Effect of cesium seeding on plasma density in hypersonic boundary layers

This paper outlines the effect of cesium seeding on the plasma density within the boundary layer around a wedge with a sharp leading edge in the Mach number range 6–18. The results are obtained through numerical simulation using two CFD codes, LeMANS and CFDWARP, which include finite-rate chemistry, non-equilibrium of the vibrational and electron energies, and real gas effects. Results obtained indicate that seeding the air flow with as little as 0.001% of cesium leads to plasma densities high enough to interfere with radio communication and to enable electron transpiration cooling (ETC) at flight Mach numbers as little as 9. When no cesium is added, it is seen that significant interference of the plasma on radio communication can occur in the Mach number range 12–18, with the interference becoming more likely for higher flight dynamic pressure.