ION EMISSION FROM RHENIUM AND LANTHANUM HEXABORIDE COATED RHENIUM FILAMENTS

When heated, rhenium, like many other metals emits positive ions of the alkali metals. However the emission properties of these ions from rhenium are found to be very different from those observed for tungsten. In addition, the ion emission from rhenium can be greatly reduced relative to that of tungsten by short term vacuum annealing at sufficiently high temperatures. Lanthanum hexaboride coated rhenium filaments also emit positive alkali ions in a manner very similar to that of bare rhenium. The implications, both practical and theoretical of these results are discussed. © 1970 The American Institute of Physics.