| 摘要 |
PURPOSE:To eliminate the spark between projected electrodes by coating the back and side of an electrode supporting structure composed of a resistor and the face for projecting the electrode with insulative material layers. CONSTITUTION:An electrode supporting structure 22 is comprised of a resistor 2a and an insulative material layer 2b coated on said resistor 2a. The insulative material layers 2b are formed on the back and side of third, fourth, fifth and six grids 8, 9, 10, 11 except the face where sections 81, 91, 101 and 111 are projected, while said layers are also formed on the projecting sections 61, 71 of the first and second grids 6, 7 to insulate the first and second grids from the resistor 2a. Then 25kV and 500V are applied through a spring 15 and a stem lead 18. Consequently 7kV is applied on the third and fifth grids to prevent the discharge occurring on the surface of the supporting structure. |
