<i>Rarefied Gas Dynamics</i>

Talbot, L.; Dryden, Hugh L.; Kármán, Th. von; Kuerti, G.; Wise, Henry

doi:10.1063/1.3057872

Cited by 4 publications

(22 citation statements)

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“…Similar expressions as (10) and (11) are valid for a cylindrical probe [8]. Basedon the theory [8] KLAGQE and Tnxr+ (15) Besides the theory [8] there is another description of the positive ion collection by a Langmuir probe which was developed by ZAKRZEWSLU and KOPICZYNSKI [5].…”

Section: ~3 1 )mentioning

confidence: 84%

“…It should be noted that the method of the evaluation of the integral J,, proposed in [8] is valid for q 2 2.…”

Section: Theories Of Lsngmuir Probe In Middle Pressure Plasmamentioning

confidence: 99%

“…TALBOT and &IOU [8] worked out a method for an approximative evaluation of this integral. This method consists in the determination of the integral J , in two limiting cases: J,, for the collisionless case (&/;io --f 00) and J,, for the continuum case (&/AD +-0 ) and in application of the ad hoc interpolation formula :…”

Section: Theories Of Lsngmuir Probe In Middle Pressure Plasmamentioning

confidence: 99%

“…The electron probe current I-is normalized with respect to the thermal random current, so that I-* = I-IIJe. For a spherical probe the normalization factor I,, is [8]:…”

Section: Theories Of Lsngmuir Probe In Middle Pressure Plasmamentioning

confidence: 99%

“…The measured ion current is normalized in similar manner as was the electron current namely using the factor ISiaci so that I+* = I+/Isi,ci for a spherical or a cylindrical probe respectively, where with mi being the mass of an ion, A the surface area of a probe, A = 4xRp2 for a spherical probe and A = 2hRpL, for a cylindrical one. TALBOT and CHOU [8] proposed to determine the integral J i using an interpolation formula similar to (6) :…”

Section: ~3 1 )mentioning

confidence: 99%

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The use of Langmuir Probe Methods for Plasma Diagnostic in Middle Pressure Discharges

David

Šı́cha

Tichý

et al. 1990

Contrib. Plasma Phys.

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The article attempts to summarize the most important knowledge about the analysis of a Langmuir probe a t middle pressures. First it briefly reviews the recent theories which deal with interpretation of Langmuir probe data at such conditions and then it applies the theory to the measurements in a Neon discharge a t pressures 1.86 and 2.46 kPa. The charged particle density and the electron temperature obtained from the same probe data using different theories is compared against each other and a satisfactory agreement is obtained. The recommended procedure of probe data interpretation is given a t the end of the paper.

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Section: ~3 1 )mentioning

confidence: 84%

“…It should be noted that the method of the evaluation of the integral J,, proposed in [8] is valid for q 2 2.…”

Section: Theories Of Lsngmuir Probe In Middle Pressure Plasmamentioning

confidence: 99%

Section: Theories Of Lsngmuir Probe In Middle Pressure Plasmamentioning

confidence: 99%

“…The electron probe current I-is normalized with respect to the thermal random current, so that I-* = I-IIJe. For a spherical probe the normalization factor I,, is [8]:…”

Section: Theories Of Lsngmuir Probe In Middle Pressure Plasmamentioning

confidence: 99%

Section: ~3 1 )mentioning

confidence: 99%

See 3 more Smart Citations

The use of Langmuir Probe Methods for Plasma Diagnostic in Middle Pressure Discharges

David

Šı́cha

Tichý

et al. 1990

Contrib. Plasma Phys.

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A Collisional Model of the Positive Ion Collection by a Cylindrical Langmuir Probe

Tichý

Šı́cha

David

et al. 1994

Contrib. Plasma Phys.

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This article presents a new theoretical model of ion collection by a cylindrical Langmuir probe at medium and higher pressures which we call the "modified TALBOT and CHOU model". The model makes use of the following theories; (a) the kinetic theory by CHOU, TALBOT and WILLIS [6, 71 and (b) the theory by ZAKRZEWSKI and KOPICZYNSKI [lo, 1 I]. The basic idea is to calculate the decrease of probe ion current due to collisions with neutrals according [6, 71 and the increase of the ion current due to destruction of an orbital motion according [lo, I I]. The computed results are presented in the form of graphs suitable for probe data interpretation at medium and higher pressures. The applicability of the results at particular plasma conditions is also discussed.

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Is the tracer velocity of a fluid continuum equal to its mass velocity?

Brenner

2004

Phys. Rev. E

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Owing to its size independence in the so-called near-continuum vanishingly small Knudsen number regime (Kn<<1) , thermophoretic particle motion occurring in an otherwise quiescent gas under the influence of a temperature gradient is here interpreted as representing the motion of a tracer, namely, an effectively point-size test particle monitoring the local velocity of the undisturbed, particle-free, compressible gas continuum through space. "Compressibility" refers here not to the usual effect of pressure on the gas's mass density rho but rather to the effect thereon of temperature. Our unorthodox continuum interpretation of thermophoresis differs from the usual one, which regards the existence of thermophoretic forces in gases as a strictly noncontinuum phenomenon, involving thermal stress-induced Maxwell slip ("thermal creep") of the gas's mass velocity vm at the surface of the particle, with vm denoting the velocity appearing in the continuity equation expressing the law of conservation of mass. Explicitly, instead of regarding the thermally animated particle as moving through the gas, we regard the particle (in its hypothesized role as a tracer of the undisturbed, particle-free, fluid motion) as moving with the gas, through space; that is, the particle is viewed as simply being entrained in the flowing gas, which, as a result of an externally applied temperature gradient, was already in motion prior to the tracer's introduction into the fluid--albeit not mass motion (which is, in fact, identically zero) but rather volume motion. This tracer-particle interpretation of experimental thermophoretic particle velocity measurements raises fundamental issues in regard to the universally accepted Newtonian rheological law constitutively specifying the viscous or deviatoric stress T as being proportional to the (symmetrized, traceless) fluid velocity gradient inverted Deltav , with v identified as being the fluid's mass velocity vm . Rather, it is argued in the case of compressible fluids, including liquids, that v should, instead, be chosen as the fluid's volume flux density or current density nv , the latter being formally equivalent to the fluid's volume velocity vv , which differs from vm except in the case of incompressible fluids. Apart from this strictly constitutive issue in regard to T , it is further argued that the fluid's tracer or Lagrangian velocity vl:=(deltax/deltat) (x0) along the fluid's spatiotemporal trajectory x=x (x0,t) is equal to vv, rather than to vm. This too is contrary to the heretofore unquestioned supposition that the conceptually distinct fluid velocities vl and vm are not only equal but are, in fact, synonymous. To the extent that vl not equal vm in the nonisothermal fluid case, an optical dye- or photochromic-type experiment (each of the latter two experiments presumably serving to measure vm) will record a different velocity than would a comparable tracer particle velocity measurement, one that measures vl .

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Rarefied Gas Dynamics

Cited by 4 publications

References 0 publications

The use of Langmuir Probe Methods for Plasma Diagnostic in Middle Pressure Discharges

The use of Langmuir Probe Methods for Plasma Diagnostic in Middle Pressure Discharges

A Collisional Model of the Positive Ion Collection by a Cylindrical Langmuir Probe

Is the tracer velocity of a fluid continuum equal to its mass velocity?

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