On the atomic state densities of plasmas produced by the “torche à injection axiale”

Jonkers, J Jeroen; Vos, H. W.; Mullen, van der Jjam Joost; Timmermans, Eah Eric

doi:10.1016/0584-8547(95)01450-0

Cited by 33 publications

(35 citation statements)

References 17 publications

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“…Applying absolute intensity measurements [11,12] of atomic lines and the continuum it was possible to determine the electron density n e and temperature T e ; these values have been compared with the results of the Stark intersection method and Thomson scattering [13][14][15][16][17]. Typical reported values for the TIA are n e = 3 · 10 21 m −3 and T e = 22000 K. For the MPT the typical values are n e = 3 · 10 20 m −3 and T e = 18000 K (see [18]).…”

Section: Introductionmentioning

confidence: 99%

“…Oxygen and nitrogen molecules sucked in by the argon flow will enhance electron loss-mechanisms and will thus affect the properties of the electrons gas and the shape of the plasma flame. To study the effect of the environment, metallic plasma vessels were constructed in [11,18,21,22], with the purpose to change the gas-environment of the plasma (e.g. by replacing air by argon).…”

Section: Introductionmentioning

confidence: 99%

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Effect of remote field electromagnetic boundary conditions on microwave-induced plasma torches

Jimenez-Diaz¹,

Dijk²,

Mullen³

2011

J. Phys. D: Appl. Phys.

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Abstract.A flexible versatile electromagnetic model constructed with the PLASIMO platform is employed to explore electromagnetic features of microwave induced plasma torches. The bases, formed by a full-vector formulation of the Maxwell equations, provides the possibility to formulate the boundary conditions in a natural way. Together with the use of a direct matrix solver this gives a convergence speed-up of more than a factor of 100 when compared to a scalar formulation on the azimuthal magnetic field that uses an iterative solver. As a result this electromagnetic model is ready to act in future studies as part of the self-consistent description of plasma-electromagnetic coupling. With the electromagnetic model three types of configuration were studied: the closed, semi-open and open configurations, all three based on the same simplified model-plasmas. It is found that the closed configuration, acting as a cavity for which the (de)tuning is extremely sensitive for the plasma conditions, is less suitable for applications in which changes in plasma compositions can be expected. The semi-open configuration can be seen as a model for the practice often used in laboratories to place Microwave Induced Plasma torches in a grid that aims to protect the environment against microwave electromagnetic radiation. Calculations show that this is good practice provided the radius of this cylindrical grid is in the order of 90 mm. For the most often used configuration, the open version, we found that the power balance as expressed by the coefficients of absorption, transmission and reflection, depends on the electron density of the plasma. The reason is that the plasma acts as an antenna, that converts the electromagnetic waves from the co-axial structure to that of the expansion region and that this antenna function depends on the electron density. The influence of various other antenna elements is investigated as well.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of remote field electromagnetic boundary conditions on microwave-induced plasma torches

Jimenez-Diaz¹,

Dijk²,

Mullen³

2011

J. Phys. D: Appl. Phys.

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“…The advantage here is that, because absolute number densities have been measured, one can add to the graph the ground state (E n = 0) number density, calculated from the ideal gas law, and using the rotational temperature of the main gas species as the gas temperature. 107 The line connecting this point and the lowest of the number densities calculated before will indicate whether the slope obtained is the same, higher than, or lower than that which connects the populations of the excited levels. If the slope is the same, the system is in LTE, while if the slope is higher or lower, the plasma is ionizing or recombining, respectively (see Fig.…”

Section: Expression Description Equation Numbermentioning

confidence: 99%

“…Deviations from equilibrium are normally represented by the parameter b(p), which is defined as the ratio between the population of the level actually measured and the value given by the SahaBol tzmann equili brium expression, [103][104][105][106][107][108] i.e., bðpÞ = nðpÞ n SB ðpÞ ð3Þ…”

Section: Expression Description Equation Numbermentioning

confidence: 99%

“…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%

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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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Microwave‐Induced Plasma Systems in Atomic Spectroscopy

Broekaert

Engel

2000

Encyclopedia of Analytical Chemistry

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The use of microwave plasmas as radiation sources for optical atomic emission (AES), absorption (AAS) and fluorescence (AFS) spectroscopy and for laser ionization spectroscopy is treated and reference is also made to the use of microwave‐induced plasmas (MIPs) as ion sources for mass spectrometry (MS). Devices for producing both single‐electrode and electrodeless microwave plasmas are treated, in addition to methods for their diagnostics, and results for the analytically relevant plasma parameters are presented. Methods for sample introduction are discussed. They include dry aerosol generation techniques (hydride generation (HG), electrothermal evaporation, spark and laser ablation (LA)) and possibilities for the uptake of wet aerosols. Special reference is made to coupling with gas chromatography (GC) and also to the potential for coupling with high‐performance liquid chromatography (HPLC) Further, the use of microwave plasmas for cross‐excitation in the case of glow discharges (GDs) is treated. The analytical figures of merit in the case of AES with low‐power microwave plasmas, single‐electrode microwave plasmas, plasma torch sources and stabilized capacitively coupled plasmas are given also in the case of atomic absorption, fluorescence and laser ionization with these sources. The developments in MS in the case of both low‐power and high‐power microwave plasmas and in the case of various types of sample introduction are discussed. Applications of MIP atomic spectroscopy are in the fields of biological samples with special reference to microanalysis, and of environmental samples with special emphasis on metal speciation, on‐line monitoring and direct solids analysis. A critical comparison of the methodology with other methods for the determination of the elements and their species is given.

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On the atomic state densities of plasmas produced by the “torche à injection axiale”

Cited by 33 publications

References 17 publications

Effect of remote field electromagnetic boundary conditions on microwave-induced plasma torches

Effect of remote field electromagnetic boundary conditions on microwave-induced plasma torches

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

Microwave‐Induced Plasma Systems in Atomic Spectroscopy

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