| 摘要 |
<p>PURPOSE:To obtain a quick-acting long-life cathode for an electron tube by regulating the distribution of the crystal grain boundaries of a base metal with diffusion paths. CONSTITUTION:The grain diameters of crystal particles near a surface of a base metal which is coated with an electron-discharging matter are made small so as to secure a number of grain boundaries with large diffusion speeds. In contrast, the grain diameters of crystal particles near an opposite surface to the surface coated with the electron-discharging matter of the base metal are made large so as to define grain boundaries with large diffusion speeds to a small number. By the means mentioned above, the dispersion of a reducing agent from the surface uncoated with the electron-discharging matter which is caused by thermal evaporation during the active life period of a cathode is suppressed. In order to give full above mentioned effect, the mean grain diameter of crystal particles located in the area which has a 1/10 the thickness of the base metal gap from the surface coated with the electron-discharging matter should be below 5mum, and the mean grain diameter of crystal particles located in the area which has a 1/10 the thickness of the base metal gap from the opposite surface to the surface coated with the electron-discharging matter should be above 20mum.</p> |
