Modes in electron-hopping transport over insulators sustained by secondary electron emission

Abstract

A general formalism for hopping electron transport over insulators sustained by secondary electron emission is presented. Steady-state electron transport takes place when the charging of the insulator, which turns out to be self-stabilizing, is such that the average secondary electron yield becomes equal to unity. The steady-state potential distribution for the electron transport is determined for various insulating geometries with the aid of Monte Carlo calculations and compared with the low-hopping approximation. The Monte Carlo results show that the steady-state potential distribution can exhibit several interesting features such as spontaneous symmetry breaking of statistical origin and the occurrence of local repulsive parts in the geometry. In several cases the numerical results, including the above two features, are found to agree well with the results of experiments.

Simulation of Electron Hop Funnels Using Version 9.2 of Lorentz-2E

“…Electron hop funnels operate by sustaining current along the dielectric funnel wall through a mechanism known as electron hopping transport [1]. To initiate the electron hopping transport mechanism in the hop funnel, primary electrons are injected into the wide end of the funnel.…”

“…In a state known as unity-gain [1], the wall charges such that the current transmitted through the funnel is equal to the current injected into the funnel. The unity gain state is achieved if the potential on the hop electrode is large enough to cause secondary electrons to gain enough energy during their lifetime to create additional secondaries when they strike the funnel wall.…”

“…When the device is less than unity gain, the electrons emitted from the FEA are turned around by surface charge on the portion of the funnel wall that does not sustain electron hopping transport and are collected on the FEA surface. This mechanism is described in great detail elsewhere [1].…”

“…An I-V curve is the comparison of the amount of current collected on an anode above the funnel exit (amount of current that is transmitted through the funnel) versus the potential on the hop electrode. This measurement provides an indication of the potential needed on the hop electrode to support electron hopping transport in the hop funnel [1].…”

“…I-V curves have been successfully measured and simulated [1,4,[6][7][8] for various types of hop funnels. The I-V curve from previous simulation work [7], using version 8 of Lorentz 2E, is shown in Fig.…”