| 摘要 |
<p>PURPOSE:To obtain an electron gun having a long life able to give the uniform strength of an electron beam covering wide range by providing a radiation region of an electron radiation member not less than three pieces in one row or in not less than three rows while putting said electron radiation region in a position about corresponding to the distribution of an electric field due to anode. CONSTITUTION:A cathode member consists of electron radiation members of LaB6 of nine pieces in all of three lines and three rows such as, for instance, 1a1-1a3, 1b1-1b3 and 1c1-1c3, while a tip of each electron radiation part is sharply or processed in the pyramid shape and thermal electrons are radiated from each tip. Anode 5 is held in positive high potential to cathode 1, while an acceleration electric field of electron rays is formed between cathode impressed by negative high voltage and itself. The electron radiation member 1b2 in the center part is put in the farmost position from anode, while eight other electron radiation members are put lower than that (in the position near anode 5). Thereby, each electron radiation member is maintained in the uniform strength of an electric field thus unifying the amount of electron radiation and about equalizing also an influence with the passage of time on the tip of each electron radiation member.</p> |
