A novel method to determine the electron temperature and density from the absolute intensity of line and continuum emission: application to atmospheric microwave induced Ar plasmas

Iordanova, EI Ekaterina; Palomares, JM Jose; Gamero, A; Sola, A; Mullen, van der Jjam Joost

doi:10.1088/0022-3727/42/15/155208

Cited by 34 publications

(36 citation statements)

References 34 publications

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“…It was found that at the position of 1 mm behind the tube exit, where the measurements takes place, the pure Ar plasma does not change substantially if the power and flow rate are changed moderately. A feature that was already observed in [24] for the pure argon TIA. On the other hand, the plasmas in Ar-H 2 mixtures are sensitive to changes in the power.…”

Section: Atmospheric Surfatron Setupsupporting

confidence: 67%

“…The ALI method is based on the bottom part of ASDF of argon [24]. By including the ASDF-top it is possible to obtain several "excitation temperatures" of the distribution.…”

Section: Electron Temperature Resultsmentioning

confidence: 99%

“…We use here the passive method of Absolute Intensity Measurements (AIM) as introduced in [24] and applied to a TIA working on argon at atmospheric pressure. This method is based on the absolute measurements of the continuum and line radiation.…”

Section: Absolute Intensity Measurementsmentioning

confidence: 99%

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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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Section: Atmospheric Surfatron Setupsupporting

confidence: 67%

“…The ALI method is based on the bottom part of ASDF of argon [24]. By including the ASDF-top it is possible to obtain several "excitation temperatures" of the distribution.…”

Section: Electron Temperature Resultsmentioning

confidence: 99%

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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.

Self Cite

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“…96 With regard to the articles cited, they can be divided into broad categories dealing with population distributions and deviations from equilibrium, [97][98][99][100][101][102][103][104][105][106][107][108][109][110] classification of diagnostic methods, 111,112 local and space-integrated intensity definitions, 113,114 ion-toneutral ratios and their diagnostic relevance, [115][116][117][118][119][120][121][122][123][124][125] line-to-continuum ratios, [126][127][128][129][130][131] scattering methods, [132][133][134][135] evaluation of electron number density and plasma temperature, including Stark broadening of H-lines, Stark broadening of non-hydrogenic transitions, influence of the instrumental profile, [199][200][201][202][203][204] calibration of...…”

Section: Local Thermodynamic Equilibrium Theoretical Equilibrium Expmentioning

confidence: 99%

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

2010

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Laser-induced breakdown spectroscopy (LIBS) has become a very popular analytical method in the last decade in view of some of its unique features such as applicability to any type of sample, practically no sample preparation, remote sensing capability, and speed of analysis. The technique has a remarkably wide applicability in many fields, and the number of applications is still growing. From an analytical point of view, the quantitative aspects of LIBS may be considered its Achilles' heel, first due to the complex nature of the laser–sample interaction processes, which depend upon both the laser characteristics and the sample material properties, and second due to the plasma–particle interaction processes, which are space and time dependent. Together, these may cause undesirable matrix effects. Ways of alleviating these problems rely upon the description of the plasma excitation-ionization processes through the use of classical equilibrium relations and therefore on the assumption that the laser-induced plasma is in local thermodynamic equilibrium (LTE). Even in this case, the transient nature of the plasma and its spatial inhomogeneity need to be considered and overcome in order to justify the theoretical assumptions made. This first article focuses on the basic diagnostics aspects and presents a review of the past and recent LIBS literature pertinent to this topic. Previous research on non-laser-based plasma literature, and the resulting knowledge, is also emphasized. The aim is, on one hand, to make the readers aware of such knowledge and on the other hand to trigger the interest of the LIBS community, as well as the larger analytical plasma community, in attempting some diagnostic approaches that have not yet been fully exploited in LIBS.

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“…The ground-state density compared to the density of the excited radiating species gives the electron temperature by employing a collisional radiative model [7]. The measurement of the continuum of atomic plasmas can give the electron density [8,9]. In the case that the degree of ionization is small, the atoms are the main scatter partners of the electrons so that again the n a value is needed for a correct interpretation of the continuum spectrum.…”

Section: Introductionmentioning

confidence: 99%

Rayleigh scattering on a microwave surfatron plasma to obtain axial profiles of the atom density and temperature

Hübner

Iordanova

Palomares

et al. 2012

Eur. Phys. J. Appl. Phys.

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Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. Abstract. The axial dependency of the central-axis value of the heavy particle density and temperature of surface-wave plasmas is studied using Rayleigh scattering (RyS). The plasma is generated at a frequency of 2.45 GHz in argon by a surfatron operating under the standard settings of a power of 45 W, a flow rate of 50 sccm and a pressure of 20 mbar. To investigate the effect of the pressure on the gas temperature, we also investigated 6 and 10 mbar plasmas. By using a two-dimensional intensified CCD array we could determine and eliminate the influence of false stray light, a major disturbing factor in the determination of the Rayleigh signal. In order to trace the energy fluxes that determine the gas temperature, we performed Thomson scattering so that the properties of the electron gas are known. It is found that the gas temperature, T a, depends on the wall temperature and the product of the gas pressure and the electron pressure. The latter implies that Ta follows the electron density axially, meaning that it is highest at the launcher and decreases monotonically in the wave propagation direction. The maximum gas temperature of around Ta = 800 K is found close to the launcher for the highest gas pressure of 20 mbar. For lower pressures we find lower Ta values. The extrapolation of Ta toward the end of the plasma column leads to a temperature of about 320 K. This study reveals that, for the argon plasmas under study, the central-axis values of the gas temperature are determined by the balance between the heating of the gas by means of elastic electron collisions and the cooling due to heat conduction from the center to the wall.

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A novel method to determine the electron temperature and density from the absolute intensity of line and continuum emission: application to atmospheric microwave induced Ar plasmas

Cited by 34 publications

References 34 publications

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

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

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

Rayleigh scattering on a microwave surfatron plasma to obtain axial profiles of the atom density and temperature

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A novel method to determine the electron temperature and density from the absolute intensity of line and continuum emission: application to atmospheric microwave induced Ar plasmas

Cited by 34 publications

References 34 publications

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

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

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

Rayleigh scattering on a microwave surfatron plasma to obtain axial profiles of the atom density and temperature

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

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