| 摘要 |
PURPOSE:To improve the efficiency of polyvalent ion generation by providing multiple solenoid coils or permanent magnets different from a main solenoid coil, near the outer wall of a plasma chamber. CONSTITUTION:A plasma chamber is fed with microwaves and generates the plasma of the sample gas, and a solenoid coil 1 generates the magnetic field in the plasma chamber. An ion beam from the plasma chamber is extracted by an extracting electrode system 5. Magnet trains 6 made of permanent magnets are arranged in four columns in the circumferential direction near the outer wall of the plasma chamber. The magnet trains 6 generate the circumferential magnetic field, and its magnetic field strength is weakest at the center portion of the plasma chamber and becomes larger toward the tube wall. Accordingly, the plasma grain loss for the wall is suppressed, and the polyvalent ion generation efficiency in the plasma chamber can be improved.
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