| 摘要 |
PROBLEM TO BE SOLVED: To extend a service life of a filament by preventing localization of wear of the filament. SOLUTION: This ion source 4a is used for taking out an ion beam 18 along the Z axis, and the filament 10 is applied with a direct current filament voltage VF from a filament power supply 20 in the generating direction of potential difference along the X axis. The inside of a plasma generating vessel 6 is applied with a magnetic field 26 from an electromagnet 24 along the Y axis. The electromagnet 24 has a C-shaped core 28 disposed along the plane including the X axis and the Y axis, and a coil 34 wound about the yoke part 32. The filament 10 is applied with the filament voltage VF using the coil 34 side of the electromagnet 24 as the negative electrode side.
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