| 摘要 |
<p>PURPOSE:To improve the insulation resistance between the cathode and the heaters and to lengthen the service life, by adhering an electron emission suppressing metal such as Ti to the portion not required of the electron emission in the cathode face. CONSTITUTION:A pellet 7 of an immersed type cathode where an electroradioactive substance is immersed in a metal base having high melting point is tightly contacted to a zig 8 to expose the portion not required to emit the electron, while a positive electrode 9 is connected to the zig 8. A target board 11 such as Ti board is held on the negative electrode 10, then high frequency voltage is applied from a power source 13 under inert gas environment 12 such as Ar. With such device Ti will adhere to the positive side of the electrode or the exposed portion of the cathode pellet 7. Said Ti layer can be adhered to the desired depth which is approximately proportional to the time being applied with high voltage. Consequently desired electron beam shape is obtained without producing the thermal deformation of the grid or the noise while causing no useless consumption of the radioactive substance, resulting in the lengthening of the service life.</p> |
