| 摘要 |
PROBLEM TO BE SOLVED: To provide an electron gun which is suitable for an electron beam exposing device and having low-intensity and high-emittance characteristics by forming a flat face, having a specific diameter or above and uniform work function at the tip of the cathode of the electron gun, protruding the cathode to the same position as a Wehnelt electrode or to the anode side, and operating the cathode in a temperature limit region. SOLUTION: This cathode 1 has a circular rod-like cross section, and a Wehnelt electrode 2 is symmetrically provided around the optical axis (the center line of the cathode 1 and an electron beam 5) below the cathode 1. A conical recess 2a is provided at the center section of the Wehnelt electrode 2. The Wehnelt electrode 2 is located above the lower end face of the cathode 1, and the tip of the cathode 1 is protruded downwards (to a first anode 3 side) from the position of the Wehnelt electrode 2. An appropriate angleθof the center section cross section of the Wehnelt electrode Z is set to 50-70 deg.. Both the first anode 3 and a second anode 4 are formed into a ring shape, and the cathode diameter is set to 1mm or above, e.g. 2mmϕ.
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