Electric and Magnetic Fields of an Intense Pulse of Relativistic Electrons Propagating through Air.

摘要

Since propagation characteristics of an electron beam traversing a neutral gas are determined by the response of the beam electrons to their self-fields, an accurate evaluation of the electric and magnetic (EM) fields is essential to any propagation analysis. We report here on theoretical models that were developed for the electromagnetic fields associated with an electron beam propagating in air. One- and two-dimensional models of the fields, and a model for the electron avalanche of the air, were solved on a computer. The major conclusions from calculational results are: the ionization model adequately describes the ionization process over a pressure range of from five Torr to 760 Torr; ionization lag from the high energy secondary electrons is unimportant; in many cases the one-dimensional model was found to be as good as the two-dimensional model; and the net current saturates near 15 kilo-Amperes at sea-level pressure, and saturates at lower values at lower air pressure. (Author)