| 摘要 |
PURPOSE:To check the functional deterioration of cathode powder and drop the gas pressure inside a gaseous body as well as to secure satisfactory emission characteristics, by impressing a high voltage on an anode and letting a beam current flow through a phosphor screen, while adding an alternating field from the outside of either a neck part or a funnel part. CONSTITUTION:A positive voltage of 10-30kV is impressed on an anode 17 to which an alternating field is arranged to be imparted by a coil 26 installed close to a funnel part 3 at the outside of a neck part 4. Therefore, when any voltage like this is impressed, the beam current 25 accelerated and deflected by the voltage of 10-30kV runs a long distance up to a phosphor screen 6 from a cathode 13 and thereby almost all of ionization and decomposition are produced inside the funnel part 3, so that a phenomenon of carbon sticking on cathode powder 21 causing deterioration in a cathod emission can be greatly decreased. With this, satisfactory emission characteristics can be secured. |
