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Online ISSN : 1880-9413
Print ISSN : 0559-8516
ISSN-L : 0559-8516
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Volume 49, Issue 8
Displaying 1-7 of 7 articles from this issue
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Special Issue 1: Recent Progress in Vacuum Technology
Reviews
  • Vacuum Component Materials for the High-intensity Proton Beam Accelerator, J-PARC
    Yoshio SAITO
    2006 Volume 49 Issue 8 Pages 453-459
    Published: 2006
    Released on J-STAGE: June 08, 2007
    DOIhttps://doi.org/10.3131/jvsj.49.453
    JOURNAL FREE ACCESS
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  • Theoretical Prediction of the Pumping Performance of Dry Pumps
    (Taking the Scroll Pump and the Screw Pump by Way of Example)
    Tadashi SAWADA, Tetsuro OHBAYASHI
    2006 Volume 49 Issue 8 Pages 460-465
    Published: 2006
    Released on J-STAGE: June 08, 2007
    DOIhttps://doi.org/10.3131/jvsj.49.460
    JOURNAL FREE ACCESS
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      Since almost all commercially provided dry pumps are of the positive displacement type, the leak flow through clearance between displacement chambers in the pump is a dominant factor which determines pumping performance. Prediction methods for the pumping performance of dry pumps are explained by comparing it to the scroll pump and the screw pump. The scroll pump has long clearances, but the screw pump has relatively short ones, and the volume of the chambers reduces from the inlet toward the outlet in the scroll pump, but that in the screw pump is kept constant throughout the pumping process. Such a structural difference produces a small difference in the way of treating leak flow. These two methods can be applied to the other dry pumps requiring only minor modification.
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  • Turbomolecular Pump
    Kenji ODAKA
    2006 Volume 49 Issue 8 Pages 466-469
    Published: 2006
    Released on J-STAGE: June 08, 2007
    DOIhttps://doi.org/10.3131/jvsj.49.466
    JOURNAL FREE ACCESS
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      Turbomolecular pumps (TMPs) are fully grown products. There are four points to say so. First, hydrodynamic designing method is well established because there is no change in the pumping speed in the last ten years. Second, ultimate pressures of the order of 10−10 Pa are achieved. This corresponds to the lowest outgassing rate developed for metals. Third, they have extended operating range to pressures as high as 100 Pa with combination of turbo-drag pumps. Fourth, TMPs with electro-magnetic bearings produce perfectly clean vacuum with clean roughing pumps. For further development TMPs might focus on special usages.
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Special Issue 2: Simulation of Rarefied Gas Flow and its Application
Reviews
Articles
  • Numerical Analysis of the Rarefied Flow in a Vacuum Pump Driven by Thermal Edge Flow
    Hiroshi SUGIMOTO
    2006 Volume 49 Issue 8 Pages 481-487
    Published: 2006
    Released on J-STAGE: June 08, 2007
    DOIhttps://doi.org/10.3131/jvsj.49.481
    JOURNAL FREE ACCESS
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      Steady gas flows in a vacuum pump driven by thermal edge flow, which is proposed in Rarefied Gas Dynamics, AIP, New York, 138-141 (2002), are investigated numerically for various Knudsen numbers by the direct simulation Monte Carlo (DSMC) method based on the Boltzmann equation for a hard-sphere gas. The data of the maximum mass flow rate, energy consumption rate, and the maximum compression ratio of the pump is presented with some additional results on the effect of geometry and temperature ratio in the pump unit.
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  • Effect of Surface Grooves on a Channel Flow
    Kyoji YAMAMOTO, Mitsuhiro TANIWAKI, Hideki TAKEUCHI, Toru HYAKUTAKE
    2006 Volume 49 Issue 8 Pages 488-492
    Published: 2006
    Released on J-STAGE: June 08, 2007
    DOIhttps://doi.org/10.3131/jvsj.49.488
    JOURNAL FREE ACCESS
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      Effects of surface grooves on the rarefied gas flow through a channel are investigated numerically using the linearized B-G-K equation. One wall of the channel has rectangular grooves engraved periodically parallel or normal to the flow direction, and the other wall is flat. Couette and Poiseuille flows are analyzed. It is shown that in case of normal grooves, the flux through the channel has a minimum when the depth of the groove is about half of its width. For parallel grooves, the flux is considerably low compared with that of the smooth walls of the channel when the groove width and pitch are comparatively smaller than the channel width.
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