Evaporative Lifetimes of Copper, Chromium, Beryllium, Nickel, Iron, and Titanium on Tungsten and Oxygenated Tungsten

Abstract

The evaporative lifetimes of Cu, Cr, Be, Ni, Fe, and Ti on W and O-covered W ribbon filaments at temperatures from 1250° to 1750°K have been measured as a function of coverage. The low-coverage lifetimes of these materials on clean polycrystalline tungsten at 1500°K are Cu, 0.01; Cr, 3.0; Be, 0.05; Ni, 1.0; and Fe, 0.7 sec. Less precise measurement of the lifetime of titanium showed it to be much longer than the lifetimes of the other metals studied and extremely coverage dependent.