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  • 1
    Electronic Resource
    Electronic Resource
    On the growth of segregated C layers on top of Fe films on pyrolytic graphite samples during high-fluence D+ irradiation at elevated temperature (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 3400-3406 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: On Fe films evaporated on pyrolytic graphite, thick C layers segregate during high-temperature (above about 800 K) light ion irradiation if the penetrating ions are energetic enough to reach the Fe-graphite interface. The thickness of the C segregated layer and the C depth distribution in the Fe film have been determined with 2-MeV 4He+ Rutherford backscattering. A steady-state carbon overlayer is reached at high fluences (above about 1019 particles/cm2), the thickness of which depends on the energy of the irradiating beam for a given thickness of the Fe evaporated film. The anisotropic structure of the pyrolytic graphite substrate influences the thickness of the steady-state C overlayer, thicker C layers being measured for edge-oriented C substrates. Using the Monte Carlo code trim, the production of defects in the graphite substrate has been calculated for different thicknesses of the C overlayer. The total amount of defects produced in the graphite substrate has been identified as the parameter regulating the growth and the steady-state value of the C overlayer. With the depth distributions of defect production generated by trim as source functions, the diffusion of C interstitials in graphite under the influence of recombination with vacancies has been modeled. The segregating C fluxes are identified with the fluxes of interstitials arriving at the Fe/graphite substrate interface for a suitable choice of the parameters in the diffusion equation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342656
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  • 2
    Electronic Resource
    Electronic Resource
    Radiation damage and annealing in graphite implanted with H+2 and Mo+ (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 2603-2608 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Radiation damage due to H+2 and Mo+ implantation into hot-worked pyrolytic graphite and into single-crystal graphite flakes has been studied using 1-MeV 4He+ ion channeling. The implant energies used, 35 keV for H+2 and 120 keV for Mo+, yielded ranges of about 1600 and 600 A(ring), respectively. For H2 implantation, a partially crystalline surface layer remains after a fluence of 2×1016 H/cm2; this layer is completely disordered at 2×1017 H/cm2. At higher hydrogen fluences a surface layer exfoliates. For Mo implantation the disorder introduced at a fluence of 5×1014 Mo/cm2 is sufficient to prevent channeling throughout the range. For both implant species, complete recrystallization of samples disordered up to the surface occurs for annealing only at temperatures above 2800 K. If a surface layer remains crystalline after implantation, recrystallization proceeds both from the bulk and from the surface, and crystallinity is restored at 2300 K. While hydrogen is known to be released at temperatures between 1100 and 1500 K, Mo remains within its original range distribution up to the temperature of complete recrystallization. At a temperature of 2300 K an ordering of the implanted Mo atoms with respect to the c axis is observed, indicating short-range migration within the range distribution. At 2800 K no more Mo could be found in the analyzed surface layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340997
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  • 3
    Electronic Resource
    Electronic Resource
    Theory of first-order plasma heating by collisional magnetic pumping (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 1034-1041 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Plasma heating by collisional magnetic pumping is investigated theoretically. This treatment yields solutions to the energy transfer equations in the form of an energy increase rate, which gives quantitatively the amount of energy increase per rf driving cycle. The energy increase rates (or heating rates) proportional to the first and second powers of the field modulation factor δ (defined as the ratio of the change in the magnitude of the magnetic field to its background dc value) are derived for an arbitrary rf waveform of the pumping magnetic field. Special cases are examined, including the sinusoidal and sawtooth pumping waveforms. The energy increase rate in the case of a sawtooth waveform was found to be proportional to the first power of δ (first-order heating). This heating rate is many orders of magnitude larger than heating for the sinusoidal case: The latter is proportional to the square of δ and is strongly dependent on the collisionality of the plasma. The use of a sawtooth pumping waveform improves the efficiency of collisional magnetic pumping and heating rates comparable to those possible with ion or electron cyclotron resonance heating methods may be achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859025
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  • 4
    Electronic Resource
    Electronic Resource
    Computational treatment of collisional magnetic pumping (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 1155-1162 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: When collisional magnetic pumping is applied to a plasma, the heating rate depends strongly on the nature of the waveform of the magnetic perturbation, whether sinusoidal, triangular, or sawtoothed in time. Numerical solutions to the energy transfer problem are obtained when these waveforms are applied to heat a plasma, and compared with previously obtained analytical results using small perturbation theory where these results are available. A specially written fortran program computes the numerical values of the parallel, perpendicular, and total energy at each time increment. The plasma heating rates and optimum heating conditions derived from this study are in good agreement with analytical limiting cases and available experimental data, except when the perturbation amplitude becomes large enough that the analytical results no longer hold.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858991
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  • 5
    Electronic Resource
    Electronic Resource
    Deceleration ion optical system for sputtering measurements between 50 and 500 eV as function of angle of incidence (1987)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 1830-1832 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A deceleration system for a parallel ion beam in the energy range of 50 to 500 eV is described. The system is used for sputtering yield measurements as a function of the angle of ion incidence. Measured yield data for Cu and Au sputtered by 100- and 300-eV D+ ions are reported and compared to computer calculations. Experimental and calculated data show only a weak dependence on the angle of incidence. However, at glancing incidence the experimental values are larger up to a factor of 2 compared to the calculated ones. This is attributed to the surface roughness not included in the calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139527
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  • 6
    Electronic Resource
    Electronic Resource
    Photographic quantitation in spark source mass spectrography using an on-line densitometer and ion intensity areas (1974)
    s.l. : American Chemical Society
    Analytical chemistry 46 (1974), S. 701-706 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac60342a007
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  • 7
    Electronic Resource
    Electronic Resource
    Mechanism of hydrocarbon formation upon interaction of energetic hydrogen ions with graphite (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 964-966 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The current model for hydrocarbon formation upon the interaction of energetic hydrogen ions with graphite assumes a reaction of adsorbed hydrogen with carbon surface atoms requiring a temperature of 800–900 K. This model is strongly questioned by results of hydrocarbon formation from a layered 13C/12C sample and by desorption measurements after room-temperature implantation. The formation of 13CD4 and 12CD4 is monitored during deuterium bombardment of a pyrolytic graphite sample covered with a layer of 200 A(ring) of 13C. Only for ion energies corresponding to ranges smaller than 200 A(ring) 13CD4 dominates, while at higher energies only 12CD4 is found. The methane is thus formed at the end of ion range rather than in a surface reaction of back-diffusing ions. Desorption experiments using a slow temperature range after room-temperature implantation show the release of CD4 prior to D2, thus indicating a diffusion-limited release of CD4 already formed during the implantation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98777
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  • 8
    Electronic Resource
    Electronic Resource
    Ion-induced C segregation on Fe films on pyrolytic graphite under high-fluence D bombardment (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 356-358 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fe films of 700–1700 A(ring) were evaporated on pyrolytic graphite surfaces with both edge and base orientations, and bombarded with D ions at energies from 2 to 13 keV at fluences of 1019 D/cm2. The different ion energies and Fe film thicknesses allow different defect distributions in the graphite substrate of the samples. The Fe sputtering yield of the samples was measured directly by means of laser-induced fluorescence at temperatures ranging from room temperature to 900 K. The depth distribution of the components during mixing is obtained by means of Rutherford backscattering spectroscopy. At 800 K, a drastic reduction of the Fe sputtering yield is observed if energetic ions can reach the graphite substrate. C segregates on top of the Fe layers for D ion ranges larger than the Fe layer thickness. The thickness of the segregated C layers depends on the graphite orientation. For 13 keV D bombardment of 700 A(ring) Fe samples, for example, it is about 100 A(ring) for base graphite and about 1000 A(ring) for edge graphite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99463
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  • 9
    Electronic Resource
    Electronic Resource
    Frameshift Mutations (1974)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Genetics 8 (1974), S. 319-346 
    Details
    ISSN: 0066-4197
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ge.08.120174.001535
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  • 10
    Electronic Resource
    Electronic Resource
    Copper-Based Auto Exhaust Oxidation Catalysts. Deactivation and Physical Attrition (1971)
    s.l. : American Chemical Society
    Industrial and engineering chemistry 10 (1971), S. 381-385 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/i360040a007
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