MASS-SPECTROMETRIC INVESTIGATION OF HIGH ENTHALPY PLASMA FLOWS

At the Institute for Space Systems three plasma wind tunnels for the s imulation of conditions encountered by space vehicles during planetary entry are available, Two of these tunnels are equipped with a magneto plasmadynamic accelerator, specially designed for the use of gas mixtu res such as N-2/O-2 and carbon-containing gas mixtures, A quadrupole m ass spectrometer that is placed inside the plasma jet is used to deter mine the plasma composition, the radial and axial distributions of all neutral and ionized particles, as well as the ion energy distribution s, A theoretical investigation of the influence of the orifice opening on the sampling of radicals leads to a correction factor, with which the effect of recombination losses inside the orifice can be estimated . Additionally, a model of the space charge sheath in front of the ori fice yields an equation for the evaluation of the ion temperatures, Di fferent plasma conditions at ambient pressures of 0.1-2.9 mbar and at specific enthalpies of 19-33 MJ/kg were investigated.