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Results for “VACUUM ULTRAVIOLET”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Generation of ultraviolet and vacuum ultraviolet radiation

The paper describes the use of nonlinear optical techniques for the generation of coherent radiation at ultraviolet, vacuum ultraviolet, and soft X-ray wavelengths. Mixtures of metal vapors and inert gases, and other mixed gas systems, allow generation to regions of the spectrum where nonlinear optical crystals are opaque; and also allow generations at high incident power and energy densities. Progress is reported on programs aimed at efficient conversion from 1.064 microns to 3547 A, and from 3547 A to 1182 A. To date, the shortest wavelength generated by this technique is 887 A. Theoretical considerations indicate that generation into the soft X-ray region should be possible. Using 1182 A radiation, a holographic grating with a fringe spacing of 836 A has been constructed and examined on an electron microscope.

Harris, S. E.↗
NASA NTRS1975

Generation of ultraviolet and vacuum ultraviolet radiation

The paper describes nonlinear optical techniques that use phase-matched mixtures of metal vapors and inert gases, or, in certain cases, only inert gases for the generation of ultraviolet radiation. These systems are transparent where nonlinear crystals are opaque and their high ionization permits optical power densities of 10 to the 10 or 10 to the 11 W/sq cm to be utilized. An experiment designed to convert incident 1.064 micron radiation to 3547 A radiation is described as are experiments designed to generate vacuum ultraviolet at 1773, 1520, 1182 and 887 A. Theoretical considerations on the use of this nonlinear optical technique for the generation of soft X-rays are presented and the construction of a vacuum ultraviolet holographic grating with a fringe spacing of 836 A is reported on.

Harris, S. E.↗
NASA NTRS1981

Photon-counting array detectors for space and ground-based studies at ultraviolet and vacuum ultraviolet /VUV/ wavelengths

The Multi-Anode Microchannel Arrays (MAMAs) are a family of photoelectric photon-counting array detectors, with formats as large as (256 x 1024)-pixels that can be operated in a windowless configuration at vacuum ultraviolet (VUV) and soft X-ray wavelengths or in a sealed configuration at ultraviolet and visible wavelengths. This paper describes the construction and modes of operation of (1 x 1024)-pixel and (24 x 1024)-pixel MAMA detector systems that are being built and qualified for use in sounding-rocket spectrometers for solar and stellar observations at wavelengths below 1300 A. The performance characteristics of the MAMA detectors at ultraviolet and VUV wavelengths are also described.

Timothy, J. G.↗
DOE OSTI2016

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

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 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{sub e}-dependent signal within a characteristic divertor detachment equilibration time of ∼10–15 ms is expected.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1992

Radiative lifetimes in B I using ultraviolet and vacuum-ultraviolet laser-induced fluorescence

Radiative lifetimes of the eight lowest even parity levels in the doublet system of B I are measured using time-resolved laser-induced fluorescence in the UV and VUV on an atomic beam of boron. The accurate lifetimes provide a base for improved determination of absolute transition probabilities in B I. The techniques described are broadly applicable to measurement of lifetimes of levels with transitions in the visible, UV, and VUV in almost any element.

O'Brian, T. R.↗
DOE OSTI2020

High-power ultraviolet (UV) and vacuum ultraviolet (VUV) lamps with micro-cavity plasma arrays

A plasma lamp includes plates that are approximately parallel, with at least one array of microcavities formed in a surface of at least one plate. When desirable, the plates are separated a fixed distance by spacers with at least one spacer being placed near the plate's edge to form a hermetic seal therewith. A gas makes contact with the microcavity array. Electrodes capable of delivering a time-varying voltage are located on the surface of each plate. At least one electrode is located on an exterior surface of at least one interior plate. Optionally, protective windows may be placed over the electrodes. The application of the time-varying voltage interacts with the gas to form a glow discharge plasma in the microcavities and the fixed volume between the plates (when present). The glow discharge plasma efficiently and uniformly emits UV/VUV radiation over the entire surface of the lamp.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

High-power ultraviolet (UV) and vacuum ultraviolet (VUV) lamps with micro-cavity plasma arrays

A product having at least one plasma lamp that includes plates that are approximately parallel, with at least one array of microcavities formed in a surface of at least one plate. When desirable, the plates are separated a fixed distance by spacers with at least one spacer being placed near the plate's edge to form a hermetic seal therewith. A gas makes contact with the microcavity array. Electrodes capable of delivering a time-varying voltage are located such that the application of the time-varying voltage interacts with the gas to form a glow discharge plasma in the microcavities and the fixed volume between the plates. The glow discharge plasma efficiently and uniformly emits radiation that is predominantly in the UV/VUV spectral range with at least a portion of the radiation being emitted from the plasma lamp.

Park, Sung-Jin↗
NASA NTRS1990

Vacuum ultraviolet thin films. I - Optical constants of BaF2, CaF2, LaF3, MgF2, Al2O3, HfO2, and SiO2 thin films. II - Vacuum ultraviolet all-dielectric narrowband filters

An iteration process matching calculated and measured reflectance and transmittance values in the 120-230 nm VUV region is presently used to ascertain the optical constants of bulk MgF2, as well as films of BaF2, CaF2, LaF3, MgF2, Al2O3, HfO2, and SiO2 deposited on MgF2 substrates. In the second part of this work, a design concept is demonstrated for two filters, employing rapidly changing extinction coefficients, centered at 135 nm for BaF2 and 141 nm for SiO2. These filters are shown to yield excellent narrowband spectral performance in combination with narrowband reflection filters.

Zukic, Muamer↗
DOE OSTI2020

Reflectance of Silicon Photomultipliers at Vacuum Ultraviolet Wavelengths

Characterization of the vacuum ultraviolet (VUV) reflectance of silicon photomultipliers (SiPMs) is important for large-scale SiPM-based photodetector systems. In this work, we report the angular dependence of the specular reflectance in vacuum of SiPMs manufactured by Fondazionc Bruno Kessler (FBK) and Hamamatsu Photonics K.K. (HPK) over wavelengths ranging from 120 to 280 nm. Refractive index and extinction coefficient of the thin silicon-dioxide film deposited on the surface of the FBK SiPMs are derived from reflectance data of an FBK silicon wafer with the same deposited oxide film as SiPMs. The diffuse reflectance of SiPMs is also measured at 193 nm. We use the VUV spectral dependence of the optical constants to predict the reflectance of the FBK silicon wafer and FBK SiPMs in liquid xenon.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗