New Data For Modeling Hypersonic Re-entry Into Earth’s Atmosphere: Electron-impact Ionization Of Atomic Nitrogen

Space vehicles returning to Earth from beyond orbit enter the atmosphere at hypersonic velocities (greater than Mach 5). The resulting shock front generates a high temperature reactive plasma around the vehicle (with temperatures greater than 10,000 K). This intense heat is transferred to the capsule by radiative and convective processes. Designing vehicles to withstand these conditions requires an accurate understanding of the underlying non-equilibrium high temperature chemistry. Nitrogen chemistry is particularly important given the abundance of nitrogen in the atmosphere. Line emission by atomic nitrogen is a major source of radiative heating during reentry. Our ability to accurately calculate this heating is hindered by uncertainties in the electron-impact ionization (EII) rate coefficient for atomic nitrogen. ¹