| 摘要 |
This invention relates to an Ion gun (10) which comprises of plasma generator (11) driven from an RF source (12), a plasma or source chamber (13), having an outlet (14), across which is mounted an accelerator grid (15). The accelerator grid (15) comprises four individual grids. The first grid (16), which is closest to the outlet (14), is maintained at a positive voltage by a DC source (16a), the second grid (17) is maintained strongly negative by DC source (17a). The third grid (18) is maintained at a negative voltage, which is much lower than that of the second grid (17), by DC source (18a) and the fourth grid is grounded. Means of mounting these grids are also described.
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