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Floating Potential of an Electron Emitting Collector that Terminates a Bounded Plasma System
Author(s) -
Gyergyek T.,
Kovačič J.
Publication year - 2012
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.201200012
Subject(s) - electric field , electron , plasma , physics , poisson's equation , ion , particle in cell , electric potential , atomic physics , cathode , kinetic energy , computational physics , electrical engineering , voltage , classical mechanics , quantum mechanics , engineering
Potential formation in one‐dimensional bounded plasma system terminated by a floating, electron emitting collector is studied by a fully kinetic one‐dimensional model and particle‐in‐cell (PIC) computer simulation. As the electron emission from the collector is gradually increased, the floating potential of the collector and the electric field at the collector both increase quite strongly. When the critical emission is reached, the electric field becomes zero. If the emission is increased further, the electric field changes sign and becomes positive and a virtual cathode is formed in front of the collector. The floating potential of the collector also increases, but much more slowly, than below the critical emission level. If the ratio between the temperatures of the emitted and of the bulk electrons is high enough, the floating potential of the collector may even exceed the zero potential of the source, but in this case the simulation becomes unstable, when the positive ions start to flow back from the collector towards the source. Simulation results obtained below the critical emission level are in very good agreement with the model, provided that the particle densities obtained from the simulation are normalized correctly. In this case the potential and electric field profiles found from the PIC simulation match almost perfectly to the profiles obtained from the numerical solution of the Poisson equation (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)