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  • 1
    Electronic Resource
    Electronic Resource
    Self-consistent model of high current density segmented hollow cathode discharges (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 554-568 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A two-dimensional model of the hollow cathode and the high-voltage segmented hollow cathode sputtering discharges at high current densities is presented. The main plasma parameters (e.g., complete electron distribution function, spatial distributions of particle densities, gas temperature, etc.) are determined self-consistently. The most important mechanisms contributing to the operating characteristics of these hollow cathode discharges are identified and described quantitatively. The most representative hollow cathode configurations are analyzed and the results are compared to existing experimental data for the helium-argon-copper system, e.g., voltage-current characteristics, density of copper atoms as a function of the discharge current, and percentage argon. Good agreement is found between model predictions and experimental results. The model can be adapted to other high-voltage variants of the hollow cathode discharges. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364198
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  • 2
    Electronic Resource
    Electronic Resource
    Atomic populations of copper and gold in a room-temperature metal vapor laser (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 2794-2799 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Sputtering in the presence of a rapid flow of gas can project a column of metal vapor with a mean Cu i ground-state concentration along the optical axis of about 3×1014 cm−3. The effective gain length using a single cathode is limited to about 20 cm for both Cu i and Au i, due to the radial expansion of the metal vapor column. The laser has been studied for double pulsed operation during a single sputtering pulse. The ratio of the peak power for the second laser pulse to that of the first, ρ, increases with interpulse delay from zero at short delays to a constant value which is less than or equal to unity. The buildup of ρ occurs on a 700-μs time scale due to the residual ionization resulting from the first discharge pulse. The constant value decreases with increasing capacitor voltage for both the Cu i and Au i lines due to the radial flow of metal atoms from the optical cavity, which results from the transient heating of the metal vapor column.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344206
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  • 3
    Electronic Resource
    Electronic Resource
    Parametric study of a room-temperature metal vapor laser (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 4285-4292 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have demonstrated laser operation at room temperature on the Cui (511,578 nm) and Aui (312,628 nm) transitions and obtained specific pulse energies for the Cui 511 nm and Aui 628 nm lines of about 5 and 2 μJ cm−3, respectively, from a single-section tube. A simple theoretical model has been used to show that the reduced outputs for the Cui 578 nm and Aui 312 nm lines are due to the significantly smaller fraction of the working volume in saturation in each case. The metal vapor column of length 20 cm and local ground-state concentration in the 1014–1015 cm−3 range is produced on demand in a single-section tube in less than 10 ms. The highest output power obtained is for a 90% He in an Ar/He mixture at a total flowrate of 1.8 l min−1, the tube pressure being 20 mbar. A specific sputtering discharge energy of approximately 600 mJ cm−3 is needed to obtain a peak power of 1 kW on either the Cui 511 nm or Aui 628 nm lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341302
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  • 4
    Electronic Resource
    Electronic Resource
    The preionized metal vapor jet of a room-temperature metal vapor laser (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 2861-2867 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the room-temperature metal vapor laser studied, a rapid flow of noble gas entrains sputtered metal atoms, metal ions, and gas ions into the laser discharge volume in the form of a narrow jet. A short rise-time discharge pumps the laser transition and is observed to concentrate onto the preionized metal vapor jet. Radial and axial measurements of the electron temperature and ion number density in the preionized jet have been made using an instantaneous triple probe, and show that the ions are concentrated within the jet and extend up to about 20 cm downstream from the sputtering cell. Electrons are carried along the jet by an axial ambipolar field, and are most energetic at the boundary of the jet where they are heated through three-body recombination. Under certain conditions, flowing gas through the sputtering glow discharge causes the plasma to oscillate with a period of between 2 and 20 μs. These oscillations are due to plasma instabilities associated with the anode glow, and have been eliminated by a suitable arrangement of the discharge electrodes. In so doing the anode glow has been extinguished, the slope resistance of the sputtering discharge reduced, and the performance of the sputtering cell improved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341597
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  • 5
    Electronic Resource
    Electronic Resource
    Gain measurements at 780.8 nm in a copper hollow anode cathode laser (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 64-69 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The results of a parametric study of a copper hollow anode cathode laser operating on the He-Cu+ infrared lines are reported. The discharge voltage, the small-signal unsaturated gain on the 780.8-nm transition, and the ground-state copper atom concentration each exhibit a universal dependence on the ratio J/p of the discharge current density to the total pressure of the helium-argon buffer gas mixture. The laser output power dependencies (780.8 and 782.5 nm) on J/p, while not resulting in universal curves, have common threshold values of J/p. The threshold value of J/p for the 782.5-nm line is approximately twice that for the 780.8-nm line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350647
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  • 6
    Electronic Resource
    Electronic Resource
    Magnetic field enhanced performance of a copper hollow anode cathode laser (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5338-5343 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The output beam power and small-signal unsaturated gain on the He-Cu 780.8 nm transition in a hollow slotted-anode cathode laser are increased significantly by the application of a longitudinal magnetic field and each shows a marked dependence on the field in the range 10 to 40 mT. The laser output power and the gain increase with the discharge current, while the optimum magnetic field (∼22 mT) results in a further significant increase both in output power and gain. These effects have their origin in the transverse deflection of the beam electrons by the magnetic field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350550
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  • 7
    Electronic Resource
    Electronic Resource
    Sputtering in the presence of a rapid gas flow (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1418-1424 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A rapid flow of noble gas through a hollow cathode glow discharge can be used to entrain a proportion of the sputtered metal atoms and form an extended high-concentration jet. This technique has been used previously to demonstrate copper i and gold i laser action at room temperature. We develop a model to predict the dependence of the ground-state metal atom concentration on the current density and the entrainment in such a system. The sputtering process depends on charge transfer collisions between metal atoms and noble gas ions. By fitting experimental results for a copper cathode to the theoretical predictions, values are found for the rate constant of this reaction and for the entrainment efficiency. In an argon/helium gas mixture, the optimum volume fraction of helium is approximately 90%. The main effects of the helium are to decrease the number of ion collisions in the cathode dark space (leading to increased sputtering yields) and to improve the charge transfer process, although there are a number of additional effects. The time and current dependencies of the copper atom concentration in the cathode region are compared with corresponding measurements taken downstream in the jet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341814
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  • 8
    Electronic Resource
    Electronic Resource
    Linewidths of Cu i(511 nm) and Au i(628 nm) laser transitions at room temperature (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 414-416 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Sharp spectral lines are obtained for the Cu i 511 nm and the Au i 628 nm transitions from a sputtering-based laser operating at room temperature. The Au i line exhibits a single peak with a linewidth of 360 MHz and the Cu i line consists of three well-resolved peaks with linewidths of 800, 700, and 700 MHz in order of increasing frequency. The spectral lines result from saturated emission on the strongest hyperfine components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102797
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  • 9
    Electronic Resource
    Electronic Resource
    The mechanisms of the formation and growth of water bubbles and associated dislocation loops in synthetic quartz (1983)
    Springer
    Physics and chemistry of minerals 9 (1983), S. 79-94 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The development of water bubbles in synthetic quartz has been monitored by measurements of (i) the intensity of the light scattered and (ii) the increase in volume of the crystal, both as a function of temperature and time. These macroscopic measurements have been complemented by observations of the resulting microstructures, using transmission electron microscopy (TEM). A mechanism is proposed on the assumption that hydrogen is incorporated in the quartz structure by means of (4 H)Si defects. On heating, these defects diffuse and clusters develop. A cluster of n(4 H)Si produces a water bubble of (n−1)H2O, without any change of volume of the crystal. At any temperature T there is a critical bubble diameter above which the “steam” pressure P exceeds the pressure p for a spherical bubble in mechanical equilibrium. If P becomes greater than p, then the bubble increases in volume until P=p, the increase in volume being achieved by the pipe diffusion of Si and O away from the bubble site into a linked edge dislocation loop. This process produces the observed increase in volume of the crystal. The two diffusion processes take place virtually simultaneously and continue until all the (4 H)Si defects have been trapped in the bubbles. Values of the diffusion constant and the activation energy for the diffusion of the (4 H)Si defects are deduced. The relevance of these observations to the hydrolytic weakening of quartz is briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00308151
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  • 10
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    Compact room‐temperature metal vapor laser (1986)
    American Institute of Physics
    Details
    Publication Date: 1986-10-13
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Published by American Institute of Physics
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