Title:
DISCHARGE CLEANER FOR ELECTRON GUN
Document Type and Number:
Japanese Patent JPH01128337
Kind Code:
A
Abstract:
PURPOSE:To make self-cleaning for an electron gun by means of discharge cleaning performable by utilizing a hot cathode filament of the electron gun as a hot cathode of a glow plasma source, and also utilizing a Wehnelt cylinder of the electron gun as an anode. CONSTITUTION:A hot cathode filament of an electron gun is utilized as a hot cathode of a plasma source, and a Whenelt (control electrode) of the electron gun is also utilized as an anode. When discharge cleaning is carried out, a leak valve 6 is opened, argon gas is led thereinto, setting the inside of a lens barrel 5 to 10<-1> Pa or so, and selector switches 7, 8 are connected to the (c) side. With this connection, a thermion discharged out of a filament 1 is accelerated between the filament 1 impressed with a voltage of -hundreds V--1kV by a glow discharge power source 13 and Wehnelt 2 impressed with a voltage of 70-500V to earth 14 by a bias circuit 10, and it passes through a mesh 15, thereby ionizing the argon gas. With this constitution, glow mode plasma is formed inside the lens barrel 5, so that discharge cleaning for the electron gun is performable in this way.
Inventors:
OKA SATOHIKO
Application Number:
JP28333887A
Publication Date:
May 22, 1989
Filing Date:
November 11, 1987
Export Citation:
Assignee:
HITACHI LTD
International Classes:
H01J37/04; H01J37/07; (IPC1-7): H01J37/04; H01J37/07
Attorney, Agent or Firm:
Katsuo Ogawa (2 outside)