Diagnostics by electron beam fluorescence in hypersonics

Mohamed, Ajmal Khan; Pot, T.; Chanetz, Bruno

doi:10.1109/iciasf.1995.519120

Cited by 12 publications

(3 citation statements)

References 7 publications

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“…Based on the advent of this new electron gun, ONERA recently carried a study aimed at designing, building, and validating a laboratory prototype to demonstrate the feasibility of obtaining a more compact EBF instrument capable of all the envisioned in- §ight measurements [7,11]. The principle of the targeted prototype is shown in Fig.…”

Section: Prototype For In-flight Measurementsmentioning

confidence: 99%

Development of a compact electron beam fluorescence instrument for high enthalpy flow characterization

Diop

Mohamed

Bonnet

2012

Progress in Flight Physics

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A prototype based on the Electron Beam Fluorescence (EBF) Technique is being developed for in- §ight measurements in the shock layer of a reentry demonstrator. The measurement objectives are rotational and vibrational temperatures of N 2 as well as the densities of N 2 and NO at di¨erent positions in and outside a shock layer. There is a renewal of interest in extending the technique to higher densities and to probe CO/CO 2 §ows (Mars atmosphere studies). The present paper gives a brief description of the status of the instrument with details on the optimization work performed to miniaturize the electron gun, the study of induced §uorescence in some gases and mixtures in laboratory vacuum chamber.

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Section: Prototype For In-flight Measurementsmentioning

confidence: 99%

Development of a compact electron beam fluorescence instrument for high enthalpy flow characterization

Diop

Mohamed

Bonnet

2012

Progress in Flight Physics

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“…A less common application, but which motivates our research work in electron guns, is in the field of optical diagnostics of low density flows. This measurement technique, named Electron Beam Fluorescence (EBF) [ 3 – 5 ] exploits the fluorescence of atoms and molecules induced by an electron beam having a current of a few mA, an energy of about 20 keV and a diameter of a few mm propagating a few tens of cm in a low pressure (less than 100 Pa) gas. Of the different types of electron guns (thermionic [ 6 ], field or cold emission [ 7 ], photocathode [ 8 ], plasma cathode [ 9 ], ionic bombardment [ 10 , 11 ], etc. )…”

Section: Introductionmentioning

confidence: 99%

Compact Electron Gun Based on Secondary Emission Through Ionic Bombardment

Diop

Bonnet

Schmid

et al. 2011

Sensors

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We present a new compact electron gun based on the secondary emission through ionic bombardment principle. The driving parameters to develop such a gun are to obtain a quite small electron gun for an in-flight instrument performing Electron Beam Fluorescence measurements (EBF) on board of a reentry vehicle in the upper atmosphere. These measurements are useful to characterize the gas flow around the vehicle in terms of gas chemical composition, temperatures and velocity of the flow which usually presents thermo-chemical non-equilibrium. Such an instrument can also be employed to characterize the upper atmosphere if placed on another carrier like a balloon. In ground facilities, it appears as a more practical tool to characterize flows in wind tunnel studies or as an alternative to complex electron guns in industrial processes requiring an electron beam. We describe in this paper the gun which has been developed as well as its different features which have been characterized in the laboratory.

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“…This has been reported in various configurations: single [12] or multiple wires [13] at low pressure, single wire at higher pressure [14]. Low pressure DC WIPS in the milliAmpere range, used for example in electron beam fluorescence (EBF) optical diagnosis [15] electron guns, exhibits two distinct modes of discharge. Apart Pigache's [12] remark that, in the high pressure mode, the cathode sheath length was of the same order of the planar Child Langmuir length, to our knowledge, no thorough model of the DC low pressure, low current wire source was given.…”

Section: Introductionmentioning

confidence: 99%

Particle in cell modelling of the observed modes of a dc wire discharge

Gueroult¹,

Elias²,

Packan³

et al. 2010

J. Phys. D: Appl. Phys.

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Low-pressure dc wire induced plasma sources exhibit two stable modes of discharge—constricted below a threshold pressure and diffuse above. Starting from experimental measurements, we conduct two-dimensional particle in cell (PIC) modelling of a dc low-pressure (10−4–10−2 mbar), low-current (∼1 mA) wire discharge in helium. 2D PIC modelling is required to capture longitudinal non-uniformity of the diffuse mode. PIC simulations reproduce the two discharge modes. The voltage versus pressure curve obtained from simulations matches fairly well the experimental data, including the transition region. Discharge voltage dependence on pressure is analysed in consideration of electron impact ionization rates' evolution with energy. In light of the PIC findings, a model of the discharge mode transition based on the Child–Langmuir theory for ions is proposed. Confrontation with simulated data shows good agreement and validates the model for mode transition prediction. Simulations show that the diffuse mode is a space-charge-dominated regime.

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Diagnostics by electron beam fluorescence in hypersonics

Cited by 12 publications

References 7 publications

Development of a compact electron beam fluorescence instrument for high enthalpy flow characterization

Development of a compact electron beam fluorescence instrument for high enthalpy flow characterization

Compact Electron Gun Based on Secondary Emission Through Ionic Bombardment

Particle in cell modelling of the observed modes of a dc wire discharge

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