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  • 1990-1994  (31)
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  • 1
    Electronic Resource
    Electronic Resource
    Magnetic laser discharge stabilization scaling to high-pressure systems (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6761-6765 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The application of the magnetic discharge stabilization technique to high-pressure laser discharges is investigated. Scaling laws are developed with the help of Monte Carlo simulations for the transverse discharge velocity and for the magnetic field strength that is necessary for discharge stability. The results that are obtained indicate that the required magnetic field strength scales as the pressure squared. Unless a cost-effective means is found for implementing a very strong magnetic field into an electrode design, the magnetic discharge stabilization technique will be mainly relegated to low-pressure systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349850
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  • 2
    Electronic Resource
    Electronic Resource
    Electron dynamics in magnetized CO2 laser and He discharges (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 3935-3946 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The energy density of the electron flux in magnetized 30-Torr He and He:N2:CO2 dc glow discharges was obtained by Monte Carlo simulation of the cathode region. The application of transverse magnetic fields to the cathode region caused an increase in collisions. This effect became increasingly important in the second half of the cathode region, where magnetic trapping of high-energy electrons occurred. Ionization was enhanced in the cathode region as well as the negative glow, with maximal electron multiplication observed for magnetic field strengths of approximately 0.1 T. This suggests both that a lower cathode fall may be possible in a magnetized discharge and that the electric field reversal in the negative glow will be accentuated. Thus, magnetization of the cathode region may improve the electrical efficiency of CO2 lasers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346279
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  • 3
    Electronic Resource
    Electronic Resource
    Gain and saturation parameters of a multichannel large-area discharge CO2 laser (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 4156-4161 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Details of an experimental investigation of the gain and saturation intensity of a multichannel extended-area discharge CO2 laser are presented. Measurements were made as a function of several discharge parameters. The gain coefficient was found to be similar in each of the individual discharge regions, having a maximum value of 0.70%/cm. Effects of gas pressure, gas mixture, and input power on gain and saturation parameters were studied. The saturation intensity varied as the square of the total gas pressure. The central interelectrode region of the device, which contained no visible discharge, exhibited a significant level of gain. The investigation reported herein provided important data for the design and optimization of optical extraction configurations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352848
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  • 4
    Electronic Resource
    Electronic Resource
    High performance automatic alignment and power stabilization system for a multikilowatt CO2 laser (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 1859-1866 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A beam profile sensor for use in an automatic alignment and power stabilization system for a multikilowatt CO2 laser is described. An inexpensive pyroelectric array is used in conjunction with a diamond machined rotating wand, to provide on-line samples of the laser beam. Interface circuits utilize the multiple outputs derived from the detector array for precise monitoring and control of the laser's output radiation. Data from a 5-kW CO2 laser are presented to characterize the response of this new beam profile sensor to major perturbations in the optical cavity and lasing gas chemistry. The device has demonstrated exceptional performance in the maintenance of both mode quality and optical power level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143295
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  • 5
    Electronic Resource
    Electronic Resource
    Variable coupling rotational wand for on-line laser beam sampling (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2482-2487 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: As power levels of industrial lasers increase, effective determination of beam profiles over extended operational regimes becomes problematic, due to dynamic range limitations of available detectors. To address this deficiency, a variable coupling rotating wand was developed for on-line monitoring of output radiation from high average power CO2 lasers. The concept features real-time beam sampling adjustment, activated by wand rotational speed change. An associated controller provides appropriate speed regulation of the wand motor drive, via a computer generated setpoint. Design parameters thereby ensure optimal sensor operation at all power levels. A safety override prevents sensor damage by terminating laser operation, if wand speed decreases below a safe value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143907
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  • 6
    Electronic Resource
    Electronic Resource
    Spark channel plasma electrode (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2625-2627 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A plasma electrode potentially suitable for dc discharge pumped lasers has been developed based on the repetitive creation of a spark channel. The high-density plasma within the arc serves as a source of charge carriers for the dc discharge, thereby largely eliminating the cathode fall. Reduction in the cathode fall potential improves with increasing spark repetition frequency until about 9 kHz, after which a constant, near-zero value is achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104814
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  • 7
    Electronic Resource
    Electronic Resource
    Multichannel slab discharge for CO2 laser excitation (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 693-695 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental results on a unique multichannel slab-type CO2 discharge system are presented. The interdigital discharge geometry incorporates both large-area and multibeam laser array concepts into a single, compact package. Small signal gain and saturation intensity values indicate that this structure is well suited for use in a CO2 laser.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105220
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  • 8
    Electronic Resource
    Electronic Resource
    Direct visualization of the focal parameters of a high power CO2 laser beam (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3616-3620 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A diagnostic method for high power CO2 laser beams is presented. The technique features imaging of high intensity infrared radiation via the thermally induced luminosity of high velocity charcoal particles contained within an air stream. The method is particularly convenient for determination of focal position, depth of field, beam diameter, and spot size. Variations of these parameters with power level are easily observed utilizing this charcoal powder imaging method. Using this "real-time'' technique, focal spot size and location accuracy are ±0.1 and ±1 mm, respectively. Results are shown to be independent of micro-particle size within specified limits. As a result, periodic, fine laser-workpiece adjustment is now cost effective when working with high power lasers. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144481
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  • 9
    Electronic Resource
    Electronic Resource
    Truncated cone as a pseudoconjugator in a high-power carbon dioxide laser (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2488-2492 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The incorporation of a retroreflecting, pseudoconjugating cone as a folding element in a double-pass unstable resonator of a high-power carbon dioxide oscillator–amplifier is presented. The concept, when implemented with a truncated cone, has yielded significant improvements in optical energy extraction efficiency, beam quality, and alignment stability. The performance of such a modified clear aperture cone resonator, in comparison with a standard roof prism cavity geometry, is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143908
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  • 10
    Electronic Resource
    Electronic Resource
    Optimization of photoinitiated impulse-enhanced electrically excited CO2 laser discharges by attachment control (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1445-1450 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Control of frequency and amplitude of the impulses used in photoinitiated, impulse-enhanced, electrically excited laser pumping determines the E/p value of the discharge. This occurs through the influence of these impulses on the processes of electron density decay and ion-electron recombination and dissociative attachment. The degree of attachment can be controlled through the use of high-frequency excitation (f(approximately-greater-than)10 kHz), while the relative importance of ion-electron recombination increases with increasing impulse potentials. The reduced electric field E/p can thus be varied by a factor of 3, while the anode fall potential Va can be reduced from 400 to 250 V. This technique appears amenable to providing fine variation and control of the laser output power. Possible applications in materials processing are pulse shaping and rapid power modulation (superpulsing).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144060
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