| 摘要 |
PURPOSE:To enable exact measurement of beam current by disconnecting all of the 2nd Faraday structures provided on an incident side of a 1st charge particle beam from a 1st Faraday structure and maintaining the same at a ground potential during the projection of the charge beam. CONSTITUTION:With this measuring mechanism, switches S1 and S2 are respectively switched and connected to fixed contacts (b) sides when a beam gate is open. The front Faraday electrode 6 and the beam gate 5 are then electrically disconnected respectively from the rear bypass electrode 4 and the rear Faraday electrode 3 and are held at the ground potential. The beam gate 5 is held at the ground potential via the switch S2 at this time and are respectively electrically disconnected from the Faraday electrode 3 and a beam ammeter 8 and, therefore, the beam current by part of the implanted ion beam does not flow in the beam ammeter. Only the current by the ion beam projected to the target 2 is, therefore, exactly measured.
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