Analysis of the JAXA Nonequilibrium Infrared Emission Spectra for Mars Entry Conditions

International audienceNonequilibrium infrared emission spectra representative of a Mars atmospheric entry mission are modeled using RADIS, a spectral code for CO and CO 2 based on the HITEMP-2010 and CDSD-4000 databases. The modeled experimental data for the free-flow and the forebody radiation were obtained in the JAXA expansion tube facility. In the expanding flow, good agreement with the experimental data can be obtained using a slightly nonequilibrium distribution and a homogeneous flow. The model suggests that all three CO 2 vibration modes share a same vibrational temperature slightly higher than the gas temperature. In the shock layer, the forebody radiation includes both CO 2 and CO emission features. It can be correctly predicted by assuming thermal and chemical equilibrium at 4000 ± 500 K. Nomenclature p = pressure [bar] T r ot = rotational temperature of the gas [K] T tr ans = translational temperature of the gas [K] T vib = vibrational temperature of the gas [K] T vib 1 , T vib 2 , T vib 3 = for CO 2 , temperature of each vibration mode: symmetric, bending and asymmetric vibration, respectively [K] x CO , x CO

Investigation of Infra-red and Nonequilibrium Air Radiation

This report summarizes the results obtained during a research program on the infrared radiation of air plasmas conducted in the High Temperature Gasdynamics Laboratory at Stanford University. This program was intended to investigate the masking of infrared signatures by the air plasma formed behind the bow shock of high velocity missiles. Prior to this work, the radiative emission of air plasmas in the infrared had been the object of few experimental investigations, and although several infrared systems were already modeled in radiation codes such as NEQAIR, measurements were required to validate numerical predictions and indicate whether all transitions of importance were accounted for in the model. The program was further motivated by the fact that 9 excited states (A, B, C, D, B', F, H, and H') of NO radiate in the infrared, especially between 1 and 1.5 microns where at least 9 transitions involving can be observed. Because these IR transitions are relatively well separated from each other, excited NO states concentrations can be easily measured, thus providing essential information on excited-state chemistry for use in optical diagnostics or in electronic excitation model validation. Detailed comparisons between measured and simulated spectra are presented

Caractérisation spatio-temporelle de NO et température par QCLAS et PLIF dans une post-décharge nanoseconde

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Meteors: A Delivery Mechanism of Organic Matter to the Early Earth

All potential exogenous pre-biotic matter arrived to Earth by ways of our atmosphere, where much material was ablated during a luminous phase called "meteors" in rarefied flows of high (up to 270) Mach number. The recent Leonid showers offered a first glimpse into the clusive physical conditions of the ablation process and atmospheric chemistry associated with high-speed meteors. Molecular emissions were detected that trace a meteor's brilliant light to a 4,300 K warm wake rather than to the meteor's head. A new theoretical approach using the direct simulation by Monte Carlo technique identified the source-region and demonstrated that the ablation process is critical in the heating of the meteor's wake. In the head of the meteor, organic carbon appears to survive flash heating and rapid cooling. The temperatures in the wake of the meteor are just right for dissociation of CO and the formation of more complex organic compounds. The resulting materials could account for the bulk of pre-biotic organic carbon on the early Earth at the time of the origin of life.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43257/1/11038_2004_Article_310535.pd

Infrared and ultraviolet measurements of C and CO within a high temperature boundary layer

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NO radiation model selection for equilibrium air plasma conditions

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Vibrational Excitation of CO2 by Nanosecond Discharges at Atmospheric Pressure

International audience[3] B L M Klarenaar et al 2017 Plasma Sources Sci. Technol.26 115008 LOS Model Nonequilibrium LBL Model Challenges ▪ Electromagnetic interferences shielded reactor design ✓ ▪ Room air absorption optical train purged for absolute calibration ✓ ▪ Spatial fluctuations (hydrodynamics) spatially resolved spectra ✓ ▪ Signal-to-dark ratio ~ 1/400 phase locked capture of dark drift ✓ ▪ Camera mistrigs post-processing detection algorithm ✓ ▪ 2D: Large data generation (~ 8 hrs, 200 Gb / full spectrum) ▪ Atmospheric pressure: broad, overlapping lines Motivatio