| 摘要 |
<p>PURPOSE:To obtain an emission current having required brightness, current regulation and energy width by maintaining a built-up tip needle within a specific temperature range. CONSTITUTION:A filament current IF is made to flow to an electrode 2 through power supply 6 for heating a tungsten tip needle 4 up to 1100-1400K. Nearby said temperature the (310) surface of the tungsten tip needle 4 starts to build up so that the temperature T of the tip needle is raised in advanced up above 1400K by heating while being returned to 1100-1400 after completely generating built-up in order to be used. Thereby, an emission current having brightness of 10<6>-10<9>A/cm<2>.ster, current regulation less than 10%/hr and energy width less than 1eV can be obtained.</p> |
