| 摘要 |
PURPOSE:To finely process a work without contaminating the same by providing many poles and many stages of permanent magnets which are different from each other in polarity in both of the cylindrical direction and axial direction of a vacuum vessel to the outside of the vacuum vessel which holds the work. CONSTITUTION:The permanent magnet 12 is disposed to the outside periphery of the vacuum vessel 5 in such a manner that the N pole and the S pole are alternated. Another permanent magnet 13 is disposed in the axial direction of the vacuum vessel 5 in such a manner that the N pole and the S pole appear alternately and that the polarities are different in the axial direction of the 1st stage of the permanent magnet 12. Plasma is formed in a plasma forming chamber 1 in such constitution and when an ion beam 14 is drawn out of the plasma forming chamber 1 into the vacuum vessel 5, the ion beam 14 diverges in the form of a parabolic shape in which the central part projects downward. The permanent magnets 12, 13 act as a magnetic lens to focus the ion beam 14 in the central axis direction and focus the drawn out ion beam 14 so as to irradiate nearly the parallel ion beams on the work 11. The work is thereby efficiency processed.
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