| 摘要 |
PURPOSE:To shorten a period of time required for reaching to thermal equilibrium by providing respectively plural number of first and second electron beam passage windows in a position where the rear side and front side flanges of an internal magnetic shield face each other while directly heating the flanges by the electron beams passing through the passage windows. CONSTITUTION:The plural number of first electron beam passage holes 11a are formed in a prescribed size on the rear side flange 10a of an internal magnetic shield 10 at proper intervals, while the second electron beam passage windows 11b are simillarly formed on the front side flange 10b. The positions and the sizes of the passage windows 11a and 11b are formed so that the electron beams 52 passing through the passage holes 11a may pass through the passage windows 11b while hitting against the flange 62a of a frame 62. Since the electron beams directly hit against the frame 62 in this way to heat it, the temperature rises quickly so as to shorten a period of time from starting of actuation to reaching to thermal equilibrium. |
