| 摘要 |
PROBLEM TO BE SOLVED: To provide an ion source which works properly for a long time, without generating abnormal electric discharges in the ionization chamber. SOLUTION: A part of positive ions (a) generated in the ionization chamber 3 is accelerated toward a cathode 2 and collides with a nonmagnetic material 2b. Most of particles (b), sputtered from the nonmagnetic material 2b by this ion collision are deposited on an inner surface I of an anode 7. At that time, since the sputtered particles (b) are not magnetized, they are deposited uniformly on the anode 7, without being affected by a magnetic field E formed in the ion chamber 3. Consequently, a needle-like part will not be formed on the anode 7 as in the conventional manner, and abnormal electric discharges can be avoided which are generated conventionally. Thus, the ion source can properly emit ions over a long time. COPYRIGHT: (C)2007,JPO&INPIT
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