表面と真空
Online ISSN : 2433-5843
Print ISSN : 2433-5835
61 巻 , 8 号
特集「真空機器メンテナンス講座」
選択された号の論文の15件中1~15を表示しています
巻頭言
特集「真空機器メンテナンス講座」
論文
  • 河原 幸太, 加藤 勇樹, 久保田 康介, 山川 紘一郎, 荒川 一郎
    原稿種別: 論文
    2018 年 61 巻 8 号 p. 533-538
    発行日: 2018/08/10
    公開日: 2018/08/10
    ジャーナル 認証あり

    An experimental system was developed for the physisorption study of hydrogen at substrate temperatures between 1.8 K and 10 K and at pressures down to 10-10 Pa. The vaccum system was separated into two rooms by a bulkhead ; the upper chamber contained a cryostat equipped with a 4 K mechanical refrigerator and the lower one a substrate kept in an extremely high vacuum. Helium was liquefied at the refrigerator in the upper chamber and was stored in a pot in the lower one. The substrate was directly attached to the helium pot. The substrate temperature was controlled with an accuracy of 0.1 K by a heater located in the helium pot. The adsorption density of hydrogen physisorbed on the copper surface was measured with use of the electron stimulated desorption method. The mean residence time of hydrogen was directly determined by applying this technique to the transient state of adsorption. The adsorption isotherms were obtained by monitoring the hydrogen ion yield as a function of the pressure in the adsorption equilibrium state.

  • 松田 七美男
    原稿種別: 論文
    2018 年 61 巻 8 号 p. 539-543
    発行日: 2018/08/10
    公開日: 2018/08/10
    ジャーナル 認証あり

    In application of one dimensional diffusion theory to gas molecular flow in the steady state through long ducts of uniform cross section, diffusion coefficient 𝒟 is generally represented as

    here λ is a kind of mean free path and v is avarage velocity of molecules. Up to now rigorous expressions of λλS where λS is Smoluchowski's expression for λ which have been given by Smoluchowski himself and other author for rectangular, ellipsoidal and annular cross section. As for triangular cross section, the rigorous expression has been obtained only on equilatera-triangle cross section. In this report, the concrete expression of λS and the correction factor α defined by the ratio of λS/λK where λK is Knudsen's expression for λ, are deduced for long ducts with isosceles-triangle cross sections. The values for λS and α, which are given by these deduced formula, are compared with those obtained from the Monte-Carlo simulation, which uses the mean free path in the duct and the mean square of free path in the axial direction of the duct .

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