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 theory for the single-channel hollow cathode (SCHC) that includes the relevant physical processes and predicts the operating parameters is presented. A SCHC consists of a cylindrical channel approximately ten diameters in length through which a working gas (taken as lithium vapor here) flows and exits as a plasma. A high current (1-100 A) is conducted into the channel by the plasma and to the...

In electron beam devices, the voltage applied to the cathode (w.r.t. grid voltage) provides the initial energy for the electrons. Based on the type of electron emission, the electron sources are (mainly) classified into thermionic cathodes and cold cathodes. The power consumption of a cold cathode is smaller than that of a thermionic cathode. The delay time of the electron emission from a cold ...

We report a photoelectron imaging study of (OCS)-2 and compare the results to OCS-.H2O. Two electron-emission mechanisms are observed for the dimer anion: direct photodetachment and autodetachment, while OCS-.H2O exhibits only the direct mechanism. The results provide evidence of covalent (OCS)-2 coexisting with the OCS-.OCS cluster anion. The autodetachment originating from the covalent specie...

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...

A detailed theory of nonisothermal electron transport perpendicular to multilayer superlattice structures is presented. The current–voltage (I – V) characteristics and the cooling power density are calculated using Fermi–Dirac statistics, density-of-states for a finite quantum well and the quantum mechanical reflection coefficient. The resulting equations are valid in a wide range of temperatur...