UNIFORM WORK FUNCTION CATHODE STUDIES FOR THERMI ONIC CONVERTERS.

X-ray analysis of vapor deposited molybdenum shows that either (111) or (100) preferred orientations can be obtained. Further work indicates that precise control of impurities is needed before reproducible results can be obtained. Cathodes having (111) orientations were produced using vapor deposition techniques. Methods of polish ing cathode surfaces were studied. X-ray studies show that heat treatment is adequate to restore the preferred orientation at a mechanically pol ished surface. The reproducibility of performance of test diodes was established by comparison of currea with data from previous work. Con struction of an emission electron microscope for cathode work function distribution studies is in progress. Preliminary work has been done with an electron mirror microscope.