Browsing by Author "Renault, Pascal Dominique"

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    An apparatus for electron impact ionization cross-section measurements
    (1990) Renault, Pascal Dominique; Stebbings, R. F.
    Cross sections for electron impact ionization of molecules and rare gases are necessary for the modeling of phenomena related to the earth's upper atmosphere and to plasmas. The construction of an apparatus to improve the accuracy of measurements of such cross sections is reported. The ions are produced in a static gas target crossed by an electron beam and are counted with a new ion detector technology, which insures a increased accuracy of the ion flux measurement and of the target length. The target gas density is measured using an ionization gauge calibrated against a high accuracy capacitive transducer. This apparatus also features a pulsed mode of operation, which allows a product analysis through time of flight measurement.
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    Experimental determination of absolute partial cross-sections for the electron impact ionization of argon and nitrogen
    (1994) Renault, Pascal Dominique; Stebbings, R. F.
    This thesis presents a description of a novel technique for the accurate experimental determination of absolute partial electron impact ionization cross sections of atoms and molecules by a calibrated time of flight mass spectrometer. The simple design of the present apparatus insures the total collection of the energetic fragment ions. Measurements for argon and nitrogen targets are presented over a range from threshold to 1 keV. Previously published electron impact data on argon, nitrogen, and oxygen are reviewed. Computer programs for the modeling of the data and fragment ions energy analysis are also presented.