Shinku
Online ISSN : 1880-9413
Print ISSN : 0559-8516
ISSN-L : 0559-8516
Volume 12, Issue 1
Displaying 1-4 of 4 articles from this issue
  • Kiyoshi TAMAI, Ken-ichi TSUTSUMI, Masanosuke TANAKA
    1969 Volume 12 Issue 1 Pages 5-17
    Published: January 20, 1969
    Released on J-STAGE: January 28, 2010
    JOURNAL FREE ACCESS
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  • Yutaka TUZI, Satoru OKADA, Munteg KIM
    1969 Volume 12 Issue 1 Pages 18-23
    Published: January 20, 1969
    Released on J-STAGE: September 29, 2009
    JOURNAL FREE ACCESS
    One of the disadvantages of the modulation technique by a modulated Bayard-Alpert type ionization gauge is the pressure variation with long time constant observed after the switching of modulator potential (Vm). This phenomenon is supposed to be caused by desorption and adsorption of molecules on the surface of modulator due to the change of the electron current to the modulator when Vm is kept higher than the filament potential (Vf). Therefore, the pressure variation is supposed to be much reduced if Vm is always kept lower than Vf.
    In order to check the possibility to use the modulation technique maintaining Vm lower than Vf for pressure measurements, the modulation factor and the sensitivity of the modulation technique were measured over wide ranges of Vm, pressure and electron current of the gauge. As a suitable mode of modulation, the change of Vm from OV to-150V is proposed. The mode has the modulation factor of ca. 0.4 and the sensitivity of ca. 5.
    The mode was applied to measured the pressure of oxygen.
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  • Kumasaburo KODERA, Isao KUSUNOKI, Takamasa IBARAKI
    1969 Volume 12 Issue 1 Pages 24-28
    Published: January 20, 1969
    Released on J-STAGE: September 29, 2009
    JOURNAL FREE ACCESS
    The most universal detector for molecular beams is an electron bombardment detector But, usually, in this detector molecular beam signal is obscured by the background and noise from the residual gas. By means of beam modulation and lock-in amplification the beam signal can be separated from the background and amplified with the improvement in signal to noise ratio. A detector of this type was constructed in our laboratory and its performance was studied with a molecular beam of naphthalene. The detector is a kind of an ionization gauge. Sensitivity of the detector as a ' vacuum gauge was 2×10-2 A/torr · mA for the residual gas. Beam signal of about 10-2 of the residual background gas signal was measured with S/N ratio of 2-3×102. Ionization efficiency of beam molecules was the order of 10-5 with electron current of 0.1 mA and a signal of 10-12A could be measured with the S/N ratio. of 1. This ion current corresponds to the beam intensity of 1012molecules/ sec.
    Beam profiles and the dependence of the beam intensity upon the oven temperature were measured. From the latter measurement heat of sublimation of naphthalene was estimated as 18. 6 kcal/mole and 19.8 kcal/mole for two different runs. The values are reasonable compared with the value 18. 8, 18. 9 kcal/mole calculated from the vapor pressure of naphthalene.
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  • Shoji WATANABE, Toshiaki NAKANE
    1969 Volume 12 Issue 1 Pages 29-31
    Published: January 20, 1969
    Released on J-STAGE: September 29, 2009
    JOURNAL FREE ACCESS
    A mixture of diphenyl and a-olefin (C11-C15 mixture) in the presence of anhydrous aluminium chloride was heated at 150°C to give a pale yellow oil boiling at 180-200°C/10-4 Torr. This oil has an excellent properties for a diffusion pump oil, for instance, the ultimate pressure was measured by Hickman type glass diffusion pump, and we certified the order of 10-7 Torr, as showed in Table 4, and thermal decomposition rate was also measured as shown in Table 5. which we realized this rate is comparably low.
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