title: Time domain simulations of preliminary breakdown pulses in natural lightning.
abstract: Lightning discharge is a complicated process with relevant physical scales spanning many orders of magnitude. In an effort to understand the electrodynamics of lightning and connect physical properties of the channel to observed behavior, we construct a simulation of charge and current flow on a narrow conducting channel embedded in three-dimensional space with the time domain electric field integral equation, the method of moments, and the thin-wire approximation. The method includes approximate treatment of resistance evolution due to lightning channel heating and the corona sheath of charge surrounding the lightning channel. Focusing our attention on preliminary breakdown in natural lightning by simulating stepwise channel extension with a simplified geometry, our simulation reproduces the broad features observed in data collected with the Huntsville Alabama Marx Meter Array. Some deviations in pulse shape details are evident, suggesting future work focusing on the detailed properties of the stepping mechanism.
  
  
  CONCLUSIONS
  Preliminary breakdown pulses can be reproduced by simulated channel extension Channel heating and corona sheath formation are crucial to proper pulse shape Extension processes and channel orientation significantly affect observations.
authors.affiliation: Department of Physics, Carthage College Kenosha, Wisconsin, USA ; Birkeland Center for Space Science, University of Bergen Bergen, Norway.
authors.forename: B E
authors.initials: BE
authors.lastname: Carlson
authors.affiliation: Electrical Engineering Department, Stanford University Stanford, California, USA.
authors.forename: C
authors.initials: C
authors.lastname: Liang
authors.affiliation: Department of Atmospheric Science, University of Alabama in Huntsville Huntsville, Alabama, USA.
authors.forename: P
authors.initials: P
authors.lastname: Bitzer
authors.affiliation: Earth Systems Science Center, University of Alabama in Huntsville Huntsville, Alabama, USA.
authors.forename: H
authors.initials: H
authors.lastname: Christian
keywords: Lightning; Preliminary Breakdown; Simulation