| 摘要 |
Upon one or both surfaces of an accelerating electrode having a center aperture is overlaid and fixed concentrically a disk member or members each having a center aperture tapered so as to converge toward the accelerating electrode. Unnecessary ink attached to the accelerating electrode may be sucked through the interface or interfaces between the disk member or members and the accelerating electrode under capillary action and ink attached to the disk members may readily flow toward the interfaces along the tapered peripheral surfaces or walls of the center apertures of the disk members. Grooves may be formed in the surfaces of the disk members in contact with the accelerating electrode so as to facilitate the collection and discharge of unnecessary ink sucked into the interfaces under capillary action. Removal of ink attached to the accelerating electrode may be much facilitated, thus assuring the stable operation of the accelerating electrode. In addition, fabrication of the accelerating electrode structure may be much facilitated and simplified yet with a higher degree of accuracy.
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