Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing end reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway. Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 6p(6p') levels is evaluated. Meanwhile, visible Xefl emissions are shown to provide plasma densities at high electron temperature conditions. The electron temperature and spatial ion number density 0 distribution were determined from the luminescence spectra measured in the discharge and plume near-field plasma of the Hall thruster, the TSNIIMASH D-55 anode layer thruster. The results are in REPORT DATE (DD-MM- SPONSORING I MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORIMONITOR'S ACRONYM(S) SPONSORIMONITOR'S REPORT NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENT Q•good agreement with the probe measurement data and simulations reported in the literature for the same thruster. The analysis of the Hall thruster XeI near-infrared spectra demonstrates that the neglect of ion-atom collisions results in an erroneous electron temperature determination at electron temperatures below 10 eV.
This paper presents a set of xenon apparent emission excitation cross sections for emission lines that have diagnostic value in the analysis of Xe-propelled Hall thruster plasmas. Emission cross sections are presented for three excitation processes involving ground-state xenon atoms: e−+Xe, Xe++Xe, and Xe2++Xe. The cross sections are derived from luminescence spectra produced at single-collision conditions. Apparent emission excitation cross sections are tabulated for 12 visible and 8 near-infrared lines for electron energies ranging from 10to70eV. In case of the near-infrared lines, radiation trapping effects are accounted for by measuring the detailed pressure dependence of the apparent emission cross sections and extrapolating to zero pressure. A semiempirical expression for the pressure dependence is derived that allows zero-pressure extrapolation from threshold to 70eV. Ion-induced cross sections are reported for the same emission lines at an energy per unit charge E∕q of 300eV, chosen for typical Hall thruster operating voltages. Radiation trapping effects are negligible for the ion emission excitation cross sections between 0.1 and 2.0mTorr in the present luminescence experiment.
The results on an investigation of nonequilibrium uv radiation in the systems of molecular bands NO and (12) in a shock layer in air are presented. The studies included the experiments on a measurement + N 2 of the nonequilibrium radiation behind a strong shock wave in an electric arc-driven shock tube within the range of shock-wave velocity change V s = 5 to 10 km/s at the initial air pressure P 1 = 0.1 torr, and numerical simulation of radiation processes behind the shock wave and in a hypersonic viscous shock layer, where the ow was simulated on the basis of Navier -Stokes equations. A numerical model of the radiation behind the strong shock wave has been used to verify a kinetic scheme of radiation processes by comparison with experimental results. Examples of emission calculations in the NO and (12) sys-+ N 2 tems for the conditions of a ight test are presented. Nomenclature B = rotational constant c = speed of light, cm /s D = energy of dissociation, K e = electron H = ight altitude, km h = Planck's constant I = radiation intensity, W /cm 3 sr mm k = rate constant of reaction m = mass, g n = concentration, cm 2 3 P = pressure, torr R = radiance, W /cm 2 sr mm T = temperature, K t = time, s or ms U = rate of electron energy exchange V = ight or shock wave velocity, km /s v = vibrational number x = distance behind shock wave, cm y = stagnation line distance, cm b, g = parameters in vibration -dissociation model l = wavelength, nm or mm u = characteristic vibrational temperature, K n = collision frequency, s 2 1 s = cross section, cm 2 t = time, lifetime, s, ns, or ms v 0 , v 0 x 0 , v 0 y 0 , v 0 z 0 = vibrational constants ai = associative ionization e = electron, electronic el = elastic f = forward m = maximum R = rotational r = reverse s = shock-wave condition v = vibrational 1 = condition ahead of a shock wavè = freestream condition Superscripts 9 = upper excited state 0 = lower excited state
Collaboration is now underway to perform space-based experiments on the interactions of rocket plume exhausts and the ambient environment at an altitude of roughly 350 km. The key element in this experiment is the use of the Mir space station as a platform for optical instrumentation. A description is given of the modeling and instrumentation involved in the execution of this experiment, as well as a description of the experiment strategy and some experimental data already obtained. In particular, a hypothesized model of the OH(A-X) ultraviolet radiation is presented and evaluated. * The research reported herein was performed by the Arnold Engineering Development Center (AEDC), Air Force Materiel Command. Work and analysis for this research were performed by personnel of Sverdrup Technology, Inc., AEDC Group, technical services contractor for AEDC. Further reproduction is authorized to satisfy needs of the U. S. Government.
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