| 摘要 |
<p>An ion source (1) comprises a plasma container (10), a pair of thermion emission devices (12, 14) for emitting thermions into the internal space of the plasma container (10), and a power source for supplying an electric current to each of the thermion emission devices (12, 14), in which the inner wall surface of the plasma container (10) exposed to plasma and a portion of the thermion emission devices (12, 14) exposed to plasma and emitting thermions are made of a material containing the same metal as a main component. Accordingly, a deposition layer adhering to the surface of the thermion emission devices (12, 14) during operation of the ion source (1) contains a component same as the component of the material of the thermion emission devices (12, 14). Consequently, thermions can be stably emitted and the operation time of the ion source (1) before replacement of the thermion emission devices (12, 14) can be prolonged.</p> |
