Application of a general electron emission equation to surface non-uniformity and current density variation

Using a recently developed model of emission that includes field, thermal, and photoemission effects simultaneously for arbitrary magnitudes of field, temperature, and laser intensity, we perform a study of the consequences of emission site variation on the subsequent electron beam. The electron emission model incorporated into the particle-in-cell (PIC) code MICHELLE, which is a conformal mesh finite-element (FE) two-dimensional (2-D) and 3-D electrostatic PIC code for modeling steady-state electron guns (and collectors), is described in detail.The addition of the generalized emission model therefore allows for assessing the impact of local thermal, field, and work function variation on the resultant electron beam.