| 摘要 |
PURPOSE:To measure the diameter and position of a beam, by setting a conducting through member electrically connected to a conductive support member on a phosphor plate as beam monitor of charged particles or the like while preventing a discharge on the phosphor plate. CONSTITUTION:A phosphor plate 1 comprising a ceramic or the like is supported with a conductive support base 2 and support rod 3. A conductive scale member 7 made up of a scale mesh of copper or the like is set on the phosphor plate 1 and the scale member 7 is electrically connected to the support base 2 and the support rod. The phosphor plate 1 is inserted into a beam optical path 6 within a vacuum chamber with a moving mechanism 4 and observed through a peep window 5. This enables measurement of the diameter an the position of a beam and eliminates the accumulation of electric charges on the phosphor plate 1 to prevent discharge on the phosphor plate 1 even when beam energy is too low to make the beam pass through the phosphor plate 1. |
