| 摘要 |
PURPOSE:To prevent the generation of an ion-exchanging discharge by enlarging the bore diameter of an annular divided electrode plate gradually from one at the high voltage end to the other at the earth potential end, and then providing a cylindrical perforated divided- electrode at the negative potential on the circumference of a passage between the edge of an accelerating tube and an electrode plate at the earth potential, which is provided with a derivation port. CONSTITUTION:The number of sheets per unit length of an annular divided electrode plate 9 is increased, and at the same time, the bore diameter (d) of the holes in some 9c of the divided electrode plates 9 in each stage is minimized at the high voltage end 9a and gradually enlarged so that it is full of the inside diameter of an accelerating column 6 at the earth potential end 9b, and then, the bore diameter of the holes in others is enlarged to the full of the inside diameter of the accelerating column 6 so that a nearly conical passage is formed in the accelerating column 6. In addition, an electrode plate 5a at the earth potential is placed so that it is opposite to the earth potential end 9b of the accelerating tube 6, and at the same time, a cylindrical perforated electrode 10 at the negative potential is provided on the circumference of a passage between the earth potential end 9b and the electrode plate 5a. And further, in the side of the perforated electrode 10 is placed an evacuation port 11. Thereby, the generation of a discharge in an accelerating tube is suppressed so that the maximum voltage can be reached quickly.
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