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  • 1
    Electronic Resource
    Electronic Resource
    Beam quality of direct nuclear pumped laser amplifiers (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 6789-6798 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The achievable beam quality resulting from heavy charged particle pumping of transverse flow, gas laser amplifiers is presented. The charged particles are generated by nuclear reactions in either B4C or UO2 coated on plates parallel to the lasant flow. The character of the laser medium aberration resulting from the nonuniform energy deposition and fluid dynamic effects is discussed as well as the effects on the far-field beam quality of the amplifier. Pumping from plates parallel to the flow produces a medium aberration which is dominated by a cylindrical focus perpendicular to the flow, and a tilt in the flow direction. Beam qualities of better than 2 times diffraction limited (TDL) are obtained with a B4C fueled 1-m-long amplifier pumped at an average power deposition of 100 W/cm3 with an inlet 0.1-MPa helium flow at 100 m/s. Amplifiers using UO2 fuel coatings to pump argon under the same flow conditions with fission fragments have similar qualitative laser medium aberrations but with larger magnitude, resulting in beam qualities of (approximately-greater-than)20 TDL for a 100 W/cm3 average power deposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347668
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Enthalpy probe performance in compressible thermal plasma jets (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 3585-3593 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Enthalpy probe measurements in compressible argon/helium thermal plasma jets are compared with results from high spectral resolution laser light scattering. In the laser scattering measurement the plasma temperature and velocity are determined directly from high-resolution line-shape analysis of light scattered by the plasma. The technique yields an unambiguous determination of gas or kinetic temperature without the assumption of local thermodynamic equilibrium. Velocity is determined directly from the measured Doppler shift. The enthalpy probe is a combination stagnation probe and flowing calorimeter. Gas temperatures and velocities are calculated from measured values using both frozen flow and equilibrium flow assumptions for the stagnation process. Over the Mach number range examined, the assumption of isentropic, frozen composition stagnation best matches the laser results. In the jet periphery a significant streamline displacement is caused by the presence of the probe. The displacement, which is a function of the nondimensional radial velocity gradient, distorts the velocity and temperature results in the wings of the profiles. In the core of the jets examined, probe measurements in both subsonic and supersonic compressible flows show excellent agreement with laser scattering results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144285
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of enthalpy probe and laser light scattering measurement of thermal plasma temperatures and velocities (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 711-718 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Gas temperature and velocity profiles in argon thermal plasmas, measured by an enthalpy probe and high spectral resolution laser light scattering, are compared. In the laser scattering measurement the plasma temperature and velocity are determined directly from high-resolution Doppler-shifted line-shape analysis of light scattered by the plasma. The technique yields an unambiguous determination of gas or kinetic temperature without the assumption of local thermodynamic equilibrium. Velocity is determined directly from the measured Doppler shift. The enthalpy probe is a combination Pitot tube and flowing calorimeter. The assumption of thermodynamic equilibrium is required to obtain velocity and temperature from measured enthalpy and stagnation pressure. Peak temperature and velocity values observed were ∼13 000 K and 1300 m s−1. The results from both the intrusive enthalpy probe and nonintrusive laser light scattering technique compare favorably. The limitations of both techniques are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144203
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Modular enthalpy probe and gas analyzer for thermal plasma measurements (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 56-62 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The enthalpy or calorimetric probe is a water-cooled stagnation/sampling probe for studying the temperature, velocity, and composition of hot-gas flow fields. In order to derive the thermodynamic properties of complex flow fields such as plasma arc jets or high-velocity oxygen fuel jets, the specie concentration must be known accurately. To this end a differentially pumped quadrapole mass spectrometer has been integrated with a fully automated enthalpy probe system. An inexpensive modular probe is described along with the system and its theory of operation. Calibration and error are also discussed. Typical results are presented for the system operating in an argon/helium plasma arc jet in atmospheric pressure air. The maximum temperature measured is 13434 K on the center line of the jet, 5 mm from the exit, with a corresponding velocity of 1295 m/s. The utility in integrating the mass spectrometer to the enthalpy probe system is not only an accurate measurement of the gas mixture components for obtaining the correct property information, but also valuable information can be obtained about demixing diffusion and chemical reaction taking place in the plasma plume. The relative amount of argon to helium is shown to deviate from the nominal mixture by as much as 40% at the center of the plume.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144402
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  • 5
    Electronic Resource
    Electronic Resource
    A Computational Examination of the Sources of Statistical Variance in Particle Parameters During Thermal Plasma Spraying (2000)
    Springer
    Plasma chemistry and plasma processing 20 (2000), S. 299-324 
    Details
    ISSN: 1572-8986
    Keywords: Plasma spraying ; computational model ; plasma jet ; particle injection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Computational modeling is used to systematically examine many of the sources of statistical variance in particle parameters during thermal plasma spraying. Using the computer program LAVA, a steady-state plasma jet typical of a commercial torch at normal operating conditions, is first developed. Then, assuming a single particle composition(ZrO2) and injection location, real world complexity (e.g., turbulent dispersion, particle size and density, injection velocity, and direction) is introduced ``one phenomenon at a time” to distinguish and characterize its effect and enable comparisons of separate effects. Calculations are also performed wherein all phenomena are considered simultaneously to enable further comparisons. Both nonswirling and swirling plasma flow fields are considered. Investigating each phenomenon separately provides valuable insight into particle behavior. For the typical plasma jet and injection conditions considered, particle dispersion in the injection direction is mostsignificantly affected by (in order of decreasing importance): particle size distribution, injection velocity distribution, turbulence, and injection direction distribution or particle density distribution. Only the distribution of injection directions and turbulence affect dispersion normal to the injection direction and are of similar magnitude in this study. With regards to particle velocity and temperature, particle size is clearly the dominant effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007088110319
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  • 6
    Electronic Resource
    Electronic Resource
    Tomographic reconstruction of volume emission coefficients from line integral data (1986)
    Springer
    Plasma chemistry and plasma processing 6 (1986), S. 127-141 
    Details
    ISSN: 1572-8986
    Keywords: Tomography ; emission coefficients ; nonsymmetric plasmas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The technique of reconstructive tomography (RT) is a powerful method of obtaining local, spatially resolved volumetric emission coefficients from line integral data. The applicability of this technique as a diagnostic for nonuniform sources is studied using simulated data with and without noise. The major advantage of RT techniques is that they may be applied, without restriction, to highly asymmetric data as well as symmetric data. When applied to symmetric data, the technique appears to be less susceptible to noise than Abel inversion techniques. Also examined is a method of accounting for self-absorption under certain circumstances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00571272
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  • 7
    Electronic Resource
    Electronic Resource
    Plasma spraying of alumina: Plasma and particle flow fields (1993)
    Springer
    Plasma chemistry and plasma processing 13 (1993), S. 579-600 
    Details
    ISSN: 1572-8986
    Keywords: Plasma spraying ; alumina ; plasma jet and particle diagnostics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A comprehensive experimental examination of the interaction between a subsonic thermal plasma jet and injected alumine, particles is presented. Measurements of plasma velocity, temperature, and entrained air were obtained from an enthalpy probe and mass spectrometer combination. A diffusive separation, or demixing, of the Ar and He plasma gas was observed. Centerline plasma velocities and temperatures ranged from 1501500 m/s and 2000 to 14,000 K, respectively, in the region between the torch and a typical substrate location of 90 mm. Measurements of particle size, velocity, tempearture and local number density were obtained from a combination laser particle sizing system, Laser doppler velocimeter (LDV), and two-color pyrometer. Centerline temperatures and velocities for the nominally 30 μm particles used were 2400–2800 K and 150–200 m/s, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01570132
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