| 摘要 |
<p>PURPOSE:To eliminate the effect of residual electromagnetic field, avoid the straying of an electron and extent the life of the electron by arranging a pinhole on the side of a beam duct where an inspection window is provided and arranging a ground glass with a specified distance from the pinhole. CONSTITUTION:A pinhole 13 is provided on the side of an inspection window 10 of a hollow, ring-shaped beam duct 1 inside which electrons run. A ground glass 15 is arranged with a specified distance from the pinhole. Namely, since the characteristic impedance is made approximately equal to that of a beam duct portion without an opening by making the size of the opening for inspecting a light emitting portion of a fluorescent plate 8 provided in the beam duct 1, wake field (residual electromagnetic field) effect is eliminated and straying of electrons can be avoided.</p> |
