Measurement of N2/plus/ plus e/-/ dissociative recombination in expanding nitrogen flows

Dunn, Michael G.; Lordi, J. A.

doi:10.2514/3.5666

Cited by 54 publications

(16 citation statements)

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“…Also included in Ref. 21 is a discussion of the neutral and charged species distributions in the nozzle flow. The dominant ion at the measuring stations was found to be N + and thus the probe data were reduced using this value of the ion mass in the theories of Refs.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…Typical Langmuir-probe and microwave-interferometer data records obtained in this plasma are presented in Ref. 21 and the data reduction procedure was discussed in Refs. 7 and 21.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…These values were calculated using the expressions summarized by Sonin 2 and the nozzle-flow properties calculated in Ref. 21. For the purpose of estimating mean free paths, the electron temperature can be assumed to be equal to the heavy-particle translational temperature from the reservoir value down to 3500 °K at which point it can be considered to freeze (see Fig.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

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Thin-wire Langmuir-probe measurements in the transition and free-molecular flow regimes

Dunn

Lordi

1970

AIAA Journal

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idea of the range of applicability of Cohen's solution, the percentage error in / + [from his Eq. (19)] as a function of r P * for constant values of K is given in Fig. 8.Cicerone and Bowhill obtain numerical solutions for the attracted ion distribution at large probe potential and the corresponding probe characteristics. The characteristics presented, covering a range of .1 < p p < I and an approximate potential range of 20 < & p * < 500, agree with the current results in the overlapping potential range, at least to within the accuracy attainable in reading the plotted data. ConclusionsNumerical solutions of the spherical continuum electrostatic probe equations have been obtained for the case of equal electron and ion temperatures for a wide range of probe radius to Debye length ratio. Since the exact numerical solutions of the complete equations are straightforward and economical to obtain (in the range 15 to 25 seconds per solution on a CDC 6500 computer), it appears that further investigations of these equations should be aimed at finding simplified solutions of closed form. The numerical results presented here should prove valuable in assessing the accuracy of any such solutions.Thin-wire Langmuir probes aligned with the flow direction have been used to measure the electron temperature and electron density in the inviscid nozzle flow of a short-duration reflected-shock tunnel. The electron density was inferred from the ion current portion of the probe characteristic and was simultaneously measured using microwave interferometers. The test gas used in these experiments was nitrogen at an equilibrium reservoir condition of 7200°K and 17.1 atm. At selected nozzle locations, the probe diameter and fineness ratio (L/D) of the probe were systematically varied in order to investigate probe performance in the transition and free-molecular flow regimes. The measured electron temperatures did not depend upon the probe diameter or the fineness ratio. The electron density inferred from the probe characteristic was found to be sensitive to collisional effects but insensitive to the fineness ratio in both the transition and free-molecular flow regimes. For free-molecular flow the results agree with Laframboise's theoretical predictions for ion collection in a portion of the orbital-motion-limited region. For probes having a radius less than a debye length in a freemolecular flow, the experimental results appear to disagree with the theory, the collected currents being larger than those predicted. In the transition-flow regime, the correction for collisional effects given by Talbot and Chou provides good agreement between the Langmuirprobe and microwave-interferometer electron-density data.

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Section: Discussion Of Resultsmentioning

confidence: 99%

“…Typical Langmuir-probe and microwave-interferometer data records obtained in this plasma are presented in Ref. 21 and the data reduction procedure was discussed in Refs. 7 and 21.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

Section: Discussion Of Resultsmentioning

confidence: 99%

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Thin-wire Langmuir-probe measurements in the transition and free-molecular flow regimes

Dunn

Lordi

1970

AIAA Journal

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“…The initial pressure conditions in the shock tube provided an equilibrium reservoir state of 7200°K and 17.1 atm pressure in nitrogen, and 8000°K and 9.35 atm pressure in argon. These particular operating conditions were chosen to duplicate those which have been employed in previous investigations of the electron temperature and number density distributions in expanding nitrogen and argon plasmas, 16 ' 17 in which the flow behavior, nozzle starting process and uniform-flow duration have been studied in detail. In order to ensure the attainment of ionization equilibrium in the reservoir gas, a small amount of nitrogen (0.0012 mole) was added to the argon test gas for these experiments.…”

Section: Details Of Experimental Apparatusmentioning

confidence: 99%

Experimental and Numerical Studies of Flush Electrostatic Probes in Hypersonic Ionized Flows: I. Experiment

Boyer

Touryan

1972

AIAA Journal

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Experimental studies were performed to determine the ion current collection characteristics of flush-mounted electrostatic probes on a sharp flat plate in ionized hypersonic flows. The effects of probe size, geometry, position, bias, and local flow properties were explored. The probe current densities measured in nitrogen, argon, and carbon monoxide plasmas were correlated in terms of the flow Reynolds number, electron convective flux, probe size, applied potential and electron-to-ion temperature ratio. The correlation predicts well similar data available in the literature. Comparison with a numerical solution of Poisson's equation yields results which validate the correlation. Nomenclature A/A# = nozzle area ratio C* = Chapman-Rubesin constant in the linear viscositytemperature relation D = diffusion coefficient e -electron charge / = probe current J = current density m = exponent in flush-probe current-voltage relationship M = Mach number n = number density p = pressure R = probe radius Re = Reynolds number Sc = Schmidt number T = temperature u = flow velocity V = probe voltage relative to ground x = distance from plate leading edge X N = axial distance from nozzle throat y = distance normal to surface of flat plate P = ratio of ion to electron diffusion coefficient 6 = boundary-layer thickness £ = TJT e K = correlation parameter, (R/A D ) 2 l/Re xo Sc t k = mean free path A 5 = sheath thickness A D = Debye length (in general based on boundary-layer edge conditions) \ JL = viscosity p = density

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“…On one hand Biondi and his associates (Bardsley and Biondi 1970) have modified a microwave cavity assembly to allow the electron temperature T, in the recombining afterglow to be varied between room temperature and 11 000 K with the ion temperature reportedly fixed at 300 K. In other approaches the translational temperature of both collision partners was raised. Dunn and Lordi (1970) conducted measurements in the flow field downstream of the nozzle expansion from a reservoir of high temperature gases created in a reflected shock tunnel and thereby had available a variation in the translational temperature between 2000 K and 7000 K. Kasner and Biondi (1968) used oven heating to raise the translational temperature of both ions and electrons in a microwave cavity to 600K. The shock tube technique, developed by Fox and Hobson (1966) and extended by Cunningham and Hobson (1969) has enabled the recombination rate coefficients to be measured for Art and Ne: in the temperature range between 600 K and 3000 K. Preliminary reports have been made of the experimental techniques employed in the latter series of experiments and this paper presents a detailed description of the shock tube technique and discusses the experimental situations involved with particular reference to K r l recombination.…”

Section: Introductionmentioning

confidence: 99%

Dependences of the polarization properties of polymer graded-index fibers of the Selfoc type

Gachechiladze¹,

Grigor'ev²,

Zguladze³

et al. 1983

Sov. J. Quantum Electron.

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A description is given of a pressure driven shock tube and the techniques which have been developed to investigate the variation with gas temperature of the electron-. molecular ion dissociative recombination coefficient c!. Double probe detectors are used to measure, at times in the afterglow, electron densities of a plasma slice located between the shock front and contact surface of the nearly one-dimensional gas flow. The experimental parameters are discussed in relation to their influence on the recombination process. In krypton at 900 K: c! is found to have the value 4.2 x cm3 s -' and at 2700 K it has followed a T 3 " variation to the value 9.6 x cm3 s -' .

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Measurement of N2/plus/ plus e/-/ dissociative recombination in expanding nitrogen flows

Cited by 54 publications

References 24 publications

Thin-wire Langmuir-probe measurements in the transition and free-molecular flow regimes

Thin-wire Langmuir-probe measurements in the transition and free-molecular flow regimes

Experimental and Numerical Studies of Flush Electrostatic Probes in Hypersonic Ionized Flows: I. Experiment

Dependences of the polarization properties of polymer graded-index fibers of the Selfoc type

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