Models of Electron Yield Roughness Coefficient

ORAL

Abstract

Models to calculate the effects of roughness on electron yield (EY) were developed for several surface morphologies and electron emission energy distributions. EY, the ratio of emitted electrons to incident electrons, plays an important role in many applications such as spacecraft charging, high voltage systems, and scanning electron microscopy. Surface roughness is known to generally reduce EY of materials by reducing the critical escape angle for an emitted electron, though coupling geometry effects with emission angular distributions can complicate the issue. Four surface morphologies were considered: square, triangular, sawtooth, and sinusoidal periodic wells, each with critical angles dependent on where the incident electrons strike along the width of the surface feature. Both secondary electron (with energies \textless 50 eV) and backscattered electron (with energies \textgreater 50 eV) yields are considered. Secondary electrons and backscattered electrons have different energy-dependent angular emission distributions (Lambertian and screened Rutherford, respectively), with backscattered electrons generally having a narrower distribution; specular and isotropic distributions were also considered as limiting cases. The results are compared to experimental EY data of roughened Cu and Al samples to verify the model.

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Authors

  • Trace Taylor

    Utah State University

  • Rupjyoti Gogoi

    Arizona State University, Colorado State University, University of Utah, Utah State University, George Mason University, Brigham Young University, University of Colorado, Boulder, Georgia Institute of Technology, University of Colorado, Boulder; North China Electric Power University, Argonne National Laboratory, Carnegie Mellon University, Purdue University, Yunnan University, University of Arizona, Ball Aerospace, Ponderosa Associates Limited, Polsinelli PC, Saleh Research Centre, New Mexico State University, Oak Ridge National Laboratory, Center for Memory and Recording research, Advanced Photon Source, Chemnitz university of technology, Tezpur University

  • JR Dennison

    Utah State University