A Unified, Universal Model for Electron Emission and Breakdown
Abstract
The importance of accurately predicting gas breakdown voltage continues to grow due to increased electronics miniaturization. Microelectromechanical systems, such as microactuators, pressure sensors, and high-frequency circuits, require microscale gaps and high operating voltages. Accurately predicting breakdown voltage for these systems prevents discharges that could damage or destroy the device. Conversely, microplasmas are used for various applications, such as electric micropropulsion and environmental mitigation. The Air Force and Navy have ongoing efforts exploring the field emission characteristics of arrays of carbon nanotubes.Although field emission systems provide high current at low voltage, system miniaturization introduces potential issues due to space charge and electric field that may result in space-charge limited flow and even gas breakdown. Recent research into microscale devices at atmospheric pressure has demonstrated that field emission dominates breakdown rather than conventional Townsend discharge, which drives breakdown for larger devices at lower pressure. Analytic expressions that provide universal curves that are consistent for both noble and non-noble gases have demonstrated the relationship between voltage, pressure, and gap distance for this breakdown behavior at microscale. Previous models have demonstrated similar unification of space-charge limited flow and field emission. Depending upon operating voltage, emission current, and even surface roughness and features, it is possible for a single device to transition between these mechanisms.This proposal aims to incorporate space charge effects into our previous field emission models coupled with Townsend discharge by modeling the trajectory of a single electron and incorporating the effects into Poisson’s equation. While improving the previous model, this also enables the extension to the Child-Langmuir and Mott-Gurney laws at vacuum and pressure, respectively. Thus, this will provi
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 09, 2018
- Source ID
- FA95501810218
Entities
People
- Allen L Garner
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Virginia