| 摘要 |
PURPOSE:To improve the load resistance when an inner filament is used and shorten the interval between focuses of inner and outer filaments by causing the orbit of electron beam emitted from the inner filament to bend outward through application of a positive bias voltage to said outer filament for collision of electrons with the larger radius position of rotation anode. CONSTITUTION:A positive bias voltage for an inner filament 4 is applied to an outer filament 2 and a focusing plate 3 from a power supply 6. When a predetermined high voltage is applied across the filament 4 and an anode 7 from a high voltage supply 8. Thermions are emitted from the filament 4 and collide with the anode 7, forcing it to radiate the X-ray. In this case, the flow of thermions from the filament 4 is bent outward more than that when a bias voltage is not applied and accordingly the focusing point is also deviated outward. Since the focusing point of inner filament is deviated toward outside of the rotation anode as described above, load resistance can be improved and deviation of focusing point between the inner and outer filaments can be reduced, making the radiation field wider. |
