The general purpose of our research program is to study problems relating to the atomic, molecular, and electronic processes occurring at gas -solid interfaces. Examples of these processes are: thermionic emission, surface ionization, adsorption, absorption, oxidation, catalysis by metals, electrode processes in electrical discharges, and the scattering of molecular beams from solid surfaces. S...

*Correspondence: Timothy S. Fisher , Birck Nanotechnology Center, 1205 West State Street, West Lafayette, IN 47907, USA e-mail: [email protected] This article describes advances in thermionic and photo-emission materials and applications dating back to the work on thermionic emission by Guthrie (1873) and the photoelectric effect by Hertz (1893). Thermionic emission has been employed for elec...

Charge neutralization of an In-FEEP thruster was demonstrated with three different electron sources by zeroing the floating potential of the thruster and neutralizer system. The three cathodes used in the investigation include a mixed metal thermionic cathode, a carbon nanotube field emission cathode, and a Spindt-type Mo field emission array cathode. The field emission cathodes significantly i...

In this paper for the first time a precise theoretical analysis of efficiencies and power densities for nano-scaled thermionic vacuum gap devices is presented. Plane electrodes with nano-gaps will be treated first. With nonplanar electrodes (nanotips) enhanced electron field emission occurs, giving rise to new design options. The theories of field and thermionic emission are combined by calcula...

The competition between electron emission and unimolecular dissociation following the absorption of a single photon is studied for small clusters of various elements. Electron emission results from either direct photoemission, observed as a series of peaks in the spectrum, or thermionic emission, giving rise to a continuous background. Depending on the energetics involved, thermionic emission i...

Electric propulsion devices for space applications greatly reduce the propellant mass requirements on a spacecraft in comparison to chemical rockets. To date, gridded ion engines and Hall effect thrusters (HETs) rely on thermionic hollow cathodes to supply electrons for propellant ionization and ion beam neutralization. Hollow cathodes consume up to 10% of the total propellant used in low-power...

Introduction Thermionic cathodes are used in many industrial vacuum electronic applications. Vacuum tubes for high-frequency or high-power applications are one example (e.g., see [1]). The emission properties of thermionic electron sources in vacuum devices are often Bimproved[ by the addition of oxide coatings on the metal cathode surface [2, 3]. The explanation of the improvement is usually b...

A 60 keV neutral Lithium beam system was designed and built up for beam emission spectroscopy measurement of edge plasma on KSTAR. The measurement will be the complementary of the heating beam based emission spectroscopy system which was built up in 2012, using the same observation system with different interference filters. The electron density and its fluctuation, thus the density distributio...

We present a numerical model in which the thermionic and tunneling mechanisms across an abrupt heterojunction interface are taken into account on the basis of the one dimensional drift-diffusion formulation. We use an expression of thermionic-field emission current formulated based on the WKB approximation as a boundary condition at the abrupt heterointerface which eventually limits the current...