Investigations of Surface-Catalyzed Recombination Reactions in the Mars Atmosphere

Dougherty, Max; Meyers, Jason M.; Fletcher, Douglas G.

doi:10.2514/6.2011-1326

Cited by 11 publications

(7 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…TALIF strategies are already being employed and have been presented targeting near surface CO and atomic O species for CO 2 plasmas. [10][11][12] This paper documents the progress of step three of this three-part investigation. A properly designed DLAS sensor capable of detecting trace amounts of high-temperature CO 2 will provide a direct assessment of CO 2 production at the surface.…”

Section: Objective and Approachmentioning

confidence: 91%

Near Surface CO2 Detection in an Inductively Coupled Plasma Facility Using Diode Laser Absorption

Meyers

Owens

Fletcher

2011

42nd AIAA Thermophysics Conference

Self Cite

View full text Add to dashboard Cite

Uncertainty exists as to whether appreciable amounts of CO2 are formed by surface recombination for Mars entry vehicles. It is well understood that highly catalytic thermal protection system (TPS) material can lead to nearly two times the heat flux to the vehicle surface as a non-catalytic material. Conservative design practice assumes a supercatalytic surface to accommodate this uncertainty. Risk avoidance leads to oversized TPS geometries that add mass to entry vehicle designs that could be otherwise employed. Determining whether significant near surface production of CO2 occurs at trajectory heating conditions would add significant insight. The University of Vermont (UVM) has developed a 30kW Inductively Coupled Plasma (ICP) Facility to provide a pure high temperature plasma environment for aerospace material testing and gas-surface interaction chemistry investigations. The goal of the present work is to develop and test a diode laser absorption spectroscopy (DLAS) sensor to target near sample surface CO2 concentrations. A DFB diode laser at 2744 nm with a tuning range of around 3 nm is chosen as the light source. Current investigations show no appreciable amount of CO2 near a highly catalytic surface (water cooled copper) within the sensors' detectivity limits. Work is ongoing to further improve these sensitivity limitations.

show abstract

Section: Objective and Approachmentioning

confidence: 91%

Near Surface CO2 Detection in an Inductively Coupled Plasma Facility Using Diode Laser Absorption

Meyers

Owens

Fletcher

2011

42nd AIAA Thermophysics Conference

Self Cite

View full text Add to dashboard Cite

show abstract

“…24 The calibration of the signals is usually performed in cold gas tests or flow reactors. 17,25,26 However, providing a well defined amount of atomic oxygen for calibration of the LIF system is very challenging. Goehlich et al therefore developed a calibration approach using xenon which has a very close lying two-photon absorption line.…”

Section: B Two Photon Absorption Laser-induced Fluorescencementioning

confidence: 99%

“…1 entry trajectories of successful Mars missions are shown, adapted from literature, [5][6][7][8] together with test conditions available in ground testing facilities (mostly ICP, not all CO 2 ). [9][10][11][12][13][14][15][16][17][18] The data in Fig. 1 shows the regions of interest for pressure, enthalpy and velocity that are to be simulated in the ground testing facility.…”

Section: Introductionmentioning

confidence: 99%

Aerothermodynamic Investigation of Inductively Heated CO2 Plasma Flows for Mars Entry Testing

Marynowski

Löhle

Zander

et al. 2014

45th AIAA Plasmadynamics and Lasers Conference

View full text Add to dashboard Cite

This paper presents the characterization of an inductively coupled CO2 plasma relevant for Mars entry. Key plasma parameters are measured using Two Photon Absorption LaserInduced Fluorescence (TALIF), Optical Emission Spectroscopy (OES) and a High-Speed Camera (HSC) as non-intrusive diagnostic methods. In addition heat flux, enthalpy and total pressure are intrusively probed to supplement the characterization. TALIF provides data about translational temperature, velocity and the density of ground state atomic oxygen. From OES rotational and vibrational temperatures for identified molecular species and excitation temperatures for atomic species are derived. Preliminary HSC results show the pulsing behaviour of the generator and, in combination with bandwidth filters, atomic emission distributions. The diversity of the applied measurement techniques offers an extensive characterization of the flow, hence enabling the identification of suitable test conditions for the early stages of Martian entries. Nomenclature A = Einstein coefficient B = mass addition factor c = speed of light D = experimental coefficient E L = laser Energy f = oscillation circuit frequency g = degeneracy g(∆ω) = line profile h = mass specific enthalpȳ hω = excitation energy I = current K = gas specific constant k = Boltzmann constanṫ m CO2 = CO 2 mass flow M = molar mass n = number density N A = Avogadro constant P el = electrical power p amb = ambient tank pressure Q = quenching coefficient R ef f = effective nose radius St = Stanton numbeṙ q = mass specific heat flux S = fluorescence signal T tr = translational temperature U = voltage v = velocity η = transmissivity/quantum efficiency factor Θ = laser incident angle λ = wavelength ν = laser excitation frequency ρ = density σ (2)= absorption cross section

show abstract

“…To circumvent the problem of optical thickness for the excitation, two photons are used to excite the oxygen ground state [29]. The calibration of the signals is usually performed in cold gas tests or flow reactors [17,25,26]. However, providing a well-defined amount of atomic oxygen for calibration of the LIF system is very challenging.…”

Section: B Two-photon Laser-induced Fluorescencementioning

confidence: 99%

“…In Fig. 1, entry trajectories of successful Mars missions [5][6][7][8][9] are shown together with test conditions available in ground testing facilities (mostly ICP, not all CO 2 ) [10][11][12][13][14][15][16][17]. The data in Fig.…”

mentioning

confidence: 99%

Two-Photon Absorption Laser-Induced Fluorescence Investigation of CO2 Plasmas for Mars Entry

Marynowski

Löhle

Fasoulas

2014

Journal of Thermophysics and Heat Transfer

View full text Add to dashboard Cite

Two-photon absorption laser-induced fluorescence measurements have been conducted to investigate atomic oxygen temperature and number density in a CO 2 plasma relevant to Martian entry. The high-enthalpy plasma flow has been produced by an inductively heated plasma generator. This paper describes the experimental setup and shows the applicability of laser diagnostics to Mars-relevant plasmas. Particular emphasis is put on the use of the generated data for the numerical simulation of the aerothermal chemistry of a Martian entry. Relative fluorescence signals are calibrated by a procedure using xenon as a reference. This calibration method allows the in situ experimental determination of the instrumental broadening of the spectroscopic setup and thus an accurate temperature measurement. The acquired, highly resolved line profiles of the fluorescence signal yield a translational temperature of 2777 K 400 K and a mean number density of 1.55 · 10 19 m −3 60%. Nomenclature= molar mass of oxygen _ m CO 2 = CO 2 mass flow n = number density N A = Avogadro constant P el = electrical power p amb = ambient tank pressure Q = quenching coefficient S = fluorescence signal T tr = translational temperature U = voltage η = transmissivity and quantum efficiency factor λ = wavelength σ 2 = absorption cross section

show abstract

Investigations of Surface-Catalyzed Recombination Reactions in the Mars Atmosphere

Cited by 11 publications

References 9 publications

Near Surface CO2 Detection in an Inductively Coupled Plasma Facility Using Diode Laser Absorption

Near Surface CO2 Detection in an Inductively Coupled Plasma Facility Using Diode Laser Absorption

Aerothermodynamic Investigation of Inductively Heated CO2 Plasma Flows for Mars Entry Testing

Two-Photon Absorption Laser-Induced Fluorescence Investigation of CO2 Plasmas for Mars Entry

Contact Info

Product

Resources

About