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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1460-1464 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spectra of highly ionized titanium and calcium in the extreme ultraviolet region were observed in laser-produced plasmas using the OMEGA 24 beam (351 nm) laser system at the University of Rochester. The plasmas were produced using glass microballoon targets coated with a layer of a medium Z element and a layer of parylene (CH). Time-integrated electron temperatures and densities were obtained by comparing measured line intensity ratios of lithiumlike charge states of Ti and Ca to numerical calculations from a collisional-radiative model. The variation of line intensity ratios with electron density and temperature using the collisional-radiative model is discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 1246-1251 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The preheating of laser-heated microballoon targets has been measured by time-resolved x-ray and extreme ultraviolet (euv) spectroscopy on the 30 kJ, 60-beam (maxima), 351 nm, laser-fusion system at the University of Rochester Laboratory for Laser Energetics. Thin coatings of aluminum overcoated with magnesium served as indicators. Both the sequence of the x-ray line emission and the intensity of euv radiation were used to determine a preheating peaking at ∼10 nsec prior to onset of the main laser pulse, with a power density (approximately-less-than)1% of the main pulse. The measurements are supported by numerical modeling. Further information is provided by absorption spectra from the aluminum coating, backlighted by continuum from the heated surface. The exact source of the preheating energy remains unknown at present, but most likely arrives from early laser leakage through the system. The present target diagnostic is particularly useful when all beams cannot be monitored directly at all laser wavelengths. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2260-2267 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A neon Z-pinch plasma, appropriate for sodium/neon photopumping experiments, is studied in detail using temporally, spatially, and spectrally resolved measurements of Ne VII, Ne VIII, and Ne IX emissions. The neon is imploded with a 1 μs rise time, 150–180 kA peak current pulse. Two successive implosions are identified. The first implosion produces a 1-mm-diam plasma with an electron density of 9×1019 cm−3 and a temperature of 200 eV. The second implosion produces a larger diameter (3.5 mm), less dense (7×1018 cm−3) plasma with a temperature of 100 eV. A 70% Ne IX ground-state population at the second implosion is deduced from the measurements.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 3163-3168 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The absolute intensity of near-ultraviolet emission from a neon Z-pinch plasma is measured with a time-gated, two-dimensional optical multichannel analyzer (OMA). The OMA provides spatial and spectral resolution with a 100 ns gate duration. Spatially resolved continuum emission, Ne viii line emission, and Ne viii line-profile measurements are used to determine the pinch diameter, the density of the neon plasma, and the Ne viii 3p level population.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 1253-1262 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spectral line shifts have been observed in the Dα transition of neutral deuterium in the Alcator C-mod [I. H. Hutchinson, Proceedings of the IEEE 13th Symposium on Fusion Engineering (IEEE, Piscataway, 1990), Vol. 1, p. 13] tokamak and interpreted as Doppler shifts due to a neutral flow of approximately 5×103 m/s. The emission originates from plasma at the inner wall, as indicated by the Zeeman patterns of the transition. The direction of the flow changes when the plasma transitions from a limited to a diverted configuration. In all cases, the flows are directed toward the point of contact with the wall or divertor plate. Narrow spectral profiles have been observed for the Dα transition near the midplane and within the divertor. Temperatures not higher than 0.86 eV are indicated for the divertor measurements. A difference in plasma conditions for separate locations along a single line of sight has been observed. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 2847-2852 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The temporal evolution of the radial profile of lithium-like oxygen (OVI or O5+) 3d-4f, 52.0 nm emission from 80 ns rise time, 6–16 kA peak current, pulsed capillary discharges in 1 mm diam, 1 cm long polyacetal capillaries, has been studied. Evidence was seen for a central "flattening'' in this emission. Extreme-ultraviolet, time-integrated, pinhole transmission grating spectra were taken of discharges at 16 and 23 kA peak currents in 0.5 mm diam, 1 cm long capillaries. Spectra obtained at the higher peak current (23 kA) showed evidence of helium-like (CV or C4+) and/or hydrogen-like carbon (CV or C5+) resonance line emission (4.0 and 3.4 nm wavelength) filling the capillary diameter. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electron density in the edge, divertor and X-point regions of Alcator C-Mod [Proceedings of the IEEE 13th Symposium on Fusion Engineering (Institute of Electrical and Electronic Engineers, New York, 1990), Vol. 1, p. 13] has been measured using the Stark broadening of high-n (n=8 through 11) transitions of the Balmer series of deuterium. These measurements have been made during typical single null, diverted operation and during gas-puffing through capillaries located within the first wall and divertor. Electron densities up to 1.6×1021 m−3 have been measured in the X-point region and slightly lower densities (5−7×1020 m−3) have been measured in the divertor and edge regions. These results are factors of 2 to 5 larger than the density measurements from the CO2 laser interferometer system in the main chamber (3×1020 m−3) and comparable with probe measurements in the divertor. The ratios of the widths of adjacent lines within the Balmer series have been compared with ratios calculated for the Stark broadening of these lines. These transitions can be used to measure electron densities from 3×1019 to 2×1021 m−3 with a modest resolution spectrograph [(Δλinst=1 A(ring) full width at half maximum)]. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 28 (1985), S. 3027-3033 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A Thomson scattering diagnostic capable of achieving one-discharge, high-resolution spectra through use of a microchannel plate image intensifier coupled to an optical multichannel analyzer has been implemented on a theta-pinch device. The improved resolution permits measurements of local average electron velocities and current densities. First-order relativistic corrections and anomalous velocity-space fluctuations are directly observable. The enhanced fluctuations are attributed to electrons interacting with unstable waves.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 2430-2436 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The quenching of spontaneous emission coefficients, presumably by electron collisions, which was recently inferred at Princeton from measured intensity ratios of visible and extreme-ultraviolet lines from a common upper level in laser blow-off plasmas, was investigated using a ruby laser. The line intensity ratios of the Civ 3s-3p and 2s-3p transitions, for similar laser targets, show a similar dependence on separation from the target as the previous experiments. Both of these results can, however, be interpreted in terms of density gradients and Stark broadening without invalidating Einstein A values. This interpretation also applies to Ciii and Nv line intensity ratios, which are further compromised by blends with other lines. The quenching of Arii lines by photon collisions, which had been reported by the same Princeton group, can finally be shown to have been mimicked by other effects, in this case by the Rabi oscillations and associated power broadening in the argon ion laser cavity.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 2058-2058 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A laser-produced plasma generates blast waves as it expands supersonically into a stationary photoionized background gas (N2) at a pressure of 1–5 Torr.1 Using a combination of spectroscopic and interferometric measurements, time- and space-resolved values of the temperature and density are obtained. This study was performed on targets in the NRL Pharos III laser facility with laser energies of 20–120 J and pulse durations of ∼5 ns. A 1-m spectrograph equipped with three photomultiplier channels, which are calibrated on an absolute scale, is used for the spectroscopic measurements. The interferometry is done with a folded-wavefront interferometer. It uses an optical probe pulse at 5270 A(ring) that is split off of the main laser pulse, reduced in pulse duration (∼300 ps), and time delayed. Interferometric measurements can be made simultaneously with the spectroscopic measurements. Experimental data and the technique of analysis will be shown. This work was supported by the Defense Nuclear Agency.
    Type of Medium: Electronic Resource
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