Entry Conditions in Planetary Atmospheres: Emission Spectroscopy of Molecular Plasma Arcjets

Lago, Viviana; Lebehot, A.; Dudeck, Michel; Pellerin, Stéphane; Renault, Thierry; Echegut, Patrick

doi:10.2514/2.6605

Cited by 29 publications

(18 citation statements)

References 16 publications

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“…7 Most ground testing typically uses a transverse probing geometry to view the gas cap emission spectra. [8][9][10] Some testing uses streamwise viewing with mirrors instead of fibers. 11,12 Another study used windowless and purged apertures to extract the optical emission, 13 which works well for the deep ultraviolet (UV) spectrum.…”

Section: Previous Workmentioning

confidence: 99%

Fiber-Based Measurement of Bow-Shock Spectra for Reentry Flight Testing

Schott

Herring

Munk

et al. 2010

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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We demonstrated a fiber-based approach for obtaining optical spectra of a glowing bow shock in a high-enthalpy air flow. The work was performed in a ground test with the NASA Ames Aerodynamic Heating Facility (AHF) that is used for atmospheric reentry simulation. The method uses a commercial fiber optic that is embedded in the nose of an ablating bluntbody model and provides a line-of-sight view in the streamwise direction -directly upstream into the hot post-shock gas flow. Both phenolic impregnated carbon ablator (PICA) and phenolic carbon (PhenCarb 28) materials were used as thermal protection systems. Results show that the fibers survive the intense heat and operate sufficiently well during the first several seconds of a typical AHF run (20 MJ/kg). This approach allowed the acquisition of optical spectra, enabling a Boltzmann-based electronic excitation temperature measurement from Cu atom impurities (averaged over a line-of-sight through the gas cap, with a 0.04 sec integration time). Nomenclature I. Backgroundadiometry and spectroradiometry instrumentation for measuring bow shock emission ahead of blunt-body atmospheric entry vehicles was successfully demonstrated in well-known NASA flight experiments in the 1960s as part of the Apollo program. In the Fire I and Fire II flight tests, 1, 2 each entry vehicle had a stacked series of three "clean" beryllium forebody heat shields, two of which were jettisoned successively during reentry. Each heat shield had its own fused quartz window at the stagnation point that provided viewing of the bow shock. The total 1 AST, Flight Systems Remote Sensing Branch, B1202/MS 468 2

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Section: Previous Workmentioning

confidence: 99%

Fiber-Based Measurement of Bow-Shock Spectra for Reentry Flight Testing

Schott

Herring

Munk

et al. 2010

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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“…The dissociation rate coefficients for CO 2 and O 2 were calculated by employing (8) and are shown in Fig. 9.…”

Section: Evaluation Of the Eedfmentioning

confidence: 99%

“…In recent years, there have been many models and experiments of CO 2 /N 2 hypersonic flows in a convergent-divergent nozzle for application to Martian atmospheric entry [8]- [10]. By using a thermochemical nonequilibrium Navier-Stokes solver, these researchers have shown how the rotational temperature, vibrational temperature, number density, and molar fractions of the gases vary in a plasma arcjet under specific laboratory conditions.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Description of Martian Atmospheric Entry Plasma

Drake

Popović

Vušković

et al. 2009

IEEE Trans. Plasma Sci.

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A kinetic model for Martian atmospheric entry plasma (MAEP) is presented. The model was calculated based on data from Viking, Pathfinder, and the Mars Exploration Rovers Opportunity and Spirit. Calculations of the density, temperature, and electron density across the shock front were made. We employed steady-state and nonsteady-state kinetic models to describe the rate of dissociation of CO 2 in the Martian atmosphere as well as the production of O 2 . Water vapor was included in the models since it represents 0.03% of the surface atmospheric composition. With the addition of small amounts of water vapor, we found a decrease in the dissociation of CO 2 in the Martian air as well as an increase in the production of O 2 . This paper is to report an analysis of MAEP and its interactions with the shock front which forms in the front of the Martian Landers.

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“…The SR5 low-pressure arcjet plasma wind tunnel available at the Laboratoire d'Aérothermique has been used during the last years for the simulation of the entry conditions in Earth, Mars, and Titan planetary atmospheres [4]. A dc vortex-stabilized arc operating at low voltages (50-100 V) and low currents (50-150 A) delivers typical powers of 5-10 kW to the flow in the throat region of the nozzle.…”

Section: Experimental Facilitymentioning

confidence: 99%

“…The physical properties of the gas flow surrounding a spacecraft depends on the nature of the molecules present in the planetary atmosphere (Mars and Venus: CO 2 -N 2 , Titan: N 2 -CH 4 ) but also on the chosen spacecraft trajectory (direct entry, aerobreaking, or aerocapture). Different ground test facilities are available today to simulate such entry conditions (low-pressure hyperenthalpic gas flows): shock tubes, inductive plasma torches, radio-frequency sources, and arcjets [1][2][3][4].…”

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confidence: 99%

Modelling of a CO2-N2 Plasma Flow in a Supersonic Arcjet Facility

Silva

Passarinho

Dudeck

2006

Journal of Thermophysics and Heat Transfer

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The Martian-type CO 2 -N 2 plasma flow obtained in the plasma generator of the SR5 arcjet facility has been simulated using two complementary fluid descriptions. An inviscid multitemperature monofluid description has firstly been used to evaluate the importance of the different chemical and exchange processes between the flow species. Then, a one-temperature Navier-Stokes description has been used to evaluate the influence of viscous and rarefaction effects. In the nozzle throat region, heat addition from the arc firstly leads to the establishment of a translation-vibration disequilibrium. Near the end of the nozzle throat, temperature and pressure increases allow more efficient exchange processes and lower this disequilibrium. In the nozzle diverging region, chemical and vibrational processes are quickly frozen as the flow strongly expands. Furthermore, a translation-rotation disequilibrium also occurs near the nozzle exit. Navier-Stokes simulation results evidence a quick increase of the diverging section boundary layers, and therefore most of the diverging section is in a fully viscous interaction regime. Moreover, rarefaction effects are predicted to appear near the nozzle exit walls. The experimental measurements carried near the nozzle exit confirm the thermal disequilibrium regime of the flow, predicted by the simulation results. Nomenclature anode = nozzle anode arc = nozzle electrical arc cathode = nozzle cathode chamber = facility vacuum chamber Da = Damköler number gas = facility gas flow generator = conditions upstream of the nozzle throat h = flow enthalpy, MJ=kg i = chemical species index Kn = Knudsen number k B = Boltzmann constant, 1:38065 10 23 J=K L = characteristic length, m M = flow Mach number _ m = mass flow, kg=s _ Q = heat transfer rate, kJ=s p = flow pressure, Pa R-T = rotation-translation processes T = flow translational temperature, K T rot = species rotational temperature, K T vib = species vibrational temperature, K T w = nozzle wall temperature, K V-D = vibration-dissociation processes V-el = vibration-electron processes V-T = vibration-translation processes V-V = vibration-vibration processes v = flow velocity, m=s ZT; T vib = nonequilibrium coupling factor for dissociation Z 1 = Parker rotational collision number E = energy transfer rate, kW = arc energy transfer efficiency = flow density, kg=m 3 = collisional cross-section, m 2 F = flow characteristic time, s vib = vibrational relaxation characteristic time, s

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Entry Conditions in Planetary Atmospheres: Emission Spectroscopy of Molecular Plasma Arcjets

Cited by 29 publications

References 16 publications

Fiber-Based Measurement of Bow-Shock Spectra for Reentry Flight Testing

Fiber-Based Measurement of Bow-Shock Spectra for Reentry Flight Testing

Kinetic Description of Martian Atmospheric Entry Plasma

Modelling of a CO2-N2 Plasma Flow in a Supersonic Arcjet Facility

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