| 摘要 |
<p>PURPOSE:To enable realization of a highly stable electron beam of a high luminance by making the point of the tip of a single crystal with a crystal structure similar to that of calcium hexaboride to have a pyramidal form, and thereby making thermally stable crystal surfaces to correspond to the pyramid surfaces. CONSTITUTION:The point of a cathode tip which is made of a single crystal of a hexaboride of either an alkaline earth metal or a rare earth metal possessing a crystal structure similar to that of calcium hexaboride, is shaped in a pyramidal form. It is preferred that the pyramide surfaces correspond to crystal surfaces of (100), (110), (210), (310) and (320). The above mentioned means enables realization of a highly stable electron beam of a high luminance.</p> |
