Advanced gas chemistry model for gasses disturbed by an intense electron beam

Summary form only given. The behavior of intense electron beams (those with current densities on the order of hundreds of kA/cm² and beam rise times on the order of 100 ns) traveling through gaseous media depends strongly on the transport properties of the media. For example, the conductivity of a gas, which depends sensitively on its ionization state and temperature, has a strong influence on the beam behavior through the plasma return current. Because the beam is responsible for ionizing and heating the gas, self-consistently solving for the gas transport properties and the beam propagation is essential for an accurate description of the system. An advanced gas chemistry model to describe the transport properties of a strongly disturbed air system is presented in this work. The model includes rate equations for the different gas states that include molecular and atomic states as well as excited and multiply ionized states. Furthermore, the model includes an energy equation for the heavy species. For validation purposes, the model is used in the simulation of an intense electron beam generated by a ring diode experiments on Gamble II [1] and injected into a gas cell. The LSP code is used for the simulations [2]. The results are compared with the previously used “swarm model” in LSP, which is only valid for very weakly ionized systems.