title: Multi-scale simulation of electron emission from a triode-type electron source with a carbon-nanotube column array cathode.
abstract: We have designed and fabricated a new type of field electron source for a novel onboard mass spectrometer. The new electron source, which is a field effect emitter in a triode configuration, consists of a CNT-column array cathode and an extraction gate with holes that are aligned concentrically with respect to the cylindrical CNT columns. In triode mode operation, cathode currents as large as ~420 μA have been emitted with an anode-to-gate current ratio of ~1.5. To account for the observed emission characteristics of the new electron source, we have carried out multi-scale simulations that combine a three-dimensional (3D) microscopic model in the vicinity of an actual emission site with a two-dimensional (2D) macroscopic model that covers the whole device structure. Because the mesh size in the microscopic 3D model is as small as 100 nm, the contributions of the extruding CNT bundle at the top edge of an electron column can be examined in detail. Unlike the macroscopic 2D simulation that shows only small field enhancement at CNT column's top edge, the multi-scale simulation successfully reproduced the local electric field strongly enough to emit the measured cathode currents and the electric field distribution which is consistent with the measured anode-to-gate current ratio.
authors.affiliation: LATMOS-CNRS/IPSL, University of Versailles Saint Quentin, Guyancourt, France.
authors.forename: Joel
authors.initials: J
authors.lastname: Becker
authors.forename: Nguyen Tuan
authors.initials: NT
authors.lastname: Hong
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Berthelier
authors.forename: Francois
authors.initials: F
authors.lastname: Leblanc
authors.forename: Soonil
authors.initials: S
authors.lastname: Lee
authors.forename: Fabrice
authors.initials: F
authors.lastname: Cipriani