NGC 4486 and NGC 4472 confirm the variation in the degree of the 'turnup' below 200 nm in the energy spectrum of the total light of elliptical galaxies. At two-color diagram of galaxies of visual/near-UV/vacuum UV indicates that colors of spiral galaxies are distributed within a strip and well-correlated with the morphological type, while elliptical galaxies are located differently from spiral galaxies.

Line spectrum and ion temperature measurements from tungsten ions at low ionization stages in large helical device based on vacuum ultraviolet spectroscopy in wavelength range of 500–2200 Å

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oishi, T., E-mail: oishi@LHD.nifs.ac.jp; Morita, S.; Goto, M.

2014-11-15

Vacuum ultraviolet spectra of emissions released from tungsten ions at lower ionization stages were measured in the Large Helical Device (LHD) in the wavelength range of 500–2200 Å using a 3 m normal incidence spectrometer. Tungsten ions were distributed in the LHD plasma by injecting a pellet consisting of a small piece of tungsten metal and polyethylene tube. Many lines having different wavelengths from intrinsic impurity ions were observed just after the tungsten pellet injection. Doppler broadening of a tungsten candidate line was successfully measured and the ion temperature was obtained.

Photocatalytic pretreatment of oily wastewater from the restaurant by a vacuum ultraviolet/TiO2 system.

PubMed

Kang, Jian-xiong; Lu, Lu; Zhan, Wei; Li, Bo; Li, Dao-sheng; Ren, Yong-zheng; Liu, Dong-qi

2011-02-15

The present study aims at investigating the performance of a vacuum ultraviolet (VUV, 185 nm) and TiO(2) oxidation system for the pretreatment of oily wastewater from restaurant. The influence of irradiation time, pH, dissolved oxygen (DO), the dosage of TiO(2) and the initial chemical oxygen demand (COD) concentration on COD removal efficiency was ascertained and optimum process conditions for stable and effective operation were determined. Under the optimum conditions of irradiation 10 min, initial COD 3981 mg/L, TiO(2) 150 mg/L, pH 7.0 and flow rate of air 40 L/h, the process of VUV and TiO(2)/VUV achieved removal efficiencies of COD, BOD(5) and oil as 50±3%, 37±2%, 86±3%, and 63±3%, 43±2%, 70±3%, respectively. The biodegradability factor f(B) of the wastewater was determined as 1.56 which indicated that the VUV/TiO(2) process improved the biodegradability of the oily wastewater significantly. Results clearly indicate that VUV/TiO(2) photolysis tends to destruct parts of COD, BOD(5), and ammonia, as well as enhances the biodegradability of the oily wastewater simultaneously. Thus, this technique could be used as a pretreatment step for conventional biological treatment of oily wastewater. Copyright © 2010 Elsevier B.V. All rights reserved.

Ultraviolet, Optical and near-infrared photometric follow up of the transient source Fermi J1654-1055 with GROND and Swift-UVOT

NASA Astrophysics Data System (ADS)

Kaur, A.; Bolmer, J.; Greiner, J.; Rau, A.; Schady, P.; Ajello, M.; Hartmann, D. H.

2016-02-01

Ultraviolet, Optical and near-infrared photometric follow up of the transient source Fermi J1654-1055 with GROND and Swift-UVOT A. Kaur (Clemson University), J. Bolmer, J. Greiner, A. Rau, P. Schady (all MPE, Garching), M. Ajello, D. H. Hartmann (Clemson University) We report the ultraviolet, optical and near IR photometric observations of the new gamma-ray source Fermi J1654-1055/PMN J1632-1052 (RA = 248.20900 deg and Dec = -10.87578 deg) detected by Fermi during the week of February 08 and 15, 2016 (see ATel #8721).

Derivation of the cut-off length from the quantum quadratic enhancement of a mass in vacuum energy constant Lambda

NASA Astrophysics Data System (ADS)

Fukushima, Kimichika; Sato, Hikaru

2018-04-01

Ultraviolet self-interaction energies in field theory sometimes contain meaningful physical quantities. The self-energies in such as classical electrodynamics are usually subtracted from the rest mass. For the consistent treatment of energies as sources of curvature in the Einstein field equations, this study includes these subtracted self-energies into vacuum energy expressed by the constant Lambda (used in such as Lambda-CDM). In this study, the self-energies in electrodynamics and macroscopic classical Einstein field equations are examined, using the formalisms with the ultraviolet cut-off scheme. One of the cut-off formalisms is the field theory in terms of the step-function-type basis functions, developed by the present authors. The other is a continuum theory of a fundamental particle with the same cut-off length. Based on the effectiveness of the continuum theory with the cut-off length shown in the examination, the dominant self-energy is the quadratic term of the Higgs field at a quantum level (classical self-energies are reduced to logarithmic forms by quantum corrections). The cut-off length is then determined to reproduce today's tiny value of Lambda for vacuum energy. Additionally, a field with nonperiodic vanishing boundary conditions is treated, showing that the field has no zero-point energy.

Vacuum ultraviolet radiation/atomic oxygen synergism in materials reactivity

NASA Technical Reports Server (NTRS)

Koontz, Steven; Leger, Lubert; Albyn, Keith; Cross, Jon

1990-01-01

Experimental results are presented which indicate that low fluxes of vacuum UV (VUV) radiation exert a pronounced influence on the atomic oxygen reactivity of such fluorocarbon and fluorocarbon spacecraft materials as the FEP Teflon and PCTFE that are under consideration for the Space Station Freedom. With simultaneous exposure to VUV fluxes comparable to those experienced in LEO, the reactivity of these materials becomes comparable to that of Kapton; VUV radiation has also been shown to increase the reactivity of Kapton with thermal-energy oxygen atoms.

Vacuum probe surface sampler

NASA Technical Reports Server (NTRS)

Zahlava, B. A. (Inventor)

1973-01-01

A vacuum probe surface sampler is described for rapidly sampling relatively large surface areas which possess relatively light loading densities of micro-organism, drug particles or the like. A vacuum head with a hollow handle connected to a suitable vacuum source is frictionally attached to a cone assembly terminating in a flared tip adapted to be passed over the surface to be sampled. A fine mesh screen carried by the vacuum head provides support for a membrane filter which collects the microorganisms or other particles. The head assembly is easily removed from the cone assembly without contacting the cone assembly with human hands.

Characterization and imaging of nanostructured materials using tabletop extreme ultraviolet light sources

NASA Astrophysics Data System (ADS)

Karl, Robert; Knobloch, Joshua; Frazer, Travis; Tanksalvala, Michael; Porter, Christina; Bevis, Charles; Chao, Weilun; Abad Mayor, Begoña.; Adams, Daniel; Mancini, Giulia F.; Hernandez-Charpak, Jorge N.; Kapteyn, Henry; Murnane, Margaret

2018-03-01

Using a tabletop coherent extreme ultraviolet source, we extend current nanoscale metrology capabilities with applications spanning from new models of nanoscale transport and materials, to nanoscale device fabrication. We measure the ultrafast dynamics of acoustic waves in materials; by analyzing the material's response, we can extract elastic properties of films as thin as 11nm. We extend this capability to a spatially resolved imaging modality by using coherent diffractive imaging to image the acoustic waves in nanostructures as they propagate. This will allow for spatially resolved characterization of the elastic properties of non-isotropic materials.

Investigating the effective range of vacuum ultraviolet-mediated breakdown in high-power microwave metamaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Chien-Hao, E-mail: cliu82@wisc.edu; Neher, Joel D., E-mail: jdneher@wisc.edu; Booske, John H., E-mail: booske@engr.wisc.edu

2014-10-14

Metamaterials and periodic structures operating under high-power excitations are susceptible to breakdown. It was recently demonstrated that a localized breakdown created in a given region of a periodic structure can facilitate breakdown in other regions of the structure where the intensity of the incident electromagnetic fields may not be high enough to cause breakdown under normal circumstances. It was also demonstrated that this phenomenon is due to the generation of vacuum ultraviolet radiation at the location of the initial discharge, which propagates to the neighboring regions (e.g., other unit cells in a periodic structure) and facilitates the generation of amore » discharge at a lower incident power level. In this paper, we present the results of an experimental study conducted to determine the effective range of this physical phenomenon for periodic structures that operate in air and in pure nitrogen gas at atmospheric pressure levels. It is demonstrated that when breakdown is induced in a periodic structure using a high-power pulse with a frequency of 9.382 GHz, duration of 0.8 μs, and peak power level of 25 kW, this phenomenon is highly likely to happen in radii of approximately 16–17 mm from the location of the initial discharge under these test conditions. The results of this study are significant in designing metamaterials and periodic structures for high-power microwave applications as they suggest that a localized discharge created in such a periodic structure with a periodicity less than 16–17 mm can spread over a large surface and result in a distributed discharge.« less

Vacuum-Ultraviolet photoionization studies of the microhydrationof DNA bases (Guanine, Cytosine, Adenine and Thymine)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belau, L.; Wilson, K.R.; Leone, S.R.

2007-01-22

In this work, we report on a photoionization study of the microhydration of the four DNA bases. Gas-phase clusters of water with DNA bases [guanine (G), cytosine (C), adenine (A), and thymine (T)] are generated via thermal vaporization of the bases and expansion of the resultant vapor in a continuous supersonic jet expansion of water seeded in Ar. The resulting clusters are investigated by single-photon ionization with tunable vacuum-ultraviolet synchrotron radiation and mass analyzed using reflectron mass spectrometry. Photoionization efficiency (PIE) curves are recorded for the DNA bases and the following water (W) clusters: G, GW{sub n} (n = 1-3);more » C, CW{sub n} (n = 1-3); A, AW{sub n} (n = 1,2); and T, TW{sub n} (n = 1-3). Appearance energies (AE) are derived from the onset of these PIE curves (all energies in eV): G (8.1 {+-} 0.1), GW (8.0 {+-} 0.1), GW{sub 2} (8.0 {+-} 0.1), and GW{sub 3} (8.0); C (8.65 {+-} 0.05), CW (8.45 {+-} 0.05), CW{sub 2} (8.4 {+-} 0.1), and CW{sub 3} (8.3 {+-} 0.1); A (8.30 {+-} 0.05), AW (8.20 {+-} 0.05), and AW{sub 2} (8.1 {+-} 0.1); T (8.90 {+-} 0.05); and TW (8.75 {+-} 0.05), TW{sub 2} (8.6 {+-} 0.1), and TW{sub 3} (8.6 {+-} 0.1). The AEs of the DNA bases decrease slightly with the addition of water molecules (up to three) but do not converge to values found for photoinduced electron removal from DNA bases in solution.« less

Production of reactive species using vacuum ultraviolet photodissociation as a tool for studying their effects in plasma medicine: simulations and measurements

NASA Astrophysics Data System (ADS)

Ono, Ryo; Tokumitsu, Yusuke; Zen, Shungo; Yonemori, Seiya

2014-11-01

We propose a method for producing OH, H, O, O3, and O2(a1Δg) using the vacuum ultraviolet photodissociation of H2O and O2 as a tool for studying the reaction processes of plasma medicine. For photodissociation, an H2O/He or O2/He mixture flowing in a quartz tube is irradiated by a Xe2 or Kr2 excimer lamp. The effluent can be applied to a target. Simulations show that the Xe2 lamp method can produce OH radicals within 0.1-1 ppm in the effluent at 5 mm from a quartz tube nozzle. This is comparable to those produced by a helium atmospheric-pressure plasma jet (He-APPJ) currently used in plasma medicine. The Xe2 lamp method also produces H atoms of, at most, 6 ppm. In contrast, the maximum O densities produced by the Xe2 and Kr2 lamp methods are 0.15 ppm and 2.5 ppm, respectively; these are much lower than those from He-APPJ (several tens of ppm). Both lamp methods can produce ozone at concentrations above 1000 ppm and O2(a1Δg) at tens of ppm. The validity of the simulations is verified by measuring the O3 and OH densities produced by the Xe2 lamp method using ultraviolet absorption and laser-induced fluorescence. The differences between the measured and simulated densities for O3 and OH are 20% and factors of 3-4, respectively.

EDITORIAL: Extreme Ultraviolet Light Sources for Semiconductor Manufacturing

NASA Astrophysics Data System (ADS)

Attwood, David

2004-12-01

The International Technology Roadmap for Semiconductors (ITRS) [1] provides industry expectations for high volume computer chip fabrication a decade into the future. It provides expectations to anticipated performance and requisite specifications. While the roadmap provides a collective projection of what international industry expects to produce, it does not specify the technology that will be employed. Indeed, there are generally several competing technologies for each two or three year step forward—known as `nodes'. Recent successful technologies have been based on KrF (248 nm), and now ArF (193 nm) lasers, combined with ultraviolet transmissive refractive optics, in what are known as step and scan exposure tools. Less fortunate technologies in the recent past have included soft x-ray proximity printing and, it appears, 157 nm wavelength F2 lasers. In combination with higher numerical aperture liquid emersion optics, 193 nm is expected to be used for the manufacture of leading edge chip performance for the coming five years. Beyond that, starting in about 2009, the technology to be employed is less clear. The leading candidate for the 2009 node is extreme ultraviolet (EUV) lithography, however this requires that several remaining challenges, including sufficient EUV source power, be overcome in a timely manner. This technology is based on multilayer coated reflective optics [2] and an EUV emitting plasma. Following Moore's Law [3] it is expected, for example, that at the 2009 `32 nm node' (printable patterns of 32 nm half-pitch), isolated lines with 18 nm width will be formed in resist (using threshold effects), and that these will be further narrowed to 13 nm in transfer to metalized electronic gates. These narrow features are expected to provide computer chips of 19 GHz clock frequency, with of the order of 1.5 billion transistors per chip [1]. This issue of Journal of Physics D: Applied Physics contains a cluster of eight papers addressing the critical

Vacuum vapor deposition

NASA Technical Reports Server (NTRS)

Poorman, Richard M. (Inventor); Weeks, Jack L. (Inventor)

1995-01-01

A method and apparatus is described for vapor deposition of a thin metallic film utilizing an ionized gas arc directed onto a source material spaced from a substrate to be coated in a substantial vacuum while providing a pressure differential between the source and the substrate so that, as a portion of the source is vaporized, the vapors are carried to the substrate. The apparatus includes a modified tungsten arc welding torch having a hollow electrode through which a gas, preferably inert, flows and an arc is struck between the electrode and the source. The torch, source, and substrate are confined within a chamber within which a vacuum is drawn. When the arc is struck, a portion of the source is vaporized and the vapors flow rapidly toward the substrate. A reflecting shield is positioned about the torch above the electrode and the source to ensure that the arc is struck between the electrode and the source at startup. The electrode and the source may be confined within a vapor guide housing having a duct opening toward the substrate for directing the vapors onto the substrate.

Synchrotron vacuum ultraviolet radiation studies of the D 1Πu state of H2

NASA Astrophysics Data System (ADS)

Dickenson, G. D.; Ivanov, T. I.; Roudjane, M.; de Oliveira, N.; Joyeux, D.; Nahon, L.; Tchang-Brillet, W.-Ü. L.; Glass-Maujean, M.; Haar, I.; Ehresmann, A.; Ubachs, W.

2010-10-01

The 3pπD Π1u state of the H2 molecule was reinvestigated with different techniques at two synchrotron installations. The Fourier transform spectrometer in the vacuum ultraviolet wavelength range of the DESIRS beamline at the SOLEIL synchrotron was used for recording absorption spectra of the D Π1u state at high resolution and high absolute accuracy, limited only by the Doppler contribution at 100 K. From these measurements, line positions were extracted, in particular, for the narrow resonances involving Π1u - states, with an accuracy estimated at 0.06 cm-1. The new data also closely match multichannel quantum defect calculations performed for the Π- components observed via the narrow Q-lines. The Λ-doubling in the D Π1u state was determined up to v =17. The 10 m normal incidence scanning monochromator at the beamline U125/2 of the BESSY II synchrotron, combined with a home-built target chamber and equipped with a variety of detectors, was used to unravel information on ionization, dissociation, and intramolecular fluorescence decay for the D Π1u vibrational series. The combined results yield accurate information on the characteristic Beutler-Fano profiles associated with the strongly predissociated Πu+ parity components of the D Π1u levels. Values for the parameters describing the predissociation width as well as the Fano-q line shape parameters for the J =1 and J =2 rotational states were determined for the sequence of vibrational quantum numbers up to v =17.

Vacuum-ultraviolet photoionization studies of the microhydration of DNA bases (guanine, cytosine, adenine, and thymine).

PubMed

Belau, Leonid; Wilson, Kevin R; Leone, Stephen R; Ahmed, Musahid

2007-08-09

In this work, we report on a photoionization study of the microhydration of the four DNA bases. Gas-phase clusters of water with DNA bases [guanine (G), cytosine (C), adenine (A), and thymine (T)] are generated via thermal vaporization of the bases and expansion of the resultant vapor in a continuous supersonic jet expansion of water seeded in Ar. The resulting clusters are investigated by single-photon ionization with tunable vacuum-ultraviolet synchrotron radiation and mass analyzed using reflectron mass spectrometry. Photoionization efficiency (PIE) curves are recorded for the DNA bases and the following water (W) clusters: G, GWn (n = 1-3); C, CWn (n = 1-3); A, AWn (n = 1,2); and T, TWn (n = 1-3). Appearance energies (AE) are derived from the onset of these PIE curves (all energies in eV): G (8.1 +/- 0.1), GW (8.0 +/- 0.1), GW2 (8.0 +/- 0.1), and GW3 (8.0); C (8.65 +/- 0.05), CW (8.45 +/- 0.05), CW2 (8.4 +/- 0.1), and CW3 (8.3 +/- 0.1); A (8.30 +/- 0.05), AW (8.20 +/- 0.05), and AW2 (8.1 +/- 0.1); T (8.90 +/- 0.05); and TW (8.75 +/- 0.05), TW2 (8.6 +/- 0.1), and TW3 (8.6 +/- 0.1). The AEs of the DNA bases decrease slightly with the addition of water molecules (up to three) but do not converge to values found for photoinduced electron removal from DNA bases in solution.

Serendipitous EUV sources detected during the first year of the Extreme Ultraviolet Explorer right angle program

NASA Technical Reports Server (NTRS)

Mcdonald, K.; Craig, N.; Sirk, M. M.; Drake, J. J.; Fruscione, A.; Vallerga, J. V.; Malina, R. F.

1994-01-01

We report the detection of 114 extreme ultraviolet (EUV; 58 - 740 A) sources, of which 99 are new serendipitous sources, based on observations made with the imaging telescopes on board the Extreme Ultraviolet Explorer (EUVE) during the Right Angle Program (RAP). These data were obtained using the survey scanners and the Deep Survey instrument during the first year of the spectroscopic guest observer phase of the mission, from January 1993 to January 1994. The data set consists of 162 discrete pointings whose exposure times are typically two orders of magnitude longer than the average exposure times during the EUVE all-sky survey. Based on these results, we can expect that EUVE will serendipitously detect approximately 100 new EUV sources per year, or about one new EUV source per 10 sq deg, during the guest observer phase of the EUVE mission. New EUVE sources of note include one B star and three extragalactic objects. The B star (HR 2875, EUVE J0729 - 38.7) is detected in both the Lexan/B (approximately 100 A) and Al/Ti/C (approximately 200 A) bandpasses, and the detection is shown not to be a result of UV leaks. We suggest that we are detecting EUV and/or soft x rays from a companion to the B star. Three sources, EUVE J2132+10.1, EUVE J2343-14.9, and EUVE J2359-30.6 are identified as the active galactic nuclei MKN 1513, MS2340.9-1511, and 1H2354-315, respectively.

An intense lithium ion beam source using vacuum baking and discharge cleaning techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moschella, J.J.; Kusse, B.R.; Longfellow, J.P.

We have developed a high-purity, intense, lithium ion beam source which operates at 500 kV and 120 A/cm{sup 2} with pulse widths of 125 ns full width half maximum. The beams were generated using a lithium chloride anode in planar magnetically insulated geometry. We have found that the combination of vacuum baking of the anode at 250 {degree}C followed by the application of 100 W of pure argon, steady-state, glow discharge cleaning reduced the impurity concentration in the beam to approximately 10% (components other than chlorine or lithium were considered impurities). Although the impurities were low, the concentration of chlorinemore » in the 1+ and 2+ charge states was significant ({similar to}25%). The remaining 65% of the beam consisted of Li{sup +} ions. Without the special cleaning process, over half the beam particles were impurities. It was determined that these impurities entered the beam at the anode surface but came originally from material in the vacuum chamber. After the cleaning process, recontamination was observed to occur in approximately 6 min. This long recontamination time, which was much greater than the expected monolayer formation time, was attributed to the elevated temperature of the anode. We also compared the electrical characteristics of the beams produced by LiCl anodes to those generated by a standard polyethylene proton source. In contrast to the polyethylene anode, the LiCl source exhibited a higher impedance, produced beams of lower ion current efficiency and had longer turn on times.« less

NSLS II Vacuum System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferreira, M.; Doom, L.; Hseuh, H.

2009-09-13

National Synchrotron Light Source II, being constructed at Brookhaven, is a 3-GeV, 500 mA, 3rd generation synchrotron radiation facility with ultra low emittance electron beams. The storage ring vacuum system has a circumference of 792 m and consists of over 250 vacuum chambers with a simulated average operating pressure of less than 1 x 10{sup -9} mbar. A summary of the update design of the vacuum system including girder supports of the chambers, gauges, vacuum pumps, bellows, beam position monitors and simulation of the average pressure will be shown. A brief description of the techniques and procedures for cleaning andmore » mounting the chambers are given.« less

Laser-produced lithium plasma as a narrow-band extended ultraviolet radiation source for photoelectron spectroscopy.

PubMed

Schriever, G; Mager, S; Naweed, A; Engel, A; Bergmann, K; Lebert, R

1998-03-01

Extended ultraviolet (EUV) emission characteristics of a laser-produced lithium plasma are determined with regard to the requirements of x-ray photoelectron spectroscopy. The main features of interest are spectral distribution, photon flux, bandwidth, source size, and emission duration. Laser-produced lithium plasmas are characterized as emitters of intense narrow-band EUV radiation. It can be estimated that the lithium Lyman-alpha line emission in combination with an ellipsoidal silicon/molybdenum multilayer mirror is a suitable EUV source for an x-ray photoelectron spectroscopy microscope with a 50-meV energy resolution and a 10-mum lateral resolution.

Construction and evaluation of an ultrahigh-vacuum-compatible sputter deposition source

NASA Astrophysics Data System (ADS)

Lackner, Peter; Choi, Joong Il Jake; Diebold, Ulrike; Schmid, Michael

2017-10-01

A sputter deposition source for the use in ultrahigh vacuum (UHV) is described, and some properties of the source are analyzed. The operating principle is based on the design developed by Mayr et al. [Rev. Sci. Instrum. 84, 094103 (2013)], where electrons emitted from a filament ionize argon gas and the Ar+ ions are accelerated to the target. In contrast to the original design, two grids are used to direct a large fraction of the Ar+ ions to the target, and the source has a housing cooled by liquid nitrogen to reduce contaminations. The source has been used for the deposition of zirconium, a material that is difficult to evaporate in standard UHV evaporators. At an Ar pressure of 9 ×1 0-6 mbar in the UHV chamber and moderate emission current, a highly reproducible deposition rate of ≈1 ML in 250 s was achieved at the substrate (at a distance of ≈50 mm from the target). Higher deposition rates are easily possible. X-ray photoelectron spectroscopy shows a high purity of the deposited films. Depending on the grid voltages, the substrate gets mildly sputtered by Ar+ ions; in addition, the substrate is also reached by electrons from the negatively biased sputter target.

Laser-induced electron source in a vacuum diode

NASA Astrophysics Data System (ADS)

Ghera, U.; Boxman, R. L.; Kleinman, H.; Ruschin, S.

1989-11-01

Experiments were conducted in which a high-power CO2 TEA laser interacted with metallic cathode in a high-vacuum (10 to the -8th Torr) diode. For power densities lower than 5 x 10 to the 7th W/sq cm, no current was detected. For power densities in the range of 5 x 10 to the 7th to 5 x 10 to the 8th W/sq cm, the Cu cathode emitted a maximum current of 40 mA. At a higher power density level, a circuit-limited current of 8 A was detected. The jump of a few orders of magnitude in the current is attributed to breakdown of the diode gap. The experimental results are similar to those of a triggered vacuum gap, and a thorough comparison is presented in this paper. The influence of the pressure in the vacuum chamber on the current magnitude shows the active role that adsorbed gas molecules have in the initial breakdown. When the cathode material was changed from metal to metal oxide, much lower laser power densities were required to reach the breakdown current region.

Research on fluorescence from photoionization, photodissociation, and vacuum, along with bending quantrum study

NASA Technical Reports Server (NTRS)

Judge, D. L.

1975-01-01

Reports of research concerning the fluorescence of CS2 are presented. Fluorescence from fragments of CS2 vapor produced by vacuum ultraviolet radiation, and fluorescence from photoionization of CS2 vapor are discussed along with fluorescence produced by photodissociation of CS2, and fluorescence from photoionization of OCS.

Online investigations on ozonation products of pyrene and benz[ a]anthracene particles with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer

NASA Astrophysics Data System (ADS)

Gao, Shaokai; Zhang, Yang; Meng, Junwang; Shu, Jinian

The reaction products of ozone with pyrene and benz[ a]anthracene absorbed on azelaic acid particles under the pseudo-first-order reaction conditions have been investigated with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The pyrene and benz[ a]anthracene particles with the initial concentrations of ˜1 mg m -3 are respectively exposed to ˜22 ppm ozone in a reaction chamber with a volume of ˜180 L. The time-of-flight mass spectra of the particulate ozonides are obtained. The assignments of the mass spectra reveal that 4-carboxy-5-phenanthrene-carboxyaldehyde (71%) and hydroxypyrene (23%) are the main solid state ozonides of pyrene, while 2-(2-formyl)phenyl-3-naphthoic acid (35%), hydroxybenz[ a]anthrone (30%), and benz[ a]anthracene-7,12-dione (18%) are the main solid state ozonides of benz[ a]anthracene. The pathways of the ozonations are proposed in the paper.

Extreme ultraviolet reflectivity studies of gold on glass and metal substrates

NASA Technical Reports Server (NTRS)

Jelinsky, Sharon R.; Malina, Roger F.; Jelinsky, Patrick

1988-01-01

The paper reports measurements of the extreme ultraviolet reflectivity of gold from 44 to 920 A at grazing incidence. Gold was deposited using vacuum evaporation and electroplating on substrates of glass and polished nickel, respectively. Measurements are also presented of the extreme ultraviolet reflectivity of electroless nickel in the same wavelength region, where one of the polished nickel substrates was used as a sample. Derived optical constants for evaporated and electroplated gold and electroless nickel are presented. Additional studies of the effects of various contaminants on the EUV reflectivity are also reported. The variations of the optical constants are discussed in terms of density variations, surface roughness and contamination effects. These results ae reported as part of studies for the Extreme Ultraviolet Explorer satellite program to determine acceptance criteria for the EUV optics, contamination budgets and calibration plans.

The extreme ultraviolet explorer

NASA Technical Reports Server (NTRS)

Bowyer, Stuart; Malina, Roger F.

1990-01-01

The Extreme Ultraviolet Explorer (EUVE) mission, currently scheduled for launch in September 1991, is described. The primary purpose of the mission is to survey the celestial sphere for astronomical sources of Extreme Ultraviolet (EUV) radiation. The survey will be accomplished with the use of three EUV telescopes, each sensitive to a different segment of the EUV band. A fourth telescope will perform a high sensitivity search of a limited sample of the sky in the shortest wavelength bands. The all sky survey will be carried out in the first six months of the mission and will be made in four bands, or colors. The second phase of the mission, conducted entirely by guest observers selected by NASA, will be devoted to spectroscopic observations of EUV sources. The performance of the instrument components is described. An end to end model of the mission, from a stellar source to the resulting scientific data, was constructed. Hypothetical data from astronomical sources processed through this model are shown.

Dependence of absolute photon flux on infrared absorbance alteration and surface roughness on photoresist polymers irradiated with vacuum ultraviolet photons emitted from HBr plasma

NASA Astrophysics Data System (ADS)

Zhang, Yan; Takeuchi, Takuya; Ishikawa, Kenji; Hayashi, Toshio; Takeda, Keigo; Sekine, Makoto; Hori, Masaru

2017-12-01

The absolute fluxes of vacuum ultraviolet (VUV) photons emitted from HBr plasma were analyzed and the effects of VUV photons on a photoresist polymer in ArF-excimer-laser (193 nm) lithography were quantitatively investigated on the basis of the infrared spectra attributed to the C=O region. The spectral peak intensity assigned to the methacrylic acid (MAA) in the photoresist drastically decreased owing to the loss of this monomer caused by the irradiation of VUV photons at dosages below 16 × 1016 photons/cm2. X-ray photoelectron spectroscopy observation showed that the removed monomer moved to the surface and generated volatile products that induced a decrease in film thickness. As a consequence, the surface became rough during the early-stage irradiation at dosages lower than 16 × 1016 photons/cm2 owing to the monomer loss of MAA with volatile product formation and subsequent cross-linking reactions.

Effects of solar ultraviolet radiations on Bacillus subtilis spores and T-7 bacteriophage

NASA Technical Reports Server (NTRS)

Spizizen, J.; Isherwood, J. E.; Taylor, G. R.

1975-01-01

Spores of Bacillus subtilis HA 101 and the DNA polymerase I-defective mutant HA 101 (59)F were exposed to selected wavelengths of solar ultraviolet light and space vacuum during the return of Apollo 16. In addition, coliphage T-7 suspensions were exposed to solar ultraviolet radiation as part of the Microbial Response to Space Environment Experiment. Optical filters were employed to provide different energy levels at wavelengths 254 nm and 280 nm. Dose-response curves for lethal and mutagenic effects were compared with ground-based data. A close parallel was observed between the results of solar radiation and ground tests with spores of the two strains. However, significantly greater inactivation of T-7 bacteriophage was observed after exposure to solar ultraviolet radiation.

Modification of anti-bacterial surface properties of textile polymers by vacuum arc ion source implantation

NASA Astrophysics Data System (ADS)

Nikolaev, A. G.; Yushkov, G. Yu.; Oks, E. M.; Oztarhan, A.; Akpek, A.; Hames-Kocabas, E.; Urkac, E. S.; Brown, I. G.

2014-08-01

Ion implantation provides an important technology for the modification of material surface properties. The vacuum arc ion source is a unique instrument for the generation of intense beams of metal ions as well as gaseous ions, including mixed metal-gas beams with controllable metal:gas ion ratio. Here we describe our exploratory work on the application of vacuum arc ion source-generated ion beams for ion implantation into polymer textile materials for modification of their biological cell compatibility surface properties. We have investigated two specific aspects of cell compatibility: (i) enhancement of the antibacterial characteristics (we chose to use Staphylococcus aureus bacteria) of ion implanted polymer textile fabric, and (ii) the "inverse" concern of enhancement of neural cell growth rate (we chose Rat B-35 neuroblastoma cells) on ion implanted polymer textile. The results of both investigations were positive, with implantation-generated antibacterial efficiency factor up to about 90%, fully comparable to alternative conventional (non-implantation) approaches and with some potentially important advantages over the conventional approach; and with enhancement of neural cell growth rate of up to a factor of 3.5 when grown on suitably implanted polymer textile material.

Method for generating extreme ultraviolet with mather-type plasma accelerators for use in Extreme Ultraviolet Lithography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hassanein, Ahmed; Konkashbaev, Isak

A device and method for generating extremely short-wave ultraviolet electromagnetic wave uses two intersecting plasma beams generated by two plasma accelerators. The intersection of the two plasma beams emits electromagnetic radiation and in particular radiation in the extreme ultraviolet wavelength. In the preferred orientation two axially aligned counter streaming plasmas collide to produce an intense source of electromagnetic radiation at the 13.5 nm wavelength. The Mather type plasma accelerators can utilize tin, or lithium covered electrodes. Tin, lithium or xenon can be used as the photon emitting gas source.

Vacuum ultraviolet emission characteristics from He-Ne-Xe gas discharge in an alternating current plasma display panel cell

NASA Astrophysics Data System (ADS)

Seo, Jeong Hyun; Jeong, Heui Seob; Lee, Joo Yul; Yoon, Cha Keun; Kim, Joong Kyun; Whang, Ki-Woong

2000-08-01

We measured the time integrated vacuum ultraviolet (VUV) emission spectra of He-Ne-Xe gas mixture from a surface type alternating current (ac) plasma display panel cell. The measured emission lines are the resonance line (147 nm) from Xe*(1s4), the first continuum (150 nm) and the second continuum (173 nm) from Xe dimer excited states. The relative intensities of VUV spectral lines from Xe* and Xe2* are dependent on the He/Ne mixing ratio as well as the Xe partial and total pressure. The intensity of 147 nm VUV increases with the Ne content increase and Xe2* molecular emission increases with the He content increase. Infrared (IR) spectra and the time variation of VUV were measured to explain the reaction pathway and the effect of the mixing ratio of He/Ne on the spectral intensity. A detailed study for the decay time shows that the decay time of 147 nm has two time constants and the radiation of 150 and 173 nm results mainly from Xe*(1s5). The IR spectra shows that the contribution from Xe**(>6 s) to Xe*(1s5) and Xe*(1s4) in He-Xe is different from that of Ne-Xe. The change of IR intensity explains the spectral intensity variations of He-Xe and Ne-Xe discharge.

HUBBLE IDENTIFIES SOURCE OF ULTRAVIOLET LIGHT IN AN OLD GALAXY

NASA Technical Reports Server (NTRS)

2002-01-01

Hubble Space Telescope's exquisite resolution has allowed astronomers to resolve, for the first time, hot blue stars deep inside an elliptical galaxy. The swarm of nearly 8,000 blue stars resembles a blizzard of snowflakes near the core (lower right) of the neighboring galaxy M32, located 2.5 million light-years away in the constellation Andromeda. Hubble confirms that the ultraviolet light comes from a population of extremely hot helium-burning stars at a late stage in their lives. Unlike the Sun, which burns hydrogen into helium, these old stars exhausted their central hydrogen long ago, and now burn helium into heavier elements. The observations, taken in October 1998, were made with the camera mode of the Space Telescope Imaging Spectrograph (STIS) in ultraviolet light. The STIS field of view is only a small portion of the entire galaxy, which is 20 times wider on the sky. For reference, the full moon is 70 times wider than the STIS field-of-view. The bright center of the galaxy was placed on the right side of the image, allowing fainter stars to be seen on the left side of the image. These results are to be published in the March 1, 2000 issue of The Astrophysical Journal. Thirty years ago, the first ultraviolet observations of elliptical galaxies showed that they were surprisingly bright when viewed in ultraviolet light. Before those pioneering UV observations, old groups of stars were assumed to be relatively cool and thus extremely faint in the ultraviolet. Over the years since the initial discovery of this unexpected ultraviolet light, indirect evidence has accumulated that it originates in a population of old, but hot, helium-burning stars. Now Hubble provides the first direct visual evidence. Nearby elliptical galaxies are thought to be relatively simple galaxies comprised of old stars. Because they are among the brightest objects in the Universe, this simplicity makes them useful for tracing the evolution of stars and galaxies. Credits: NASA and Thomas

Occupational Skin Hazards From Ultraviolet (UV) Exposures

NASA Astrophysics Data System (ADS)

Urbach, F.; Wolbarsht, M. L.

1980-10-01

The various types of UV effects on the skin are classified according to the part of the spectrum and their beneficial or deleterious nature. Some hazardous ultraviolet sources used in industrial processes are described, and examples of photoallergy, phototoxicity, and photosensitization resulting from UV exposures are given. The incidence of skin cancer as a function of geographical location and exposure to sunlight is discussed in relation to natural and artificial exposures to long and short wavelength UV, especially in connection with tanning booths. The conclusion is reached that there is enough ultraviolet in a normal environment to propose a hazard, and additional ultraviolet exposure from industrial or consumer sources is not necessary, and should be eliminated wherever possible.

Occupational Skin Hazards From Ultraviolet (UV) Exposures

NASA Astrophysics Data System (ADS)

Urbach, F.; Wolbarsht, M. L.

1981-11-01

The various types of UV effects on the skin are classified according to the part of the spectrum and their beneficial or deleterious nature. Some hazardous ultraviolet sources used in industrial processes are described, and examples of photoallergy, phototoxicity, and photosensitization resulting from UV exposures are given. The incidence of skin cancer as a function of geographical location and exposure to sunlight is discussed in relation to natural and artificial exposures to long and short wavelength UV, especially in connection with tanning booths. The conclusion is reached that there is enough ultraviolet in a normal environment to propose a hazard, and additional ultraviolet exposure from industrial or consumer sources is not necessary, and should be eliminated wherever possible.

Generation of multicomponent ion beams by a vacuum arc ion source with compound cathode.

PubMed

Savkin, K P; Yushkov, Yu G; Nikolaev, A G; Oks, E M; Yushkov, G Yu

2010-02-01

This paper presents the results of time-of-flight mass spectrometry studies of the elemental and mass-to-charge state compositions of metal ion beams produced by a vacuum arc ion source with compound cathode (WC-Co(0.5), Cu-Cr(0.25), Ti-Cu(0.1)). We found that the ion beam composition agrees well with the stoichiometric composition of the cathode material from which the beam is derived, and the maximum ion charge state of the different plasma components is determined by the ionization capability of electrons within the cathode spot plasma, which is common to all components. The beam mass-to-charge state spectrum from a compound cathode features a greater fraction of multiply charged ions for those materials with lower electron temperature in the vacuum arc cathode spot, and a smaller fraction for those with higher electron temperature within the spot. We propose a potential diagram method for determination of attainable ion charge states for all components of the compound cathodes.

An innovative Yb-based ultrafast deep ultraviolet source for time-resolved photoemission experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boschini, F.; Hedayat, H.; Dallera, C.

2014-12-15

Time- and angle-resolved photoemission spectroscopy is a powerful technique to study ultrafast electronic dynamics in solids. Here, an innovative optical setup based on a 100-kHz Yb laser source is presented. Exploiting non-collinear optical parametric amplification and sum-frequency generation, ultrashort pump (hν = 1.82 eV) and ultraviolet probe (hν = 6.05 eV) pulses are generated. Overall temporal and instrumental energy resolutions of, respectively, 85 fs and 50 meV are obtained. Time- and angle-resolved measurements on BiTeI semiconductor are presented to show the capabilities of the setup.

Modeling of radiative properties of Sn plasmas for extreme-ultraviolet source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sasaki, Akira; Sunahara, Atsushi; Furukawa, Hiroyuki

Atomic processes in Sn plasmas are investigated for application to extreme-ultraviolet (EUV) light sources used in microlithography. We develop a full collisional radiative (CR) model of Sn plasmas based on calculated atomic data using Hebrew University Lawrence Livermore Atomic Code (HULLAC). Resonance and satellite lines from singly and multiply excited states of Sn ions, which contribute significantly to the EUV emission, are identified and included in the model through a systematic investigation of their effect on the emission spectra. The wavelengths of the 4d-4f+4p-4d transitions of Sn{sup 5+} to Sn{sup 13+} are investigated, because of their importance for determining themore » conversion efficiency of the EUV source, in conjunction with the effect of configuration interaction in the calculation of atomic structure. Calculated emission spectra are compared with those of charge exchange spectroscopy and of laser produced plasma EUV sources. The comparison is also carried out for the opacity of a radiatively heated Sn sample. A reasonable agreement is obtained between calculated and experimental EUV emission spectra observed under the typical condition of EUV sources with the ion density and ionization temperature of the plasma around 10{sup 18} cm{sup -3} and 20 eV, respectively, by applying a wavelength correction to the resonance and satellite lines. Finally, the spectral emissivity and opacity of Sn plasmas are calculated as a function of electron temperature and ion density. The results are useful for radiation hydrodynamics simulations for the optimization of EUV sources.« less

Eco-sewerage System Design for Modern Office Buildings: based on Vacuum and Source-separation Technology

NASA Astrophysics Data System (ADS)

Xu, Kangning; Wang, Chengwen; Zheng, Min; Yuan, Xin

2010-11-01

This study aimed to construct an on-site eco-sewerage system for modern office buildings in urban area based on combined innovative technologies of vacuum and source-separation. Results showed that source-separated grey water had low concentrations of pollutants, which helped the reuse of grey water. However, the system had a low separation efficiency between the yellow water and the brown water, which was caused by the plug problem in the urine collection from the urine-diverting toilets. During the storage of yellow water for liquid fertilizer production, nearly all urea nitrogen transferred to ammonium nitrogen and about 2/3 phosphorus was lost because of the struvite precipitation. Total bacteria and coliforms increased first in the storage, but then decreased to low concentrations. The anaerobic/anoxic/aerobic MBR had high elimination rates of COD, ammonium nitrogen and total nitrogen of the brown water, which were 94.2%, 98.1% and 95.1%, respectively. However, the effluent still had high contents of colority, nitrate and phosphorus, which affected the application of the effluent for flushing water. Even though, the effluent might be used as dilution water for the yellow water fertilizer. Based on the results and the assumption of an ideal operation of the vacuum source-separation system, a future plan for on-site eco-sewerage system of modern office buildings was constructed. Its sustainability was validated by the analysis of the substances flow of water and nutrients.

Online characterization of isomeric/isobaric components in the gas phase of mainstream cigarette smoke by tunable synchrotron radiation vacuum ultraviolet photoionization time-of-flight mass spectrometry and photoionization efficiency curve simulation.

PubMed

Pan, Yang; Hu, Yonghua; Wang, Jian; Ye, Lili; Liu, Chengyuan; Zhu, Zhixiang

2013-12-17

A newly developed, qualitative and quantitative method based on tunable synchrotron radiation vacuum ultraviolet photoionization time-of-flight mass spectrometry (SR-VUV-PI-TOFMS) and photoionization efficiency (PIE) curve simulation was applied for the online analysis of isomers and isobaric compounds in the gas phase of mainstream cigarette smoke. After blocking the particulate phase components by the Cambridge filter pad, a puff of fresh gas-phase cigarette smoke was immediately introduced into a vacuum ionization chamber through a heated capillary, then was photoionized, and analyzed by a TOF mass spectrometer. The PIE curves for the mass peaks up to m/z = 106 were measured between 8.0 and 10.7 eV. Some components could be directly identified by their discriminated ionization energies (IEs) on the PIE curve. By simulating the PIE curve with the sum of scaled absolute photoionization cross sections (PICSs), complex isomeric/isobaric compounds along with their mole fractions could be obtained when the best-fitting was realized between experimental and simulated PIE curves. A series of reported toxic compounds for quantification, such as 1,3-butadiene (m/z = 54), 1,3-cyclopentadiene (m/z = 66), benzene (m/z = 78), xylene (m/z = 106), 2-propenal (m/z = 56), acetone and propanal (m/z = 58), crotonaldehyde (m/z = 70), furan and isoprene (m/z = 68), were all found to have other isomers and/or isobaric compounds with considerable abundances. Some isomers have never been reported previously in cigarette smoke, like C5H6 isomers 1-penten-3-yne, 3-penten-1-yne, and 1-penten-4-yne at m/z = 66. Isomeric/isobaric compounds characterization for the mass peaks and mole fraction calculations were discussed in detail below 10.7 eV, an energy value covering several conventional used VUV light sources.

Carbon Nanotube Bundle Array Cold Cathodes for THz Vacuum Tube Sources

NASA Astrophysics Data System (ADS)

Manohara, Harish M.; Toda, Risaku; Lin, Robert H.; Liao, Anna; Bronikowski, Michael J.; Siegel, Peter H.

2009-12-01

We present high performance cold cathodes composed of arrays of carbon nanotube bundles that routinely produce > 15 A/cm2 at applied fields of 5 to 8 V/µm without any beam focusing. They have exhibited robust operation in poor vacuums of 10-6 to 10-4 Torr- a typically achievable range inside hermetically sealed microcavities. A new double-SOI process was developed to monolithically integrate a gate and additional beam tailoring electrodes. The ability to design the electrodes for specific requirements makes carbon nanotube field emission sources extremely flexible. The lifetime of these cathodes is found to be affected by two effects: a gradual decay of emission due to anode sputtering, and catastrophic failure because of dislodging of CNT bundles at high fields ( > 10 V/µm).

Nonperturbative vacuum polarization effects in two-dimensional supercritical Dirac-Coulomb system II. Vacuum energy

NASA Astrophysics Data System (ADS)

Davydov, A.; Sveshnikov, K.; Voronina, Yu.

2018-01-01

Nonperturbative vacuum polarization effects are explored for a supercritical Dirac-Coulomb system with Z > Zcr,1 in 2+1D, based on the original combination of analytical methods, computer algebra and numerical calculations, proposed recently in Refs. 1-3. Both the vacuum charge density ρV P(r→) and vacuum energy ℰV P are considered. Due to a lot of details of calculation the whole work is divided into two parts I and II. Taking account of results, obtained in the part I4 for ρV P, in the present part II, the evaluation of the vacuum energy ℰV P is investigated with emphasis on the renormalization and convergence of the partial expansion for ℰV P. It is shown that the renormalization via fermionic loop turns out to be the universal tool, which removes the divergence of the theory both in the purely perturbative and essentially nonperturbative regimes of the vacuum polarization. The main result of calculation is that for a wide range of the system parameters in the overcritical region ℰV P turns out to be a rapidly decreasing function ˜-ηeffZ3/R with ηeff > 0 and R being the size of the external Coulomb source. To the end the similarity in calculations of ℰV P in 2+1 and 3+1D is discussed, and qualitative arguments are presented in favor of the possibility for complete screening of the classical electrostatic energy of the Coulomb source by the vacuum polarization effects for Z ≫ Zcr,1 in 3+1D.

Waveguide quantum electrodynamics in squeezed vacuum

NASA Astrophysics Data System (ADS)

You, Jieyu; Liao, Zeyang; Li, Sheng-Wen; Zubairy, M. Suhail

2018-02-01

We study the dynamics of a general multiemitter system coupled to the squeezed vacuum reservoir and derive a master equation for this system based on the Weisskopf-Wigner approximation. In this theory, we include the effect of positions of the squeezing sources which is usually neglected in the previous studies. We apply this theory to a quasi-one-dimensional waveguide case where the squeezing in one dimension is experimentally achievable. We show that while dipole-dipole interaction induced by ordinary vacuum depends on the emitter separation, the two-photon process due to the squeezed vacuum depends on the positions of the emitters with respect to the squeezing sources. The dephasing rate, decay rate, and the resonance fluorescence of the waveguide-QED in the squeezed vacuum are controllable by changing the positions of emitters. Furthermore, we demonstrate that the stationary maximum entangled NOON state for identical emitters can be reached with arbitrary initial state when the center-of-mass position of the emitters satisfies certain conditions.

Reference ultraviolet wavelengths of CrIII measured by Fourier transform spectrometry

NASA Astrophysics Data System (ADS)

Smillie, D. G.; Pickering, J. C.; Smith, P. L.

2008-10-01

We report CrIII ultraviolet (UV) transition wavelengths measured using a high-resolution Fourier transform spectrometer (FTS), for the first time, available for use as wavelength standards. The doubly ionized iron group element spectra dominate the observed opacity of hot B stars in the UV, and improved, accurate, wavelengths are required for the analysis of astronomical spectra. The spectrum was excited using a chromium-neon Penning discharge lamp and measured with the Imperial College vacuum ultraviolet FTS. 140 classified 3d34s-3d34p CrIII transition lines, in the spectral range 38000 to 49000 cm-1 (2632 to 2041 Å), the strongest having wavelength uncertainties less than one part in 107, are presented.

A straightforward method for Vacuum-Ultraviolet flux measurements: The case of the hydrogen discharge lamp and implications for solid-phase actinometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fulvio, D., E-mail: daniele.fulvio@uni-jena.de, E-mail: dfu@oact.inaf.it; Brieva, A. C.; Jäger, C.

2014-07-07

Vacuum-Ultraviolet (VUV) radiation is responsible for the photo-processing of simple and complex molecules in several terrestrial and extraterrestrial environments. In the laboratory such radiation is commonly simulated by inexpensive and easy-to-use microwave-powered hydrogen discharge lamps. However, VUV flux measurements are not trivial and the methods/devices typically used for this purpose, mainly actinometry and calibrated VUV silicon photodiodes, are not very accurate or expensive and lack of general suitability to experimental setups. Here, we present a straightforward method for measuring the VUV photon flux based on the photoelectric effect and using a gold photodetector. This method is easily applicable to mostmore » experimental setups, bypasses the major problems of the other methods, and provides reliable flux measurements. As a case study, the method is applied to a microwave-powered hydrogen discharge lamp. In addition, the comparison of these flux measurements to those obtained by O{sub 2} actinometry experiments allow us to estimate the quantum yield (QY) values QY{sub 122} = 0.44 ± 0.16 and QY{sub 160} = 0.87 ± 0.30 for solid-phase O{sub 2} actinometry.« less

Measurement of partial pressures in vacuum technology and vacuum physics

NASA Technical Reports Server (NTRS)

Huber, W. K.

1986-01-01

It is pointed out that the measurement of gaseous pressures of less than 0.0001 torr is based on the ionization of gas atoms and molecules due to collisions with electrons. The particle density is determined in place of the pressure. The ionization cross sections for molecules of various gases are discussed. It is found that the true pressure in a vacuum system cannot be determined with certainty if it is unknown which gas is present. Effects of partial pressure determination on the condition of the vacuum system are discussed together with ion sources, systems of separation, and ion detection.

Ion source research and development at University of Jyväskylä: Studies of different plasma processes and towards the higher beam intensities.

PubMed

Koivisto, H; Kalvas, T; Tarvainen, O; Komppula, J; Laulainen, J; Kronholm, R; Ranttila, K; Tuunanen, J; Thuillier, T; Xie, D; Machicoane, G

2016-02-01

Several ion source related research and development projects are in progress at the Department of Physics, University of Jyväskylä (JYFL). The work can be divided into investigation of the ion source plasma and development of ion sources, ion beams, and diagnostics. The investigation covers the Electron Cyclotron Resonance Ion Source (ECRIS) plasma instabilities, vacuum ultraviolet (VUV) and visible light emission, photon induced electron emission, and the development of plasma diagnostics. The ion source development covers the work performed for radiofrequency-driven negative ion source, RADIS, beam line upgrade of the JYFL 14 GHz ECRIS, and the development of a new room-temperature-magnet 18 GHz ECRIS, HIISI.

Development and fabrication of the vacuum systems for an elliptically polarized undulator at Taiwan Photon Source

NASA Astrophysics Data System (ADS)

Chang, Chin-Chun; Chan, Che-Kai; Wu, Ling-Hui; Shueh, Chin; Shen, I.-Ching; Cheng, Chia-Mu; Yang, I.-Chen

2017-05-01

Three sets of a vacuum system were developed and fabricated for elliptically polarized undulators (EPU) of a 3-GeV synchrotron facility. These chambers were shaped with low roughness extrusion and oil-free machining; the design combines aluminium and stainless steel. The use of a bimetallic material to connect the EPU to the vacuum system achieves the vacuum sealing and to resolve the leakage issue due to bake process induced thermal expansion difference. The interior of the EPU chamber consists of a non-evaporable-getter strip pump in a narrow space to absorb photon-stimulated desorption and to provide a RF bridge design to decrease impedance effect in the two ends of EPU chamber. To fabricate these chambers and to evaluate the related performance, we performed a computer simulation to optimize the structure. During the machining and welding, the least deformation was achieved, less than 0.1 mm near 4 m. In the installation, the linear slider can provide a stable and precision moved along parallel the electron beam direction smoothly for the EPU chamber to decrease the twist issue during baking process. The pressure of the EPU chamber attained less than 2×10-8 Pa through baking. These vacuum systems of the EPU magnet have been installed in the electron storage ring of Taiwan Photon Source in 2015 May and have normally operated at 300 mA continuously since, and to keep beam life time achieved over than 12 h.

Cluster beam targets for laser plasma extreme ultraviolet and soft x-ray sources

DOEpatents

Kublak, G.D.; Richardson, M.C.

1996-11-19

Method and apparatus for producing extreme ultraviolet (EUV) and soft x-ray radiation from an ultra-low debris plasma source are disclosed. Targets are produced by the free jet expansion of various gases through a temperature controlled nozzle to form molecular clusters. These target clusters are subsequently irradiated with commercially available lasers of moderate intensity (10{sup 11}--10{sup 12} watts/cm{sup 2}) to produce a plasma radiating in the region of 0.5 to 100 nanometers. By appropriate adjustment of the experimental conditions the laser focus can be moved 10--30 mm from the nozzle thereby eliminating debris produced by plasma erosion of the nozzle. 5 figs.

The Extreme Ultraviolet Explorer

NASA Technical Reports Server (NTRS)

Malina, R. F.; Bowyer, S.; Lampton, M.; Finley, D.; Paresce, F.; Penegor, G.; Heetderks, H.

1982-01-01

The Extreme Ultraviolet Explorer Mission is described. The purpose of this mission is to search the celestial sphere for astronomical sources of extreme ultraviolet (EUV) radiation (100 to 1000 A). The search will be accomplished with the use of three EUV telescopes, each sensitive to different bands within the EUV band. A fourth telescope will perform a higher sensitivity search of a limited sample of the sky in a single EUV band. In six months, the entire sky will be scanned at a sensitivity level comparable to existing surveys in other more traditional astronomical bandpasses.

The trace anomaly and dynamical vacuum energy in cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mottola, Emil

2010-04-30

The trace anomaly of conformal matter implies the existence of massless scalar poles in physical amplitudes involving the stress-energy tensor. These poles may be described by a local effective action with massless scalar fields, which couple to classical sources, contribute to gravitational scattering processes, and can have long range gravitational effects at macroscopic scales. In an effective field theory approach, the effective action of the anomaly is an infrared relevant term that should be added to the Einstein-Hilbert action of classical General Relativity to take account of macroscopic quantum effects. The additional scalar degrees of freedom contained in this effectivemore » action may be understood as responsible for both the Casimir effect in flat spacetime and large quantum backreaction effects at the horizon scale of cosmological spacetimes. These effects of the trace anomaly imply that the cosmological vacuum energy is dynamical, and its value depends on macroscopic boundary conditions at the cosmological horizon scale, rather than sensitivity to the extreme ultraviolet Planck scale.« less

High throughput vacuum chemical epitaxy

NASA Astrophysics Data System (ADS)

Fraas, L. M.; Malocsay, E.; Sundaram, V.; Baird, R. W.; Mao, B. Y.; Lee, G. Y.

1990-10-01

We have developed a vacuum chemical epitaxy (VCE) reactor which avoids the use of arsine and allows multiple wafers to be coated at one time. Our vacuum chemical epitaxy reactor closely resembles a molecular beam epitaxy system in that wafers are loaded into a stainless steel vacuum chamber through a load chamber. Also as in MBE, arsenic vapors are supplied as reactant by heating solid arsenic sources thereby avoiding the use of arsine. However, in our VCE reactor, a large number of wafers are coated at one time in a vacuum system by the substitution of Group III alkyl sources for the elemental metal sources traditionally used in MBE. Higher wafer throughput results because in VCE, the metal-alkyl sources for Ga, Al, and dopants can be mixed at room temperature and distributed uniformly though a large area injector to multiple substrates as a homogeneous array of mixed element molecular beams. The VCE reactor that we have built and that we shall describe here uniformly deposits films on 7 inch diameter substrate platters. Each platter contains seven two inch or three 3 inch diameter wafers. The load chamber contains up to nine platters. The vacuum chamber is equipped with two VCE growth zones and two arsenic ovens, one per growth zone. Finally, each oven has a 1 kg arsenic capacity. As of this writing, mirror smooth GaAs films have been grown at up to 4 μm/h growth rate on multiple wafers with good thickness uniformity. The background doping is p-type with a typical hole concentration and mobility of 1 × 10 16/cm 3 and 350 cm 2/V·s. This background doping level is low enough for the fabrication of MESFETs, solar cells, and photocathodes as well as other types of devices. We have fabricated MESFET devices using VCE-grown epi wafers with peak extrinsic transconductance as high as 210 mS/mm for a threshold voltage of - 3 V and a 0.6 μm gate length. We have also recently grown AlGaAs epi layers with up to 80% aluminum using TEAl as the aluminum alkyl source. The Al

A dense plasma ultraviolet source

NASA Technical Reports Server (NTRS)

Lee, J. H.; Mcfarland, D. R.

1978-01-01

The intense ultraviolet emission from the NASA Hypocycloidal-Pinch (HCP) plasma is investigated. The HCP consists of three disk electrodes whose cross section has a configuration similar to the cross section of a Mather-type plasma focus. Plasma foci were produced in deuterium, helium, xenon, and krypton gases in order to compare their emission characteristics. Time-integrated spectra in the wavelength range from 200 nm to 350 nm and temporal variations of the uv emission were obtained with a uv spectrometer and a photomultiplier system. Modifications to enhance uv emission in the iodine-laser pump band (250 to 290 nm) and preliminary results produced by these modifications are presented. Finally, the advantages of the HCP as a uv over use of conventional xenon lamps with respect to power output limit, spectral range, and lifetime are discussed.

Technical specification for vacuum systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khaw, J.

The vacuum systems at the Stanford Linear Accelerator Center (SLAC) are primarily of all-metal construction and operate at pressures from 10/sup -5/ to 10/sup -11/ Torr. The primary gas loads during operation result from thermal desorption and beam-induced desorption from the vacuum chamber walls. These desorption rates can be extremely high in the case of hydrocarbons and other contaminants. These specifications place a major emphasis on eliminating contamination sources. The specifications and procedures have been written to insure the cleanliness and vacuum integrity of all SLAC vacuum systems, and to assist personnel involved with SLAC vacuum systems in choosing andmore » designing components that are compatible with existing systems and meet the quality and reliability of SLAC vacuum standards. The specification includes requirements on design, procurement, fabrication, chemical cleaning, clean room practices, welding and brazing, helium leak testing, residual gas analyzer testing, bakeout, venting, and pumpdown. Also appended are specifications regarding acceptable vendors, isopropyl alcohol, bakeable valve cleaning procedure, mechanical engineering safety inspection, notes on synchrotron radiation, and specifications of numerous individual components. (LEW)« less

Optimizing image-based patterned defect inspection through FDTD simulations at multiple ultraviolet wavelengths

NASA Astrophysics Data System (ADS)

Barnes, Bryan M.; Zhou, Hui; Henn, Mark-Alexander; Sohn, Martin Y.; Silver, Richard M.

2017-06-01

The sizes of non-negligible defects in the patterning of a semiconductor device continue to decrease as the dimensions for these devices are reduced. These "killer defects" disrupt the performance of the device and must be adequately controlled during manufacturing, and new solutions are required to improve optics-based defect inspection. To this end, our group has reported [Barnes et al., Proc. SPIE 1014516 (2017)] our initial five-wavelength simulation study, evaluating the extensibility of defect inspection by reducing the inspection wavelength from a deep-ultraviolet wavelength to wavelengths in the vacuum ultraviolet and the extreme ultraviolet. In that study, a 47 nm wavelength yielded enhancements in the signal to noise (SNR) by a factor of five compared to longer wavelengths and in the differential intensities by as much as three orders-of-magnitude compared to 13 nm. This paper briefly reviews these recent findings and investigates the possible sources for these disparities between results at 13 nm and 47 nm wavelengths. Our in-house finite-difference time-domain code (FDTD) is tested in both two and three dimensions to determine how computational conditions contributed to the results. A modified geometry and materials stack is presented that offers a second viewpoint of defect detectability as functions of wavelength, polarization, and defect type. Reapplication of the initial SNR-based defect metric again yields no detection of a defect at λ = 13 nm, but additional image preprocessing now enables the computation of the SNR for λ = 13 nm simulated images and has led to a revised defect metric that allows comparisons at all five wavelengths.

Modelling and Display of the Ultraviolet Sky

NASA Astrophysics Data System (ADS)

Daniels, J.; Henry, R.; Murthy, J.; Allen, M.; McGlynn, T. A.; Scollick, K.

1994-12-01

A computer program is currently under development to model in 3D - one dimension of which is wavelength - all the known and major speculated sources of ultraviolet (900 A - 3100 A ) radiation over the celestial sphere. The software is being written in Fortran 77 and IDL and currently operates under IRIX (the operating system of the Silicon Graphics Iris Machine); all output models are in FITS format. Models along with display software will become available to the astronomical community. The Ultraviolet Sky Model currently includes the Zodiacal Light, Point Sources of Emission, and the Diffuse Galactic Light. The Ultraviolet Sky Model is currently displayed using SkyView: a package under development at NASA/ GSFC, which allows users to retrieve and display publically available all-sky astronomical survey data (covering many wavebands) over the Internet. We present a demonstration of the SkyView display of the Ultraviolet Model. The modelling is a five year development project: the work illustrated here represents product output at the end of year one. Future work includes enhancements to the current models and incorporation of the following models: Galactic Molecular Hydrogen Fluorescence; Galactic Highly Ionized Atomic Line Emission; Integrated Extragalactic Light; and speculated sources in the intergalactic medium such as Ionized Plasma and radiation from Non-Baryonic Particle Decay. We also present a poster which summarizes the components of the Ultraviolet Sky Model and outlines a further package that will be used to display the Ultraviolet Model. This work is supported by United States Air Force Contract F19628-93-K-0004. Dr J. Daniels is supported with a post-doctoral Fellowship from the Leverhulme Foundation, London, United Kingdom. We are also grateful for the encouragement of Dr Stephen Price (Phillips Laboratory, Hanscomb Air Force Base, MA)

A Grazing Incidence Spectrograph as Applied to Vacuum Ultraviolet, Soft X-Ray, Pulsed Plasma Sources.

DTIC Science & Technology

A 2.2-meter variable angle of incidence grazing incidence spectrograph is described for photographic recording of spectra down to 10A. Also a method for determining the absolute total fluence from a pulsed plasma source, knowing the absolute sensitivity of the instrument, is described. Spectra are presented from a low-inductance sliding spark gap and a 20-kj dense plasma focus . A program for spectram analysis is included. (Modified author abstract)

High-resolution, vacuum-ultraviolet absorption spectrum of boron trifluoride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughes, Patrick P.; Thompson, Alan K.; Vest, Robert E.

2014-11-21

In the course of investigations of thermal neutron detection based on mixtures of {sup 10}BF{sub 3} with other gases, knowledge was required of the photoabsorption cross sections of {sup 10}BF{sub 3} for wavelengths between 135 and 205 nm. Large discrepancies in the values reported in existing literature led to the absolute measurements reported in this communication. The measurements were made at the SURF III Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology. The measured absorption cross sections vary from 10{sup −20} cm{sup 2} at 135 nm to less than 10{sup −21} cm{sup 2} in the regionmore » from 165 to 205 nm. Three previously unreported absorption features with resolvable structure were found in the regions 135–145 nm, 150–165 nm, and 190–205 nm. Quantum mechanical calculations, using the TD-B3LYP/aug-cc-pVDZ variant of time-dependent density functional theory implemented in Gaussian 09, suggest that the observed absorption features arise from symmetry-changing adiabatic transitions.« less

Multistep Ionization of Argon Clusters in Intense Femtosecond Extreme Ultraviolet Pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bostedt, C.; Thomas, H.; Hoener, M.

The interaction of intense extreme ultraviolet femtosecond laser pulses ({lambda}=32.8 nm) from the FLASH free electron laser (FEL) with clusters has been investigated by means of photoelectron spectroscopy and modeled by Monte Carlo simulations. For laser intensities up to 5x10{sup 13} W/cm{sup 2}, we find that the cluster ionization process is a sequence of direct electron emission events in a developing Coulomb field. A nanoplasma is formed only at the highest investigated power densities where ionization is frustrated due to the deep cluster potential. In contrast with earlier studies in the IR and vacuum ultraviolet spectral regime, we find nomore » evidence for electron emission from plasma heating processes.« less

Reference Ultraviolet Wavelengths of Cr III Measured by Fourier Transform Spectrometry

NASA Technical Reports Server (NTRS)

Smillie, D.G.; Pickering, J.C.; Smith, P.L.

2008-01-01

We report Cr III ultraviolet (UV) transition wavelengths measured using a high-resolution Fourier transform spectrometer (FTS), for the first time, available for use as wavelength standards. The doubly ionized iron group element spectra dominate the observed opacity of hot B stars in the UV, and improved, accurate, wavelengths are required for the analysis of astronomical spectra. The spectrum was excited using a chromium-neon Penning discharge lamp and measured with the Imperial College vacuum ultraviolet FTS. 140 classified 3d(exp 3)4s- 3d(exp 3)4p Cr III transition lines, in the spectral range 38,000 to 49,000 cm(exp -1) (2632 to 2041 A), the strongest having wavelength uncertainties less than one part in 10(exp 7), are presented.

Rotation of dwarf star chromospheres in the ultraviolet

NASA Technical Reports Server (NTRS)

Hallam, K. L.; Wolff, C. L.

1981-01-01

Periodic variations in the ultraviolet fluxes of chromospheric emission line multiplets are investigated for F, G and K stars as evidence of rotational modulation. Vacuum ultraviolet spectra were obtained with the IUE spacecraft for six stars as many as 11 times over the period April 23 to December 3, 1980. Variations in the emission fluxes of the hydrogen Lyman-alpha, Si II and Mg II lines are observed with periods up to 47 days. The periodicity, which is identified with rotational modulation, is found to persist over many rotational cycles, although the periods and time dependences of the fluxes from the different ionic species are not identical, probably due to differential rotation and global distributions. The spread of the UV periods is observed to be within 10%, with one or two peaks per cycle and a ratio of modulated to umodulated flux ranging from 1.1 to 3.0, analogous to solar behavior.

Airfoil sampling of a pulsed Laval beam with tunable vacuum ultraviolet synchrotron ionization quadrupole mass spectrometry: application to low-temperature kinetics and product detection.

PubMed

Soorkia, Satchin; Liu, Chen-Lin; Savee, John D; Ferrell, Sarah J; Leone, Stephen R; Wilson, Kevin R

2011-12-01

A new pulsed Laval nozzle apparatus with vacuum ultraviolet (VUV) synchrotron photoionization quadrupole mass spectrometry is constructed to study low-temperature radical-neutral chemical reactions of importance for modeling the atmosphere of Titan and the outer planets. A design for the sampling geometry of a pulsed Laval nozzle expansion has been developed that operates successfully for the determination of rate coefficients by time-resolved mass spectrometry. The new concept employs airfoil sampling of the collimated expansion with excellent sampling throughput. Time-resolved profiles of the high Mach number gas flow obtained by photoionization signals show that perturbation of the collimated expansion by the airfoil is negligible. The reaction of C(2)H with C(2)H(2) is studied at 70 K as a proof-of-principle result for both low-temperature rate coefficient measurements and product identification based on the photoionization spectrum of the reaction product versus VUV photon energy. This approach can be used to provide new insights into reaction mechanisms occurring at kinetic rates close to the collision-determined limit.

The Extreme Ultraviolet Explorer Mission

NASA Technical Reports Server (NTRS)

Bowyer, S.; Malina, R. F.

1991-01-01

The Extreme Ultraviolet Explorer (EUVE) mission, currently scheduled from launch in September 1991, is described. The primary purpose of the mission is to survey the celestial sphere for astronomical sources of extreme ultraviolet (EUV) radiation with the use of three EUV telescope, each sensitive to a different segment of the EUV band. A fourth telescope is planned to perform a high-sensitivity search of a limited sample of the sky in the shortest wavelength bands. The all-sky survey is planned to be carried out in the first six months of the mission in four bands, or colors, 70-180 A, 170-250 A, 400-600 A, and 500-700 A. The second phase of the mission is devoted to spectroscopic observations of EUV sources. A high-efficiency grazing-incidence spectrometer using variable line-space gratings is planned to provide spectral data with about 1-A resolution. An end-to-end model of the mission, from a stellar source to the resulting scientific data, is presented. Hypothetical data from astronomical sources were processed through this model and are shown.

Infrared-Vacuum Ultraviolet Pulsed Field Ionization-Photoelectron Study of C₂H₄ + Using a High-Resolution Infrared Laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xing, Xi; Reed, Beth; Bahng, Mi-Kyung

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The infrared (IR)-vacuum ultraviolet (VUV)-pulsed field ionization-photoelectron (IR-VUV-PFI-PE) spectrum for C₂H₄(X 1A g, V 11 = 1, N' Ka' Kc'=3₀₃) in the VUV range of 83 000-84 800 cm -1 obtained using a single mode infrared laser revealed 24 rotationally resolved vibrational bands for the ion C₂H₄ +(X 2B 3u) ground state. The frequencies and symmetry of the vibrational bandsmore » thus determined, together with the anharmonic frequency predictions calculated at the CCSD(T)/aug-cc-pVQZ level, have allowed the unambiguous assignment of these vibrational bands. These bands are mostly combination bands. The measured frequencies of these bands yield the fundamental frequencies for V 8 + ) 1103± ( 10 cm -1 and V 10 + ) 813 ( 10 cm -1 of C₂H₄ +(X 2B 3u), which have not been determined previously. The present IR-VUV-PFI-PE study also provides truly rovibrationally selected and resolved state-to-state cross sections for the photoionization transitions C₂H₄(X~ 1A g; V 11, N' Ka' Kc') → C₂H₄ +(X ~ 2B 3u; V i +, N + Ka + Kc +), where N' Ka' Kc' denotes the rotational level of C₂H₄(X ~ 1Ag; V 11), and V i + and N + Ka + Kc + represent the vibrational and rotational states of the cation.« less

Valence and ionic lowest-lying electronic states of ethyl formate as studied by high-resolution vacuum ultraviolet photoabsorption, He(I) photoelectron spectroscopy, and ab initio calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Śmiałek, M. A., E-mail: smialek@pg.gda.pl; Łabuda, M.; Guthmuller, J.

2014-09-14

The highest resolution vacuum ultraviolet photoabsorption spectrum of ethyl formate, C{sub 2}H{sub 5}OCHO, yet reported is presented over the wavelength range 115.0–275.5 nm (10.75–4.5 eV) revealing several new spectral features. Valence and Rydberg transitions and their associated vibronic series, observed in the photoabsorption spectrum, have been assigned in accordance with new ab initio calculations of the vertical excitation energies and oscillator strengths. Calculations have also been carried out to determine the ionization energies and fine structure of the lowest ionic state of ethyl formate and are compared with a newly recorded He(I) photoelectron spectrum (from 10.1 to 16.1 eV). Newmore » vibrational structure is observed in the first photoelectron band. The photoabsorption cross sections have been used to calculate the photolysis lifetime of ethyl formate in the upper stratosphere (20–50 km)« less

Selected highlights from the Extreme Ultraviolet Explorer

NASA Technical Reports Server (NTRS)

Bowyer, S.; Malina, R. F.

1995-01-01

We present a few scientific highlights from the Extreme Ultraviolet Explorer (EUVE) all-sky and deep surveys, from the EUVE Righ Angle Program, and from the EUVE Guest Observer Program. The First EUVE Source Catalog includes 410 extreme ultraviolet (EUV) sources detected in the initial processing of the EUVE all-sky data. A program of optical identification indicates that counterparts include cool star coronae, flare stars, hot white dwarfs, central stars of planetary nebulae, B star photospheres and winds, an X-ray binary, extragalactic objects (active galactic nuclei, BL Lacertae), solar system objects (Moon, Mars, Io,), supernova remnants, and two novae.

Ultrafast High Harmonic, Soft X-Ray Probing of Molecular Dynamics

DTIC Science & Technology

2013-04-30

590 L/s scroll pump and a titanium sublimation pump . A TOF-PES has been designed and constructed to analyze the energy of the photoelectrons...are studied using the quasi-continuous vacuum ultraviolet light of the Advanced Light Source at Lawrence Berkeley National Laboratory. The molecular...34), the method of high order harmonic generation of ultrashort vacuum ultraviolet pulses was used to investigate molecular photodissociation, ultrafast

Vacuum ultraviolet coatings of Al protected with MgF(2) prepared both by ion-beam sputtering and by evaporation.

PubMed

Fernández-Perea, Mónica; Larruquert, Juan I; Aznárez, José A; Pons, Alicia; Méndez, José A

2007-08-01

Ion-beam sputtering (IBS) and evaporation are the two deposition techniques that have been used to deposit coatings of Al protected with MgF(2) with high reflectance in the vacuum ultraviolet down to 115 nm. Evaporation deposited (ED) Al protected with IBS MgF(2) resulted in a larger (smaller) reflectance below (above) 125 nm than the well-known all-evaporated coatings. A similar comparison is obtained when the Al film is deposited by IBS instead of evaporation. The lower reflectance of the coatings protected with IBS versus ED MgF(2) above 125 nm is because of larger absorption of the former. Both nonprotected IBS Al, as well as IBS Al protected with ED MgF(2), resulted in a band of reflectance loss that was peaked at 127 and 157 nm, respectively. This result was attributed to the excitation of surface plasmons due to the enhancement of surface roughness with large spatial wave vectors in the sputter deposition. This reflectance loss for IBS Al protected with MgF(2) is small at the short (lambda~120 nm) and long (lambda<350 nm) wavelengths investigated. IBS Al protected with ED MgF(2) is thus a promising coating for these two spectral regions. Coatings protected with IBS MgF(2) resulted in a reflectance as high as coatings protected with ED MgF(2) at wavelengths longer than 550 nm, whereas the former had a lower reflectance below this wavelength.

Ultraviolet radiation effects on the infrared damage rate of a thermal control coating

NASA Technical Reports Server (NTRS)

Bass, J. A.

1972-01-01

The effects of ultraviolet radiation on the infrared reflectance of ZnO silicone white thermal coatings were investigated. Narrow band ultraviolet radiation for wavelengths in the 2200A to 3500A range by a monochromator and a high pressure, 150-W Eimac xenon lamp. The sample was irradiated while in a vacuum of at least 0.000001 torr, and infrared reflectance was measured in situ with a spectroreflectometer at 19,500A. Reflectance degradation was studied as a function of wavelength, time, intensity, and dose. Damage was wavelength dependent at constant exposure, but no maximum was evident above the shortest wavelength investigated here. The degradation rate at constant intensity was an exponential function of time and varies with intensity.

Enhanced attosecond pulse generation in the vacuum ultraviolet using a two-colour driving field for high harmonic generation

NASA Astrophysics Data System (ADS)

Matía-Hernando, P.; Witting, T.; Walke, D. J.; Marangos, J. P.; Tisch, J. W. G.

2018-03-01

High-harmonic radiation in the extreme ultraviolet and soft X-ray spectral regions can be used to generate attosecond pulses and to obtain structural and dynamic information in atoms and molecules. However, these sources typically suffer from a limited photon flux. An additional issue at lower photon energies is the appearance of satellites in the time domain, stemming from insufficient temporal gating and the spectral filtering required for the isolation of attosecond pulses. Such satellites limit the temporal resolution. The use of multi-colour driving fields has been proven to enhance the harmonic yield and provide additional control, using the relative delays between the different spectral components for waveform shaping. We describe here a two-colour high-harmonic source that combines a few-cycle near-infrared pulse with a multi-cycle second harmonic pulse, with both relative phase and carrier-envelope phase stabilization. We observe strong modulations in the harmonic flux, and present simulations and experimental results supporting the suppression of satellites in sub-femtosecond pulses at 20 eV compared to the single colour field case, an important requirement for attosecond pump-probe measurements.

Design, fabrication and performance of two grazing incidence telescopes for celestial extreme ultraviolet astronomy

NASA Technical Reports Server (NTRS)

Lampton, M.; Cash, W.; Malina, R. F.; Bowyer, S.

1977-01-01

The design and performance of grazing incidence telescopes for celestial extreme ultraviolet (EUV) astronomy are described. The telescopes basically consist of a star tracker, collimator, grazing incidence mirror, vacuum box lid, vacuum housing, filters, a ranicon detector, an electronics box, and an aspect camera. For the survey mirror a Wolter-Schwarzschild type II configuration was selected. Diamond-turning was used for mirror fabrication, a technique which machines surfaces to the order of 10 microns over the required dimensions. The design of the EUV spectrometer is discussed with particular reference to the optics for a primarily spectroscopic application and the fabrication of the f/10 optics.

Far Ultraviolet Imaging from the Image Spacecraft

NASA Technical Reports Server (NTRS)

Mende, S. B.; Heetderks, H.; Frey, H. U.; Lampton, M.; Geller, S. P.; Stock, J. M.; Abiad, R.; Siegmund, O. H. W.; Tremsin, A. S.; Habraken, S.

2000-01-01

Direct imaging of the magnetosphere by the IMAGE spacecraft will be supplemented by observation of the global aurora. The IMAGE satellite instrument complement includes three Far Ultraviolet (FUV) instruments. The Wideband Imaging Camera (WIC) will provide broad band ultraviolet images of the aurora for maximum spatial and temporal resolution by imaging the LBH N2 bands of the aurora. The Spectrographic Imager (SI), a novel form of monochromatic imager, will image the aurora, filtered by wavelength. The proton-induced component of the aurora will be imaged separately by measuring the Doppler-shifted Lyman-a. Finally, the GEO instrument will observe the distribution of the geocoronal emission to obtain the neutral background density source for charge exchange in the magnetosphere. The FUV instrument complement looks radially outward from the rotating IMAGE satellite and, therefore, it spends only a short time observing the aurora and the Earth during each spin. To maximize photon collection efficiency and use efficiently the short time available for exposures the FUV auroral imagers WIC and SI both have wide fields of view and take data continuously as the auroral region proceeds through the field of view. To minimize data volume, the set of multiple images are electronically co-added by suitably shifting each image to compensate for the spacecraft rotation. In order to minimize resolution loss, the images have to be distort ion-corrected in real time. The distortion correction is accomplished using high speed look up tables that are pre-generated by least square fitting to polynomial functions by the on-orbit processor. The instruments were calibrated individually while on stationary platforms, mostly in vacuum chambers. Extensive ground-based testing was performed with visible and near UV simulators mounted on a rotating platform to emulate their performance on a rotating spacecraft.

Far ultraviolet excitation processes in comets

NASA Technical Reports Server (NTRS)

Feldman, P. D.; Opal, C. B.; Meier, R. R.; Nicolas, K. R.

1976-01-01

Recent observations of atomic oxygen and carbon in the far ultraviolet spectrum of comet Kohoutek have demonstrated the existence of these atomic species in the cometary coma. However, in order to identify the source of their origin, it is necessary to relate the observed ultraviolet flux to the atomic production rate. Analyses of observed OI wavelength 1304 and CI wavelength 1657 A multiplets have been carried out using high resolution solar spectra. Also examined is the possibility of observing ultraviolet fluorescence from molecules such as CO and H2, as well as resonance scattering either from atomic ions for which there are strong corresponding solar lines (CII) or from atoms for which there is an accidental wavelength coincidence (SI).

Vapor-barrier Vacuum Isolation System

NASA Technical Reports Server (NTRS)

Weinstein, Leonard M. (Inventor); Taminger, Karen M. (Inventor)

2014-01-01

A system includes a collimated beam source within a vacuum chamber, a condensable barrier gas, cooling material, a pump, and isolation chambers cooled by the cooling material to condense the barrier gas. Pressure levels of each isolation chamber are substantially greater than in the vacuum chamber. Coaxially-aligned orifices connect a working chamber, the isolation chambers, and the vacuum chamber. The pump evacuates uncondensed barrier gas. The barrier gas blocks entry of atmospheric vapor from the working chamber into the isolation chambers, and undergoes supersonic flow expansion upon entering each isolation chamber. A method includes connecting the isolation chambers to the vacuum chamber, directing vapor to a boundary with the working chamber, and supersonically expanding the vapor as it enters the isolation chambers via the orifices. The vapor condenses in each isolation chamber using the cooling material, and uncondensed vapor is pumped out of the isolation chambers via the pump.

Nonperturbative vacuum polarization effects in two-dimensional supercritical Dirac-Coulomb system I. Vacuum charge density

NASA Astrophysics Data System (ADS)

Davydov, A.; Sveshnikov, K.; Voronina, Yu.

2018-01-01

Based on the original combination of analytical methods, computer algebra tools and numerical calculations, proposed recently in Refs. 1-3, the nonperturbative vacuum polarization effects in the 2+1D supercritical Dirac-Coulomb system with Z > Zcr,1 are explored. Both the vacuum charge density ρV P(r→) and vacuum energy ℰV P are considered. The main result of the work is that in the overcritical region ℰV P turns out to be a rapidly decreasing function ˜-ηeffZ3/R with ηeff > 0 and R being the size of the external Coulomb source. Due to a lot of details of calculation the whole work is divided into two parts I and II. In the present part I, we consider the evaluation and behavior of the vacuum density ρV P, which further is used in part II for evaluation of the vacuum energy, with emphasis on the renormalization, convergence of the partial expansion for ρV P and behavior of the integral induced charge QV P in the overcritical region.

Absolute photoionization cross section of the ethyl radical in the range 8-11.5 eV: synchrotron and vacuum ultraviolet laser measurements.

PubMed

Gans, Bérenger; Garcia, Gustavo A; Boyé-Péronne, Séverine; Loison, Jean-Christophe; Douin, Stéphane; Gaie-Levrel, François; Gauyacq, Dolores

2011-06-02

The absolute photoionization cross section of C(2)H(5) has been measured at 10.54 eV using vacuum ultraviolet (VUV) laser photoionization. The C(2)H(5) radical was produced in situ using the rapid C(2)H(6) + F → C(2)H(5) + HF reaction. Its absolute photoionization cross section has been determined in two different ways: first using the C(2)H(5) + NO(2) → C(2)H(5)O + NO reaction in a fast flow reactor, and the known absolute photoionization cross section of NO. In a second experiment, it has been measured relative to the known absolute photoionization cross section of CH(3) as a reference by using the CH(4) + F → CH(3) + HF and C(2)H(6) + F → C(2)H(5) + HF reactions successively. Both methods gave similar results, the second one being more precise and yielding the value: σ(C(2)H(5))(ion) = (5.6 ± 1.4) Mb at 10.54 eV. This value is used to calibrate on an absolute scale the photoionization curve of C(2)H(5) produced in a pyrolytic source from the C(2)H(5)NO(2) precursor, and ionized by the VUV beam of the DESIRS beamline at SOLEIL synchrotron facility. In this latter experiment, a recently developed ion imaging technique is used to discriminate the direct photoionization process from dissociative ionization contributions to the C(2)H(5)(+) signal. The imaging technique applied on the photoelectron signal also allows a slow photoelectron spectrum with a 40 meV resolution to be extracted, indicating that photoionization around the adiabatic ionization threshold involves a complex vibrational overlap between the neutral and cationic ground states, as was previously observed in the literature. Comparison with earlier photoionization studies, in particular with the photoionization yield recorded by Ruscic et al. is also discussed. © 2011 American Chemical Society

Full observation of ultrafast cascaded radiationless transitions from S{sub 2}(ππ{sup ∗}) state of pyrazine using vacuum ultraviolet photoelectron imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horio, Takuya; Spesyvtsev, Roman; Nagashima, Kazuki

A photoexcited molecule undergoes multiple deactivation and reaction processes simultaneously or sequentially, which have been observed by combinations of various experimental methods. However, a single experimental method that enables complete observation of the photo-induced dynamics would be of great assistance for such studies. Here we report a full observation of cascaded electronic dephasing from S{sub 2}(ππ{sup *}) in pyrazine (C{sub 4}N{sub 2}H{sub 4}) by time-resolved photoelectron imaging (TRPEI) using 9.3-eV vacuum ultraviolet pulses with a sub-20 fs time duration. While we previously demonstrated a real-time observation of the ultrafast S{sub 2}(ππ{sup *}) → S{sub 1}(nπ{sup *}) internal conversion in pyrazinemore » using TRPEI with UV pulses, this study presents a complete observation of the dynamics including radiationless transitions from S{sub 1} to S{sub 0} (internal conversion) and T{sub 1}(nπ{sup *}) (intersystem crossing). Also discussed are the role of {sup 1}A{sub u}(nπ{sup *}) in the internal conversion and the configuration interaction of the S{sub 2}(ππ{sup *}) electronic wave function.« less

Near-ultraviolet laser diodes for brilliant ultraviolet fluorophore excitation.

PubMed

Telford, William G

2015-12-01

Although multiple lasers are now standard equipment on most modern flow cytometers, ultraviolet (UV) lasers (325-365 nm) remain an uncommon excitation source for cytometry. Nd:YVO4 frequency-tripled diode pumped solid-state lasers emitting at 355 nm are now the primary means of providing UV excitation on multilaser flow cytometers. Although a number of UV excited fluorochromes are available for flow cytometry, the cost of solid-state UV lasers remains prohibitively high, limiting their use to all but the most sophisticated multilaser instruments. The recent introduction of the brilliant ultraviolet (BUV) series of fluorochromes for cell surface marker detection and their importance in increasing the number of simultaneous parameters for high-dimensional analysis has increased the urgency of including UV sources in cytometer designs; however, these lasers remain expensive. Near-UV laser diodes (NUVLDs), a direct diode laser source emitting in the 370-380 nm range, have been previously validated for flow cytometric analysis of most UV-excited probes, including quantum nanocrystals, the Hoechst dyes, and 4',6-diamidino-2-phenylindole. However, they remain a little-used laser source for cytometry, despite their significantly lower cost. In this study, the ability of NUVLDs to excite the BUV dyes was assessed, along with their compatibility with simultaneous brilliant violet (BV) labeling. A NUVLD emitting at 375 nm was found to excite most of the available BUV dyes at least as well as a UV 355 nm source. This slightly longer wavelength did produce some unwanted excitation of BV dyes, but at sufficiently low levels to require minimal additional compensation. NUVLDs are compact, relatively inexpensive lasers that have higher power levels than the newest generation of small 355 nm lasers. They can, therefore, make a useful, cost-effective substitute for traditional UV lasers in multicolor analysis involving the BUV and BV dyes. Published 2015 Wiley Periodicals Inc. on

Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air

NASA Astrophysics Data System (ADS)

Gulati, P.; Prakash, R.; Pal, U. N.; Kumar, M.; Vyas, V.

2014-07-01

A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl2 deteriorates the performance of the developed source and around 2% Cl2 in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

Sealing Materials for Use in Vacuum at High Temperatures

NASA Technical Reports Server (NTRS)

Pettit, Donald R.; Camarda, Charles J.; Lee Vaughn, Wallace

2012-01-01

Sealing materials that can be applied and left in place in vacuum over a wide range of temperatures (especially temperatures of a few thousand degrees Celsius) have been conceived and investigated for potential utility in repairing thermal-protection tiles on the space shuttles in orbit before returning to Earth. These materials are also adaptable to numerous terrestrial applications that involve vacuum processing and/or repair of structures that must withstand high temperatures. These materials can be formulated to have mechanical handling characteristics ranging from almost freely flowing liquid-like consistency through paste-like consistency to stiff puttylike consistency, and to retain these characteristics in vacuum until heated to high curing temperatures. A sealing material of this type can be formulated to be used in any of several different ways for example, to be impregnated into a high-temperature-fabric patch, impregnated into a high-temperature-fabric gasket for sealing a patch, applied under a patch, or applied alone in the manner of putty or wallboard compound. The sealing material must be formulated to be compatible with, and adhere to, the structural material(s) to be repaired. In general, the material consists of a vacuum-compatible liquid containing one or more dissolved compound(s) and/or mixed with suspended solid particles. Depending on the intended application, the liquid can be chosen to be of a compound that can remain in place in vacuum for a time long enough to be useful, and/or to evaporate or decompose in a controlled way to leave a useful solid residue behind. The evaporation rate is determined by proper choice of vapor pressure, application of heat, and/or application of ultraviolet light or other optical radiation. The liquid chosen for the original space shuttle application is a commercial silicone vacuum-pump oil.

Web-Resources for Astronomical Data in the Ultraviolet

NASA Astrophysics Data System (ADS)

Sachkov, M. E.; Malkov, O. Yu.

2017-12-01

In this paper we describe databases of space projects that are operating or have operated in the ultraviolet spectral region. We give brief descriptions and links to major sources for UV data on the web: archives, space mission sites, databases, catalogues. We pay special attention to the World Space Observatory—Ultraviolet mission that will be launched in 2021.

Imaging performance improvement of coherent extreme-ultraviolet scatterometry microscope with high-harmonic-generation extreme-ultraviolet source

NASA Astrophysics Data System (ADS)

Mamezaki, Daiki; Harada, Tetsuo; Nagata, Yutaka; Watanabe, Takeo

2017-06-01

In extreme-ultraviolet (EUV) lithography, the development of a review apparatus for the EUV mask pattern at an exposure wavelength of 13.5 nm is required. The EUV mask is composed of an absorber pattern and a Mo/Si multilayer on a glass substrate. This mask pattern has a three-dimensional (3D) structure. The 3D structure would modulate the EUV reflection phase, which would cause focus and pattern shifts. Thus, the review of the EUV phase image is also important. We have developed a coherent EUV scatterometry microscope (CSM), which is a simple microscope without objective optics. The EUV phase and intensity images were reconstructed with diffraction images by ptychography. For a standalone mask review, the high-harmonic-generation (HHG) EUV source was employed. In this study, we updated the sample stage, pump-laser reduction system, and gas-pressure control system to reconstruct the image. As a result, an 88 nm line-and-space pattern and a cross-line pattern were reconstructed. In addition, a particle defect of 2 µm diameter was well reconstructed. This demonstrated the high capability of the standalone CSM, which can hence be used in factories, such as mask shops and semiconductor fabrication plants.

The Study of Compact Plasma Source of SXR of Vacuum Spark Type with Capillary Concentrator and It's Application

NASA Astrophysics Data System (ADS)

Kantsyrev, V. L.; Kopytok, K. I.; Shlyaptseva, A. S.

1994-03-01

The results are presented dealing with the working out and study of the plasma source of soft X-ray (SXR) of the new type. Experimental set up included compact low-inductance vacuum spark (LIVS) with initial energy supply equal up to 2.5 kJ and glass-capillary concentrator (GCC) of SXR. The characteristics of SXR of vacuum spark and properties of SXR were studied using diagnostic complex. The coefficient of conversion of initial energy supply into SXR (η) amounted to 0.01 in range 1.2nm. Value η had peak dependence on atomic number of anode Za. The spectra were recorded belonging to Ne-like, F-like ions of Fe, Cu ions and He-like, H-like ions of Al, Ti, Fe. Glass capillary concentrator consists of about several hundreds glass capillaries Flux density of SXR in focusing spot was up to 105-106 Wt/cm, density of energy is up to 20-30 mJ/cm2 at diameter of SXR focusing spot equal to about 2-3mm in the range 0.7-1.0 nm. The plasma source of the new type is intended for X-ray microscopy, study of influence of SXR on the surface of solid state. It allows to carry out experiments making only on electron synchrotronic sources of SXR.

Mimicking Mars: a vacuum simulation chamber for testing environmental instrumentation for Mars exploration.

PubMed

Sobrado, J M; Martín-Soler, J; Martín-Gago, J A

2014-03-01

We have built a Mars environmental simulation chamber, designed to test new electromechanical devices and instruments that could be used in space missions. We have developed this environmental system aiming at validating the meteorological station Rover Environment Monitoring Station of NASA's Mars Science Laboratory mission currently installed on Curiosity rover. The vacuum chamber has been built following a modular configuration and operates at pressures ranging from 1000 to 10(-6) mbars, and it is possible to control the gas composition (the atmosphere) within this pressure range. The device (or sample) under study can be irradiated by an ultraviolet source and its temperature can be controlled in the range from 108 to 423 K. As an important improvement with respect to other simulation chambers, the atmospheric gas into the experimental chamber is cooled at the walls by the use of liquid-nitrogen heat exchangers. This chamber incorporates a dust generation mechanism designed to study Martian-dust deposition while modifying the conditions of temperature, and UV irradiated.

A theoretical analysis of vacuum arc thruster performance

NASA Technical Reports Server (NTRS)

Polk, James E.; Sekerak, Mike; Ziemer, John K.; Schein, Jochen; Qi, Niansheng; Binder, Robert; Anders, Andre

2001-01-01

In vacuum arc discharges the current is conducted through vapor evaporated from the cathode surface. In these devices very dense, highly ionized plasmas can be created from any metallic or conducting solid used as the cathode. This paper describes theoretical models of performance for several thruster configurations which use vacuum arc plasma sources. This analysis suggests that thrusters using vacuum arc sources can be operated efficiently with a range of propellant options that gives great flexibility in specific impulse. In addition, the efficiency of plasma production in these devices appears to be largely independent of scale because the metal vapor is ionized within a few microns of the cathode electron emission sites, so this approach is well-suited for micropropulsion.

Inorganic volumetric light source excited by ultraviolet light

DOEpatents

Reed, Scott; Walko, Robert J.; Ashley, Carol S.; Brinker, C. Jeffrey

1994-01-01

The invention relates to a composition for the volumetric generation of radiation. The composition comprises a porous substrate loaded with a component capable of emitting radiation upon interaction with an exciting radiation. Preferably, the composition is an aerogel substrate loaded with a component, e.g., a phosphor, capable of interacting with exciting radiation of a first energy, e.g., ultraviolet light, to produce radiation of a second energy, e.g., visible light.

Inorganic volumetric light source excited by ultraviolet light

DOEpatents

Reed, S.; Walko, R.J.; Ashley, C.S.; Brinker, C.J.

1994-04-26

The invention relates to a composition for the volumetric generation of radiation. The composition comprises a porous substrate loaded with a component capable of emitting radiation upon interaction with an exciting radiation. Preferably, the composition is an aerogel substrate loaded with a component, e.g., a phosphor, capable of interacting with exciting radiation of a first energy, e.g., ultraviolet light, to produce radiation of a second energy, e.g., visible light. 4 figures.

Vacuum compatible miniature CCD camera head

DOEpatents

Conder, Alan D.

2000-01-01

A charge-coupled device (CCD) camera head which can replace film for digital imaging of visible light, ultraviolet radiation, and soft to penetrating x-rays, such as within a target chamber where laser produced plasmas are studied. The camera head is small, capable of operating both in and out of a vacuum environment, and is versatile. The CCD camera head uses PC boards with an internal heat sink connected to the chassis for heat dissipation, which allows for close(0.04" for example) stacking of the PC boards. Integration of this CCD camera head into existing instrumentation provides a substantial enhancement of diagnostic capabilities for studying high energy density plasmas, for a variety of military industrial, and medical imaging applications.

Semi-automated high-efficiency reflectivity chamber for vacuum UV measurements

NASA Astrophysics Data System (ADS)

Wiley, James; Fleming, Brian; Renninger, Nicholas; Egan, Arika

2017-08-01

This paper presents the design and theory of operation for a semi-automated reflectivity chamber for ultraviolet optimized optics. A graphical user interface designed in LabVIEW controls the stages, interfaces with the detector system, takes semi-autonomous measurements, and monitors the system in case of error. Samples and an optical photodiode sit on an optics plate mounted to a rotation stage in the middle of the vacuum chamber. The optics plate rotates the samples and diode between an incident and reflected position to measure the absolute reflectivity of the samples at wavelengths limited by the monochromator operational bandpass of 70 nm to 550 nm. A collimating parabolic mirror on a fine steering tip-tilt motor enables beam steering for detector peak-ups. This chamber is designed to take measurements rapidly and with minimal oversight, increasing lab efficiency for high cadence and high accuracy vacuum UV reflectivity measurements.

A vacuum-sealed, gigawatt-class, repetitively pulsed high-power microwave source

NASA Astrophysics Data System (ADS)

Xun, Tao; Fan, Yu-wei; Yang, Han-wu; Zhang, Zi-cheng; Chen, Dong-qun; Zhang, Jian-de

2017-06-01

A compact L-band sealed-tube magnetically insulated transmission line oscillator (MILO) has been developed that does not require bulky external vacuum pump for repetitive operations. This device with a ceramic insulated vacuum interface, a carbon fiber array cathode, and non-evaporable getters has a base vacuum pressure in the low 10-6 Pa range. A dynamic 3-D Monte-Carlo model for the molecular flow movement and collision was setup for the MILO chamber. The pulse desorption, gas evolution, and pressure distribution were exactly simulated. In the 5 Hz repetition rate experiments, using a 600 kV diode voltage and 48 kA beam current, the average radiated microwave power for 25 shots is about 3.4 GW in 45 ns pulse duration. The maximum equilibrium pressure is below 4.0 × 10-2 Pa, and no pulse shortening limitations are observed during the repetitive test in the sealed-tube condition.

Carbon nanotube vacuum gauges with wide-dynamic range and processes thereof

NASA Technical Reports Server (NTRS)

Manohara, Harish (Inventor); Kaul, Anupama B. (Inventor)

2013-01-01

A miniature thermal conductivity gauge employs a carbon single-walled-nanotube. The gauge operates on the principle of thermal exchange between the voltage-biased nanotube and the surrounding gas at low levels of power and low temperatures to measure vacuum across a wide dynamic range. The gauge includes two terminals, a source of constant voltage to the terminals, a single-walled carbon nanotube between the terminals, a calibration of measured conductance of the nanotube to magnitudes of surrounding vacuum and a current meter in electrical communication with the source of constant voltage. Employment of the nanotube for measuring vacuum includes calibrating the electrical conductance of the nanotube to magnitudes of vacuum, exposing the nanotube to a vacuum, applying a constant voltage across the nanotube, measuring the electrical conductance of the nanotube in the vacuum with the constant voltage applied and converting the measured electrical conductance to the corresponding calibrated magnitude of vacuum using the calibration. The nanotube may be suspended to minimize heat dissipation through the substrate, increasing sensitivity at even tower pressures.

Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gulati, P., E-mail: pgulati1512@gmail.com; Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022; Prakash, R.

2014-07-07

A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl{sub 2} deteriorates the performance of the developed source and around 2% Cl{sub 2} in this source produced optimum results. Furthermore, anmore » addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.« less

Ultraviolet, visible, and infrared rays

NASA Technical Reports Server (NTRS)

Taylor, J. H.; Letavet, A. A.

1975-01-01

Sources of infrared, visible and ultraviolet radiation are discussed, and important associated biological and psychophysiological effects are described. The problem of protection from excessively high or low levels of radiant energy in these spectral regions is considered and optimal levels are suggested.

Two year operational experience with the TPS vacuum system

NASA Astrophysics Data System (ADS)

Yang, Y. C.; Chan, C. K.; Sheng, I. C.; Huang, I. T.; Y Chung, J.; Liang, C. C.

2017-07-01

The Taiwan Photon Source (TPS), a 3-GeV third generation synchrotron light source, was commissioned in 2014 December and is now currently operated in top-up mode at 300mA for users. During the past two years, the machine was completed to meet design goals with among others the installation of superconducting cavities (SRF), the installation of insertion devices (ID) and the correction of vacuum chamber structure downstream from the IDs. The design goal of 500mA beam current was achieved with a total accumulated beam dose of more than 1000Ah, resulting in three orders of magnitude reduction of out-gassing. As the beam current was increased, a few vacuum problems were encountered, including vacuum leaks, unexpected pressure bursts, etc. Vacuum related issues including high pressure events, lessons learned and operational experience will be presented and discussed in this paper.

Formation of protein sub-visible particles during vacuum degassing of etanercept solutions.

PubMed

Wang, Haibin; Zheng, Hong-Jian; Wang, Zhao; Bai, Hua; Carpenter, John F; Chen, Shuqing; Fang, Wei-Jie

2014-05-01

The main purpose of this manuscript is to describe a phenomenon in which vacuum degassing a reconstituted freeze-dried fusion protein etanercept formulation caused a significant amount of protein sub-visible particles (SbVP). Physical stability of etanercept was monitored by micro-flow imaging (MFI), dynamic light scattering (DLS), size-exclusion high pressure liquid chromatography (SE-HPLC) and far- and near-ultraviolet circular dichroism (far- and near-UV CD). One potential explanation of this phenomenon is that bubble collapses when the vacuum is applied, leads to substantial heat formation, and ultimately free radical formation. Subsequently, the effect of a free-radical scavenger (ascorbic acid, AA) on SbVP formation was also evaluated. Degassing of etanercept solution by applying vacuum caused substantial increase of SbVP, as detected by MFI and DLS. However, traditional techniques such as SE-HPLC could not detect any change. The addition of free-radical scavenger had minimal effect on SbVP formation, therefore the formation of free radicals was probably not the main cause for this effect. Copyright © 2014 Elsevier B.V. All rights reserved.

Microbial survival of space vacuum and extreme ultraviolet irradiation: strain isolation and analysis during a rocket flight.

PubMed

Saffary, Roya; Nandakumar, Renu; Spencer, Dennis; Robb, Frank T; Davila, Joseph M; Swartz, Marvin; Ofman, Leon; Thomas, Roger J; DiRuggiero, Jocelyne

2002-09-24

We have recovered new isolates from hot springs, in Yellowstone National Park and the Kamchatka Peninsula, after gamma-irradiation and exposure to high vacuum (10(-6) Pa) of the water and sediment samples. The resistance to desiccation and ionizing radiation of one of the isolates, Bacillus sp. strain PS3D, was compared to that of the mesophilic bacterium, Deinococcus radiodurans, a species well known for its extraordinary resistance to desiccation and high doses of ionizing radiation. Survival of these two microorganisms was determined in real and simulated space conditions, including exposure to extreme UV radiation (10-100 nm) during a rocket flight. We found that up to 15 days of desiccation alone had little effect on the viability of either bacterium. In contrast, exposure to space vacuum ( approximately 10(-6) Pa) decreased cell survival by two and four orders of magnitude for Bacillus sp. strain PS3D and D. radiodurans, respectively. Simultaneous exposure to space vacuum and extreme UV radiation further decreased the survival of both organisms, compared to unirradiated controls. This is the first report on the isolated effect of extreme UV at 30 nm on cell survival. Extreme UV can only be transmitted through high vacuum, therefore its penetration into the cells may only be superficial, suggesting that in contrast to near UV, membrane proteins rather than DNA were damaged by the radiation.

Vacuum force

NASA Astrophysics Data System (ADS)

Han, Yongquan

2015-03-01

To study on vacuum force, we must clear what is vacuum, vacuum is a space do not have any air and also ray. There is not exist an absolute the vacuum of space. The vacuum of space is relative, so that the vacuum force is relative. There is a certain that vacuum vacuum space exists. In fact, the vacuum space is relative, if the two spaces compared to the existence of relative vacuum, there must exist a vacuum force, and the direction of the vacuum force point to the vacuum region. Any object rotates and radiates. Rotate bend radiate- centripetal, gravity produced, relative gravity; non gravity is the vacuum force. Gravity is centripetal, is a trend that the objects who attracted wants to Centripetal, or have been do Centripetal movement. Any object moves, so gravity makes the object curve movement, that is to say, the radiation range curve movement must be in the gravitational objects, gravity must be existed in non vacuum region, and make the object who is in the region of do curve movement (for example: The earth moves around the sun), or final attracted in the form gravitational objects, and keep relatively static with attract object. (for example: objects on the earth moves but can't reach the first cosmic speed).

Pneumatically Actuated Miniature Peristaltic Vacuum Pumps

NASA Technical Reports Server (NTRS)

Feldman, Sabrina; Feldman, Jason; Svehla, Danielle

2003-01-01

pressure or to a partial vacuum source. The design would be such that the higher pneumatic pressure would be sufficient to push the silicone arches down onto the substrates, blocking the channels. Thus, by connecting pneumatic- actuation channels to the two pneumatic sources in spatial and temporal alternation, waves of opening and closing, equivalent to peristalsis, could be made to move along the pump channels. A pump according to this concept could be manufactured inexpensively. Pneumatic sources (compressors and partial vacuum sources) similar those needed for actuation are commercially available; they typically have masses of .100 g and power demands of the order of several W. In a design-optimization effort, it should be possible to reduce masses and power demands below even these low levels and to integrate pneumatic sources along with the proposed pumps into miniature units with overall dimensions of no more than a few centimeters per side.

Extreme ultraviolet spectroscopy of low pressure helium microwave driven discharges

NASA Astrophysics Data System (ADS)

Espinho, Susana; Felizardo, Edgar; Tatarova, Elena; Alves, Luis Lemos

2016-09-01

Surface wave driven discharges are reliable plasma sources that can produce high levels of vacuum and extreme ultraviolet radiation (VUV and EUV). The richness of the emission spectrum makes this type of discharge a possible alternative source in EUV/VUV radiation assisted applications. However, due to challenging experimental requirements, publications concerning EUV radiation emitted by microwave plasmas are scarce and a deeper understanding of the main mechanisms governing the emission of radiation in this spectral range is required. To this end, the EUV radiation emitted by helium microwave driven plasmas operating at 2.45 GHz has been studied for low pressure conditions. Spectral lines from excited helium atoms and ions were detected via emission spectroscopy in the EUV/VUV regions. Novel data concerning the spectral lines observed in the 23 - 33 nm wavelength range and their intensity behaviour with variation of the discharge operational conditions are presented. The intensity of all the spectral emissions strongly increases with the microwave power delivered to the plasma up to 400 W. Furthermore, the intensity of all the ion spectral emissions in the EUV range decreases by nearly one order of magnitude as the pressure was raised from 0.2 to 0.5 mbar. Work funded by FCT - Fundacao para a Ciencia e a Tecnologia, under Project UID/FIS/50010/2013 and grant SFRH/BD/52412/2013 (PD-F APPLAuSE).

Vacuum-Induction, Vacuum-Arc, and Air-Induction Melting of a Complex Heat-Resistant Alloy

NASA Technical Reports Server (NTRS)

Decker, R. F.; Rowe, John P.; Freeman, J. W.

1959-01-01

The relative hot-workability and creep-rupture properties at 1600 F of a complex 55Ni-20Cr-15Co-4Mo-3Ti-3Al alloy were evaluated for vacuum-induction, vacuum-arc, and air-induction melting. A limited study of the role of oxygen and nitrogen and the structural effects in the alloy associated with the melting process was carried out. The results showed that the level of boron and/or zirconium was far more influential on properties than the melting method. Vacuum melting did reduce corner cracking and improve surface during hot-rolling. It also resulted in more uniform properties within heats. The creep-rupture properties were slightly superior in vacuum heats at low boron plus zirconium or in heats with zirconium. There was little advantage at high boron levels and air heats were superior at high levels of boron plus zirconium. Vacuum heats also had fewer oxide and carbonitride inclusions although this was a function of the opportunity for separation of the inclusions from high oxygen plus nitrogen heats. The removal of phosphorous by vacuum melting was not found to be related to properties. Oxygen plus nitrogen appeared to increase ductility in creep-rupture tests suggesting that vacuum melting removes unidentified elements detrimental to ductility. Oxides and carbonitrides in themselves did not initiate microcracks. Carbonitrides in the grain boundaries of air heats did initiate microcracks. The role of microcracking from this source and as a function of oxygen and nitrogen content was not clear. Oxygen and nitrogen did intensify corner cracking during hot-rolling but were not responsible for poor surface which resulted from rolling heats melted in air.

Radiation damage effects in far-ultraviolet filters, thin films, and substrates.

PubMed

Keffer, C E; Torr, M R; Zukic, M; Spann, J F; Torr, D G; Kim, J

1994-09-01

Advances in vacuum ultraviolet thin-film filter technology have been made through the use of filter designs with multilayers of materials such as Al(2)O(3), BaF(2), CaF(2), HfO(2), LaF(3), MgF(2), and SiO(2). Our immediate application for these filters will be in an imaging system to be flown on a satellite where a 2 × 9 R(E) orbit will expose the instrument to approximately 250 krad of radiation. Because to our knowledge no previous studies have been made on the potential radiation damage of these materials in the thin-film format, we report on such an assessment here. Transmittances and reflectances of BaF(2), CaF(2), HfO(2), MgF(2), and SiO(2) thin films on MgF(2) substrates, Al(2)O(3) thin films on fused-silica substrates, uncoated fused silica and MgF(2), and four multilayer filters made from these materials were measured from 120 to 180 nm beforeand after irradiation by 250 krad from a (60)Co gamma radiation source. No radiation-induced losses in transmittance or reflectance occurred in this wavelength range. Additional postradiation measurements from 160 to 300 nm indicates 2-5% radiation-induced absorption near 260 nm in some of the samples with MgF(2) substrates. From these measurements we conclude that far-ultraviolet filters made from the materials tested should experience less than 5% change from exposure to up to 250 krad of high-energy radiation in space applications.

Infrared absorption of methanol clusters (CH3OH)n with n = 2-6 recorded with a time-of-flight mass spectrometer using infrared depletion and vacuum-ultraviolet ionization.

PubMed

Han, Hui-Ling; Camacho, Cristopher; Witek, Henryk A; Lee, Yuan-Pern

2011-04-14

We investigated IR spectra in the CH- and OH-stretching regions of size-selected methanol clusters, (CH(3)OH)(n) with n = 2-6, in a pulsed supersonic jet by using the IR-VUV (vacuum-ultraviolet) ionization technique. VUV emission at 118 nm served as the source of ionization in a time-of-flight mass spectrometer. The tunable IR laser emission served as a source of predissociation or excitation before ionization. The variations of intensity of protonated methanol cluster ions (CH(3)OH)(n)H(+) and CH(3)OH(+) and (CH(3)OH)(2)(+) were monitored as the IR laser light was tuned across the range 2650-3750 cm(-1). Careful processing of these action spectra based on photoionization efficiencies and the production and loss of each cluster due to photodissociation yielded IR spectra of the size-selected clusters. Spectra of methanol clusters in the OH region have been extensively investigated; our results are consistent with previous reports, except that the band near 3675 cm(-1) is identified as being associated with the proton acceptor of (CH(3)OH)(2). Spectra in the CH region are new. In the region 2800-3050 cm(-1), bands near 2845, 2956, and 3007 cm(-1) for CH(3)OH split into 2823, 2849, 2934, 2955, 2984, and 3006 cm(-1) for (CH(3)OH)(2) that correspond to proton donor and proton acceptor, indicating that the methanol dimer has a preferred open-chain structure. In contrast, for (CH(3)OH)(3), the splitting diminishes and the bands near 2837, 2954, and 2987 cm(-1) become narrower, indicating a preferred cyclic structure. Anharmonic vibrational wavenumbers predicted for the methanol open-chain dimer and the cyclic trimer with the B3LYP∕VPT2∕ANO1 level of theory are consistent with experimental results. For the tetramer and pentamer, the spectral pattern similar to that of the trimer but with greater widths was observed, indicating that the most stable structures are also cyclic.

Variable frequency matching to a radiofrequency source immersed in vacuum

NASA Astrophysics Data System (ADS)

Charles, C.; Boswell, R. W.; Bish, A.

2013-09-01

A low-weight (0.12 kg) low-volume fixed ceramic capacitor impedance matching system is developed for frequency agile tuning of a radiofrequency (rf) Helicon plasma thruster. Three fixed groups of capacitors are directly mounted onto a two loop rf antenna with the thruster immersed in a vacuum chamber. Optimum plasma tuning at the resonance frequency is demonstrated via measurements of the load impedance, power transfer efficiency and plasma density versus driving frequency in the 12.882-14.238 MHz range. The resonance frequency with the plasma on is higher than the resonance frequency in vacuum. The minimum rf power necessary for ignition decreases when the ignition frequency is shifted downwards from the resonance frequency. This development has direct applications in space qualification and space use of rf plasma thrusters.

A highly miniaturized vacuum package for a trapped ion atomic clock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwindt, Peter D. D., E-mail: pschwin@sandia.gov; Jau, Yuan-Yu; Partner, Heather

2016-05-15

We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm{sup 3} in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, it wasmore » sealed with a copper pinch-off and was subsequently pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of {sup 171}Y b{sup +}. The fractional frequency stability of the clock was measured to be 2 × 10{sup −11}/τ{sup 1/2}.« less

A highly miniaturized vacuum package for a trapped ion atomic clock

DOE PAGES

Schwindt, Peter D. D.; Jau, Yuan-Yu; Partner, Heather; ...

2016-05-12

We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm 3 in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, the packagemore » was sealed with a copper pinch-off and was then pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of 171Yb +. The fractional frequency stability of the clock was measured to be 2 × 10 -11 / τ 1/2.« less

INTRODUCTION: The 8th International Conference on Vacuum Ultraviolet Radiation Physics

NASA Astrophysics Data System (ADS)

Nilsson, Per Olof; Hedin, Lars

1987-01-01

The VUV conferences series The international conferences on vacuum ultraviolet radiation physics started in 1962, and are now being held every third year. VUV-8 took place at Lund University, August 4-8, 1986. VUV-9 will be arranged at the University of Hawaii, USA, August 14-18, 1989, with Prof. C S Fadley as conference chairman. Chairman of the international advisory board for the period 1986-89 is Prof. L Hedin. The theme of the series can be summarized as experimental and theoretical progress in research fields utilizing the interaction of VUV radiation with matter. The topics cover broad areas within atomic and molecular physics, solid state physics and VUV instrumentation. The conferences emphasize interdisciplinary aspects. To these belong common experimental techniques as, e.g., synchrotron radiation instrumentation, and common theoretical foundations for the description of photon interactions with matter. The VUV-8 conference The VUV-8 conference in Lund was attended by 300 participants from 26 countries. An address list of the participants is given at the end of this volume. There were 33 invited papers given as plenary or key-note talks. As many as 229 posters were presented; 49 of them were also given orally. These numbers are typical for the VUV conferences, except for the number of posters, which was unusually large. In the conference planning the poster sessions were stressed, and particular care was taken to provide a good atmosphere at these sessions. Thus the posters were kept up during the whole conference, coffee was served in the hail with the posters and there were convenient places to sit down close to the posters. Considering the wide scope of the conference it was necessary to emphasize a limited number of topics of high current interest and importance. Thus besides traditional topics, several rapidly expanding fields were discussed in special sessions. At VUV-8 there were the following sessions. Theory of atoms and molecules

Overview of High Power Vacuum Dry RF Load Designs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krasnykh, Anatoly

2015-08-27

A specific feature of RF linacs based on the pulsed traveling wave (TW) mode of operation is that only a portion of the RF energy is used for the beam acceleration. The residual RF energy has to be terminated into an RF load. Higher accelerating gradients require higher RF sources and RF loads, which can stably terminate the residual RF power. RF feeders (from the RF source though the accelerating section to the load) are vacuumed to transmit multi-megawatt high power RF. This overview will outline vacuumed RF loads only. A common method to terminate multi-MW RF power is tomore » use circulated water (or other liquid) as an absorbing medium. A solid dielectric interface (a high quality ceramic) is required to separate vacuum and liquid RF absorber mediums. Using such RF load approaches in TW linacs is troubling because there is a fragile ceramic window barrier and a failure could become catastrophic for linac vacuum and RF systems. Traditional loads comprising of a ceramic disk have limited peak and average power handling capability and are therefore not suitable for high gradient TW linacs. This overview will focus on ''vacuum dry'' or ''all-metal'' loads that do not employ any dielectric interface between vacuum and absorber. The first prototype is an original design of RF loads for the Stanford Two-Mile Accelerator.« less

An ultraviolet imager to study bright UV sources

NASA Astrophysics Data System (ADS)

Mathew, Joice; Prakash, Ajin; Sarpotdar, Mayuresh; Sreejith, A. G.; Safonova, Margarita; Murthy, Jayant

2016-07-01

We have designed and developed a compact ultraviolet imaging payload to y on a range of possible platforms such as high altitude balloon experiments, cubesats, space missions, etc. The primary science goals are to study the bright UV sources (mag < 10) and also to look for transients in the Near UV (200 - 300 nm) domain. Our first choice is to place this instrument on a spacecraft going to the Moon as part of the Indian entry into Google lunar X-Prize competition. The major constraints for the instrument are, it should be lightweight (< 2Kg), compact (length < 50cm) and cost effective. The instrument is an 80 mm diameter Cassegrain telescope with a field of view of around half a degree designated for UV imaging. In this paper we will discuss about the various science cases that can be performed by having observations with the instrument on different platforms. We will also describe the design, development and the current state of implementation of the instrument. This includes opto-mechanical and electrical design of the instrument. We have adopted an all spherical optical design which would make the system less complex to realize and a cost effective solution compared to other telescope configuration. The structural design has been chosen in such a way that it will ensure that the instrument could withstand all the launch load vibrations. An FPGA based electronics board is used for the data acquisition, processing and CCD control. We will also brie y discuss about the hardware implementation of the detector interface and algorithms for the detector readout and data processing.

Galileo Ultraviolet Spectrometer experiment

NASA Technical Reports Server (NTRS)

Hord, C. W.; Mcclintock, W. E.; Stewart, A. I. F.; Barth, C. A.; Esposito, L. W.; Thomas, G. E.; Sandel, B. R.; Hunten, D. M.; Broadfoot, A. L.; Shemansky, D. E.

1992-01-01

The Galileo ultraviolet spectrometer experiment uses data obtained by the Ultraviolet Spectrometer (UVS) mounted on the pointed orbiter scan platform and from the Extreme Ultraviolet Spectrometer (EUVS) mounted on the spinning part of the orbiter with the field of view perpendicular to the spin axis. The UVS is a Ebert-Fastie design that covers the range 113-432 nm with a wavelength resolution of 0.7 nm below 190 and 1.3 nm at longer wavelengths. The UVS spatial resolution is 0.4 deg x 0.1 deg for illuminated disk observations and 1 deg x 0.1 deg for limb geometries. The EUVS is a Voyager design objective grating spectrometer, modified to cover the wavelength range from 54 to 128 nm with wavelength resolution 3.5 nm for extended sources and 1.5 nm for point sources and spatial resolution of 0.87 deg x 0.17 deg. The EUVS instrument will follow up on the many Voyager UVS discoveries, particularly the sulfur and oxygen ion emissions in the Io torus and molecular and atomic hydrogen auroral and airglow emissions from Jupiter. The UVS will obtain spectra of emission, absorption, and scattering features in the unexplored, by spacecraft, 170-432 nm wavelength region. The UVS and EUVS instruments will provide a powerful instrument complement to investigate volatile escape and surface composition of the Galilean satellites, the Io plasma torus, micro- and macro-properties of the Jupiter clouds, and the composition structure and evolution of the Jupiter upper atmosphere.

Electronic Structure and Optical Properties of Cu2ZnGeSe4 : First-Principles Calculations and Vacuum-Ultraviolet Spectroscopic Ellipsometric Studies

NASA Astrophysics Data System (ADS)

Choi, S. G.; Park, J.-S.; Donohue, A. L.; Christensen, S. T.; To, B.; Beall, C.; Wei, S.-H.; Repins, I. L.

2015-11-01

Cu2ZnGeSe4 is of interest for the development of next-generation thin-film photovoltaic technologies. To understand its electronic structure and related fundamental optical properties, we perform first-principles calculations for three structural variations: kesterite, stannite, and primitive-mixed CuAu phases. The calculated data are compared with the room-temperature dielectric function ɛ =ɛ1+i ɛ2 spectrum of polycrystalline Cu2ZnGeSe4 determined by vacuum-ultraviolet spectroscopic ellipsometry in the photon-energy range of 0.7 to 9.0 eV. Ellipsometric data are modeled with the sum of eight Tauc-Lorentz oscillators, and the best-fit model yields the band-gap and Tauc-gap energies of 1.25 and 1.19 eV, respectively. A comparison of overall peak shapes and relative intensities between experimental spectra and the calculated ɛ data for three structural variations suggests that the sample may not have a pure (ordered) kesterite phase. The complex refractive index N =n +i k , normal-incidence reflectivity R , and absorption coefficients α are calculated from the modeled ɛ spectrum, which are also compared with those of Cu2ZnSnSe4 . The spectral features for Cu2ZnGeSe4 appear to be weaker and broader than those for Cu2ZnSnSe4 , which is possibly due to more structural imperfections presented in Cu2ZnGeSe4 than Cu2ZnSnSe4 .

Elastomeric Seal Performance after Terrestrial Ultraviolet Radiation Exposure

NASA Technical Reports Server (NTRS)

Daniels, Christopher C.; Oravec, Heather A.; Mather, Janice L.; Taylor, Shawn C.; Dunlap, Patrick H.

2015-01-01

Ultraviolet radiation was evaluated to determine its negative effects on the performance of elastomeric gas pressure seals. The leak rates of the silicone elastomer S0383-70 O-ring test articles were used to quantify the degradation of the seals after exposure to vacuum-ultraviolet and/or middle-to-near-ultraviolet wavelength radiation. Three groups of seals were exposed in terrestrial facilities to 115-165 nm wavelength radiation, 230-500 nm wavelength radiation, or both spectrums, for an orbital spaceflight equivalent of 125 hours. The leak rates of the silicone elastomer S0383-70 seals were quantified and compared to samples that received no radiation. Each lot contained six samples and statistical t-tests were used to determine the separate and combined influences of exposure to the two wavelength ranges. A comparison of the mean leak rates of samples exposed to 115-165 nm wavelength radiation to the control specimens showed no difference, suggesting that spectrum was not damaging. The 230-500 nm wavelength appeared to be damaging, as the mean leak rates of the specimens exposed to that range of wavelengths, and those exposed to the combined 115-165 nm and 230-500 nm spectrums, were significantly different from the leak rates of the control specimens. Most importantly, the test articles exposed to both wavelength spectrums exhibited mean leak rates two orders of magnitude larger than any other exposed specimens, which suggested that both wavelength spectrums are important when simulating the orbital environment.

Far-ultraviolet imagery of the Orion Nebula

NASA Technical Reports Server (NTRS)

Carruthers, G. R.; Opal, C. B.

1977-01-01

Two electrographic cameras carried on a sounding rocket have yielded useful-resolution far-ultraviolet (1000-2000 A) imagery of the Orion Nebula. The brightness distribution in the images is consistent with a primary source which is due to scattering of starlight by dust grains, although an emission-line contribution, particularly in the fainter outer regions, is not ruled out. The results are consistent with an albedo of the dust grains that is high in the far-ultraviolet and which increases toward shorter wavelengths below 1230 A.

Developing a Vacuum Electrospray Source To Implement Efficient Atmospheric Sampling for Miniature Ion Trap Mass Spectrometer.

PubMed

Yu, Quan; Zhang, Qian; Lu, Xinqiong; Qian, Xiang; Ni, Kai; Wang, Xiaohao

2017-12-05

The performance of a miniature mass spectrometer in atmospheric analysis is closely related to the design of its sampling system. In this study, a simplified vacuum electrospray ionization (VESI) source was developed based on a combination of several techniques, including the discontinuous atmospheric pressure interface, direct capillary sampling, and pneumatic-assisted electrospray. Pulsed air was used as a vital factor to facilitate the operation of electrospray ionization in the vacuum chamber. This VESI device can be used as an efficient atmospheric sampling interface when coupled with a miniature rectilinear ion trap (RIT) mass spectrometer. The developed VESI-RIT instrument enables regular ESI analysis of liquid, and its qualitative and quantitative capabilities have been characterized by using various solution samples. A limit of detection of 8 ppb could be attained for arginine in a methanol solution. In addition, extractive electrospray ionization of organic compounds can be implemented by using the same VESI device, as long as the gas analytes are injected with the pulsed auxiliary air. This methodology can extend the use of the proposed VESI technique to rapid and online analysis of gaseous and volatile samples.

Simple Refractometers for Index Measurements by Minimum Deviation Method from Far-ultraviolet to Near Infrared

NASA Technical Reports Server (NTRS)

Leviton, Douglas B.; Madison, Timothy J.; Petrone, Peter

1998-01-01

The focal shift of an optical filter used in non-collimated light depends directly on substrate thickness and index of refraction. The HST Advanced Camera for Surveys (ACS) requires a set of filters whose focal shifts are tightly matched. Knowing the index of refraction for substrate glasses allows precise substrate thicknesses to be specified. Two refractometers have been developed at the Goddard Space Flight Center (GSFC) to determine the indices of refraction of materials from which ACS filters are made. Modem imaging detectors for the near infrared, visible, and far ultraviolet spectral regions make these simple yet sophisticated refractometers possible. A new technology, high accuracy, angular encoder also developed at GSFC makes high precision index measurement possible in the vacuum ultraviolet.

Vacuum MOCVD fabrication of high efficience cells

NASA Technical Reports Server (NTRS)

Partain, L. D.; Fraas, L. M.; Mcleod, P. S.; Cape, J. A.

1985-01-01

Vacuum metal-organic-chemical-vapor-deposition (MOCVD) is a new fabrication process with improved safety and easier scalability due to its metal rather than glass construction and its uniform multiport gas injection system. It uses source materials more efficiently than other methods because the vacuum molecular flow conditions allow the high sticking coefficient reactants to reach the substrates as undeflected molecular beams and the hot chamber walls cause the low sticking coefficient reactants to bounce off the walls and interact with the substrates many times. This high source utilization reduces the materials costs power device and substantially decreases the amounts of toxic materials that must be handled as process effluents. The molecular beams allow precise growth control. With improved source purifications, vacuum MOCVD has provided p GaAs layers with 10-micron minority carrier diffusion lengths and GaAs and GaAsSb solar cells with 20% AMO efficiencies at 59X and 99X sunlight concentration ratios. Mechanical stacking has been identified as the quickest, most direct and logical path to stacked multiple-junction solar cells that perform better than the best single-junction devices. The mechanical stack is configured for immediate use in solar arrays and allows interconnections that improve the system end-of-life performance in space.

Mimicking Mars: A vacuum simulation chamber for testing environmental instrumentation for Mars exploration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sobrado, J. M., E-mail: sobradovj@inta.es; Martín-Soler, J.; Martín-Gago, J. A.

We have built a Mars environmental simulation chamber, designed to test new electromechanical devices and instruments that could be used in space missions. We have developed this environmental system aiming at validating the meteorological station Rover Environment Monitoring Station of NASA's Mars Science Laboratory mission currently installed on Curiosity rover. The vacuum chamber has been built following a modular configuration and operates at pressures ranging from 1000 to 10{sup −6} mbars, and it is possible to control the gas composition (the atmosphere) within this pressure range. The device (or sample) under study can be irradiated by an ultraviolet source andmore » its temperature can be controlled in the range from 108 to 423 K. As an important improvement with respect to other simulation chambers, the atmospheric gas into the experimental chamber is cooled at the walls by the use of liquid-nitrogen heat exchangers. This chamber incorporates a dust generation mechanism designed to study Martian-dust deposition while modifying the conditions of temperature, and UV irradiated.« less

Plates for vacuum thermal fusion

DOEpatents

Davidson, James C.; Balch, Joseph W.

2002-01-01

A process for effectively bonding arbitrary size or shape substrates. The process incorporates vacuum pull down techniques to ensure uniform surface contact during the bonding process. The essence of the process for bonding substrates, such as glass, plastic, or alloys, etc., which have a moderate melting point with a gradual softening point curve, involves the application of an active vacuum source to evacuate interstices between the substrates while at the same time providing a positive force to hold the parts to be bonded in contact. This enables increasing the temperature of the bonding process to ensure that the softening point has been reached and small void areas are filled and come in contact with the opposing substrate. The process is most effective where at least one of the two plates or substrates contain channels or grooves that can be used to apply vacuum between the plates or substrates during the thermal bonding cycle. Also, it is beneficial to provide a vacuum groove or channel near the perimeter of the plates or substrates to ensure bonding of the perimeter of the plates or substrates and reduce the unbonded regions inside the interior region of the plates or substrates.

Global modeling of thermospheric airglow in the far ultraviolet

NASA Astrophysics Data System (ADS)

Solomon, Stanley C.

2017-07-01

The Global Airglow (GLOW) model has been updated and extended to calculate thermospheric emissions in the far ultraviolet, including sources from daytime photoelectron-driven processes, nighttime recombination radiation, and auroral excitation. It can be run using inputs from empirical models of the neutral atmosphere and ionosphere or from numerical general circulation models of the coupled ionosphere-thermosphere system. It uses a solar flux module, photoelectron generation routine, and the Nagy-Banks two-stream electron transport algorithm to simultaneously handle energetic electron distributions from photon and auroral electron sources. It contains an ion-neutral chemistry module that calculates excited and ionized species densities and the resulting airglow volume emission rates. This paper describes the inputs, algorithms, and code structure of the model and demonstrates example outputs for daytime and auroral cases. Simulations of far ultraviolet emissions by the atomic oxygen doublet at 135.6 nm and the molecular nitrogen Lyman-Birge-Hopfield bands, as viewed from geostationary orbit, are shown, and model calculations are compared to limb-scan observations by the Global Ultraviolet Imager on the TIMED satellite. The GLOW model code is provided to the community through an open-source academic research license.

Extreme Ultraviolet Explorer. Long look at the next window

NASA Technical Reports Server (NTRS)

Maran, Stephen P.

1991-01-01

The Extreme Ultraviolet Explorer (EUVE) will map the entire sky to determine the existence, direction, brightness, and temperature of thousands of objects that are sources of so-called extreme ultraviolet (EUV) radiation. The EUV spectral region is located between the x-ray and ultraviolet regions of the electromagnetic spectrum. From the sky survey by EUVE, astronomers will determine the nature of sources of EUV light in our galaxy, and infer the distribution of interstellar gas for hundreds of light years around the solar system. It is from this gas and the accompanying dust in space that new stars and solar systems are born and to which evolving and dying stars return much of their material in an endless cosmic cycle of birth, death, and rebirth. Besides surveying the sky, astronomers will make detailed studies of selected objects with EUVE to determine their physical properties and chemical compositions. Also, they will learn about the conditions that prevail and the processes at work in stars, planets, and other sources of EUV radiation, maybe even quasars. The EUVE mission and instruments are described. The objects that EUVE will likely find are described.

Evaluation and study of advanced optical contamination, deposition, measurement, and removal techniques. [including computer programs and ultraviolet reflection analysis

NASA Technical Reports Server (NTRS)

Linford, R. M. F.; Allen, T. H.; Dillow, C. F.

1975-01-01

A program is described to design, fabricate and install an experimental work chamber assembly (WCA) to provide a wide range of experimental capability. The WCA incorporates several techniques for studying the kinetics of contaminant films and their effect on optical surfaces. It incorporates the capability for depositing both optical and contaminant films on temperature-controlled samples, and for in-situ measurements of the vacuum ultraviolet reflectance. Ellipsometer optics are mounted on the chamber for film thickness determinations, and other features include access ports for radiation sources and instrumentation. Several supporting studies were conducted to define specific chamber requirements, to determine the sensitivity of the measurement techniques to be incorporated in the chamber, and to establish procedures for handling samples prior to their installation in the chamber. A bibliography and literature survey of contamination-related articles is included.

Pauli-Zeldovich cancellation of the vacuum energy divergences, auxiliary fields and supersymmetry

NASA Astrophysics Data System (ADS)

Kamenshchik, Alexander Yu.; Starobinsky, Alexei A.; Tronconi, Alessandro; Vardanyan, Tereza; Venturi, Giovanni

2018-03-01

We have considered the Pauli-Zeldovich mechanism for the cancellation of the ultraviolet divergences in vacuum energy. This mechanism arises because bosons and fermions give contributions of the opposite signs. In contrast with the preceding papers devoted to this topic wherein mainly free fields were studied, here we have taken their interactions into account to the lowest order of perturbation theory. We have constructed some simple toy models having particles with spin 0 and spin 1 / 2, where masses of the particles are equal while the interactions can be quite non-trivial.

Quasi-supercontinuum source in the extreme ultraviolet using multiple frequency combs from high-harmonic generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wünsche, Martin; Fuchs, Silvio; Aull, Stefan

A quasi-supercontinuum source in the extreme ultraviolet (XUV) is demonstrated using a table-top femtosecond laser and a tunable optical parametric amplifier (OPA) as a driver for high-harmonic generation (HHG). The harmonic radiation, which is usually a comb of odd multiples of the fundamental frequency, is generated by near-infrared (NIR) laser pulses from the OPA. A quasi-continuous XUV spectrum in the range of 30 to 100 eV is realized by averaging over multiple harmonic comb spectra with slightly different fundamental frequencies and thus different spectral spacing between the individual harmonics. The driving laser wavelength is swept automatically during an averaging timemore » period. With a total photon flux of 4×10 9 photons/s in the range of 30 eV to 100 eV and 1×10 7 photons/s in the range of 100 eV to 200 eV, the resulting quasi-supercontinuum XUV source is suited for applications such as XUV coherence tomography (XCT) or near-edge absorption fine structure spectroscopy (NEXAFS).« less

Quasi-supercontinuum source in the extreme ultraviolet using multiple frequency combs from high-harmonic generation

DOE PAGES

Wünsche, Martin; Fuchs, Silvio; Aull, Stefan; ...

2017-03-16

A quasi-supercontinuum source in the extreme ultraviolet (XUV) is demonstrated using a table-top femtosecond laser and a tunable optical parametric amplifier (OPA) as a driver for high-harmonic generation (HHG). The harmonic radiation, which is usually a comb of odd multiples of the fundamental frequency, is generated by near-infrared (NIR) laser pulses from the OPA. A quasi-continuous XUV spectrum in the range of 30 to 100 eV is realized by averaging over multiple harmonic comb spectra with slightly different fundamental frequencies and thus different spectral spacing between the individual harmonics. The driving laser wavelength is swept automatically during an averaging timemore » period. With a total photon flux of 4×10 9 photons/s in the range of 30 eV to 100 eV and 1×10 7 photons/s in the range of 100 eV to 200 eV, the resulting quasi-supercontinuum XUV source is suited for applications such as XUV coherence tomography (XCT) or near-edge absorption fine structure spectroscopy (NEXAFS).« less

Lifetime estimation of extreme-ultraviolet pellicle at 500 W source power by thermal stress analysis

NASA Astrophysics Data System (ADS)

Park, Eun-Sang; Ban, Chung-Hyun; Park, Jae-Hun; Oh, Hye-Keun

2017-10-01

The analysis of the thermal stress and the extreme-ultraviolet (EUV) pellicle is important since the pellicle could be easily damaged since the thickness of the pellicle is 50 nm thin due to 90% required EUV transmission. One of the solution is using a high emissivity metallic material on the both sides of the pellicle and it can lower the thermal stress. However, using a metallic coating on pellicle core which is usually consist of silicon group can decrease the EUV transmission compared to using a single core layer pellicle only. Therefore, we optimized thermal and optical properties of the pellicle and elect three types of the pellicle. In this paper we simulated our optimized pellicles with 500W source power. The result shows that the difference of the thermal stress is small for each case. Therefore, our result also shows that using a high emissivity coating is necessary since the cooling of the pellicle strongly depends on emissivity and it can lower the stress effectively even at high EUV source power.

Ejector/liquid ring pump provides <0. 30 mm Hg vacuum for polymerization vessel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lockwood, A.; Gaines, A.

1982-03-01

Firestone Fibers and Textiles Company, a division of Firestone Tire and Rubber Company, manufactures tire and industrial yarns of polyester and nylon-6. Nylon-6 molding and extrusion resins are also produced at the plant in Hopewell, Virginia. The process for making polyester requires an extremely low vacuum on the polymerization reactor. A consistent polymerization vessel vacuum of 0.3 mm Hg is needed, but the existing vacuum source, a five-stage steam jet ejector, could only provide a 0.5 mm Hg level. Two options were considered when the company decided to replace the original system with a system designed for 0.15 mm Hgmore » with a non-condensible gas load of 10.8 lb/hr. A new five-stage jet ejector system to meet these requirements would use 1395 lb/hr of 100 psig steam. The other option was a hybrid vacuum source composed of a three-stage steam ejector system and a liquid ring vacuum pump that is more energy efficient than ejectors for low vacuum applications. The hybrid system was selected because the three-stage jet ejector would use only 1240 lb/hr of 100 psig steam. The liquid ring vacuum pump would increase the material and installation cost of the system by about $4000, but the savings in steam consumption would pay back the added cost in less than two years. The jet ejector/liquid ring vacuum pump system has provided both the capacity and the extremely low vacuum needed for the polyester polymerization vessel, after making a small modification. The hybrid vacuum source is reliable, requires only routine maintenance, and will contiue to save substantial amounts of steam each year compared to the five-stage steam jet ejector.« less

Spectroscopic ellipsometry in vacuum ultraviolet spectral area

NASA Astrophysics Data System (ADS)

Fuchs, Detlef

An ellipsometer is developed and built, which allows the direct spectroscopic evaluation of dielectric function of solid bodies in the energy area 5 to 35 eV. A linear polarized synchrotron radiation was used as light source. The Stokes parameters and the Mueller matrices were used for the mathematical modeling, which take into account the properties of the synchrotron light and the analyzer, which depend on the wavelength. The crystals of the semiconductor bindings GaAs, GaP, InP and ZnS were examined. Ellipsometric measurements and reflection spectra show a displacement of spectral structures towards lower photon energies after the storage.

Microfabricated Millimeter-Wave High-Power Vacuum Electronic Amplifiers

DTIC Science & Technology

2015-01-01

Applications filed 2012). In spite of the challenges, high power sources of electromagnetic radiation are needed in the mmW bands for advanced DoD...Research Laboratory is demonstrating and developing millimeter-wave vacuum electronic traveling wave tube amplifiers at W- and G- band in the 10’ s to 100... s of watts power range at several percent instantaneous bandwidth. Keywords: Traveling wave tube; millimeter wave; vacuum electron device

The difficulty of ultraviolet emssion from supernovae

NASA Technical Reports Server (NTRS)

Colgate, S. A.

1971-01-01

There are certain conceptual difficulties in the theory of the generation of ultraviolet radiation which is presumed for the creation of the optical fluorescence mechanism of supernova light emission and ionization of a nebula as large as the Gum nebula. Requirements concerning the energy distribution of the ultraviolet photons are: 1) The energy of the greater part of the photons must be sufficient to cause both helium fluorescence and hydrogen ionization. 2) If the photons are emitted in an approximate black body spectrum, the fraction of energy emitted in the optical must be no more than what is already observed. Ultraviolet black body emission depends primarily on the energy source. The probability that the wide mixture of elements present in the interstellar medium and supernova ejecta results in an emission localized in a limited region with less than 0.001 emission in the visible, for either ionization or fluorescence ultraviolet, is remote. Therefore transparent emission must be excluded as unlikely, and black body or at least quasi-black-body emission is more probable.

Ultraviolet Extensions

NASA Technical Reports Server (NTRS)

2008-01-01

[figure removed for brevity, see original site] Side-by-Side Comparison Click on image for larger view

This ultraviolet image from NASA's Galaxy Evolution Explorer shows the Southern Pinwheel galaxy, also know as Messier 83 or M83. It is located 15 million light-years away in the southern constellation Hydra.

Ultraviolet light traces young populations of stars; in this image, young stars can be seen way beyond the main spiral disk of M83 up to 140,000 light-years from its center. Could life exist around one of these far-flung stars? Scientists say it's unlikely because the outlying regions of a galaxy are lacking in the metals required for planets to form.

The image was taken at scheduled intervals between March 15 and May 20, 2007. It is one of the longest-exposure, or deepest, images ever taken of a nearby galaxy in ultraviolet light. Near-ultraviolet light (or longer-wavelength ultraviolet light) is colored yellow, and far-ultraviolet light is blue.

What Lies Beyond the Edge of a Galaxy The side-by-side comparison shows the Southern Pinwheel galaxy, or M83, as seen in ultraviolet light (right) and at both ultraviolet and radio wavelengths (left). While the radio data highlight the galaxy's long, octopus-like arms stretching far beyond its main spiral disk (red), the ultraviolet data reveal clusters of baby stars (blue) within the extended arms.

The ultraviolet image was taken by NASA's Galaxy Evolution Explorer between March 15 and May 20, 2007, at scheduled intervals. Back in 2005, the telescope first photographed M83 over a shorter period of time. That picture was the first to reveal far-flung baby stars forming up to 63,000 light-years from the edge of the main spiral disk. This came as a surprise to astronomers because a galaxy's outer territory typically lacks high densities of star-forming materials.

The newest picture of M83 from the Galaxy Evolution Explorer is shown at the right, and was taken over a longer period of

Miniature x-ray source

DOEpatents

Trebes, James E.; Bell, Perry M.; Robinson, Ronald B.

2000-01-01

A miniature x-ray source utilizing a hot filament cathode. The source has a millimeter scale size and is capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature source consists of a compact vacuum tube assembly containing the hot filament cathode, an anode, a high voltage feedthru for delivering high voltage to the cathode, a getter for maintaining high vacuum, a connector for initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is fabricated from highly x-ray transparent materials, such as sapphire, diamond, or boron nitride.

Particle monitoring and control in vacuum processing equipment

NASA Astrophysics Data System (ADS)

Borden, Peter G., Dr.; Gregg, John

1989-10-01

Particle contamination during vacuum processes has emerged as the largest single source of yield loss in VLSI manufacturing. While a number of tools have been available to help understand the sources and nature of this contamination, only recently has it been possible to monitor free particle levels within vacuum equipment in real-time. As a result, a better picture is available of how particle contamination can affect a variety of processes. This paper reviews some of the work that has been done to monitor particles in vacuum loadlocks and in processes such as etching, sputtering and ion implantation. The aim has been to make free particles in vacuum equipment a measurable process parameter. Achieving this allows particles to be controlled using statistical process control. It will be shown that free particle levels in load locks correlate to wafer surface counts, device yield and process conditions, but that these levels are considerable higher during production than when dummy wafers are run to qualify a system. It will also be shown how real-time free particle monitoring can be used to monitor and control cleaning cycles, how major episodic events can be detected, and how data can be gathered in a format suitable for statistical process control.

Indian Vacuum Society: The Indian Vacuum Society

NASA Astrophysics Data System (ADS)

Saha, T. K.

2008-03-01

The Indian Vacuum Society (IVS) was established in 1970. It has over 800 members including many from Industry and R & D Institutions spread throughout India. The society has an active chapter at Kolkata. The society was formed with the main aim to promote, encourage and develop the growth of Vacuum Science, Techniques and Applications in India. In order to achieve this aim it has conducted a number of short term courses at graduate and technician levels on vacuum science and technology on topics ranging from low vacuum to ultrahigh vacuum So far it has conducted 39 such courses at different parts of the country and imparted training to more than 1200 persons in the field. Some of these courses were in-plant training courses conducted on the premises of the establishment and designed to take care of the special needs of the establishment. IVS also regularly conducts national and international seminars and symposia on vacuum science and technology with special emphasis on some theme related to applications of vacuum. A large number of delegates from all over India take part in the deliberations of such seminars and symposia and present their work. IVS also arranges technical visits to different industries and research institutes. The society also helped in the UNESCO sponsored post-graduate level courses in vacuum science, technology and applications conducted by Mumbai University. The society has also designed a certificate and diploma course for graduate level students studying vacuum science and technology and has submitted a syllabus to the academic council of the University of Mumbai for their approval, we hope that some colleges affiliated to the university will start this course from the coming academic year. IVS extended its support in standardizing many of the vacuum instruments and played a vital role in helping to set up a Regional Testing Centre along with BARC. As part of the development of vacuum education, the society arranges the participation of

Vacuum-Compatible Wideband White Light and Laser Combiner Source System

NASA Technical Reports Server (NTRS)

Azizi, Alineza; Ryan, Daniel J.; Tang, Hong; Demers, Richard T.; Kadogawa, Hiroshi; An, Xin; Sun, George Y.

2010-01-01

For the Space Interferometry Mission (SIM) Spectrum Calibration Development Unit (SCDU) testbed, wideband white light is used to simulate starlight. The white light source mount requires extremely stable pointing accuracy (<3.2 microradians). To meet this and other needs, the laser light from a single-mode fiber was combined, through a beam splitter window with special coating from broadband wavelengths, with light from multimode fiber. Both lights were coupled to a photonic crystal fiber (PCF). In many optical systems, simulating a point star with broadband spectrum with stability of microradians for white light interferometry is a challenge. In this case, the cameras use the white light interference to balance two optical paths, and to maintain close tracking. In order to coarse align the optical paths, a laser light is sent into the system to allow tracking of fringes because a narrow band laser has a great range of interference. The design requirements forced the innovators to use a new type of optical fiber, and to take a large amount of care in aligning the input sources. The testbed required better than 1% throughput, or enough output power on the lowest spectrum to be detectable by the CCD camera (6 nW at camera). The system needed to be vacuum-compatible and to have the capability for combining a visible laser light at any time for calibration purposes. The red laser is a commercially produced 635-nm laser 5-mW diode, and the white light source is a commercially produced tungsten halogen lamp that gives a broad spectrum of about 525 to 800 nm full width at half maximum (FWHM), with about 1.4 mW of power at 630 nm. A custom-made beam splitter window with special coating for broadband wavelengths is used with the white light input via a 50-mm multi-mode fiber. The large mode area PCF is an LMA-8 made by Crystal Fibre (core diameter of 8.5 mm, mode field diameter of 6 mm, and numerical aperture at 625 nm of 0.083). Any science interferometer that needs a

Surface Chemical Conversion of Organosilane Self-Assembled Monolayers with Active Oxygen Species Generated by Vacuum Ultraviolet Irradiation of Atmospheric Oxygen Molecules

NASA Astrophysics Data System (ADS)

Kim, Young-Jong; Lee, Kyung-Hwang; Sano, Hikaru; Han, Jiwon; Ichii, Takashi; Murase, Kuniaki; Sugimura, Hiroyuki

2008-01-01

The chemical conversion of the top surface of n-octadecyltrimethoxy silane self-assembled monolayers (ODS-SAMs) on oxide-covered Si substrates using active oxygen species generated from atmospheric oxygen molecules irradiated with vacuum ultraviolet (VUV) light at 172 nm in wavelength has been studied on the basis of water contact angle measurements, ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy. An ODS-SAM whose water contact angle was 104° on average was prepared using chemical vapor deposition with substrate and vapor temperatures of 150 °C. The VUV treatment of an ODS-SAM sample was carried out by placing the sample in air and then irradiating the sample surface with a Xe-excimer lamp. The distance between the lamp and the sample was regulated so that the VUV light emitted from the lamp was almost entirely absorbed by atmospheric oxygen molecules to generate active oxygen species, such as ozone and atomic oxygen before reaching the sample surface. Hence, the surface chemical conversion of the ODS-SAM was primarily promoted through chemical reactions with the active oxygen species. Photochemical changes in the ODS-SAM were found to be the generation of polar functional groups, such as -COOH, -CHO, and -OH, on the surface and the subsequent etching of the monolayer. Irradiation parameters, such as irradiation time, were optimized to achieve a better functionalization of the SAM top surface while minimizing the etching depth of the ODS-SAM. The ability to graft another SAM onto the modified ODS-SAM bearing polar functional groups was demonstrated by the formation of alkylsilane bilayers.

Electronic Structure and Optical Properties of Cu 2ZnGeSe 4. First-Principles Calculations and Vacuum-Ultraviolet Spectroscopic Ellipsometric Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Sukgeun; Park, Ji-Sang; Donohue, Andrea

2015-11-19

Cu 2ZnGeSe 4 is of interest for the development of next-generation thin-film photovoltaic technologies. To understand its electronic structure and related fundamental optical properties, we perform first-principles calculations for three structural variations: kesterite, stannite, and primitive-mixed CuAu phases. The calculated data are compared with the room-temperature dielectric functionϵ=ϵ1+iϵ2 spectrum of polycrystalline Cu 2ZnGeSe 4 determined by vacuum-ultraviolet spectroscopic ellipsometry in the photon-energy range of 0.7 to 9.0 eV. Ellipsometric data are modeled with the sum of eight Tauc-Lorentz oscillators, and the best-fit model yields the band-gap and Tauc-gap energies of 1.25 and 1.19 eV, respectively. A comparison of overall peakmore » shapes and relative intensities between experimental spectra and the calculated ϵ data for three structural variations suggests that the sample may not have a pure (ordered) kesterite phase. We found that the complex refractive index N=n+ik, normal-incidence reflectivity R, and absorption coefficients α are calculated from the modeled ϵ spectrum, which are also compared with those of Cu 2ZnSnSe 4 . The spectral features for Cu 2ZnGeSe 4 appear to be weaker and broader than those for Cu 2ZnSnSe 4 , which is possibly due to more structural imperfections presented in Cu 2ZnGeSe 4 than Cu 2ZnSnSe 4 .« less

Indigenous Manufacturing realization of TWIN Source

NASA Astrophysics Data System (ADS)

Pandey, R.; Bandyopadhyay, M.; Parmar, D.; Yadav, R.; Tyagi, H.; Soni, J.; Shishangiya, H.; Sudhir Kumar, D.; Shah, S.; Bansal, G.; Pandya, K.; Parmar, K.; Vuppugalla, M.; Gahlaut, A.; Chakraborty, A.

2017-04-01

TWIN source is two RF driver based negative ion source that has been planned to bridge the gap between single driver based ROBIN source (currently operational) and eight river based DNB source (to be operated under IN-TF test facility). TWIN source experiments have been planned at IPR keeping the objective of long term domestic fusion programme to gain operational experiences on vacuum immersed multi driver RF based negative ion source. High vacuum compatible components of twin source are designed at IPR keeping an aim on indigenous built in attempt. These components of TWIN source are mainly stainless steel and OFC-Cu. Being high heat flux receiving components, one of the major functional requirements is continuous heat removal via water as cooling medium. Hence for the purpose stainless steel parts are provided with externally milled cooling lines and that shall be covered with a layer of OFC-cu which would be on the receiving side of high heat flux. Manufacturability of twin source components requires joining of these dissimilar materials via process like electrode position, electron beam welding and vacuum brazing. Any of these manufacturing processes shall give a vacuum tight joint having proper joint strength at operating temperature and pressure. Taking the indigenous development effort vacuum brazing (in non-nuclear environment) has been opted for joining of dissimilar materials of twin source being one of the most reliable joining techniques and commercially feasible across the suppliers of country. Manufacturing design improvisation for the components has been done to suit the vacuum brazing process requirement and to ease some of the machining without comprising over the functional and operational requirements. This paper illustrates the details on the indigenous development effort, design improvisation to suits manufacturability, vacuum brazing basics and its procedures for twin source components.

Nonevaporable getter coating chambers for extreme high vacuum

DOE PAGES

Stutzman, Marcy L.; Adderley, Philip A.; Mamun, Md Abdullah Al; ...

2018-03-01

Techniques for NEG coating a large diameter chamber are presented along with vacuum measurements in the chamber using several pumping configurations, with base pressure as low as 1.56x10^-12 Torr (N2 equivalent) with only a NEG coating and small ion pump. We then describe modifications to the NEG coating process to coat complex geometry chambers for ultra-cold atom trap experiments. Surface analysis of NEG coated samples are used to measure composition and morphology of the thin films. Finally, pressure measurements are compared for two NEG coated polarized electron source chambers: the 130 kV polarized electron source at Jefferson Lab and themore » upgraded 350 kV polarized 2 electron source, both of which are approaching or within the extreme high vacuum (XHV) range, defined as P<7.5x10^-13 Torr.« less

Nonevaporable getter coating chambers for extreme high vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stutzman, Marcy L.; Adderley, Philip A.; Mamun, Md Abdullah Al

Techniques for NEG coating a large diameter chamber are presented along with vacuum measurements in the chamber using several pumping configurations, with base pressure as low as 1.56x10^-12 Torr (N2 equivalent) with only a NEG coating and small ion pump. We then describe modifications to the NEG coating process to coat complex geometry chambers for ultra-cold atom trap experiments. Surface analysis of NEG coated samples are used to measure composition and morphology of the thin films. Finally, pressure measurements are compared for two NEG coated polarized electron source chambers: the 130 kV polarized electron source at Jefferson Lab and themore » upgraded 350 kV polarized 2 electron source, both of which are approaching or within the extreme high vacuum (XHV) range, defined as P<7.5x10^-13 Torr.« less

Measurement of temperature and density fluctuations in turbulence using an ultraviolet laser

NASA Technical Reports Server (NTRS)

Massey, G. A.

1984-01-01

Noninvasive measurement of density and temperature fluctuations in turbulent air flow was examined. The approach used fluorescence of oxygen molecules which are selectively excited by a tunable vacuum ultraviolet laser beam. The strength of the fluorescence signal and its dependence on laser wavelength vary with the density and temperature of the air in the laser beam. Because fluorescence can be detected at 90 degrees from the beam propagation direction, spatial resolution in three dimensions, rather than path-integrated measurements can be achieved. With spatial resolutions of the order of a millimeter and at supersonic air velocities it is necessary to perform each measurement in a time of the order of a microsecond; this is possible by by using laser pulses of ten nanosecond duration. In this method atmospheric O2 is excited by the emission of a tunable ArF excimer laser, and the fluorescence, which spans the 210 to 420 range, is detected by an ultraviolet phototube.

[Effect of long-wave ultraviolet light (UV-A) and medium-wave ultraviolet rays (UV-B) on human skin. Critical comparison].

PubMed

Raab, W

1980-04-15

When discussing the effects of ultraviolet radiation on human skin, one should carefully distinguish between the long wave ultraviolet light (UV-A) and the short wave radiations (UV-B and UV-C). Ultraviolet A induces immediate pigmentation but, if high energies are applied, a permanent pigmentation is elicited. This type of ultraviolet A-induced pigmentation has been called "spontaneous" pigmentation as no erythematous reaction is necessary to induce or accelerate melanine formation. Ultraviolet B provokes erythema and consecutive pigmentation. Upon chronic exposure, ultraviolet B causes the wellknown actinic damage of the skin and even provokes carcinoma. With exposures to the sunlight (global radiation), one should be most careful. The public must be informed extensively about the dangers of excessive sunbaths. The use of artificial "suns" with spectra between 260 and 400 nm is limited as it may cause the same type of damage as the global radiation. An exact schedule for use of artificial lamps is strongly recommended. After one cycle of exposures, an interruption is necessary until the next cycle of irradiations may start. Upon continual use for tanning of the skin, artificial lamps may provoke irreversible damage of the skin. Radiation sources with emission spectra of wavelengths between 315 and 400 nm exclusively are well suited for the induction of skin pigmentation (cosmetic use). Potent radiation such as UVASUN systems provoke a "pleasant" permanent pigmentation after exposures for less than one hour. The use of ultraviolet A (UV-A) does not carry any risk for the human skin.

An Underappreciated Radiation Hazard from High Voltage Electrodes in Vacuum.

PubMed

West, Adam D; Lasner, Zack; DeMille, David; West, Elizabeth P; Panda, Cristian D; Doyle, John M; Gabrielse, Gerald; Kryskow, Adam; Mitchell, Corinne

2017-01-01

The use of high voltage (HV) electrodes in vacuum is commonplace in physics laboratories. In such systems, it has long been known that electron emission from an HV cathode can lead to bremsstrahlung x rays; indeed, this is the basic principle behind the operation of standard x-ray sources. However, in laboratory setups where x-ray production is not the goal and no electron source is deliberately introduced, field-emitted electrons accelerated by HV can produce x rays as an unintended hazardous byproduct. Both the level of hazard and the safe operating regimes for HV vacuum electrode systems are not widely appreciated, at least in university laboratories. A reinforced awareness of the radiation hazards associated with vacuum HV setups would be beneficial. The authors present a case study of a HV vacuum electrode device operated in a university atomic physics laboratory. They describe the characterization of the observed x-ray radiation, its relation to the observed leakage current in the device, the steps taken to contain and mitigate the radiation hazard, and suggested safety guidelines.

Wide-field direct CCD observations supporting the Astro-1 Space Shuttle mission's Ultraviolet Imaging Telescope

NASA Technical Reports Server (NTRS)

Hintzen, Paul; Angione, Ron; Talbert, Freddie; Cheng, K.-P.; Smith, Eric; Stecher, Theodore P.

1993-01-01

Wide field direct CCD observations are being obtained to support and complement the vacuum-ultraviolet (VUV) images provided by Astro's Ultraviolet Imaging Telescope (UIT) during a Space Shuttle flight in December 1990. Because of the wide variety of projects addressed by UIT, the fields observed include (1) galactic supernova remnants such as the Cygnus Loop and globular clusters such as Omega Cen and M79; (2) the Magellanic Clouds, M33, M81, and other galaxies in the Local Group; and (3) rich clusters of galaxies, principally the Perseus cluster and Abell 1367. Ground-based observations have been obtained for virtually all of the Astro-1 UIT fields. The optical images allow identification of individual UV sources in each field and provide the long baseline in wavelength necessary for accurate analysis of UV-bright sources. To facilitate use of our optical images for analysis of UIT data and other projects, we plan to archive them, with the UIT images, at the National Space Science Data Center (NSSDC), where they will be universally accessible via anonymous FTP. The UIT, one of three telescopes comprising the Astro spacecraft, is a 38-cm f/9 Ritchey-Chretien telescope on which high quantum efficiency, solar-blind image tubes are used to record VUV images on photographic film. Five filters with passbands centered between 1250A and 2500A provide both VUV colors and a measurement of extinction via the 2200A dust feature. The resulting calibrated VUV pictures are 40 arcminutes in diameter at 2.5 arcseconds resolution. The capabilities of UIT, therefore, complement HST's WFPC: the latter has 40 times greater collecting area, while UIT's usable field has 170 times WFPC's field area.

A Plasma Ultraviolet Source for Short Wavelength Lasers.

DTIC Science & Technology

1988-04-15

plasma focus (DPF) device was evaluated for the feasibility of blue-green and near ultraviolet laser pumping. As the result of optimizing the operating conditions of DPF and laser system, the maximum untuned laser output exceeded 4.0mJ corresponding to the energy density 8.3J/liter which is much higher than the typical flashlamp dye laser. The spectral irradiance of DPF at the absorption bands for LD390 and LD490 were 5.5W/sq cm-nm, 0.3W.sq cm-nm, respectively. Due to the lower pump power of DPF at 355nm than the threshold of LD390, the laser pumping of LD390 dye was not

Deterministic Impulsive Vacuum Foundations for Quantum-Mechanical Wavefunctions

NASA Astrophysics Data System (ADS)

Valentine, John S.

2013-09-01

By assuming that a fermion de-constitutes immediately at source, that its constituents, as bosons, propagate uniformly as scalar vacuum terms with phase (radial) symmetry, and that fermions are unique solutions for specific phase conditions, we find a model that self-quantizes matter from continuous waves, unifying bosons and fermion ontologies in a single basis, in a constitution-invariant process. Vacuum energy has a wavefunction context, as a mass-energy term that enables wave collapse and increases its amplitude, with gravitational field as the gradient of the flux density. Gravitational and charge-based force effects emerge as statistics without special treatment. Confinement, entanglement, vacuum statistics, forces, and wavefunction terms emerge from the model's deterministic foundations.

Influence of vacuum chamber impurities on the lifetime of organic light-emitting diodes

PubMed Central

Fujimoto, Hiroshi; Suekane, Takashi; Imanishi, Katsuya; Yukiwaki, Satoshi; Wei, Hong; Nagayoshi, Kaori; Yahiro, Masayuki; Adachi, Chihaya

2016-01-01

We evaluated the influence of impurities in the vacuum chamber used for the fabrication of organic light-emitting diodes on the lifetime of the fabricated devices and found a correlation between lifetime and the device fabrication time. The contact angle of the ITO substrates stored the chamber under vacuum were used to evaluate chamber cleanliness. Liquid chromatography-mass spectrometry was performed on Si wafers stored in the vacuum chamber before device fabrication to examine the impurities in the chamber. Surprisingly, despite the chamber and evaporation sources being at room temperature, a variety of materials were detected, including previously deposited materials and plasticizers from the vacuum chamber components. We show that the impurities, and not differences in water content, in the chamber were the source of lifetime variations even when the duration of exposure to impurities only varied before and after deposition of the emitter layer. These results suggest that the impurities floating in the vacuum chamber significantly impact lifetime values and reproducibility. PMID:27958304

Influence of vacuum chamber impurities on the lifetime of organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Fujimoto, Hiroshi; Suekane, Takashi; Imanishi, Katsuya; Yukiwaki, Satoshi; Wei, Hong; Nagayoshi, Kaori; Yahiro, Masayuki; Adachi, Chihaya

2016-12-01

We evaluated the influence of impurities in the vacuum chamber used for the fabrication of organic light-emitting diodes on the lifetime of the fabricated devices and found a correlation between lifetime and the device fabrication time. The contact angle of the ITO substrates stored the chamber under vacuum were used to evaluate chamber cleanliness. Liquid chromatography-mass spectrometry was performed on Si wafers stored in the vacuum chamber before device fabrication to examine the impurities in the chamber. Surprisingly, despite the chamber and evaporation sources being at room temperature, a variety of materials were detected, including previously deposited materials and plasticizers from the vacuum chamber components. We show that the impurities, and not differences in water content, in the chamber were the source of lifetime variations even when the duration of exposure to impurities only varied before and after deposition of the emitter layer. These results suggest that the impurities floating in the vacuum chamber significantly impact lifetime values and reproducibility.

Application of Laser Plasma Sources of Soft X-rays and Extreme Ultraviolet (EUV) in Imaging, Processing Materials and Photoionization Studies

NASA Astrophysics Data System (ADS)

Fiedorowicz, H.; Bartnik, A.; Wachulak, P. W.; Jarocki, R.; Kostecki, J.; Szczurek, M.; Ahad, I. U.; Fok, T.; Szczurek, A.; Wȩgrzyński, Ł.

In the paper we present new applications of laser plasma sources of soft X-rays and extreme ultraviolet (EUV) in various areas of plasma physics, nanotechnology and biomedical engineering. The sources are based on a gas puff target irradiated with nanosecond laser pulses from commercial Nd: YAG lasers, generating pulses with time duration from 1 to 10 ns and energies from 0.5 to 10 J at a 10 Hz repetition rate. The targets are produced with the use of a double valve system equipped with a special nozzle to form a double-stream gas puff target which allows for high conversion efficiency of laser energy into soft X-rays and EUV without degradation of the nozzle. The sources are equipped with various optical systems to collect soft X-ray and EUV radiation and form the radiation beam. New applications of these sources in imaging, including EUV tomography and soft X-ray microscopy, processing of materials and photoionization studies are presented.

Ultrafast, high repetition rate, ultraviolet, fiber-laser-based source: application towards Yb⁺ fast quantum-logic.

PubMed

Hussain, Mahmood Irtiza; Petrasiunas, Matthew Joseph; Bentley, Christopher D B; Taylor, Richard L; Carvalho, André R R; Hope, Joseph J; Streed, Erik W; Lobino, Mirko; Kielpinski, David

2016-07-25

Trapped ions are one of the most promising approaches for the realization of a universal quantum computer. Faster quantum logic gates could dramatically improve the performance of trapped-ion quantum computers, and require the development of suitable high repetition rate pulsed lasers. Here we report on a robust frequency upconverted fiber laser based source, able to deliver 2.5 ps ultraviolet (UV) pulses at a stabilized repetition rate of 300.00000 MHz with an average power of 190 mW. The laser wavelength is resonant with the strong transition in Ytterbium (Yb⁺) at 369.53 nm and its repetition rate can be scaled up using high harmonic mode locking. We show that our source can produce arbitrary pulse patterns using a programmable pulse pattern generator and fast modulating components. Finally, simulations demonstrate that our laser is capable of performing resonant, temperature-insensitive, two-qubit quantum logic gates on trapped Yb⁺ ions faster than the trap period and with fidelity above 99%.

Miniature x-ray source

DOEpatents

Trebes, James E.; Stone, Gary F.; Bell, Perry M.; Robinson, Ronald B.; Chornenky, Victor I.

2002-01-01

A miniature x-ray source capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature x-ray source comprises a compact vacuum tube assembly containing a cathode, an anode, a high voltage feedthru for delivering high voltage to the anode, a getter for maintaining high vacuum, a connection for an initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is highly x-ray transparent and made, for example, from boron nitride. The compact size and potential for remote operation allows the x-ray source, for example, to be placed adjacent to a material sample undergoing analysis or in proximity to the region to be treated for medical applications.

Ultraviolet 320 nm laser excitation for flow cytometry.

PubMed

Telford, William; Stickland, Lynn; Koschorreck, Marco

2017-04-01

Although multiple lasers and high-dimensional analysis capability are now standard on advanced flow cytometers, ultraviolet (UV) lasers (usually 325-365 nm) remain an uncommon excitation source for cytometry. This is primarily due to their cost, and the small number of applications that require this wavelength. The development of the Brilliant Ultraviolet (BUV fluorochromes, however, has increased the importance of this formerly niche excitation wavelength. Historically, UV excitation was usually provided by water-cooled argon- and krypton-ion lasers. Modern flow cytometers primary rely on diode pumped solid state lasers emitting at 355 nm. While useful for all UV-excited applications, DPSS UV lasers are still large by modern solid state laser standards, and remain very expensive. Smaller and cheaper near UV laser diodes (NUVLDs) emitting at 375 nm make adequate substitutes for 355 nm sources in many situations, but do not work as well with very short wavelength probes like the fluorescent calcium chelator indo-1. In this study, we evaluate a newly available UV 320 nm laser for flow cytometry. While shorter in wavelength that conventional UV lasers, 320 is close to the 325 nm helium-cadmium wavelength used in the past on early benchtop cytometers. A UV 320 nm laser was found to excite almost all Brilliant Ultraviolet dyes to nearly the same level as 355 nm sources. Both 320 nm and 355 nm sources worked equally well for Hoechst and DyeCycle Violet side population analysis of stem cells in mouse hematopoetic tissue. The shorter wavelength UV source also showed excellent excitation of indo-1, a probe that is not compatible with NUVLD 375 nm sources. In summary, a 320 nm laser module made a suitable substitute for conventional 355 nm sources. This laser technology is available in a smaller form factor than current 355 nm units, making it useful for small cytometers with space constraints. © 2017 International Society for Advancement of Cytometry. © 2017 International

Low-debris, efficient laser-produced plasma extreme ultraviolet source by use of a regenerative liquid microjet target containing tin dioxide (SnO2) nanoparticles

NASA Astrophysics Data System (ADS)

Higashiguchi, Takeshi; Dojyo, Naoto; Hamada, Masaya; Sasaki, Wataru; Kubodera, Shoichi

2006-05-01

We demonstrated a low-debris, efficient laser-produced plasma extreme ultraviolet (EUV) source by use of a regenerative liquid microjet target containing tin-dioxide (SnO2) nanoparticles. By using a low SnO2 concentration (6%) solution and dual laser pulses for the plasma control, we observed the EUV conversion efficiency of 1.2% with undetectable debris.

Vacuum ultraviolet radiation/atomic oxygen synergism in fluorinated ethylene propylene Teflon erosion

NASA Technical Reports Server (NTRS)

Stiegman, A. E.; Brinza, David E.; Laue, Eric G.; Anderson, Mark S.; Liang, Ranty H.

1992-01-01

A micrographic investigation is reported of samples of the fluorinated ethylene propylene (FEP) Teflon thermal-blanketing materials recovered from the Long-Duration Exposure Facility (LDEF) satellite. The samples are taken from the trailing edge and row 8 which correspond to exposures to vacuum UV (VUV) and VUV + atomic O, respectively. Data are taken from SEM and IR-spectra observations, and the LDEF leading-edge FEP shows a high degree of erosion, roughening, and sharp peaks angled in the direction of the flow of atomic O. The trailing edge sample influenced primarily by VUV shows a hard brittle layer and some cracked mosaic patterns. Comparisons to a reference sample suggest that the brittle layer is related to exposure to VUV and is removed by atomic-O impingement. Polymers that are stable to VUV radiation appear to be more stable in terms of atomic oxygen.

Ion source

DOEpatents

Brobeck, W. M.

1959-04-14

This patent deals with calutrons and more particularly to an arrangement therein whereby charged bottles in a calutron source unit may be replaced without admitting atmospheric air to the calutron vacuum chamber. As described, an ion unit is disposed within a vacuum tank and has a reservoir open toward a wall of the tank. A spike projects from the source into the reservoir. When a charge bottle is placed in the reservoir, the spike breaks a frangible seal on the bottle. After the contents of the bottle are expended the bottle may be withdrawn and replaced with another charge bottle by a vacuum lock arrangement in conjunction with an arm for manipulating the bottle.

Vibrational autoionization of state-selective jet-cooled methanethiol (CH 3SH) investigated with infrared + vacuum-ultraviolet photoionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Min; Shen, Zhitao; Pratt, S. T.

Vibrational autoionization of Rydberg states provides key information about nonadiabatic processes above an ionization threshold. In this work, we employed time-of-flight mass detection of CH 3SH + to record vibrational-state selective photo-ionization efficiency (PIE) spectra of jet-cooled methanethiol (CH 3SH) on exciting CH 3SH to a specific vibrationally excited state with an infrared (IR) laser, followed by excitation with a tunable laser in the vacuum-ultraviolet (VUV) region for ionization. Autoionizing Rydberg states assigned to the ns, np, nd and nf series are identified. When IR light at 2601 (ν 3, SH stretching mode) and 2948 cm -1 (ν 2, CHmore » 3 symmetric stretching mode) was employed, the Rydberg series converged to the respective vibrationally excited (ν 3 and ν 2) states of CH 3SH +. When IR light at 3014 cm -1 (overlapped ν 1/ν 9, CH 3 antisymmetric stretching and CH 2 antisymmetric stretching modes) was employed, Rydberg series converging to two vibrationally excited states (ν 1 and ν 9) of CH 3SH + were observed. When IR light at 2867 cm -1 (2ν 10, overtone of CH 3 deformation mode) and 2892 cm -1 (2ν 4, overtone of CH 2 scissoring mode) was employed, both Δν = -1 and Δν = -2 ionization transitions were observed; there is evidence for direct ionization from the initial state into the CH 3SH + (ν 4 + = 1) continuum. In all observed IR-VUV-PIE spectra, the ns and nd series show intensity greater than the other Rydberg series, which is consistent with the fact that the highest-occupied molecular orbital of CH 3SH is a p-like lone pair orbital on the S atom. Finally, the quantum yields for autoionization of various vibrational excited states are discussed. Values of ν 1 = 3035, ν 2 = 2884, ν 3 = 2514, and ν 9 = 2936 cm -1 for CH 3SH + derived from the converged limits agree satisfactorily with values observed for Ar-tagged CH 3SH + at 3026, 2879, 2502, and 2933 cm -1.« less

Vibrational autoionization of state-selective jet-cooled methanethiol (CH 3SH) investigated with infrared + vacuum-ultraviolet photoionization

DOE PAGES

Xie, Min; Shen, Zhitao; Pratt, S. T.; ...

2017-10-24

Vibrational autoionization of Rydberg states provides key information about nonadiabatic processes above an ionization threshold. In this work, we employed time-of-flight mass detection of CH 3SH + to record vibrational-state selective photo-ionization efficiency (PIE) spectra of jet-cooled methanethiol (CH 3SH) on exciting CH 3SH to a specific vibrationally excited state with an infrared (IR) laser, followed by excitation with a tunable laser in the vacuum-ultraviolet (VUV) region for ionization. Autoionizing Rydberg states assigned to the ns, np, nd and nf series are identified. When IR light at 2601 (ν 3, SH stretching mode) and 2948 cm -1 (ν 2, CHmore » 3 symmetric stretching mode) was employed, the Rydberg series converged to the respective vibrationally excited (ν 3 and ν 2) states of CH 3SH +. When IR light at 3014 cm -1 (overlapped ν 1/ν 9, CH 3 antisymmetric stretching and CH 2 antisymmetric stretching modes) was employed, Rydberg series converging to two vibrationally excited states (ν 1 and ν 9) of CH 3SH + were observed. When IR light at 2867 cm -1 (2ν 10, overtone of CH 3 deformation mode) and 2892 cm -1 (2ν 4, overtone of CH 2 scissoring mode) was employed, both Δν = -1 and Δν = -2 ionization transitions were observed; there is evidence for direct ionization from the initial state into the CH 3SH + (ν 4 + = 1) continuum. In all observed IR-VUV-PIE spectra, the ns and nd series show intensity greater than the other Rydberg series, which is consistent with the fact that the highest-occupied molecular orbital of CH 3SH is a p-like lone pair orbital on the S atom. Finally, the quantum yields for autoionization of various vibrational excited states are discussed. Values of ν 1 = 3035, ν 2 = 2884, ν 3 = 2514, and ν 9 = 2936 cm -1 for CH 3SH + derived from the converged limits agree satisfactorily with values observed for Ar-tagged CH 3SH + at 3026, 2879, 2502, and 2933 cm -1.« less

Studies on cryogenic Xe capillary jet target for laser-produced plasma EUV-light source

NASA Astrophysics Data System (ADS)

Inoue, T.; Nica, P. E.; Kaku, K.; Shimoura, A.; Amano, S.; Miyamoto, S.; Mochizuki, T.

2006-03-01

In this paper, characterizations of a cryogenic Xe capillary jet target for a laser-produced plasma extreme ultraviolet (EUV) light source are reported. The capillary jet target is a candidate of fast-supplying targets for mitigating debris generation and target consumption in a vacuum chamber without reducing the EUV conversion efficiency. Xe capillary jets (jet velocity ~ 0.4 m/s) were generated in vacuum by using annular nozzles chilled to ~ 170 K at a Xe backing pressure of ~ 0.7 MPa. Forming mechanisms of the capillary jet targets were studied by using numerical calculations. Furthermore, laser-produced plasma EUV generation was performed by irradiating a Nd:YAG laser (1064 nm, ~ 0.5 J, 10 ns, 120 μmφ, ~ 4×10 11 W/cm2) on a Xe capillary jet target (outer / inner diameter = 100 / 70 μmφ). The angular distribution of EUV generation was approximately uniform around the Xe capillary jet target, and the peak kinetic energy of the fast-ions was evaluated to be ~ 2 keV.

True random numbers from amplified quantum vacuum.

PubMed

Jofre, M; Curty, M; Steinlechner, F; Anzolin, G; Torres, J P; Mitchell, M W; Pruneri, V

2011-10-10

Random numbers are essential for applications ranging from secure communications to numerical simulation and quantitative finance. Algorithms can rapidly produce pseudo-random outcomes, series of numbers that mimic most properties of true random numbers while quantum random number generators (QRNGs) exploit intrinsic quantum randomness to produce true random numbers. Single-photon QRNGs are conceptually simple but produce few random bits per detection. In contrast, vacuum fluctuations are a vast resource for QRNGs: they are broad-band and thus can encode many random bits per second. Direct recording of vacuum fluctuations is possible, but requires shot-noise-limited detectors, at the cost of bandwidth. We demonstrate efficient conversion of vacuum fluctuations to true random bits using optical amplification of vacuum and interferometry. Using commercially-available optical components we demonstrate a QRNG at a bit rate of 1.11 Gbps. The proposed scheme has the potential to be extended to 10 Gbps and even up to 100 Gbps by taking advantage of high speed modulation sources and detectors for optical fiber telecommunication devices.

Cancer cell classification with coherent diffraction imaging using an extreme ultraviolet radiation source

PubMed Central

Zürch, Michael; Foertsch, Stefan; Matzas, Mark; Pachmann, Katharina; Kuth, Rainer; Spielmann, Christian

2014-01-01

Abstract. In cancer treatment, it is highly desirable to classify single cancer cells in real time. The standard method is polymerase chain reaction requiring a substantial amount of resources and time. Here, we present an innovative approach for rapidly classifying different cell types: we measure the diffraction pattern of a single cell illuminated with coherent extreme ultraviolet (XUV) laser-generated radiation. These patterns allow distinguishing different breast cancer cell types in a subsequent step. Moreover, the morphology of the object can be retrieved from the diffraction pattern with submicron resolution. In a proof-of-principle experiment, we prepared single MCF7 and SKBR3 breast cancer cells on gold-coated silica slides. The output of a laser-driven XUV light source is focused onto a single unstained and unlabeled cancer cell. With the resulting diffraction pattern, we could clearly identify the different cell types. With an improved setup, it will not only be feasible to classify circulating tumor cells with a high throughput, but also to identify smaller objects such as bacteria or even viruses. PMID:26158049

Cancer cell classification with coherent diffraction imaging using an extreme ultraviolet radiation source.

PubMed

Zürch, Michael; Foertsch, Stefan; Matzas, Mark; Pachmann, Katharina; Kuth, Rainer; Spielmann, Christian

2014-10-01

In cancer treatment, it is highly desirable to classify single cancer cells in real time. The standard method is polymerase chain reaction requiring a substantial amount of resources and time. Here, we present an innovative approach for rapidly classifying different cell types: we measure the diffraction pattern of a single cell illuminated with coherent extreme ultraviolet (XUV) laser-generated radiation. These patterns allow distinguishing different breast cancer cell types in a subsequent step. Moreover, the morphology of the object can be retrieved from the diffraction pattern with submicron resolution. In a proof-of-principle experiment, we prepared single MCF7 and SKBR3 breast cancer cells on gold-coated silica slides. The output of a laser-driven XUV light source is focused onto a single unstained and unlabeled cancer cell. With the resulting diffraction pattern, we could clearly identify the different cell types. With an improved setup, it will not only be feasible to classify circulating tumor cells with a high throughput, but also to identify smaller objects such as bacteria or even viruses.

Vacuum system of the cyclotrons in VECC, Kolkata

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roy, Anindya; Bhole, R.B.; Akhtar, J.

2011-07-01

The vacuum system of the K=130 Room Temperature Cyclotron (RTC) (operational since 1978) has been recently modernized and the same of the K{sub bend}=520 Superconducting Cyclotron (SCC), currently under commissioning, is being deployed for remote monitoring and control. The vacuum system of RTC is designed to achieve and maintain vacuum level of 2 X 10{sup -6} mbar inside 23 m{sup 3} volume of Resonator tank and DEE tank. This has been upgraded by replacing several valves, Freon units, gauges and pumps. The relay based manual control system has been replaced by PLC based automated system. The SCC vacuum system alsomore » has an elaborate arrangement comprising of turbo molecular pumping modules with associated isolation valves and characteristic gauges. This paper describes essential elements, typically used to obtain high (1X10{sup -7} mbar) vacuum using rotary pumps, diffusion pumps and cold traps/turbo-molecular pumps and other system components such as valves, gauges and baffles. The supervisory control methodology/scheme of both the vacuum systems, developed in-house using EPICS (Experimental Physics and Industrial Control System), a standard open-source software tool for designing distributed control system, is also elaborated here. (author)« less

Research in extreme ultraviolet and far ultraviolet astronomy

NASA Technical Reports Server (NTRS)

Labov, S. E.

1985-01-01

Instruments designed to explore different aspects of far and extreme ultraviolet cosmic radiation were studied. The far ultraviolet imager (FUVI) was flown on the Aries sounding rocket. Its unique large format 75mm detector mapped out the far ultraviolet background radiation with a resolution of only a few arc minutes. Analysis of this data indicates to what extent the FUVI background is extra galactic in origin. A power spectrum of the spatial fluctuations will have direct consequences for galactic evolution.

Sequestering the standard model vacuum energy.

PubMed

Kaloper, Nemanja; Padilla, Antonio

2014-03-07

We propose a very simple reformulation of general relativity, which completely sequesters from gravity all of the vacuum energy from a matter sector, including all loop corrections and renders all contributions from phase transitions automatically small. The idea is to make the dimensional parameters in the matter sector functionals of the 4-volume element of the Universe. For them to be nonzero, the Universe should be finite in spacetime. If this matter is the standard model of particle physics, our mechanism prevents any of its vacuum energy, classical or quantum, from sourcing the curvature of the Universe. The mechanism is consistent with the large hierarchy between the Planck scale, electroweak scale, and curvature scale, and early Universe cosmology, including inflation. Consequences of our proposal are that the vacuum curvature of an old and large universe is not zero, but very small, that w(DE) ≃ -1 is a transient, and that the Universe will collapse in the future.

A sterilization system using ultraviolet photochemical reactions based on nitrous oxide and oxygen gases.

PubMed

Ohnishi, Yasutaka; Matsumoto, Hiroyuki; Iwamori, Satoru

2016-03-01

Active oxygen species (AOS) generated under ultraviolet (UV) lamps can be applied for various industrial processes owing to extremely strong oxidative abilities. We have already reported on an application of the AOS for a sterilization process of microorganisms. Here, a sterilization method using active oxygen generated under ultraviolet (UV) lamps introducing nitrous oxide (N2O) and oxygen gases into a vacuum chamber was investigated. Nitrogen dioxide (NO2) gas was readily produced from N2O by UV photochemical reactions under the low-pressure mercury lamp and then used to sterilize medical devices. We compared the ability of the N2O gas to sterilize Geobacillus stearothermophilus spores with those of conventional methods. Successful sterilization of spores on various biological indicators was achieved within 60 min, not only in sterilization bags but also in a lumen device. Copyright © 2016 Elsevier B.V. All rights reserved.

Vacuum mechatronics

NASA Technical Reports Server (NTRS)

Hackwood, Susan; Belinski, Steven E.; Beni, Gerardo

1989-01-01

The discipline of vacuum mechatronics is defined as the design and development of vacuum-compatible computer-controlled mechanisms for manipulating, sensing and testing in a vacuum environment. The importance of vacuum mechatronics is growing with an increased application of vacuum in space studies and in manufacturing for material processing, medicine, microelectronics, emission studies, lyophylisation, freeze drying and packaging. The quickly developing field of vacuum mechatronics will also be the driving force for the realization of an advanced era of totally enclosed clean manufacturing cells. High technology manufacturing has increasingly demanding requirements for precision manipulation, in situ process monitoring and contamination-free environments. To remove the contamination problems associated with human workers, the tendency in many manufacturing processes is to move towards total automation. This will become a requirement in the near future for e.g., microelectronics manufacturing. Automation in ultra-clean manufacturing environments is evolving into the concept of self-contained and fully enclosed manufacturing. A Self Contained Automated Robotic Factory (SCARF) is being developed as a flexible research facility for totally enclosed manufacturing. The construction and successful operation of a SCARF will provide a novel, flexible, self-contained, clean, vacuum manufacturing environment. SCARF also requires very high reliability and intelligent control. The trends in vacuum mechatronics and some of the key research issues are reviewed.

High-resolution crystal spectrometer for the 10-60 A extreme ultraviolet region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beiersdorfer, P.; Brown, G.V.; Goddard, R.

2004-10-01

A vacuum crystal spectrometer with nominal resolving power approaching 1000 is described for measuring emission lines with wavelength in the extreme ultraviolet region up to 60 A. The instrument utilizes a flat octadecyl hydrogen maleate crystal and a thin-window 1D position-sensitive gas proportional detector. This detector employs a 1-{mu}m-thick 100x8 mm{sup 2} aluminized polyimide window and operates at one atmosphere pressure. The spectrometer has been implemented on the Livermore electron beam ion traps. The performance of the instrument is illustrated in measurements of the newly discovered magnetic field-sensitive line in Ar{sup 8+}.

SCOUT: a small vacuum chamber for nano-wire grid polarizer tests in the ultraviolet band

NASA Astrophysics Data System (ADS)

Landini, F.; Pancrazzi, M.; Totaro, M.; Pennelli, G.; Romoli, M.

2012-01-01

Within the Section of Astronomy of the Department of Physics and Astronomy of the University of Firenze, Italy), the XUVLab laboratory is active since 1998 dedicated to technological development, mainly UV oriented. The technological research is focused both on electronics and optics. Our last approach is dedicated to the development of innovative wiregrid polarizers optimized to work in transmission at 121.6 nm. The manufacturing of such optical devices requires advanced technological expertise and suitable experimental structures. First, nanotechnology capability is necessary, in order to build several tiny parallel conductive lines separated by tens of nanometers on wide areas to be macroscopically exploitable in an optical laboratory. Moreover, the characterization of such an advanced optical device has to be performed in vacuum, being air absorptive at 121.6 nm. A dedicated small vacuum chamber, SCOUT (Small Chamber for Optical UV Tests) was developed within our laboratory in order to perform practical and fast measurements. SCOUT hosts an optical bench and is equipped with several opening flanges, in order to be as flexible as possible. The flexibility that has been reached with SCOUT allows us to use the chamber beyond the goals it was thought for. It is exploitable by whatever compact (within 1 m) optical experiment that investigates the UV band of the spectrum.

Kr photoionized plasma induced by intense extreme ultraviolet pulses

NASA Astrophysics Data System (ADS)

Bartnik, A.; Wachulak, P.; Fiedorowicz, H.; Skrzeczanowski, W.

2016-04-01

Irradiation of any gas with an intense EUV (extreme ultraviolet) radiation beam can result in creation of photoionized plasmas. The parameters of such plasmas can be significantly different when compared with those of the laser produced plasmas (LPP) or discharge plasmas. In this work, the photoionized plasmas were created in a krypton gas irradiated using an LPP EUV source operating at a 10 Hz repetition rate. The Kr gas was injected into the vacuum chamber synchronously with the EUV radiation pulses. The EUV beam was focused onto a Kr gas stream using an axisymmetrical ellipsoidal collector. The resulting low temperature Kr plasmas emitted electromagnetic radiation in the wide spectral range. The emission spectra were measured either in the EUV or an optical range. The EUV spectrum was dominated by emission lines originating from Kr III and Kr IV ions, and the UV/VIS spectra were composed from Kr II and Kr I lines. The spectral lines recorded in EUV, UV, and VIS ranges were used for the construction of Boltzmann plots to be used for the estimation of the electron temperature. It was shown that for the lowest Kr III and Kr IV levels, the local thermodynamic equilibrium (LTE) conditions were not fulfilled. The electron temperature was thus estimated based on Kr II and Kr I species where the partial LTE conditions could be expected.

Kr photoionized plasma induced by intense extreme ultraviolet pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartnik, A., E-mail: andrzej.bartnik@wat.edu.pl; Wachulak, P.; Fiedorowicz, H.

Irradiation of any gas with an intense EUV (extreme ultraviolet) radiation beam can result in creation of photoionized plasmas. The parameters of such plasmas can be significantly different when compared with those of the laser produced plasmas (LPP) or discharge plasmas. In this work, the photoionized plasmas were created in a krypton gas irradiated using an LPP EUV source operating at a 10 Hz repetition rate. The Kr gas was injected into the vacuum chamber synchronously with the EUV radiation pulses. The EUV beam was focused onto a Kr gas stream using an axisymmetrical ellipsoidal collector. The resulting low temperature Krmore » plasmas emitted electromagnetic radiation in the wide spectral range. The emission spectra were measured either in the EUV or an optical range. The EUV spectrum was dominated by emission lines originating from Kr III and Kr IV ions, and the UV/VIS spectra were composed from Kr II and Kr I lines. The spectral lines recorded in EUV, UV, and VIS ranges were used for the construction of Boltzmann plots to be used for the estimation of the electron temperature. It was shown that for the lowest Kr III and Kr IV levels, the local thermodynamic equilibrium (LTE) conditions were not fulfilled. The electron temperature was thus estimated based on Kr II and Kr I species where the partial LTE conditions could be expected.« less

Natural vacuum electronics

NASA Technical Reports Server (NTRS)

Leggett, Nickolaus

1990-01-01

The ambient natural vacuum of space is proposed as a basis for electron valves. Each valve is an electron controlling structure similiar to a vacuum tube that is operated without a vacuum sustaining envelope. The natural vacuum electron valves discussed offer a viable substitute for solid state devices. The natural vacuum valve is highly resistant to ionizing radiation, system generated electromagnetic pulse, current transients, and direct exposure to space conditions.

In-vacuum exposure shutter

DOEpatents

Johnson, Terry A.; Replogle, William C.; Bernardez, Luis J.

2004-06-01

An in-vacuum radiation exposure shutter device can be employed to regulate a large footprint light beam. The shutter device includes (a) a source of radiation that generates an energy beam; (2) a shutter that includes (i) a frame defining an aperture toward which the energy beam is directed and (ii) a plurality of blades that are secured to the frame; and (3) device that rotates the shutter to cause the plurality of blades to intercept or allow the energy beam to travel through the aperture. Each blade can have a substantially planar surface and the plurality of blades are secured to the frame such that the planar surfaces of the plurality of blades are substantially parallel to each other. The shutter device is particularly suited for operation in a vacuum environment and can achieve shuttering speeds from about 0.1 second to 0.001 second or faster.

Vacuum ultraviolet laser

DOEpatents

Berkowitz, Joseph; Ruscic, Branko M.; Greene, John P.

1986-01-01

Transitions from the 2p.sup.4 (.sup.1 S.sub.0)3s .sup.2 S.sub.1/2 state of atomic fluorine to all allowed lower states produces laser emission at six new wavelengths: 680.7 .ANG., 682.6 .ANG., 3592.7 .ANG., 3574.1 .ANG., 6089.2 .ANG., and 6046.8 .ANG.. Coherent radiation at these new wavelengths can be generated in an atomic fluorine laser operated as an amplifier or as an oscillator.

Remote vacuum compaction of compressible hazardous waste

DOEpatents

Coyne, M.J.; Fiscus, G.M.; Sammel, A.G.

1998-10-06

A system is described for remote vacuum compaction and containment of low-level radioactive or hazardous waste comprising a vacuum source, a sealable first flexible container, and a sealable outer flexible container for receiving one or more first flexible containers. A method for compacting low level radioactive or hazardous waste materials at the point of generation comprising the steps of sealing the waste in a first flexible container, sealing one or more first containers within an outer flexible container, breaching the integrity of the first containers, evacuating the air from the inner and outer containers, and sealing the outer container shut. 8 figs.

Remote vacuum compaction of compressible hazardous waste

DOEpatents

Coyne, Martin J.; Fiscus, Gregory M.; Sammel, Alfred G.

1998-01-01

A system for remote vacuum compaction and containment of low-level radioactive or hazardous waste comprising a vacuum source, a sealable first flexible container, and a sealable outer flexible container for receiving one or more first flexible containers. A method for compacting low level radioactive or hazardous waste materials at the point of generation comprising the steps of sealing the waste in a first flexible container, sealing one or more first containers within an outer flexible container, breaching the integrity of the first containers, evacuating the air from the inner and outer containers, and sealing the outer container shut.

Remote vacuum compaction of compressible hazardous waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coyne, M.J.; Fiscus, G.M.; Sammel, A.G.

1996-12-31

A system is described for remote vacuum compaction and containment of low-level radioactive or hazardous waste comprising a vacuum source, a sealable first flexible container, and a sealable outer flexible container for receiving one or more first flexible containers. A method for compacting low level radioactive or hazardous waste materials at the point of generation comprising the steps of sealing the waste in a first flexible container, sealing one or more first containers within an outer flexible container, breaching the integrity of the first containers, evacuating the air from the inner and outer containers, and sealing the outer container shut.

In situ focus characterization by ablation technique to enable optics alignment at an XUV FEL source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerasimova, N.; Dziarzhytski, S.; Weigelt, H.

2013-06-15

In situ focus characterization is demonstrated by working at an extreme ultraviolet (XUV) free-electron laser source using ablation technique. Design of the instrument reported here allows reaching a few micrometres resolution along with keeping the ultrahigh vacuum conditions and ensures high-contrast visibility of ablative imprints on optically transparent samples, e.g., PMMA. This enables on-line monitoring of the beam profile changes and thus makes possible in situ alignment of the XUV focusing optics. A good agreement between focal characterizations retrieved from in situ inspection of ablative imprints contours and from well-established accurate ex situ analysis with Nomarski microscope has been observedmore » for a typical micro-focus experiment.« less

VACUUM TRAP

DOEpatents

Gordon, H.S.

1959-09-15

An improved adsorption vacuum trap for use in vacuum systems was designed. The distinguishing feature is the placement of a plurality of torsionally deformed metallic fins within a vacuum jacket extending from the walls to the central axis so that substantially all gas molecules pass through the jacket will impinge upon the fin surfaces. T fins are heated by direct metallic conduction, thereby ol taining a uniform temperature at the adeorbing surfaces so that essentially all of the condensible impurities from the evacuating gas are removed from the vacuum system.

Vacuum stress energy density and its gravitational implications

NASA Astrophysics Data System (ADS)

Estrada, Ricardo; Fulling, Stephen A.; Kaplan, Lev; Kirsten, Klaus; Liu, Zhonghai; Milton, Kimball A.

2008-04-01

In nongravitational physics the local density of energy is often regarded as merely a bookkeeping device; only total energy has an experimental meaning—and it is only modulo a constant term. But in general relativity the local stress-energy tensor is the source term in Einstein's equation. In closed universes, and those with Kaluza-Klein dimensions, theoretical consistency demands that quantum vacuum energy should exist and have gravitational effects, although there are no boundary materials giving rise to that energy by van der Waals interactions. In the lab there are boundaries, and in general the energy density has a nonintegrable singularity as a boundary is approached (for idealized boundary conditions). As pointed out long ago by Candelas and Deutsch, in this situation there is doubt about the viability of the semiclassical Einstein equation. Our goal is to show that the divergences in the linearized Einstein equation can be renormalized to yield a plausible approximation to the finite theory that presumably exists for realistic boundary conditions. For a scalar field with Dirichlet or Neumann boundary conditions inside a rectangular parallelepiped, we have calculated by the method of images all components of the stress tensor, for all values of the conformal coupling parameter and an exponential ultraviolet cutoff parameter. The qualitative features of contributions from various classes of closed classical paths are noted. Then the Estrada-Kanwal distributional theory of asymptotics, particularly the moment expansion, is used to show that the linearized Einstein equation with the stress-energy near a plane boundary as source converges to a consistent theory when the cutoff is removed. This paper reports work in progress on a project combining researchers in Texas, Louisiana and Oklahoma. It is supported by NSF Grants PHY-0554849 and PHY-0554926.

The results of the study of compact gas-puff and vacuum spark plasma sources of SXR with Glass-Capillary Converters (GCC)

NASA Astrophysics Data System (ADS)

Shlyaptseva, Alla; Kantsyrev, Victor; Inozemtsev, Andrei; Petrukhin, Oleg

1994-06-01

The results are presented dealing with the working out and study of the SXR compact plasma source. The experimental set up included a compact new 'gas-puff' source with parameters being better than the traditional ones and a new type of SXR source - low-inductance vacuum spark (LIVS) with glass-capillary converters (GCC) of SXR. The compact plasma 'gas-puff' source had the high value of the z approx. (1-2) 10(exp -2) (conversion coefficient of initial energy supply into SXR); a small effective size of emission region and greater resource. The characteristics of LIVS with GCC were studied. GCC consisting of about several hundreds of glass capillaries allowed us to focus SXR, to change the cross section of SXR beams to plasma sources, and to change SXR spectrum. The possibility was shown of using of GCC in plasma diagnostics of powerful plasma devices: for X-ray microscopy and to study the influence of SXR on the solid state surface.

The Far Ultra-Violet Imager on the Icon Mission

NASA Astrophysics Data System (ADS)

Mende, S. B.; Frey, H. U.; Rider, K.; Chou, C.; Harris, S. E.; Siegmund, O. H. W.; England, S. L.; Wilkins, C.; Craig, W.; Immel, T. J.; Turin, P.; Darling, N.; Loicq, J.; Blain, P.; Syrstad, E.; Thompson, B.; Burt, R.; Champagne, J.; Sevilla, P.; Ellis, S.

2017-10-01

ICON Far UltraViolet (FUV) imager contributes to the ICON science objectives by providing remote sensing measurements of the daytime and nighttime atmosphere/ionosphere. During sunlit atmospheric conditions, ICON FUV images the limb altitude profile in the shortwave (SW) band at 135.6 nm and the longwave (LW) band at 157 nm perpendicular to the satellite motion to retrieve the atmospheric O/N2 ratio. In conditions of atmospheric darkness, ICON FUV measures the 135.6 nm recombination emission of O+ ions used to compute the nighttime ionospheric altitude distribution. ICON Far UltraViolet (FUV) imager is a Czerny-Turner design Spectrographic Imager with two exit slits and corresponding back imager cameras that produce two independent images in separate wavelength bands on two detectors. All observations will be processed as limb altitude profiles. In addition, the ionospheric 135.6 nm data will be processed as longitude and latitude spatial maps to obtain images of ion distributions around regions of equatorial spread F. The ICON FUV optic axis is pointed 20 degrees below local horizontal and has a steering mirror that allows the field of view to be steered up to 30 degrees forward and aft, to keep the local magnetic meridian in the field of view. The detectors are micro channel plate (MCP) intensified FUV tubes with the phosphor fiber-optically coupled to Charge Coupled Devices (CCDs). The dual stack MCP-s amplify the photoelectron signals to overcome the CCD noise and the rapidly scanned frames are co-added to digitally create 12-second integrated images. Digital on-board signal processing is used to compensate for geometric distortion and satellite motion and to achieve data compression. The instrument was originally aligned in visible light by using a special grating and visible cameras. Final alignment, functional and environmental testing and calibration were performed in a large vacuum chamber with a UV source. The test and calibration program showed that ICON

Vacuum Ultraviolet Photodissociation and Fourier Transform-Ion Cyclotron Resonance (FT-ICR) Mass Spectrometry: Revisited.

PubMed

Shaw, Jared B; Robinson, Errol W; Paša-Tolić, Ljiljana

2016-03-15

We revisited the implementation of 193 nm ultraviolet photodissociation (UVPD) within the ion cyclotron resonance (ICR) cell of a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer. UVPD performance characteristics were examined in the context of recent developments in the understanding of UVPD and in-cell tandem mass spectrometry. Efficient UVPD and photo-ECD of a model peptide and proteins within the ICR cell of a FT-ICR mass spectrometer are accomplished through appropriate modulation of laser pulse timing, relative to ion magnetron motion and the potential applied to an ion optical element upon which photons impinge. It is shown that UVPD yields efficient and extensive fragmentation, resulting in excellent sequence coverage for model peptide and protein cations.

Transmission geometry laserspray ionization vacuum using an atmospheric pressure inlet.

PubMed

Lutomski, Corinne A; El-Baba, Tarick J; Inutan, Ellen D; Manly, Cory D; Wager-Miller, James; Mackie, Ken; Trimpin, Sarah

2014-07-01

This represents the first report of laserspray ionization vacuum (LSIV) with operation directly from atmospheric pressure for use in mass spectrometry. Two different types of electrospray ionization source inlets were converted to LSIV sources by equipping the entrance of the atmospheric pressure inlet aperture with a customized cone that is sealed with a removable glass plate holding the matrix/analyte sample. A laser aligned in transmission geometry (at 180° relative to the inlet) ablates the matrix/analyte sample deposited on the vacuum side of the glass slide. Laser ablation from vacuum requires lower inlet temperature relative to laser ablation at atmospheric pressure. However, higher inlet temperature is required for high-mass analytes, for example, α-chymotrypsinogen (25.6 kDa). Labile compounds such as gangliosides and cardiolipins are detected in the negative ion mode directly from mouse brain tissue as intact doubly deprotonated ions. Multiple charging enhances the ion mobility spectrometry separation of ions derived from complex tissue samples.

Transmission Geometry Laserspray Ionization Vacuum Using an Atmospheric Pressure Inlet

PubMed Central

2015-01-01

This represents the first report of laserspray ionization vacuum (LSIV) with operation directly from atmospheric pressure for use in mass spectrometry. Two different types of electrospray ionization source inlets were converted to LSIV sources by equipping the entrance of the atmospheric pressure inlet aperture with a customized cone that is sealed with a removable glass plate holding the matrix/analyte sample. A laser aligned in transmission geometry (at 180° relative to the inlet) ablates the matrix/analyte sample deposited on the vacuum side of the glass slide. Laser ablation from vacuum requires lower inlet temperature relative to laser ablation at atmospheric pressure. However, higher inlet temperature is required for high-mass analytes, for example, α-chymotrypsinogen (25.6 kDa). Labile compounds such as gangliosides and cardiolipins are detected in the negative ion mode directly from mouse brain tissue as intact doubly deprotonated ions. Multiple charging enhances the ion mobility spectrometry separation of ions derived from complex tissue samples. PMID:24896880

Far-Ultraviolet Observations of Outflows from Infrared-Luminous Galaxies

NASA Astrophysics Data System (ADS)

Leitherer, Claus; Chandar, Rupali; Tremonti, Christy A.; Wofford, Aida

2013-03-01

We have obtained ultraviolet spectra between 1150 and 1450 Å of four ultraviolet-bright, infrared-luminous starburst galaxies. Our selected sight-lines towards the starburst nuclei probe the conditions in the starburst-driven outflows. We detect outflowing gas with velocities of up to ˜900 km s-1. It is likely that the outflows are a major source of metal enrichment of the galaxies' halos. The mass outflow rates of several tens of M⊙ yr-1 are similar to the star-formation rates. The outflows may quench star formation and ultimately regulate the starburst.

A Miniaturized Linear Wire Ion Trap with Electron Ionization and Single Photon Ionization Sources

NASA Astrophysics Data System (ADS)

Wu, Qinghao; Tian, Yuan; Li, Ailin; Andrews, Derek; Hawkins, Aaron R.; Austin, Daniel E.

2017-05-01

A linear wire ion trap (LWIT) with both electron ionization (EI) and single photon ionization (SPI) sources was built. The SPI was provided by a vacuum ultraviolet (VUV) lamp with the ability to softly ionize organic compounds. The VUV lamp was driven by a pulse amplifier, which was controlled by a pulse generator, to avoid the detection of photons during ion detection. Sample gas was introduced through a leak valve, and the pressure in the system is shown to affect the signal-to-noise ratio and resolving power. Under optimized conditions, the limit of detection (LOD) for benzene was 80 ppbv using SPI, better than the LOD using EI (137 ppbv). System performance was demonstrated by distinguishing compounds in different classes from gasoline.

Polybrominated diphenyl ethers (PBDEs) in U.S. computers and domestic carpet vacuuming: possible sources of human exposure.

PubMed

Schecter, Arnold; Päpke, Olaf; Joseph, Jean Elizabeth; Tung, Kuang-Chi

2005-04-09

Polybrominated diphenyl ethers (PBDEs), a type of brominated flame retardant chemically and toxicologically similar to polychlorinated biphenyls (PCBs), are a class of emerging environmental and human contaminants. They have recently been detected in U.S. milk, blood, and food at the highest levels in the world. This pilot study was undertaken with the aim of determining levels of PBDE in the U.S. indoor environment, to assess the potential exposure to PBDEs from computer surfaces and carpets. Food of animal origin is the usual source of polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofurans (PCDF), and PCBs in humans, but there may also be environmental sources for intake of PBDEs. It was also our aim to characterize the PBDE congener profile in these indoor environmental samples. Four computer wipe samples and 9 domestic vacuum-sweeping samples were analyzed for 13 PBDE congeners, PBDEs 17 (2,2',4), 28 (2,4,4'?), 47 (2,2',4,4'?), 66 (2,3',4,4'?), 77 (3,3',4,4'?), 85 (2,2',3,4,4'?), 99 (2,2'4,4',5), 100 (2,2',4,4',6), 138 (2,2',3,4,4',5'?), 153 (2,2',4,4',5,5'?), 154 (2,2',4,4',5,6'?), 183 (2,2',3,4,4',5',6), and 209 (2,2',3,3',4,4',5,5',6,6'?). All samples tested positive for PBDEs. PBDE 209 was the dominant congener in all 4 computer wipe samples and in 7 out of the 9 vacuum dust samples. The congener profiles observed in this study varied considerably, a finding that has been observed previously. However these congener profiles differ from the pattern seen in U.S. human milk, human blood and in food, where PBDEs 47 and 99 predominate.

Ultraviolet spectrometer experiment for the Voyager mission

NASA Technical Reports Server (NTRS)

Broadfoot, A. L.; Sandel, B. R.; Shemansky, D. E.; Atreya, S. K.; Donahue, T. M.; Moos, H. W.; Bertaux, J. L.; Blamont, J. E.; Ajello, J. M.; Strobel, D. F.

1977-01-01

An objective grating spectrometer covering the wavelength range of 500 to 1700 A with a 10-A resolution is employed for the Voyager ultraviolet spectrometer experiment. In determining the composition and structure of the atmospheres of Saturn, Jupiter and several satellites, the ultraviolet spectrometer will rely on airglow mode observations to measure radiation from the atmospheres due to resonant scattering of solar flux, and the occultation mode for assessments of the atmospheric extinction of solar or stellar radiation as the spacecraft enters shadow zones. Since it is capable of prolonged stellar observations in the 500 to 1000 A wavelength range, the spectrometer is expected to make important contributions to exploratory studies of UV sources.

Venturi vacuum systems for hypobaric chamber operations.

PubMed

Robinson, R; Swaby, G; Sutton, T; Fife, C; Powell, M; Butler, B D

1997-11-01

Physiological studies of the effects of high altitude on man often require the use of a hypobaric chamber to simulate the reduced ambient pressures. Typical "altitude" chambers in use today require complex mechanical vacuum systems to evacuate the chamber air, either directly or via reservoir system. Use of these pumps adds to the cost of both chamber procurement and maintenance, and service of these pumps requires trained support personnel and regular upkeep. In this report we describe use of venturi vacuum pumps to perform the function of mechanical vacuum pumps for human and experimental altitude chamber operations. Advantages of the venturi pumps include their relatively low procurement cost, small size and light weight, ease of installation and plumbing, lack of moving parts, and independence from electrical power sources, fossil fuels and lubricants. Conversion of three hyperbaric chambers to combined hyper/hypobaric use is described.

Degradation and Its Control of Ultraviolet Avalanche Photodiodes Using PEDOT:PSS/ZnSSe Organic-Inorganic Hybrid Structure

NASA Astrophysics Data System (ADS)

Abe, Tomoki; Uchida, Shigeto; Tanaka, Keita; Fujisawa, Takanobu; Kasada, Hirofumi; Ando, Koshi; Akaiwa, Kazuaki; Ichino, Kunio

2018-05-01

We investigated device degradation in PEDOT:PSS/ZnSSe organic-inorganic hybrid ultraviolet avalanche photodiodes (UV-APDs). ZnSSe/n-GaAs wafers were grown by molecular beam epitaxy, and PEDOT:PSS window layers were formed by inkjet technique. We observed rapid degradation with APD-mode stress (˜ 30 V) in the N2 (4 N) atmosphere, while we observed no marked change in forward bias current stress and photocurrent stress. In the case of a vacuum condition, we observed no detectable degradation in the dark avalanche current with APD-mode stress. Therefore, the degradation in the PEDOT:PSS/ZnSSe interface under the APD-mode stress was caused by the residual water vapor or oxygen in the N2 atmosphere and could be controlled by vacuum packaging.

New measurements on water ice photodesorption and product formation under ultraviolet irradiation

NASA Astrophysics Data System (ADS)

Cruz-Diaz, Gustavo A.; Martín-Doménech, Rafael; Moreno, Elena; Muñoz Caro, Guillermo M.; Chen, Yu-Jung

2018-03-01

The photodesorption of icy grain mantles has been claimed to be responsible for the abundance of gas-phase molecules towards cold regions. Being water a ubiquitous molecule, it is crucial to understand its role in photochemistry and its behaviour under an ultraviolet field. We report new measurements on the ultraviolet (UV) photodesorption of water ice and its H2, OH, and O2 photoproducts using a calibrated quadrupole mass spectrometer. Solid water was deposited under ultra-high-vacuum conditions and then UV-irradiated at various temperatures starting from 8 K with a microwave discharged hydrogen lamp. Deuterated water was used for confirmation of the results. We found a photodesorption yield of 1.3 × 10-3 molecules per incident photon for water and 0.7 × 10-3 molecules per incident photon for deuterated water at the lowest irradiation temperature, 8 K. The photodesorption yield per absorbed photon is given and comparison with astrophysical scenarios, where water ice photodesorption could account for the presence of gas-phase water towards cold regions in the absence of a thermal desorption process, is addressed.

Calibration techniques and results in the soft X-ray and extreme ultraviolet for components of the Extreme Ultraviolet Explorer Satellite

NASA Technical Reports Server (NTRS)

Malina, Roger F.; Jelinsky, Patrick; Bowyer, Stuart

1986-01-01

The calibration facilities and techniques for the Extreme Ultraviolet Explorer (EUVE) from 44 to 2500 A are described. Key elements include newly designed radiation sources and a collimated monochromatic EUV beam. Sample results for the calibration of the EUVE filters, detectors, gratings, collimators, and optics are summarized.

Integrated ultraviolet and tunable mid-infrared laser source for analyses of proteins

NASA Astrophysics Data System (ADS)

Hazama, Hisanao; Takatani, Yoshiaki; Awazu, Kunio

2007-02-01

Mass spectrometry using matrix-assisted laser desorption/ionization (MALDI) technique is one of the most widely used method to analyze proteins in biological research fields. However, it is difficult to analyze insoluble proteins which have important roles in researches on disease mechanisms or in developments of drugs by using ultraviolet (UV) lasers which have commonly been used for MALDI. Recently, a significant improvement in MALDI process of insoluble proteins using a combination of a UV nitrogen laser and a tunable mid-infrared (MIR) free electron laser (FEL) was reported. Since the FEL is a very large and expensive equipment, we have developed a tabletop laser source which can generate both UV and tunable MIR lasers. A tunable MIR laser (5.5-10 μm) was obtained by difference frequency generation (DFG) between a Nd:YAG and a tunable Cr:forsterite lasers using two AgGaS II crystals. The MIR laser can generate pulses with an energy of up to 1.4 mJ at a repetition rate of 10 Hz. A UV laser was obtained by third harmonic generation of a Nd:YAG laser splitted from that used for DFG. A time interval between the UV and the MIR laser pulses can be adjusted with a variable optical delay.

Comparison of vacuum and non-vacuum urine tubes for urinary sediment analysis.

PubMed

Topcuoglu, Canan; Sezer, Sevilay; Kosem, Arzu; Ercan, Mujgan; Turhan, Turan

2017-12-01

Urine collection systems with aspiration system for vacuum tubes are becoming increasingly common for urinalysis, especially for microscopic examination of the urine. In this study, we aimed to examine whether vacuum aspiration of the urine sample has any adverse effect on sediment analysis by comparing results from vacuum and non-vacuum urine tubes. The study included totally 213 urine samples obtained from inpatients and outpatients in our hospital. Urine samples were collected to containers with aspiration system for vacuum tubes. Each sample was aliquoted to both vacuum and non-vacuum urine tubes. Urinary sediment analysis was performed using manual microscope. Results were evaluated using chi-square test. Comparison of the sediment analysis results from vacuum and non-vacuum urine tubes showed that results were highly concordant for erythrocyte, leukocyte and epithelial cells (gamma values 1, 0.997, and 0.994, respectively; p < .001). Results were also concordant for urinary casts, crystals and yeast (kappa values 0.815, 0.945 and 1, respectively; p < .001). The results show that in urinary sediment analysis, vacuum aspiration has no adverse effect on the cellular components except on casts.

Psoralen-ultraviolet A treatment with Psoralen-ultraviolet B therapy in the treatment of psoriasis.

PubMed

Ahmed Asim, Sadaf; Ahmed, Sitwat; Us-Sehar, Najam

2013-05-01

To compare the conventional psoralen-ultraviolet A treatment with psoralen-ultraviolet B therapy in the treatment of psoriasis. We studied 50 patients of plaque type psoriasis who were selected to receive either conventional psoralen-ultraviolet A or psoralen-ultraviolet B treatment. There was no significant difference between the two treatment groups in the number of patients whose skin cleared of psoriasis or the number of exposures required for clearance. Profile of side effects and disease status was also similar after three months of follow up. Psoralen-ultraviolet B treatment is as effective as conventional psoralen-ultraviolet A in the treatment of psoriasis. Further long term studies are needed to assess the safety of psoralen-ultraviolet B.

Far-ultraviolet stellar photometry: A field in Orion

NASA Astrophysics Data System (ADS)

Schmidt, Edward G.; Carruthers, George R.

1993-12-01

Far-ultraviolet photometry for 625 objects in Orion is presented. These data were extracted from electrographic camera images obtained during sounding rocket flights in 1975 and 1982. The 1975 images were centered close to the belt of Orion while the 1982 images were centered approximately 9 deg further north. One hundred and fifty stars fell in the overlapping region and were observed with both cameras. Sixty-eight percent of the objects were tentatively identified with known stars using the SIMBAD database while another 24% are blends of objects too close together to separate with our resolution. As in previous studies, the majority of the identified ultraviolet sources are early-type stars. However, there are a significant number for which no such identification was possible, and we suggest that these are interesting objects which should be further investigated. Seven stars were found which were bright in the ultraviolet but faint in the visible. We suggest that some of these are nearby white dwarfs.

Nakedly singular non-vacuum gravitating equilibrium states

NASA Astrophysics Data System (ADS)

Woszczyna, Andrzej; Kutschera, Marek; Kubis, Sebastian; Czaja, Wojciech; Plaszczyk, Piotr; Golda, Zdzisław A.

2016-01-01

Non-vacuum static spherically symmetric spacetimes with central point-like repulsive gravity sources are investigated. Both the symmetries of spacetime and the degree of irregularity of curvature invariants, are the same as for the Schwarzschild case. The equilibrium configurations are modelled using the neutron star polytrope equation of state.

Electronic excitation of carbonyl sulphide (COS) by high-resolution vacuum ultraviolet photoabsorption and electron-impact spectroscopy in the energy region from 4 to 11 eV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Limão-Vieira, P., E-mail: plimaovieira@fct.unl.pt; Department of Physics, Sophia University, Tokyo 102-8554; Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA

2015-02-14

The electronic state spectroscopy of carbonyl sulphide, COS, has been investigated using high resolution vacuum ultraviolet photoabsorption spectroscopy and electron energy loss spectroscopy in the energy range of 4.0–10.8 eV. The spectrum reveals several new features not previously reported in the literature. Vibronic structure has been observed, notably in the low energy absorption dipole forbidden band assigned to the (4π←3π) ({sup 1}Δ←{sup 1}Σ{sup +}) transition, with a new weak transition assigned to ({sup 1}Σ{sup −}←{sup 1}Σ{sup +}) reported here for the first time. The absolute optical oscillator strengths are determined for ground state to {sup 1}Σ{sup +} and {sup 1}Πmore » transitions. Based on our recent measurements of differential cross sections for the optically allowed ({sup 1}Σ{sup +} and {sup 1}Π) transitions of COS by electron impact, the optical oscillator strength f{sub 0} value and integral cross sections (ICSs) are derived by applying a generalized oscillator strength analysis. Subsequently, ICSs predicted by the scaling are confirmed down to 60 eV in the intermediate energy region. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of carbonyl sulphide in the upper stratosphere (20–50 km)« less

Method for the protection of extreme ultraviolet lithography optics

DOEpatents

Grunow, Philip A.; Clift, Wayne M.; Klebanoff, Leonard E.

2010-06-22

A coating for the protection of optical surfaces exposed to a high energy erosive plasma. A gas that can be decomposed by the high energy plasma, such as the xenon plasma used for extreme ultraviolet lithography (EUVL), is injected into the EUVL machine. The decomposition products coat the optical surfaces with a protective coating maintained at less than about 100 .ANG. thick by periodic injections of the gas. Gases that can be used include hydrocarbon gases, particularly methane, PH.sub.3 and H.sub.2S. The use of PH.sub.3 and H.sub.2S is particularly advantageous since films of the plasma-induced decomposition products S and P cannot grow to greater than 10 .ANG. thick in a vacuum atmosphere such as found in an EUVL machine.

Psoralen-ultraviolet A treatment with Psoralen-ultraviolet B therapy in the treatment of psoriasis

PubMed Central

Ahmed Asim, Sadaf; Ahmed, Sitwat; us-Sehar, Najam

2013-01-01

Objective: To compare the conventional psoralen-ultraviolet A treatment with psoralen-ultraviolet B therapy in the treatment of psoriasis. Methodology: We studied 50 patients of plaque type psoriasis who were selected to receive either conventional psoralen-ultraviolet A or psoralen-ultraviolet B treatment. Results: There was no significant difference between the two treatment groups in the number of patients whose skin cleared of psoriasis or the number of exposures required for clearance. Profile of side effects and disease status was also similar after three months of follow up. Conclusion: Psoralen-ultraviolet B treatment is as effective as conventional psoralen-ultraviolet A in the treatment of psoriasis. Further long term studies are needed to assess the safety of psoralen-ultraviolet B. PMID:24353623

Diphotons, new vacuum angles, and strong CP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Draper, Patrick; McKeen, David

The Standard Model contains a well-understood, natural, spin-0 diphoton resonance: the π 0. Numerous studies have pointed out that the hint of a new diphoton resonance at 750 GeV could be a pion analog, identified with the pseudo-Nambu-Goldstone boson of a chiral symmetry spontaneously broken by new strong dynamics at the TeV scale. These “hypercolor” models are generically expected to violate parity through a topological angle θ ~. We discuss the physics of θ ~ and its impact on the phenomenology of the new sector. We also describe some of the theoretical implications of a nonzero θ ~. In particular,more » θ ~ can generate an O(1) threshold correction to the QCD vacuum angle θ near the TeV scale, sharply constraining ultraviolet solutions to the strong CP problem. Furthermore, finding that θ ~ is small may be interpreted as evidence in favor of UV solutions to strong CP, particularly those based on spontaneously broken P or CP symmetries.« less

Diphotons, new vacuum angles, and strong CP

DOE PAGES

Draper, Patrick; McKeen, David

2016-04-20

The Standard Model contains a well-understood, natural, spin-0 diphoton resonance: the π 0. Numerous studies have pointed out that the hint of a new diphoton resonance at 750 GeV could be a pion analog, identified with the pseudo-Nambu-Goldstone boson of a chiral symmetry spontaneously broken by new strong dynamics at the TeV scale. These “hypercolor” models are generically expected to violate parity through a topological angle θ ~. We discuss the physics of θ ~ and its impact on the phenomenology of the new sector. We also describe some of the theoretical implications of a nonzero θ ~. In particular,more » θ ~ can generate an O(1) threshold correction to the QCD vacuum angle θ near the TeV scale, sharply constraining ultraviolet solutions to the strong CP problem. Furthermore, finding that θ ~ is small may be interpreted as evidence in favor of UV solutions to strong CP, particularly those based on spontaneously broken P or CP symmetries.« less

Reactor for simulation and acceleration of solar ultraviolet damage

NASA Technical Reports Server (NTRS)

Laue, E.; Gupta, A.

1979-01-01

An environmental test chamber providing acceleration of UV radiation and precise temperature control (+ or -)1 C was designed, constructed and tested. This chamber allows acceleration of solar ultraviolet up to 30 suns while maintaining temperature of the absorbing surface at 30 C - 60 C. This test chamber utilizes a filtered medium pressure mercury arc as the source of radiation, and a combination of selenium radiometer and silicon radiometer to monitor solar ultraviolet (295-340 nm) and total radiant power output, respectively. Details of design and construction and operational procedures are presented along with typical test data.

49 CFR 570.56 - Vacuum brake assist unit and vacuum brake system.

Code of Federal Regulations, 2010 CFR

2010-10-01

.... The following requirements apply to vehicles with vacuum brake assist units and vacuum brake systems. (a) Vacuum brake assist unit integrity. The vacuum brake assist unit shall demonstrate integrity as... maintained on the pedal. (1) Inspection procedure. Stop the engine and apply service brake several times to...

Vacuum system of the compact Energy Recovery Linac

DOE Office of Scientific and Technical Information (OSTI.GOV)

Honda, T., E-mail: tohru.honda@kek.jp; Tanimoto, Y.; Nogami, T.

2016-07-27

The compact Energy Recovery Linac (cERL), a test accelerator to establish important technologies demanded for future ERL-based light sources, was constructed in late 2013 at KEK. The accelerator was successfully commissioned in early 2014, and demonstrated beam circulation with energy recovery. In the cERL vacuum system, low-impedance vacuum components are required to circulate high-intensity, low-emittance and short-bunch electron beams. We therefore developed ultra-high-vacuum (UHV)-compatible flanges that can connect beam tubes seamlessly, and employed retractable beam monitors, namely, a movable Faraday cup and screen monitors. In most parts of the accelerator, pressures below 1×10{sup −7} Pa are required to mitigate beam-gasmore » interactions. Particularly, near the photocathode electron gun and the superconducting (SC) cavities, pressures below 1×10{sup −8} Pa are required. The beam tubes in the sections adjoining the SC cavities were coated with non-evaporable getter (NEG) materials, to reduce gas condensation on the cryo-surfaces. During the accelerator commissioning, stray magnetic fields from the permanent magnets of some cold cathode gauges (CCGs) were identified as a source of the disturbance to the beam orbit. Magnetic shielding was specially designed as a remedy for this issue.« less

Demonstrations with a Vacuum: Old Demonstrations for New Vacuum Pumps.

ERIC Educational Resources Information Center

Greenslade, Thomas B., Jr.

1989-01-01

Explains mechanisms of 19th-century vacuum pumps. Describes demonstrations using the pump including guinea and feather tube, aurora tube, electric egg, Gassiots cascade, air mill, bell in vacuum, density and buoyancy of air, fountain in vacuum, mercury shower, palm and bladder glasses, Bacchus demonstration, pneumatic man-lifter, and Magdeburg…

Refurbishment of a used in-vacuum undulator from the National Synchrotron Light Source for the National Synchrotron Light Source-II ring

DOE PAGES

Tanabe, Toshiya; Bassan, Harmanpreet; Broadbent, Andrew; ...

2017-08-01

The National Synchrotron Light Source (NSLS) ceased operation in September 2014 and was succeeded by NSLS-II. There were four in-vacuum undulators (IVUs) in operation at NSLS. The most recently constructed IVU for NSLS was the mini-gap undulator (MGU-X25, to be renamed IVU18 for NSLS-II), which was constructed in 2006. This device was selected to be reused for the New York Structural Biology Consortium Microdiffraction beamline at NSLS-II. At the time of construction, IVU18 was a state-of-the-art undulator designed to be operated as a cryogenic permanent-magnet undulator. Due to the more stringent field quality and impedance requirements of the NSLS-II ring,more » the transition region was redesigned. The control system was also updated to NSLS-II specifications. As a result, this paper reports the details of the IVU18 refurbishment activities including additional magnetic measurement and tuning.« less

Refurbishment of a used in-vacuum undulator from the National Synchrotron Light Source for the National Synchrotron Light Source-II ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanabe, Toshiya; Bassan, Harmanpreet; Broadbent, Andrew

The National Synchrotron Light Source (NSLS) ceased operation in September 2014 and was succeeded by NSLS-II. There were four in-vacuum undulators (IVUs) in operation at NSLS. The most recently constructed IVU for NSLS was the mini-gap undulator (MGU-X25, to be renamed IVU18 for NSLS-II), which was constructed in 2006. This device was selected to be reused for the New York Structural Biology Consortium Microdiffraction beamline at NSLS-II. At the time of construction, IVU18 was a state-of-the-art undulator designed to be operated as a cryogenic permanent-magnet undulator. Due to the more stringent field quality and impedance requirements of the NSLS-II ring,more » the transition region was redesigned. The control system was also updated to NSLS-II specifications. As a result, this paper reports the details of the IVU18 refurbishment activities including additional magnetic measurement and tuning.« less

Venturi Air-Jet Vacuum Ejector For Sampling Air

NASA Technical Reports Server (NTRS)

Hill, Gerald F.; Sachse, Glen W.; Burney, L. Garland; Wade, Larry O.

1990-01-01

Venturi air-jet vacuum ejector pump light in weight, requires no electrical power, does not contribute heat to aircraft, and provides high pumping speeds at moderate suctions. High-pressure motive gas required for this type of pump bled from compressor of aircraft engine with negligible effect on performance of engine. Used as source of vacuum for differential-absorption CO-measurement (DACOM), modified to achieve in situ measurements of CO at frequency response of 10 Hz. Provides improvement in spatial resolution and potentially leads to capability to measure turbulent flux of CO by use of eddy-correlation technique.

Vacuum Processing Technique for Development of Primary Standard Blackbodies

PubMed Central

Navarro, M.; Bruce, S. S.; Johnson, B. Carol; Murthy, A. V.; Saunders, R. D.

1999-01-01

Blackbody sources with nearly unity emittance that are in equilibrium with a pure freezing metal such as gold, silver, or copper are used as primary standard sources in the International Temperature Scale of 1990 (ITS-90). Recently, a facility using radio-frequency induction heating for melting and filling the blackbody crucible with the freeze metal under vacuum conditions was developed at the National Institute of Standards and Technology (NIST). The blackbody development under a vacuum environment eliminated the possibility of contamination of the freeze metal during the process. The induction heating, compared to a resistively heated convection oven, provided faster heating of crucible and resulted in shorter turn-around time of about 7 h to manufacture a blackbody. This paper describes the new facility and its application to the development of fixed-point blackbodies.

Multilayer Thin Film Polarizer Design for Far Ultraviolet using Induced Transmission and Absorption Technique

NASA Technical Reports Server (NTRS)

Kim, Jongmin; Zukic, Muamer; Wilson, Michele M.; Park, Jung Ho; Torr, Douglas G.

1994-01-01

Good theoretical designs of far ultraviolet polarizers have been reported using a MgF2/Al/MgF2 three layer structure on a thick Al layer as a substrate. The thicknesses were determined to induce transmission and absorption of p-polarized light. In these designs Al optical constants were used from films produced in ultrahigh vacuum (UHV: 10(exp -10) torr). Reflectance values for polarizers fabricated in a conventional high vacuum (p approx. 10(exp -6 torr)) using the UHV design parameters differed dramatically from the design predictions. Al is a highly reactive material and is oxidized even in a high vacuum chamber. In order to solve the problem other metals have been studied. It is found that a larger reflectance difference is closely related to higher amplitude and larger phase difference of Fresnel reflection coefficients between two polarizations at the boundary of MgF2/metal. It is also found that for one material a larger angle of incidence from the surface normal brings larger amplitude and phase difference. Be and Mo are found good materials to replace Al. Polarizers designed for 121.6 nm with Be at 60 deg and with Mo at 70 deg are shown as examples.

Characterization of an ultraviolet imaging detector with high event rate ROIC (HEROIC) readout

NASA Astrophysics Data System (ADS)

Nell, Nicholas; France, Kevin; Harwit, Alex; Bradley, Scott; Franka, Steve; Freymiller, Ed; Ebbets, Dennis

2016-07-01

We present characterization results from a photon counting imaging detector consisting of one microchannel plate (MCP) and an array of two readout integrated circuits (ROIC) that record photon position. The ROICs used in the position readout are the high event rate ROIC (HEROIC) devices designed to handle event rates up to 1 MHz per pixel, recently developed by the Ball Aerospace and Technologies Corporation in collaboration with the University of Colorado. An opaque cesium iodide (CsI) photocathode sensitive in the far-ultraviolet (FUV; 122-200 nm), is deposited on the upper surface of the MCP. The detector is characterized in a chamber developed by CU Boulder that is capable of illumination with vacuum-ultraviolet (VUV) monochromatic light and measurement of absolute ux with a calibrated photodiode. Testing includes investigation of the effects of adjustment of internal settings of the HEROIC devices including charge threshold, gain, and amplifier bias. The detector response to high count rates is tested. We report initial results including background, uniformity, and quantum detection efficiency (QDE) as a function of wavelength.

Real-time detection of S(1D2) photofragments produced from the 1B2(1Σu+) state of CS2 by vacuum ultraviolet photoelectron imaging using 133 nm probe pulses

NASA Astrophysics Data System (ADS)

Horio, Takuya; Spesyvtsev, Roman; Furumido, Yu; Suzuki, Toshinori

2017-07-01

Ultrafast photodissociation dynamics from the 1B2(1Σu+) state of CS2 are studied by time-resolved photoelectron imaging using the fourth (4ω, 198 nm) and sixth (6ω, 133 nm) harmonics of a femtosecond Ti:sapphire laser. The 1B2 state of CS2 was prepared with the 4ω pulses, and subsequent dynamics were probed using the 6ω vacuum ultraviolet (VUV) pulses. The VUV pulses enabled real-time detection of S(1D2) photofragments, produced via CS2*(1B2(1Σu+)) → CS(X 1Σ+) + S(1D2). The photoionization signal of dissociating CS2*(1B2(1Σu+)) molecules starts to decrease at about 100 fs, while the S(1D2) fragments appear with a finite (ca. 400 fs) delay time after the pump pulse. Also discussed is the configuration interaction of the 1B2(1Σu+) state based on relative photoionization cross-sections to different cationic states.

Improved Vacuum Bazooka

NASA Astrophysics Data System (ADS)

Cockman, John

2003-04-01

This apparatus is a modification to the well-known "vacuum bazooka" (PIRA 2B30.70). My vacuum bazooka is easy to construct and demonstrate, requires no precise fittings, foil, or vacuum grease, and propels ping-pong balls at a tremendous velocity!

Investigations Of A Pulsed Cathodic Vacuum Arc

NASA Astrophysics Data System (ADS)

Oates, T. W. H.; Pigott, J.; Denniss, P.; Mckenzie, D. R.; Bilek, M. M. M.

2003-06-01

Cathodic vacuum arcs are well established as a method for producing thin films for coatings and as a source of metal ions. Research into DC vacuum arcs has been going on for over ten years in the School of Physics at the University of Sydney. Recently a project was undertaken in the school to design and build a pulsed CVA for use in the investigation of plasma sheaths and plasma immersion ion implantation. Pulsed cathodic vacuum arcs generally have a higher current and plasma density and also provide a more stable and reproducible plasma density than their DC counterparts. Additionally it has been shown that if a high repetition frequency can be established the deposition rate of pulsed arcs is equal to or greater than that of DC arcs with a concomitant reduction in the rate of macro-particle formation. We present here results of our investigations into the building of a center-triggered pulsed cathodic vacuum arc. The design of the power supply and trigger mechanism and the geometry of the anode and cathode are examined. Observations of type I and II arc spots using a CCD camera, and cathode spot velocity dependence on arc current will be presented. The role of retrograde motion in a high current pulsed arc is discussed.

Global Ultraviolet Imager (GUVI) investigation

NASA Technical Reports Server (NTRS)

Christensen, Andrew B.

1995-01-01

This report covers the activities performed under NAS5-32572. The results of those activities are included in this Final Report. TIMED Science Objectives: (1) To determine the temperature, density, and wind structure of the MLTI (mixed layer thermal inertia), including the seasonal and latitudinal variations; and (2) To determine the relative importance of the various radiative, chemical, electrodynamical, and dynamical sources and sinks of energy for the thermal structure of the MLTI. GUVI Science Goals: (1) Determine the spatial and temporal variations of temperature and constituent densities in the lower thermosphere; and (2) Determine the importance of auroral energy sources and solar EUV (extreme ultraviolet) to the energy balance of the region.

Vacuum die attach for integrated circuits

DOEpatents

Schmitt, Edward H.; Tuckerman, David B.

1991-01-01

A thin film eutectic bond for attaching an integrated circuit die to a circuit substrate is formed by coating at least one bonding surface on the die and substrate with an alloying metal, assembling the die and substrate under compression loading, and heating the assembly to an alloying temperature in a vacuum. A very thin bond, 10 microns or less, which is substantially void free, is produced. These bonds have high reliability, good heat and electrical conduction, and high temperature tolerance. The bonds are formed in a vacuum chamber, using a positioning and loading fixture to compression load the die, and an IR lamp or other heat source. For bonding a silicon die to a silicon substrate, a gold silicon alloy bond is used. Multiple dies can be bonded simultaneously. No scrubbing is required.

Tunable, continuous-wave, ultraviolet source based on intracavity sum-frequency-generation in an optical parametric oscillator using BiB₃O₆.

PubMed

Devi, Kavita; Kumar, S Chaitanya; Ebrahim-Zadeh, M

2013-10-21

We report a continuous-wave (cw) source of tunable radiation across 333-345 nm in the ultraviolet (UV) using bismuth triborate, BiB₃O₆ (BIBO) as the nonlinear gain material. The source is based on internal sum-frequency-generation (SFG) in a cw singly-resonant optical parametric oscillator (OPO) pumped at 532 nm. The compact tunable source employs a 30-mm-long MgO:sPPLT crystal as the OPO gain medium and a 5-mm-long BIBO crystal for intracavity SFG of the signal and pump, providing up to 21.6 mW of UV power at 339.7 nm, with >15 mW over 64% of the SFG tuning range. The cw OPO is also tunable across 1158-1312 nm in the idler, delivering as much as 1.7 W at 1247 nm, with >1W over 65% of the tuning range. The UV output at maximum power exhibits passive power stability better than 3.4% rms and frequency stability of 193 GHz over more than one minute.

The Classical Vacuum.

ERIC Educational Resources Information Center

Boyer, Timothy H.

1985-01-01

The classical vacuum of physics is not empty, but contains a distinctive pattern of electromagnetic fields. Discovery of the vacuum, thermal spectrum, classical electron theory, zero-point spectrum, and effects of acceleration are discussed. Connection between thermal radiation and the classical vacuum reveals unexpected unity in the laws of…

Partial-Vacuum-Gasketed Electrochemical Corrosion Cell

NASA Technical Reports Server (NTRS)

Bonifas, Andrew P.; Calle, Luz M.; Hintze, Paul E.

2006-01-01

An electrochemical cell for making corrosion measurements has been designed to prevent or reduce crevice corrosion, which is a common source of error in prior such cells. The present cell (see figure) includes an electrolyte reservoir with O-ring-edged opening at the bottom. In preparation for a test, the reservoir, while empty, is pressed down against a horizontal specimen surface to form an O-ring seal. A purge of air or other suitable gas is begun in the reservoir, and the pressure in the reservoir is regulated to maintain a partial vacuum. While maintaining the purge and partial vacuum, and without opening the interior of the reservoir to the atmosphere, the electrolyte is pumped into the reservoir. The reservoir is then slowly lifted a short distance off the specimen. The level of the partial vacuum is chosen such that the differential pressure is just sufficient to keep the electrolyte from flowing out of the reservoir through the small O-ring/specimen gap. Electrochemical measurements are then made. Because there is no gasket (and, hence, no crevice between the specimen and the gasket), crevice corrosion is unlikely to occur.

Long-life micro vacuum chamber for a micromachined cryogenic cooler

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Haishan, E-mail: H.Cao@utwente.nl, E-mail: HaishanCao@gmail.com; Vermeer, Cristian H.; Vanapalli, Srinivas

2015-11-15

Micromachined cryogenic coolers can be used for cooling small electronic devices to improve their performance. However, for reaching cryogenic temperatures, they require a very good thermal insulation from the warm environment. This is established by a vacuum space that for adequate insulation has to be maintained at a pressure of 0.01 Pa or lower. In this paper, the challenge of maintaining a vacuum chamber with a volume of 3.6 × 10{sup −5} m{sup 3} and an inner wall area of 8.1 × 10{sup −3} m{sup 2} at a pressure no higher than 0.01 Pa for five years is theoretically analyzed. The possiblemore » sources of gas, the mechanisms by which these gases enter the vacuum space and their effects on the pressure in the vacuum chamber are discussed. In a long-duration experiment with four stainless steel chambers of the above dimensions and equipped with a chemical getter, the vacuum pressures were monitored for a period of two years. In that period, the measured pressure increase stayed within 0.01 Pa. This study can be used to guide the design of long-lifetime micro vacuum chambers that operate without continuous mechanical pumping.« less

The effect of prescription eyewear on ocular exposure to ultraviolet radiation.

PubMed Central

Rosenthal, F S; Bakalian, A E; Taylor, H R

1986-01-01

Several studies have suggested that ultraviolet radiation in sunlight may cause cataracts and other eye disease. We evaluated the effect of prescription eyewear in attenuating ocular exposure to ultraviolet radiation (UVR) in the sunlight portions of the ultraviolet spectrum (295-350 nm). Using natural sunlight as the source, the attenuation was measured with two ultraviolet detectors, one sensitive to only UVB (295-315 nm) and one sensitive to both UVA and UVB (295-350 nm). A random sample of spectacles, spectacle lenses, and contact lenses was examined. The average transmission, as measured with either detector, was highest for soft contact lenses, followed by glass spectacle lenses, untinted hard contact lenses, and plastic spectacle lenses. Measurements performed with mannikins wearing spectacles showed that an average of 6.6 per cent of incident radiation reached the eye even when the lenses were covered with black opaque tape. The amount of exposure was increased substantially when the spectacles were moved 0.6 cm away from the forehead. The results show that the protection against ultraviolet exposure provided by prescription eyewear is highly variable and depends largely on its composition, size, and wearing position. PMID:3752323

Germanium detector vacuum encapsulation

NASA Technical Reports Server (NTRS)

Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.

1991-01-01

This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.

Generation of nanosecond neutron pulses in vacuum accelerating tubes

NASA Astrophysics Data System (ADS)

Didenko, A. N.; Shikanov, A. E.; Rashchikov, V. I.; Ryzhkov, V. I.; Shatokhin, V. L.

2014-06-01

The generation of neutron pulses with a duration of 1-100 ns using small vacuum accelerating tubes is considered. Two physical models of acceleration of short deuteron bunches in pulse neutron generators are described. The dependences of an instantaneous neutron flux in accelerating tubes on the parameters of pulse neutron generators are obtained using computer simulation. The results of experimental investigation of short-pulse neutron generators based on the accelerating tube with a vacuum-arc deuteron source, connected in the circuit with a discharge peaker, and an accelerating tube with a laser deuteron source, connected according to the Arkad'ev-Marx circuit, are given. In the experiments, the neutron yield per pulse reached 107 for a pulse duration of 10-100 ns. The resultant experimental data are in satisfactory agreement with the results of computer simulation.

Surface phenomena related to mirror degradation in extreme ultraviolet (EUV) lithography

NASA Astrophysics Data System (ADS)

Madey, Theodore E.; Faradzhev, Nadir S.; Yakshinskiy, Boris V.; Edwards, N. V.

2006-12-01

One of the most promising methods for next generation device manufacturing is extreme ultraviolet (EUV) lithography, which uses 13.5 nm wavelength radiation generated from freestanding plasma-based sources. The short wavelength of the incident illumination allows for a considerable decrease in printed feature size, but also creates a range of technological challenges not present for traditional optical lithography. Contamination and oxidation form on multilayer reflecting optics surfaces that not only reduce system throughput because of the associated reduction in EUV reflectivity, but also introduce wavefront aberrations that compromise the ability to print uniform features. Capping layers of ruthenium, films ∼2 nm thick, are found to extend the lifetime of Mo/Si multilayer mirrors used in EUV lithography applications. However, reflectivities of even the Ru-coated mirrors degrade in time during exposure to EUV radiation. Ruthenium surfaces are chemically reactive and are very effective as heterogeneous catalysts. In the present paper we summarize the thermal and radiation-induced surface chemistry of bare Ru exposed to gases; the emphasis is on H2O vapor, a dominant background gas in vacuum processing chambers. Our goal is to provide insights into the fundamental physical processes that affect the reflectivity of Ru-coated Mo/Si multilayer mirrors exposed to EUV radiation. Our ultimate goal is to identify and recommend practices or antidotes that may extend mirror lifetimes.

CITIUS: An infrared-extreme ultraviolet light source for fundamental and applied ultrafast science

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grazioli, C.; Gauthier, D.; Ivanov, R.

2014-02-15

We present the main features of CITIUS, a new light source for ultrafast science, generating tunable, intense, femtosecond pulses in the spectral range from infrared to extreme ultraviolet (XUV). The XUV pulses (about 10{sup 5}-10{sup 8} photons/pulse in the range 14-80 eV) are produced by laser-induced high-order harmonic generation in gas. This radiation is monochromatized by a time-preserving monochromator, also allowing one to work with high-resolution bandwidth selection. The tunable IR-UV pulses (10{sup 12}-10{sup 15} photons/pulse in the range 0.4-5.6 eV) are generated by an optical parametric amplifier, which is driven by a fraction of the same laser pulse thatmore » generates high order harmonics. The IR-UV and XUV pulses follow different optical paths and are eventually recombined on the sample for pump-probe experiments. We also present the results of two pump-probe experiments: with the first one, we fully characterized the temporal duration of harmonic pulses in the time-preserving configuration; with the second one, we demonstrated the possibility of using CITIUS for selective investigation of the ultra-fast dynamics of different elements in a magnetic compound.« less

Vacuum-actuated percutaneous insertion/implantation tool for flexible neural probes and interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheth, Heeral; Bennett, William J.; Pannu, Satinderpall S.

A flexible device insertion tool including an elongated stiffener with one or more suction ports, and a vacuum connector for interfacing the stiffener to a vacuum source, for attaching the flexible device such as a flexible neural probe to the stiffener during insertion by a suction force exerted through the suction ports to, and to release the flexible device by removing the suction force.

High Accuracy Ultraviolet Index of Refraction Measurements Using a Fourier Transform Spectrometer

PubMed Central

Gupta, Rajeev; Kaplan, Simon G.

2003-01-01

We have constructed a new facility at the National Institute of Standards and Technology (NIST) to measure the index of refraction of transmissive materials in the wavelength range from the visible to the vacuum ultraviolet. An etalon of the material is illuminated with synchrotron radiation, and the interference fringes in the transmittance spectrum are measured using a Fourier transform spectrometer. The refractive index of calcium fluoride, CaF2, has been measured from 600 nm to 175 nm and the resulting values agree with a traditional goniometric measurement to within 1 × 10−5. The uncertainty in the index values is currently limited by the uncertainty in the thickness measurement of the etalon. PMID:27413620

Development of High Interruption Capability Vacuum Circuit Breaker -Technology of Vacuum Arc Control-

NASA Astrophysics Data System (ADS)

Niwa, Yoshimitsu; Kaneko, Eiji

Vacuum circuit breakers (VCB) have been widely used for power distribution systems. Vacuum Interrupters, which are the current interruption unit, have been increased its interruption capability with the development of vacuum arc control technology by magnetic field. There are three major type electrodes: disk shaped electrodes, radial magnetic field electrodes, axial magnetic field (AMF) electrodes. In the disk shaped electrode, the vacuum arc between the electrodes is not controlled. In the AMF electrode, the vacuum arc is diffused and stabilized by an axial magnetic field, which is parallel to the arc current. In the last type of electrodes, the vacuum arc column is rotated by magnetic force generated by the current flowing in the electrodes. The interruption current and the voltage of one break VCB is increased to 100 kA, 144 kV respectively. This paper describes basic configurations and functions of VCB, vacuum arc control technology in vacuum interrupters, recent researches and applications of VCB.

Visible and near-ultraviolet spectra of low-pressure rare-gas microwave discharges

NASA Technical Reports Server (NTRS)

Campbell, J. P.; Spisz, E. W.; Bowman, R. L.

1971-01-01

The spectral emission characteristics of three commercial low pressure rare gas discharge lamps wire obtained in the near ultraviolet and visible wavelength range. All three lamps show a definite continuum over the entire wavelength range from 0.185 to 0.6 micrometers. Considerable line emission is superimposed on much of the continuum for wavelengths greater than 0.35 micrometers. These sources were used to make transmittance measurements on quartz samples in the near ultraviolet wavelength range.

Ultraviolet complete dark energy model

NASA Astrophysics Data System (ADS)

Narain, Gaurav; Li, Tianjun

2018-04-01

We consider a local phenomenological model to explain a nonlocal gravity scenario which has been proposed to address dark energy issues. This nonlocal gravity action has been seen to fit the data as well as Λ -CDM and therefore demands a more fundamental local treatment. The induced gravity model coupled with higher-derivative gravity is exploited for this proposal, as this perturbatively renormalizable model has a well-defined ultraviolet (UV) description where ghosts are evaded. We consider a generalized version of this model where we consider two coupled scalar fields and their nonminimal coupling with gravity. In this simple model, one of the scalar field acquires a vacuum expectation value (VEV), thereby inducing a mass for one of the scalar fields and generating Newton's constant. The induced mass however is seen to be always above the running energy scale thereby leading to its decoupling. The residual theory after decoupling becomes a platform for driving the accelerated expansion under certain conditions. Integrating out the residual scalar generates a nonlocal gravity action. The leading term of which is the nonlocal gravity action used to fit the data of dark energy.

Research on the calibration of ultraviolet energy meters

NASA Astrophysics Data System (ADS)

Lin, Fangsheng; Yin, Dejin; Li, Tiecheng; Lai, Lei; Xia, Ming

2016-10-01

Ultraviolet (UV) radiation is a kind of non-lighting radiation with the wavelength range from 100nm to 400nm. Ultraviolet irradiance meters are now widely used in many areas. However, as the development of science and technology, especially in the field of light-curing industry, there are more and more UV energy meters or UV-integrators need to be measured. Because the structure, wavelength band and measured power intensity of UV energy meters are different from traditional UV irradiance meters, it is important for us to take research on the calibration. With reference to JJG879-2002, we SIMT have independently developed the UV energy calibration device and the standard of operation and experimental methods for UV energy calibration in detail. In the calibration process of UV energy meter, many influencing factors will affect the final results, including different UVA-band UV light sources, different spectral response for different brands of UV energy meters, instability and no uniformity of UV light source and temperature. Therefore we need to take all of these factors into consideration to improve accuracy in UV energy calibration.

Characteristics of extreme ultraviolet emission from high-Z plasmas

NASA Astrophysics Data System (ADS)

Ohashi, H.; Higashiguchi, T.; Suzuki, Y.; Kawasaki, M.; Suzuki, C.; Tomita, K.; Nishikino, M.; Fujioka, S.; Endo, A.; Li, B.; Otsuka, T.; Dunne, P.; O'Sullivan, G.

2016-03-01

We demonstrate the extreme ultraviolet (EUV) and soft x-ray sources in the 2 to 7 nm spectral region related to the beyond EUV (BEUV) question at 6.x nm and the water window source based on laser-produced high-Z plasmas. Resonance emission from multiply charged ions merges to produce intense unresolved transition arrays (UTAs), extending below the carbon K edge (4.37 nm). An outline of a microscope design for single-shot live cell imaging is proposed based on high-Z plasma UTA source, coupled to multilayer mirror optics.

Vacuum die attach for integrated circuits

DOEpatents

Schmitt, E.H.; Tuckerman, D.B.

1991-09-10

A thin film eutectic bond for attaching an integrated circuit die to a circuit substrate is formed by coating at least one bonding surface on the die and substrate with an alloying metal, assembling the die and substrate under compression loading, and heating the assembly to an alloying temperature in a vacuum. A very thin bond, 10 microns or less, which is substantially void free, is produced. These bonds have high reliability, good heat and electrical conduction, and high temperature tolerance. The bonds are formed in a vacuum chamber, using a positioning and loading fixture to compression load the die, and an IR lamp or other heat source. For bonding a silicon die to a silicon substrate, a gold silicon alloy bond is used. Multiple dies can be bonded simultaneously. No scrubbing is required. 1 figure.

Apparatus for coating a surface with a metal utilizing a plasma source

DOEpatents

Brown, Ian G.; MacGill, Robert A.; Galvin, James E.

1991-01-01

An apparatus and method for coating or layering a surface with a metal utilizing a metal vapor vacuum arc plasma source. The apparatus includes a trigger mechanism for actuating the metal vacuum vapor arc plasma source in a pulsed mode at a predetermined rate. The surface or substrate to be coated or layered is supported in position with the plasma source in a vacuum chamber. The surface is electrically biased for a selected period of time during the pulsed mode of operation of the plasma source. Both the pulsing of the metal vapor vacuum arc plasma source and the electrical biasing of the surface are synchronized for selected periods of time.

K(3)EDTA Vacuum Tubes Validation for Routine Hematological Testing.

PubMed

Lima-Oliveira, Gabriel; Lippi, Giuseppe; Salvagno, Gian Luca; Montagnana, Martina; Poli, Giovanni; Solero, Giovanni Pietro; Picheth, Geraldo; Guidi, Gian Cesare

2012-01-01

Background and Objective. Some in vitro diagnostic devices (e.g, blood collection vacuum tubes and syringes for blood analyses) are not validated before the quality laboratory managers decide to start using or to change the brand. Frequently, the laboratory or hospital managers select the vacuum tubes for blood collection based on cost considerations or on relevance of a brand. The aim of this study was to validate two dry K(3)EDTA vacuum tubes of different brands for routine hematological testing. Methods. Blood specimens from 100 volunteers in two different K(3)EDTA vacuum tubes were collected by a single, expert phlebotomist. The routine hematological testing was done on Advia 2120i hematology system. The significance of the differences between samples was assessed by paired Student's t-test after checking for normality. The level of statistical significance was set at P < 0.05. Results and Conclusions. Different brand's tubes evaluated can represent a clinically relevant source of variations only on mean platelet volume (MPV) and platelet distribution width (PDW). Basically, our validation will permit the laboratory or hospital managers to select the brand's vacuum tubes validated according to him/her technical or economical reasons for routine hematological tests.

Comparative survival analysis of Deinococcus radiodurans and the haloarchaea Natrialba magadii and Haloferax volcanii exposed to vacuum ultraviolet irradiation.

PubMed

Abrevaya, Ximena C; Paulino-Lima, Ivan G; Galante, Douglas; Rodrigues, Fabio; Mauas, Pablo J D; Cortón, Eduardo; Lage, Claudia de Alencar Santos

2011-12-01

The haloarchaea Natrialba magadii and Haloferax volcanii, as well as the radiation-resistant bacterium Deinococcus radiodurans, were exposed to vacuum UV (VUV) radiation at the Brazilian Synchrotron Light Laboratory. Cell monolayers (containing 10(5) to 10(6) cells per sample) were prepared over polycarbonate filters and irradiated under high vacuum (10(-5) Pa) with polychromatic synchrotron radiation. N. magadii was remarkably resistant to high vacuum with a survival fraction of (3.77±0.76)×10(-2), which was larger than that of D. radiodurans (1.13±0.23)×10(-2). The survival fraction of the haloarchaea H. volcanii, of (3.60±1.80)×10(-4), was much smaller. Radiation resistance profiles were similar between the haloarchaea and D. radiodurans for fluences up to 150 J m(-2). For fluences larger than 150 J m(-2), there was a significant decrease in the survival of haloarchaea, and in particular H. volcanii did not survive. Survival for D. radiodurans was 1% after exposure to the higher VUV fluence (1350 J m(-2)), while N. magadii had a survival lower than 0.1%. Such survival fractions are discussed regarding the possibility of interplanetary transfer of viable microorganisms and the possible existence of microbial life in extraterrestrial salty environments such as the planet Mars and Jupiter's moon Europa. This is the first work to report survival of haloarchaea under simulated interplanetary conditions.

A soft X-ray source based on a low divergence, high repetition rate ultraviolet laser

NASA Astrophysics Data System (ADS)

Crawford, E. A.; Hoffman, A. L.; Milroy, R. D.; Quimby, D. C.; Albrecht, G. F.

The CORK code is utilized to evaluate the applicability of low divergence ultraviolet lasers for efficient production of soft X-rays. The use of the axial hydrodynamic code wih one ozone radial expansion to estimate radial motion and laser energy is examined. The calculation of ionization levels of the plasma and radiation rates by employing the atomic physics and radiation model included in the CORK code is described. Computations using the hydrodynamic code to determine the effect of laser intensity, spot size, and wavelength on plasma electron temperature are provided. The X-ray conversion efficiencies of the lasers are analyzed. It is observed that for a 1 GW laser power the X-ray conversion efficiency is a function of spot size, only weakly dependent on pulse length for time scales exceeding 100 psec, and better conversion efficiencies are obtained at shorter wavelengths. It is concluded that these small lasers focused to 30 micron spot sizes and 10 to the 14th W/sq cm intensities are useful sources of 1-2 keV radiation.

Evolution of Structural and Optical Properties of ZnO Nanorods Grown on Vacuum Annealed Seed Crystallites

PubMed Central

Khan, Fasihullah; Ajmal, Hafiz Muhammad Salman; Huda, Noor Ul; Kim, Ji Hyun; Kim, Sam-Dong

2018-01-01

In this study, the ambient condition for the as-coated seed layer (SL) annealing at 350 °C is varied from air or nitrogen to vacuum to examine the evolution of structural and optical properties of ZnO nanorods (NRs). The NR crystals of high surface density (~240 rods/μm2) and aspect ratio (~20.3) show greatly enhanced (002) degree of orientation and crystalline quality, when grown on the SLs annealed in vacuum, compared to those annealed in air or nitrogen ambient. This is due to the vacuum-annealed SL crystals of a highly preferred orientation toward (002) and large grain sizes. X-ray photoelectron spectroscopy also reveals that the highest O/Zn atomic ratio of 0.89 is obtained in the case of vacuum-annealed SL crystals, which is due to the effective desorption of hydroxyl groups and other contaminants adsorbed on the surface formed during aqueous solution-based growth process. Near band edge emission (ultra violet range of 360–400 nm) of the vacuum-annealed SLs is also enhanced by 44% and 33% as compared to those annealed in air and nitrogen ambient, respectively, in photoluminescence with significant suppression of visible light emission associated with deep level transition. Due to this improvement of SL optical crystalline quality, the NR crystals grown on the vacuum-annealed SLs produce ~3 times higher ultra violet emission intensity than the other samples. In summary, it is shown that the ZnO NRs preferentially grow along the wurtzite c-axis direction, thereby producing the high crystalline quality of nanostructures when they grow on the vacuum-annealed SLs of high crystalline quality with minimized impurities and excellent preferred orientation. The ZnO nanostructures of high crystalline quality achieved in this study can be utilized for a wide range of potential device applications such as laser diodes, light-emitting diodes, piezoelectric transducers and generators, gas sensors, and ultraviolet detectors. PMID:29373523

Vacuum microelectronics for beam power and rectennas

NASA Technical Reports Server (NTRS)

Gray, Henry F.

1989-01-01

Vacuum Microelectronic devices can be described as vacuum transistors or micro-miniature vacuum tubes, as one chooses. The fundamental reason behind this new technology is the very large current densities available from field emitters, namely as high as 10(8) A/sq cm. Array current densities as high as 1000 A/sq cm have been measured. Total electron transit times from source to drain for 1 micron feature size devices have been predicted to be about 150fs. This very short transit time implies the possibility of submillimeter wave transmitters and rectennas in devices which can operate with reasonably high voltages and which are small in size and are lightweight. In addition, they are expected to be extremely radiation hard and very temperature insensitive. That is, they are expected to have radiation hardness characteristics similar to vacuum tubes, and both the high temperature and low temperature limits should be determined by the package. That is, there should be no practical intrinsic temperature or carrier freezeout problems for devices based on metals or composites. But the technology is difficult to implement at the present time because it is based on 300 to 500 angstrom radius field emitters which must be relatively uniform. There is also the need to understand the non-equilibrium transport physics in the near-surface regions of the field emitters.

Regulated-current dc power supply for gaseous-discharge lamps

NASA Technical Reports Server (NTRS)

Freeman, W.; Huguenin, D.

1970-01-01

Controlled current source having a high output resistance feeds continuous-flow hydrogen lamps in vacuum-ultraviolet photometric equipment. The power supply, also used with low-pressure sealed lamps, has a short recovery time and smooth regulation without overshoot.

Infrared lessons for ultraviolet gravity: the case of massive gravity and Born-Infeld

NASA Astrophysics Data System (ADS)

Beltrán Jiménez, Jose; Heisenberg, Lavinia; Olmo, Gonzalo J.

2014-11-01

We generalize the ultraviolet sector of gravitation via a Born-Infeld action using lessons from massive gravity. The theory contains all of the elementary symmetric polynomials and is treated in the Palatini formalism. We show how the connection can be solved algebraically to be the Levi-Civita connection of an effective metric. The non-linearity of the algebraic equations yields several branches, one of which always reduces to General Relativity at low curvatures. We explore in detail a minimal version of the theory, for which we study solutions in the presence of a perfect fluid with special attention to the cosmological evolution. In vacuum we recover Ricci-flat solutions, but also an additional physical solution corresponding to an Einstein space. The existence of two physical branches remains for non-vacuum solutions and, in addition, the branch that connects to the Einstein space in vacuum is not very sensitive to the specific value of the energy density. For the branch that connects to the General Relativity limit we generically find three behaviours for the Hubble function depending on the equation of state of the fluid, namely: either there is a maximum value for the energy density that connects continuously with vacuum, or the energy density can be arbitrarily large but the Hubble function saturates and remains constant at high energy densities, or the energy density is unbounded and the Hubble function grows faster than in General Relativity. The second case is particularly interesting because it could offer an interesting inflationary epoch even in the presence of a dust component. Finally, we discuss the possibility of avoiding certain types of singularities within the minimal model.

Research in extreme ultraviolet and far ultraviolet astronomy

NASA Technical Reports Server (NTRS)

Bowyer, C. S.

1985-01-01

The Far Ultraviolet imager (FUVI) was flown on the Aries class sounding rocket 24.015, producing outstanding results. The diffuse extreme ultraviolet (EUV) background spectrometer which is under construction is described. It will be launched on the Black Brant sounding rocket flight number 27.086. Ongoing design studies of a high resolution spectrometer are discussed. This instrument incorporates a one meter normal incidence mirror and will be suitable for an advanced Spartan mission.

The Spartan-281 Far Ultraviolet Imaging Spectrograph

NASA Technical Reports Server (NTRS)

Carruthers, George R.; Heckathorn, Harry M.; Dufour, Reginald J.; Opal, Chet B.; Raymond, John C.

1988-01-01

The U.S. Naval Research Laboratory's Far Ultraviolet Imaging Spectrograph (FUVIS), currently under development for flight as a Spartan shuttle payload, is designed to perform spectroscopy of diffuse sources in the FUV with very high sensitivity and moderate spatial and spectral resolution. Diffuse nebulae, the general galactic background radiation, and artificially induced radiation associated with the Space Shuttle vehicle are sources of particular interest. The FUVIS instrument will cover the wavelength range of 970-2000 A with selectable resolutions of 5 and 30 A. It is a slit imaging spectrograph having 3 arcmin spatial resolution along its 2.7 deg long slit.

Recycling of laser and plasma radiation energy for enhancement of extreme ultraviolet sources for nanolithography

NASA Astrophysics Data System (ADS)

Sizyuk, V.; Sizyuk, T.; Hassanein, A.; Johnson, K.

2018-01-01

We have developed comprehensive integrated models for detailed simulation of laser-produced plasma (LPP) and laser/target interaction, with potential recycling of the escaping laser and out-of-band plasma radiation. Recycling, i.e., returning the escaping laser and plasma radiation to the extreme ultraviolet (EUV) generation region using retroreflective mirrors, has the potential of increasing the EUV conversion efficiency (CE) by up to 60% according to our simulations. This would result in significantly reduced power consumption and/or increased EUV output. Based on our recently developed models, our High Energy Interaction with General Heterogeneous Target Systems (HEIGHTS) computer simulation package was upgraded for LPP devices to include various radiation recycling regimes and to estimate the potential CE enhancement. The upgraded HEIGHTS was used to study recycling of both laser and plasma-generated radiation and to predict possible gains in conversion efficiency compared to no-recycling LPP devices when using droplets of tin target. We considered three versions of the LPP system including a single CO2 laser, a single Nd:YAG laser, and a dual-pulse device combining both laser systems. The gains in generating EUV energy were predicted and compared for these systems. Overall, laser and radiation energy recycling showed the potential for significant enhancement in source efficiency of up to 60% for the dual-pulse system. Significantly higher CE gains might be possible with optimization of the pre-pulse and main pulse parameters and source size.

The B3-VLA CSS sample. VIII. New optical identifications from the Sloan Digital Sky Survey The ultraviolet-optical spectral energy distribution of the young radio sources

NASA Astrophysics Data System (ADS)

Fanti, C.; Fanti, R.; Zanichelli, A.; Dallacasa, D.; Stanghellini, C.

2011-04-01

Context. Compact steep-spectrum radio sources and giga-hertz peaked spectrum radio sources (CSS/GPS) are generally considered to be mostly young radio sources. In recent years we studied at many wavelengths a sample of these objects selected from the B3-VLA catalog: the B3-VLA CSS sample. Only ≈60% of the sources were optically identified. Aims: We aim to increase the number of optical identifications and study the properties of the host galaxies of young radio sources. Methods: We cross-correlated the CSS B3-VLA sample with the Sloan Digital Sky Survey (SDSS), DR7, and complemented the SDSS photometry with available GALEX (DR 4/5 and 6) and near-IR data from UKIRT and 2MASS. Results: We obtained new identifications and photometric redshifts for eight faint galaxies and for one quasar and two quasar candidates. Overall we have 27 galaxies with SDSS photometry in five bands, for which we derived the ultraviolet-optical spectral energy distribution (UV-O-SED). We extended our investigation to additional CSS/GPS selected from the literature. Most of the galaxies show an excess of ultra-violet (UV) radiation compared with the UV-O-SED of local radio-quiet ellipticals. We found a strong dependence of the UV excess on redshift and analyzed it assuming that it is generated either from the nucleus (hidden quasar) or from a young stellar population (YSP). We also compare the UV-O-SEDs of our CSS/GPS sources with those of a selection of large size (LSO) powerful radio sources from the literature. Conclusions: If the major process of the UV excess is caused by a YSP, our conclusion is that it is the result of the merger process that also triggered the onset of the radio source with some time delay. We do not see evidence for a major contribution from a YSP triggered by the radio sources itself. Appendices A-G are only available in electronic form at http://www.aanda.org

High Current Density Cathodes for Future Vacuum Electronics Applications

DTIC Science & Technology

2008-05-30

Tube - device for generating high levels of RF power DARPA Defense Advanced Research Agency PBG Photonic band gap W- Band 75-111 GHz dB Decibels GHz...Extended interaction klystron 1. Introduction All RF vacuum electron sources require a high quality electron beam for efficient operation. Research on...with long life. Pres- ently, only thermionic dispenser cathodes are practical for high power RF sources. Typical thermi- onic cathodes consists of a

A multi purpose source chamber at the PLEIADES beamline at SOLEIL for spectroscopic studies of isolated species: cold molecules, clusters, and nanoparticles.

PubMed

Lindblad, Andreas; Söderström, Johan; Nicolas, Christophe; Robert, Emmanuel; Miron, Catalin

2013-11-01

This paper describes the philosophy and design goals regarding the construction of a versatile sample environment: a source capable of producing beams of atoms, molecules, clusters, and nanoparticles in view of studying their interaction with short wavelength (vacuum ultraviolet and x-ray) synchrotron radiation. In the design, specific care has been taken of (a) the use standard components, (b) ensuring modularity, i.e., that swiftly switching between different experimental configurations was possible. To demonstrate the efficiency of the design, proof-of-principle experiments have been conducted by recording x-ray absorption and photoelectron spectra from isolated nanoparticles (SiO2) and free mixed clusters (Ar/Xe). The results from those experiments are showcased and briefly discussed.

An assessment of the hardness of miniature vacuum tubes to high-voltage transients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orvis, W.J.

1990-03-01

Miniature vacuum tubes are vacuum switching and control devices fabricated on a silicon wafer, using the same technology as is used to make integrated circuits. They operate in much the same manner as conventional vacuum tubes, but with two important differences: they are micron sized devices, and they employ field emission instead of thermionic emission as the electron source. As these devices have a vacuum as their active region, they will be extremely hard to nuclear radiation and relatively insensitive to temperature effects, they are also expected to be extremely fast devices. We have estimated here that their hardness tomore » high-voltage transients will be at least as good as existing semiconductor devices and possibly better. 5 figs.« less

WF/PC internal molecular contamination during system thermal-vacuum test

NASA Technical Reports Server (NTRS)

Taylor, Daniel M.; Barengoltz, J.; Jenkins, T.; Leschly, K.; Triolo, J.

1988-01-01

During the recent system thermal vacuum test of the Wide-Field/Planetary Camera (WF/PC), instrumentation was added to the WF/PC to characterize the internal molecular contamination and verify the instrument throughput down to 1470 angstroms. Analysis of data elements revealed two contaminants affecting the far-ultraviolet (FUV) performance of the WF/PC. The one contaminant (heavy volatile) is correlated with the electronic and housing temperature, and the contamination is significantly reduced when the electronics are operated below plus 8 degrees to plus 10 degrees C. The other contaminant (light volatile) is controlled by the heat pipe temperature, and the contamination is significantly reduced when the Thermal Electric Cooler (TEC) hot-junction temperature is below minus 40 degrees to minus 50 degrees C. The utility of contamination sensors located behind instruments during system tests was demonstrated.

Radiation hard vacuum switch

DOEpatents

Boettcher, Gordon E.

1990-01-01

A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction.

Radiation hard vacuum switch

DOEpatents

Boettcher, Gordon E.

1990-03-06

A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction.

Apparatus for coating a surface with a metal utilizing a plasma source

DOEpatents

Brown, I.G.; MacGill, R.A.; Galvin, J.E.

1991-05-07

An apparatus and method are disclosed for coating or layering a surface with a metal utilizing a metal vapor vacuum arc plasma source. The apparatus includes a trigger mechanism for actuating the metal vacuum vapor arc plasma source in a pulsed mode at a predetermined rate. The surface or substrate to be coated or layered is supported in position with the plasma source in a vacuum chamber. The surface is electrically biased for a selected period of time during the pulsed mode of operation of the plasma source. Both the pulsing of the metal vapor vacuum arc plasma source and the electrical biasing of the surface are synchronized for selected periods of time. 10 figures.

The Inherent Visible Light Signature of an Intense Underwater Ultraviolet Light Source Due to Combined Raman and Fluorescence Effects

DTIC Science & Technology

2000-01-01

Humans cannot see ultraviolet light. The blue-sensitive cones in the retina would respond weakly to ultraviolet wavelengths if exposed to them, but...545, 1992. 3. C. S. Yentsch, and D. A. Phinney, " Autofluorescence and Raman scattering in the marine underwater environment," Ocean Optics X, SPIE

Ultraviolet Spectra of Comets Observed with the International Ultraviolet Explorer Satellite Observatory.

NASA Astrophysics Data System (ADS)

Weaver, Harold Anthony, Jr.

Ultraviolet spectra of seven comets observed with the International Ultraviolet Explorer (IUE) satellite are presented. Observations of comet Bradfield (1979 X) made in early 1980 allow a comprehensive study of the production of water by this comet. By comparing the observations to the predictions of two water models of the coma (Haser and vectorial), it is determined that these measurements support the idea of a comet composed principally of water ice. The vaporization of the water has a rather unexpected heliocentric variation, decreasing as r('-3.7) over the entire range of observations. Atomic carbon is relatively abundant in the coma of comet Bradfield; the production rate of carbon is roughly 5-10% of the water production rate. Analysis of the spatial brightness profiles of the strongest atomic carbon emission does not reveal the identity of the source of the observed carbon, but the data are apparently inconsistent with a photodissociation source that is either CO or CO(,2). A comparison of the ultraviolet spectrum of periodic comet Encke, recorded by the IUE between 1980 October 24 and November 5, with similar spectra of short and long period comets shows the gaseous composition of P/Encke to be virtually identical to that of the other comets. If P/Encke is indeed the remains of a once giant comet, this similarity implies a homogeneous structure for the cometary ice nucleus. The OH(0,0) band brightness distribution shows a spatial variation similar to the visible fan-shaped image of the comet. Comets P/Tuttle (1980h), P/Stephan-Oterma (1980g), and Meier (1980q) were observed during November-December 1980 with IUE, while comets P/Borrelly (1980i) and Panther (1980u) were observed with IUE on 6 March 1981. The spectra of these comets are compared with those of comets Bradfield (1979 X) and P/Encke, as well as with each other. In order to simplify the interpretation of the data and to minimize the dependence upon a specific model, the spectra are compared at

Continuous-wave ultraviolet generation at 320 nm by intracavity frequency doubling of red-emitting Praseodymium lasers

NASA Astrophysics Data System (ADS)

Richter, A.; Pavel, N.; Heumann, E.; Huber, G.; Parisi, D.; Toncelli, A.; Tonelli, M.; Diening, A.; Seelert, W.

2006-04-01

We describe a new approach for the generation of coherent ultraviolet radiation. Continuous-wave ultraviolet light at 320 nm has been obtained by intracavity frequency doubling of red-emitting Praseodymium lasers. Lasing at the 640-nm fundamental wavelength in Pr:LiYF4 and Pr:BaY2F8 was realized by employing an optically pumped semiconductor laser at 480 nm as pump source.Using LiB3O5 as nonlinear medium, ~19 mW of ultraviolet radiation with ~9% optical efficiency with respect to absorbed power was reached for both laser crystals; the visible-to-ultraviolet conversion efficiency was 26% and 35% for Pr:LiYF4 and Pr:BaY2F8, respectively.

Three new extreme ultraviolet spectrometers on NSTX-U for impurity monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weller, M. E., E-mail: weller4@llnl.gov; Beiersdorfer, P.; Soukhanovskii, V. A.

2016-11-15

Three extreme ultraviolet (EUV) spectrometers have been mounted on the National Spherical Torus Experiment–Upgrade (NSTX-U). All three are flat-field grazing-incidence spectrometers and are dubbed X-ray and Extreme Ultraviolet Spectrometer (XEUS, 8–70 Å), Long-Wavelength Extreme Ultraviolet Spectrometer (LoWEUS, 190–440 Å), and Metal Monitor and Lithium Spectrometer Assembly (MonaLisa, 50–220 Å). XEUS and LoWEUS were previously implemented on NSTX to monitor impurities from low- to high-Z sources and to study impurity transport while MonaLisa is new and provides the system increased spectral coverage. The spectrometers will also be a critical diagnostic on the planned laser blow-off system for NSTX-U, which will bemore » used for impurity edge and core ion transport studies, edge-transport code development, and benchmarking atomic physics codes.« less

Vacuum pull down method for an enhanced bonding process

DOEpatents

Davidson, James C.; Balch, Joseph W.

1999-01-01

A process for effectively bonding arbitrary size or shape substrates. The process incorporates vacuum pull down techniques to ensure uniform surface contact during the bonding process. The essence of the process for bonding substrates, such as glass, plastic, or alloys, etc., which have a moderate melting point with a gradual softening point curve, involves the application of an active vacuum source to evacuate interstices between the substrates while at the same time providing a positive force to hold the parts to be bonded in contact. This enables increasing the temperature of the bonding process to ensure that the softening point has been reached and small void areas are filled and come in contact with the opposing substrate. The process is most effective where at least one of the two plates or substrates contain channels or grooves that can be used to apply vacuum between the plates or substrates during the thermal bonding cycle. Also, it is beneficial to provide a vacuum groove or channel near the perimeter of the plates or substrates to ensure bonding of the perimeter of the plates or substrates and reduce the unbonded regions inside the interior region of the plates or substrates.

Ultra high vacuum test setup for electron gun

NASA Astrophysics Data System (ADS)

Pandiyar, M. L.; Prasad, M.; Jain, S. K.; Kumar, R.; Hannurkar, P. R.

2008-05-01

Ultra High Vacuum (UHV) test setup for electron gun testing has been developed. The development of next generation light sources and accelerators require development of klystron as a radio frequency power source, and in turn electron gun. This UHV electron gun test setup can be used to test the electron guns ranging from high average current, quasi-continuous wave to high peak current, single pulse etc. An electron gun has been designed, fabricated, assembled and tested for insulation up to 80 kV under the programme to develop high power klystron for future accelerators. Further testing includes the electron emission parameters characterization of the cathode, as it determines the development of a reliable and efficient electron gun with high electron emission current and high life time as well. This needs a clean ultra high vacuum to study these parameters particularly at high emission current. The cathode emission current, work function and vapour pressure of cathode surface material at high temperature studies will further help in design and development of high power electron gun The UHV electron gun test setup consists of Turbo Molecular Pump (TMP), Sputter Ion Pump (SIP), pressure gauge, high voltage and cathode power supplies, current measurement device, solenoid magnet and its power supply, residual gas analyser etc. The ultimate vacuum less than 2×10-9 mbar was achieved. This paper describes the UHV test setup for electron gun testing.

Vacuum fluctuations in an ancestor vacuum: A possible dark energy candidate

NASA Astrophysics Data System (ADS)

Aoki, Hajime; Iso, Satoshi; Lee, Da-Shin; Sekino, Yasuhiro; Yeh, Chen-Pin

2018-02-01

We consider an open universe created by bubble nucleation, and study possible effects of our "ancestor vacuum," a de Sitter space in which bubble nucleation occurred, on the present universe. We compute vacuum expectation values of the energy-momentum tensor for a minimally coupled scalar field, carefully taking into account the effect of the ancestor vacuum by the Euclidean prescription. We pay particular attention to the so-called supercurvature mode, a non-normalizable mode on a spatial slice of the open universe, which has been known to exist for sufficiently light fields. This mode decays in time most slowly, and may leave residual effects of the ancestor vacuum, potentially observable in the present universe. We point out that the vacuum energy of the quantum field can be regarded as dark energy if mass of the field is of order the present Hubble parameter or smaller. We obtain preliminary results for the dark energy equation of state w (z ) as a function of the redshift.

ION SOURCE

DOEpatents

Brobeck, W.M.

1959-04-14

This patent deals with calutrons and more particularly to an arrangement therein whereby charged bottles in a calutron source unit may be replaced without admitting atmospheric air to the calutron vacuum chamber. As described, an ion unit is disposed within a vacuum tank and has a reservoir open toward a wall of the tank. A spike projects from thc source into the reservoir. When a charge bottle is placed in the reservoir, the spike breaks a frangible seal on the bottle. After the contents of the bottle are expended the bottle may be withdrawn and replaced with another charge bottle by a varuum lock arrangement in conjunction with an arm for manipulating the bottle.

K3EDTA Vacuum Tubes Validation for Routine Hematological Testing

PubMed Central

Lima-Oliveira, Gabriel; Lippi, Giuseppe; Salvagno, Gian Luca; Montagnana, Martina; Poli, Giovanni; Solero, Giovanni Pietro; Picheth, Geraldo; Guidi, Gian Cesare

2012-01-01

Background and Objective. Some in vitro diagnostic devices (e.g, blood collection vacuum tubes and syringes for blood analyses) are not validated before the quality laboratory managers decide to start using or to change the brand. Frequently, the laboratory or hospital managers select the vacuum tubes for blood collection based on cost considerations or on relevance of a brand. The aim of this study was to validate two dry K3EDTA vacuum tubes of different brands for routine hematological testing. Methods. Blood specimens from 100 volunteers in two different K3EDTA vacuum tubes were collected by a single, expert phlebotomist. The routine hematological testing was done on Advia 2120i hematology system. The significance of the differences between samples was assessed by paired Student's t-test after checking for normality. The level of statistical significance was set at P < 0.05. Results and Conclusions. Different brand's tubes evaluated can represent a clinically relevant source of variations only on mean platelet volume (MPV) and platelet distribution width (PDW). Basically, our validation will permit the laboratory or hospital managers to select the brand's vacuum tubes validated according to him/her technical or economical reasons for routine hematological tests. PMID:22888448

Far Ultraviolet Refractive Index of Optical Materials for Solar Blind Channel (SBC) Filters for HST Advanced Camera for Surveys

NASA Technical Reports Server (NTRS)

Leviton, Douglas B.; Madison, Timothy J.; Petrone, Peter

1998-01-01

Refractive index measurements using the minimum deviation method have been carried out for prisms of a variety of far ultraviolet optical materials used in the manufacture of Solar Blind Channel (SBC) filters for the HST Advanced Camera for Surveys (ACS). Some of the materials measured are gaining popularity in a variety of high technology applications including high power excimer lasers and advanced microlithography optics operating in a wavelength region where high quality knowledge of optical material properties is sparse. Our measurements are of unusually high accuracy and precision for this wavelength region owing to advanced instrumentation in the large vacuum chamber of the Diffraction Grating Evaluation Facility (DGEF) at Goddard Space Flight Center (GSFC). Index values for CaF2, BaF2, LiF, and far ultraviolet grades of synthetic sapphire and synthetic fused silica are reported and compared with values from the literature.

Design and fabrication of a reflection far ultraviolet polarizer and retarder

NASA Technical Reports Server (NTRS)

Kim, Jongmin; Zukic, Muamer; Wilson, Michele M.; Torr, Douglas G.

1993-01-01

New methods have been developed for the design of a far ultraviolet multilayer reflection polarizer and retarder. A MgF2/Al/MgF2 three-layer structure deposited on a thick opaque Al film (substrate) is used for the design of polarizers and retarders. The induced transmission and absorption method is used for the design of a polarizer and layer-by-layer electric field calculation method is used for the design of a quarterwave retarder. In order to fabricate these designs in a conventional high vacuum chamber, we have to minimize the oxidation of the Al layers and somehow characterize the oxidized layer. X-ray photoelectron spectroscopy is used to investigate the amount and profile of oxidation. Depth profiling results and a seven layer oxidation model are presented.

Vacuum Virtues

ERIC Educational Resources Information Center

Rathey, Allen

2007-01-01

Upright vacuums, like cars, vary in quality, features and performance. Like automobiles, some uprights are reliable, others may be problematic, and some become a problem as a result of neglect or improper use. So, how do education institutions make an informed choice and, having done so, ensure that an upright vacuum goes the distance? In this…

Specific ultra-violet absorbance as an indicator measurement of merucry sources in an Adirondack River basin

USGS Publications Warehouse

Burns, Douglas A.; Aiken, George R.; Bradley, Paul M.; Journey, Celeste A.; Schelker, Jakob

2013-01-01

The Adirondack region of New York has been identified as a hot spot where high methylmercury concentrations are found in surface waters and biota, yet mercury (Hg) concentrations vary widely in this region. We collected stream and groundwater samples for Hg and organic carbon analyses across the upper Hudson River, a 493 km2 basin in the central Adirondacks to evaluate and model the sources of variation in filtered total Hg (FTHg) concentrations. Variability in FTHg concentrations during the growing seasons (May-Oct) of 2007-2009 in Fishing Brook, a 66-km2 sub-basin, was better explained by specific ultra-violet absorbance at 254 nm (SUVA254), a measure of organic carbon aromaticity, than by dissolved organic carbon (DOC) concentrations, a commonly used Hg indicator. SUVA254 was a stronger predictor of FTHg concentrations during the growing season than during the dormant season. Multiple linear regression models that included SUVA254 values and DOC concentrations could explain 75 % of the variation in FTHg concentrations on an annual basis and 84 % during the growing season. A multiple linear regression landscape modeling approach applied to 27 synoptic sites across the upper Hudson basin found that higher SUVA254 values are associated with gentler slopes, and greater riparian area, and lower SUVA254 values are associated with an increasing influence of open water. We hypothesize that the strong Hg?SUVA254 relation in this basin reflects distinct patterns of FTHg and SUVA254 that are characteristic of source areas that control the mobilization of Hg to surface waters, and that the seasonal influence of these source areas varies in this heterogeneous basin landscape.

The Galex Time Domain Survey. I. Selection And Classification of Over a Thousand Ultraviolet Variable Sources

NASA Technical Reports Server (NTRS)

Gezari, S.; Martin, D. C.; Forster, K.; Neill, J. D.; Huber, M.; Heckman, T.; Bianchi, L.; Morrissey, P.; Neff, S. G.; Seibert, M.;