| 摘要 |
PURPOSE:To calibrate th ion amount of ion beams precisely with the movement of a Faraday cup and a magnetic shield, by covering the Faraday cup with the magnetic shield which has a slit in the same direction as the slit of the disk, and placing the shield movable in the direction rectangular to the slit. CONSTITUTION:By moving a magnetic Faraday cup 8 and a magnetic shield 10 along a rail 11, and by scanning the projection area of the ion beams 1 at the slit 9 of the shield 10, the wave form I' of the ion current is obtained. The total current IT of the ion beams 1 can be found by integrating the value I', and the ion mass of the ion beams 1 can be calibrated by finding the percentage of the current I1 of the cup to the IT, when the Faraday cup is placed at a specific position. Since the extension portion of the slit 7 of the disk 2 is of no use to measure the ion current of the ion beams 1, the slit 7 can be made shorter, and the diameter of the disk 2 may be smaller, resulting in a smaller driving power for the disk 2.
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