| 摘要 |
PURPOSE:To obtain an electron beam exciting ion source with the large current density, long life, and low power consumption quantity by making the diameter of through holes 0.65mm or less when electrons are extracted from a plasma generation region by the voltage of an electrode with many through holes. CONSTITUTION:Discharge gas is guided into a chamber 1 through the through hole 4 of a cathode electrode 5, a glow discharge is generated across the electrode 5 and an anode electrode 2 to form plasma. Next, electrons extracted from the plasma by an electron beam accelerating electrode 3 collide with arsenic gas in an ion generating chamber 10 to generate plasma, which is extracted by a plasma ion extracting electrode 11. In this constitution, through holes (b) with a diameter of 0.5-0.6mm capable of extracting an electron beam most efficiently are arranged with a pitch of 0.7-1.0mm. As a result, a large quantity of the electron beam can be extracted without impairing the durability of these electrodes, the current can be reduced, thus the life of the electrode 5 is extended, and the power consumption can be reduced.
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