公开(公告)号：US3619684A

公开(公告)日：1971-11-09

申请号：US3619684D

申请日：1970-04-23

Applicant: PHILIPS CORP

Inventor： ANDREW DEREK ,  PITTAWAY LAWRENCE GRAHAM ,  CHRISHOLM THOMAS

IPC: H01J49/14 ,  H05H1/00

CPC classification number: H01J49/14

Abstract: A nonmagnetic, electron impact ion source comprising an evacuated envelope having means for passing ionizing gases through the envelope. Within the envelope, an electron emitting cathode is positioned adjacent a grid-shaped ionization chamber. A conducting wall section of the ionization chamber that is impenetrable to ions has an ion exiting aperture, which is adjacent to a grid-shaped electrode for extracting ions. The extracting electrode is positioned at a distance of a few tenths of a mm. from the ion exiting aperture, and kept at a small negative voltage not exceeding 5 volts relative to the ionization chamber. An acceleration electrode adjacent to the extracting electrode forms ions from the ionization chamber into beams. A screen grid placed between the extracting and acceleration electrodes prevents the high negative voltage of the acceleration electrode from affecting the electric field within the ionization chamber.