| 摘要 |
PROBLEM TO BE SOLVED: To prevent turbulence in an electric field due to the electrification of an electrode retaining material, and also facilitate the wiring check between an electrode and a vacuum vessel, by retaining the electrode within a vacuum vessel, so that the electric resistance, between the electrode and the vacuum vessel, can be a specific value. SOLUTION: An electrode 3 is retained by an electrode retaining material 6 composed of e.g. a cube of 1cm×1cm×1cm. The electric resistance of the material 6 is preferably in a range of R=10<0> -10<9> > for simply measuring the electric resistance. At that time, the volume receptivityρof material can be sufficient from R=l/sρ(l=1cm, s=1cm<2> ) toρ=10<-2>Ωm-10<7>Ωm. Moreover, since, when the electric resistance is reduced, an electric current, flowing between the electrode and a vacuum vessel, is increased to cause a heat generation problem, and also to need a large capacity electric powder source too, practically, the electric resistance, between the electrode and the vacuum vessel, is preferably in a range of 10<3>Ω-10<9>Ω.
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