Two-dimensional space-charge-limited emission: Beam-edge characteristics and applications - art. no. 145002

There is, at present, no analytic solution that extends Child-Langmuir spac e-charge-limited emission beyond ID. Herein, we investigate the characteris tics of planar diode electron emission in 2D space with the emphasis on the transition region between the beam and vacuum. Current density above that predicted by Child-Langmuir is observed near the beam edges in a 2D finite element, electrostatic ray-tracing code. The properties of these increased current density "wings" are examined and then discussed in terms of their a pplications to cathodes which have large reservoirs of free electrons.