| 摘要 |
The cathode has an insulating oxide film (4) formed on a conducting silicon layer (1). The film is covered by a resistive layer (5) which is in contact (2,3) with the silicon layer around an annular ring and in a central circular disc at a perpendicular distance, L, from the external and internal edge of the cathode. The pattern may be changed so that there are two annular rings of contacts between the resistive layer and the silicon at a perpendicular distance, L, from a narrower annular ring of emitters and from a central circular cluster of emitters. The emitters lie on the resistive layer in cylindrical holes in a second insulating layer (6) on which lies the grid electrode (7). |
