PURPOSE: To prevent a microwave permeating window from being broken by high-speed reverse electrons during a long-period operation under high accelerating voltage and obtain a microwave ion source with high reliability by providing the microwave permeating window at the position not faced to ion extracting electrodes.
CONSTITUTION: A wave guide 1 transferring microwaves is not located on the faces faced to ion extracting electrodes 9a, 9b in a discharge chamber 4, and it is located on the face perpendicular to them. The face 4a faced to the face where slots 2 of the wave guide 1 are provided in the discharge chamber 4 (face of a microwave permeating window 5) is provided incliningly toward the ion extracting electrodes 9a, 9b. High-speed reverse electrons 15 are generated when an ion beam 13 is generated, the high-speed reveres electrons 15 only collide with faces 4a, 4b in the discharge chamber 4, and the microwave permeating window 5 is not exposed to the collision with the high-speed reverse electrons 15. The breakage of the microwave permeating window 15 can be prevented.
TSUDA YOSHIYUKI
KODERA KOICHI
YASUI HIDEAKI
