Open AccessAnalysis of Anode Current From a Thermionic Cathode With a 2-D Work Function Distribution
Author(s) -
Abhijit Jassem,
David Chernin,
John J. Petillo,
Y. Y. Lau,
Aaron Jensen,
Serguei Ovtchinnikov
Publication year - 2021
Publication title -
ieee transactions on plasma science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.46
H-Index - 106
eISSN - 1939-9375
pISSN - 0093-3813
DOI - 10.1109/tps.2020.3048097
Subject(s) - engineered materials, dielectrics and plasmas , fields, waves and electromagnetics
A model of a thermionic cathode in a planar diode in which the Poisson and Vlasov equations are solved in 3-D assuming an infinite magnetic field is presented. We explore how 2-D work function variations across the cathode surface may affect the transition between temperature-limited and space-charge-limited flow, commonly known as the “knee” of the Miram curve. We study a variety of work function distributions, both realistic and idealized, and demonstrate how emission from the lowest work function regions dominates the total anode current even when such regions make up a relatively small fraction of cathode area. Our model also illustrates the ability of cathodes to reach the full Child-Langmuir current despite the presence of a sizeable nonemitting region. We find that as the length scale of these work function variations decreases, the Miram knee grows sharper, indicating improved cathode performance.