Modeling the Effects of Electron-Ion Collisions on Electric Field and Conductivity in an E-Beam Driven Gas Chamber Using Turbopy

An electron beam propagating through a low-pressure gas creates a breakdown plasma which affects the transport of the beam. Such a system is relevant to many applications which include plasma processing, naturally occurring ionospheric events, and electromagnetic pulse events. This system is being studied by NRL using a 1-D rigid-beam approximation model within the NRL turboPy framework. 1 This paper expands upon this work to consider the effects of electron-ion collisions in this system on the electric field and conductivity of the gas. These effects are captured through the total momentum transfer frequency term that is present in the expressions for the plasma electron energy and the induced electric field. Previously, the total momentum transfer frequency included contributions from elastic collisions, ionizing collisions, and inelastic collisions between electrons and gas molecules while the electron-ion collision contribution was assumed to be negligible. A parameterized study over a range of beam current densities and ambient gas pressures will be conducted in order to assess the region of validity for this approximation. Finally, the use of turboPy to systematically vary the plasma chemistry reaction network and run automatic parameter sweeps will be discussed in the context of planned uncertainty quantification studies.