Electric charge buildup in hypersonic wind tunnels with electron-beam energy addition

A two-dimensional axisymmetric model is developed to predict electric charge and voltage buildup in supersonic/ hypersonic nozzle flows of dense air with upstream-propagating high-energy electron beams depositing energy and electric charge into the air. The flowfield and the electron-beam power-deposition profiles were taken from calculations performed elsewhere. The present model includes kinetics of plasma species (electrons, positive ions, and negative ions) and the Poisson equation for electric potential. Both the case of grounded conducting nozzle walls and that of walls covered by a dielectric layer were considered. The model was applied to quantify the important charge and voltage buildup and removal under the conditions expected in medium- and large-scale electron-beam-driven hypersonic wind tunnels.