Air entrainment in an inductively coupled plasma measured by Raman and Rayleigh scattering

Regt, de Jm Hans; Groote, de Fpj Frank; Mullen, van der Jjam Joost; Schram, DC Daan

doi:10.1016/0584-8547(96)01519-4

Cited by 11 publications

(10 citation statements)

References 5 publications

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“…The principle of Rayleigh scattering and the setup has been described in detail in [39,42]. It is noted that the Rayleigh scattering cross sections of air, O 2 , and Ar differ less than 2% [43,44]. Hence, the Rayleigh signal intensity does not significantly depend on the varying gas composition in the effluent.…”

Section: Methodsmentioning

confidence: 99%

Gas flow characteristics of a time modulated APPJ: the effect of gas heating on flow dynamics

Zhang

Sobota

Veldhuizen

et al. 2014

J. Phys. D: Appl. Phys.

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This work investigates the flow dynamics of a radio-frequency (RF) non-equilibrium argon atmospheric pressure plasma jet. The RF power is at a frequency of 50 Hz or 20 kHz. Combined flow pattern visualizations (obtained by shadowgraphy) and gas temperature distributions (obtained by Rayleigh scattering) are used to study the formation of transient vortex structures in initial flow field shortly after the plasma is switched on and off in the case of 50 Hz modulation. The transient vortex structures correlate well with observed temperature differences. Experimental results of the fast modulated (20 kHz) plasma jet that does not induce changes of the gas temperature are also presented. The latter result suggests that momentum transfer by ions does not have dominant effect on the flow pattern close to the tube. It is argued that the increased gas temperature and corresponding gas velocity increase at the tube exit due to the plasma heating increases the admixing of surrounding air and reduces the effective potential core length. With increasing plasma power a reduction of the effective potential core length is observed with a minimum length for 5.6 W after which the length extends again. Possible mechanisms related to viscosity effects and ionic momentum transfer are discussed.

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Section: Methodsmentioning

confidence: 99%

Gas flow characteristics of a time modulated APPJ: the effect of gas heating on flow dynamics

Zhang

Sobota

Veldhuizen

et al. 2014

J. Phys. D: Appl. Phys.

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“…The effect of a possible entrainment of air into the flame can be neglected: even assuming an excessive contamination of 10% of air (N 2 80% + O 2 20%) leads to a relative error in the gas temperature determination smaller than 1%. This because the values of the RyS cross section for argon, nitrogen and oxygen (σ N2 = 1.12σ Ar , σ O2 = 0.915σ Ar ) [30] are close to each other. All these considerations lead to a final estimation of the relative error for the gas temperature in the order of 15%.…”

Section: Rayleigh Scatteringmentioning

confidence: 99%

Atmospheric microwave-induced plasmas in Ar/H₂ mixtures studied with a combination of passive and active spectroscopic methods

Palomares¹,

Iordanova²,

Gamero³

et al. 2010

J. Phys. D: Appl. Phys.

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Several active and passive diagnostic methods have been used to study atmospheric microwave induced plasmas created by a surfatron operating at a frequency of 2.45 GHz and with power values between 57 and 88 W. By comparing the results with each other, insight is obtained into essential plasma quantities, their radial distributions and the reliability of the diagnostic methods. Two laser techniques have been used, namely Thomson scattering (TS) for the determination of the electron density, n e , and temperature, T e , and Rayleigh scattering (RyS) for the determination of the heavy particle temperature, T g . In combination, three passive spectroscopic techniques are applied, the line broadening of the H β line to determine n e , and two methods of absolute intensity measurements to obtain n e and T e . The active techniques provide spatial resolution in small plasmas with sizes in the order of 0.5 mm. The results of n e measured with three different methods show good agreement, independent of the plasma settings. The T e values obtained with two techniques are in good agreement for the condition of a pure argon plasma, but they show deviations when H 2 is introduced. The introduction of a small amount (0.3 %) of H 2 into an argon plasma induces contraction, reduces n e , increases T e , enhances the departure from equilibrium and leads to conditions that are close to those found in cool atmospheric plasmas.

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“…At low power levels (<1 kW) also the second positive system of N 2 is strongly present. Moreover, a significant entrainment of air into an ICP, which is also expanding in the open air, was measured by de Regt and co-workers [13].…”

Section: Mixing With the Surrounding Airmentioning

confidence: 99%

“…To determine the quantitative effect of the air entrainment on the particle balance measurements of the molecular nitrogen density are necessary. In the past this was done in our laboratory using vibrational Raman scattering on an atmospheric ICP [13]. However, in that case a laser beam with a large diameter was used, which is not suitable in case of the TIA.…”

Section: The Influence Of the Surrounding Atmospherementioning

confidence: 99%

“…For instance, it is known that although in atmospheric cascaded arcs LTE is present in the main channel (due to the high electron density), deviations from LTE are found in the neighbourhood of the cathode [11,12]. Another example is the edge of an atmospheric inductively coupled plasma (ICP), where (partly) due to entrainment of air [13], the gradient lengths are small and the fluxes high. In all these cases we essentially meet with the same phenomenon: boundaries with steep gradients which influence the properties of a considerable plasma part.…”

Section: Introductionmentioning

confidence: 99%

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Steep plasma gradients studied with spatially resolved Thomson scattering measurements

Jonkers

Selen

Mullen

et al. 1997

Plasma Sources Sci. Technol.

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Abstract. Plasmas created by the microwave torch Torcheà Injection Axiale (TIA), which are around 2 mm in diameter and 15 mm long, are investigated. In these plasmas large gradients are present so that the edge is supposed to play an important role. Using global Thomson scattering measurements, in which global refers to the fact that the size of the laser beam is approximately equal to the diameter of the plasma, the electron densities and temperatures were determined. However, these results lead to discrepancies in the particle balance: the production of free electrons is much larger than the classical losses due to recombination, convection and diffusion. Radially resolved Thomson scattering measurements show the plasma has a hollow structure. Although this enhances the losses due to diffusion, still a large discrepancy remains between production and destruction of free electrons in the argon plasmas. Probably some molecular processes are significant as well. A good candidate is the charge transfer between argon ions and nitrogen molecules, since mixing with the surrounding air has a large impact on the plasma.

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Air entrainment in an inductively coupled plasma measured by Raman and Rayleigh scattering

Cited by 11 publications

References 5 publications

Gas flow characteristics of a time modulated APPJ: the effect of gas heating on flow dynamics

Gas flow characteristics of a time modulated APPJ: the effect of gas heating on flow dynamics

Atmospheric microwave-induced plasmas in Ar/H₂ mixtures studied with a combination of passive and active spectroscopic methods

Steep plasma gradients studied with spatially resolved Thomson scattering measurements

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Air entrainment in an inductively coupled plasma measured by Raman and Rayleigh scattering

Cited by 11 publications

References 5 publications

Gas flow characteristics of a time modulated APPJ: the effect of gas heating on flow dynamics

Gas flow characteristics of a time modulated APPJ: the effect of gas heating on flow dynamics

Atmospheric microwave-induced plasmas in Ar/H2 mixtures studied with a combination of passive and active spectroscopic methods

Steep plasma gradients studied with spatially resolved Thomson scattering measurements

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Product

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Atmospheric microwave-induced plasmas in Ar/H₂ mixtures studied with a combination of passive and active spectroscopic methods