To provide an electron source in which the service life of a window foil can be prolonged by preventing an electron beam from being focused at a grid electrode formed in a ladder state thereby reducing thermal load on the window toil.
The electron source comprises filaments 4a (4b) arranged in the longitudinal direction of electron discharge openings 3a (3b) at a plane position opposite to the electron discharge openings 3a (3b) in a shield electrode 3, rod-like grid electrodes 5a (5b) arranged in a ladder at the electron discharge openings 3a (3b) in the shield electrode 3 in the longitudinal direction thereof, and preferably three rod-like grid electrodes 9a, 9b, 9c extending in parallel in the rudder direction of the grid electrodes 5a (5b) while intersecting therewith in the center thereof. According to the structure, penetration of the field is suppressed in the longitudinal and breadthwise directions of the electron discharge openings 3a and the width of the electron beam is widened.
| JP2003320039 | DEVICE AND METHOD FOR IRRADIATING CHARGED PARTICLE BEAM |
| JPH08329880 | FARADAY DEVICE FOR ION IMPLANTING DEVICE |
| JPS6252842 | FOCUSED ION BEAM IRRADIATOR |
MIZUSAWA KENICHI
BABA TAKASHI
