Effect of Cesium Vapor on the Emission Characteristics of Uranium Carbide at Elevated Pressures

The saturated emission currents from uranium carbide in cesium vapor were measured for four different bath temperatures T: 167°, 197°, 227°, and 250°C (the cesium arival rates μa, in 1019 atoms/cm2, were 0.3, 1, 3, and 6, respectively). The measurements were made with a ``plasma anode'' tube at constant temperature. The plot of logμa vs 1000/T was used to extrapolate the electron emission ``S'' curves to arrival rates that differed by a factor of ten. Since calculations based on the assumption of a homogeneous surface yields unexpectedly high binding energies and surface coverages, it seems likely that some surface patchiness exists.