| 摘要 |
PURPOSE:To make the power density of a beam uniform by radially dividing the Wehnelt of an electron gun composing electron beam generating equipment into two or more from the center hole and by applying an independent electric potential to each divided Wehnelt. CONSTITUTION:A ribbon filament 1 made of a material such as W-Re, a resistance 11 and a bias power source 10 for filament are connected in parallel, Wehnelts 2-5 are installed around the filament 1 and to the Wehnelts 2-5 and to the middle point of the resistance 11, Wehnelt power sources 12-5 are connected. Between the middle point of the resistance 11 and an anode 6, an acceleration power source 16 is provided, a lens coil 7 and a deflection coil 8 are provided under the anode 6 and through these, a beam is irradiated from the filament 1 on an object to be treated which is not shown in the drawing. In this construction, the Wehnelts 2-5 are divided into four around a center hole 17 as shown by the figures and the four Wehnelt power sources 12-5 for supplying voltage to the Wehnelts 2-5 are used as shown by the figures to control the electric potential of the Wehnelts independently. No.9 is a Faraday gauge for measuring power distribution. |
