An innovative approach to measure the effects of heterogeneous catalysis during re-entry has been proposed in the framework of the instrumentation planned for the ESA-EXPERT mission. So far measurements of species concentrations during re-entry by a spectrometer has been performed only by the Japanese READ experiment (USERS mission), using a spectrometer located inside the capsule and oriented toward the stagnation point. The goal is to measure the recombination coefficient by measuring gas species close to the surface. The main elements of the diagnostic system are: a light capture device and a multi-channel spectrometer. Dimensions and features of the diagnostic system components have been defined. A sapphire pole, 3mm high from the surface, is used to look directly at the surface during re-entry, measuring what ’happens’ close to the surface of a SiC/C sample. Sapphire is necessary to stand high temperatures (its melting point is almost 2300 K) and to transmit in the UV (where emission of NO is strong). The multi-channel spectrometer has 24 channels and a spectral resolution of 0.25 nm/pixel. A multi-channel spectrometer is needed to determine the spectra at a location. The pole will be located at about 500 mm from the end of the EXPERT nose, protruding from a SiC/C sample. A preliminary test to validate the feasibility of the device has been planned: the CFD results obtained by CIRA for the flow close to the SiC/C sample, in condition of max heat flux, will be fed to a spectra rebuilding software (PARADE); the spectra calculated in this way will be compared with the spectra measured by the light capture device and generated by the 1200KW VKI induction Plasmatron. By knowing the spectral emissions of species such as O, N and their molecules, including NO, it will be possible to determine the presence and concentration of these species. The species produced by surface recombination are excited; therefore the concentration of recombined molecules will be determined by distinguishing the excited gas species with respect to the non excited. The recombination coefficient will be calculated applying the kinetic model of Bruno et al. for heterogeneous catalysis. The surface heat flux has to be known to perform this calculation, and it will eventually be provided by other EXPERT measurements.

A Spectrometric Device To Measure Species Concentrations Close to the Surface During Re-entry / Finamore, F; Bruno, Claudio; Paolozzi, Antonio; Currie, D.. - In: SPACE TECHNOLOGY. - ISSN 0892-9270. - 26:(2006), pp. 25-32.

A Spectrometric Device To Measure Species Concentrations Close to the Surface During Re-entry

BRUNO, Claudio;PAOLOZZI, Antonio;
2006

Abstract

An innovative approach to measure the effects of heterogeneous catalysis during re-entry has been proposed in the framework of the instrumentation planned for the ESA-EXPERT mission. So far measurements of species concentrations during re-entry by a spectrometer has been performed only by the Japanese READ experiment (USERS mission), using a spectrometer located inside the capsule and oriented toward the stagnation point. The goal is to measure the recombination coefficient by measuring gas species close to the surface. The main elements of the diagnostic system are: a light capture device and a multi-channel spectrometer. Dimensions and features of the diagnostic system components have been defined. A sapphire pole, 3mm high from the surface, is used to look directly at the surface during re-entry, measuring what ’happens’ close to the surface of a SiC/C sample. Sapphire is necessary to stand high temperatures (its melting point is almost 2300 K) and to transmit in the UV (where emission of NO is strong). The multi-channel spectrometer has 24 channels and a spectral resolution of 0.25 nm/pixel. A multi-channel spectrometer is needed to determine the spectra at a location. The pole will be located at about 500 mm from the end of the EXPERT nose, protruding from a SiC/C sample. A preliminary test to validate the feasibility of the device has been planned: the CFD results obtained by CIRA for the flow close to the SiC/C sample, in condition of max heat flux, will be fed to a spectra rebuilding software (PARADE); the spectra calculated in this way will be compared with the spectra measured by the light capture device and generated by the 1200KW VKI induction Plasmatron. By knowing the spectral emissions of species such as O, N and their molecules, including NO, it will be possible to determine the presence and concentration of these species. The species produced by surface recombination are excited; therefore the concentration of recombined molecules will be determined by distinguishing the excited gas species with respect to the non excited. The recombination coefficient will be calculated applying the kinetic model of Bruno et al. for heterogeneous catalysis. The surface heat flux has to be known to perform this calculation, and it will eventually be provided by other EXPERT measurements.
2006
.
01 Pubblicazione su rivista::01a Articolo in rivista
A Spectrometric Device To Measure Species Concentrations Close to the Surface During Re-entry / Finamore, F; Bruno, Claudio; Paolozzi, Antonio; Currie, D.. - In: SPACE TECHNOLOGY. - ISSN 0892-9270. - 26:(2006), pp. 25-32.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/233788
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