単結晶LaB₆陰極電子銃の輝度

抄録

The brightness of single-crystal LaB6 cathodes of <100>, <110> and <111> orientations were each measured for cathode temperatures from 1500 to 1950K at 20 kV.
As a preliminary examination of the present technique, the brightness of W-hairpin cathode was measured from 2300 to 2800K. This result has agreed very well with the theoretical brightness for φ=4.4 eV and A=120 A/cm²deg².
The maximum brightness of each of the <100>, <110> and <111> LaB₆ cathodes were almost the same and were twice as high as those for the cross-over point of the single spot which is obtained by applying a higher bias voltage (negative to cathode). These maximum brightness are described quite well by the theoretical brightness for φ=2.6 eV and A=60 A/cm²deg² within the limited region of cathode temperatures restricted by space charge effect and oxidation on the cathode surface.