Entwicklung eines Simulationsmodells für neuartige Plasma-Anregungsquellen zur analytischen Nutzung in der Atomspektrometrie - SIMONA
Zusammenfassung der Projektergebnisse
In the SIMONA project a computerized simulation model was developed that allows the numerical simulation of the electrical, physical and chemical processes in novel inductively coupled plasma excitation sources (ICP) with low gas flow (SHIP: static high sensitivity ICP). This simulation model enables the computerized optimization of entire plasma sources incl. torch geometry, torch cooling efficiency, and the coupling process of radio frequency (RF) energy into the plasma. The computerized model calculations contain beside the electrical processes also gas flows, thermal energy transport processes, and transport, excitation, and ionization of the plasma constituting species like argon atoms, singly and multiply ionized argon atoms, and electrons. From the beginning of the project the theoretical modeling approach was continuously quality controlled and accompanied by a practical control measurement process in which the plasma properties were determined and compared with the computer simulation´s results. To achieve the project goals, two different types of plasma excitation sources were chosen as subjects of investigation, the conventional Fassel-type ICP torch and the SHIP low flow torch. Two different ICP models were implemented in the SIMONA project. The first one is a two-dimensional axially symmetric ICP model, which is based on the publications by Mostaghimi, Proulx, Boulus, Barnes, et al. and assumes LTE conditions (local thermodynamic equilibrium). To describe deviation of the plasma from LTE and improve agreement with experimental results, a second model, which is a twotemperature model developed by Mostaghimi, Proulx, Boulus was also implemented. In this model the temperature of electrons is treated differently from the temperature of heavy particles, what appeared to be much closer to the real plasma properties. The developed models extend the previous simulations of the ICP sources by introducing the following features: 1. Models are applied for standard ICP torch, SHIP torch and its modifications, and are also applicable to other ICP geometries. 2. Until now, the temperature inside the torch walls was simulated by applying a heating coupled boundary condition from FLUENT or was included in the model with room temperature boundary conditions in the outer surface layer of the walls. In the present study, calculation of the temperature inside the torch walls is included in the model together with radiative loss of energy by the heated torch walls, which should provide the possibility to also optimize the cooling of the torches by simulations in the future. 3. Typically, the gas flow is introduced tangentially into ICP torches. This question was investigated in the SIMONA project and it was found that inclusion of the tangential flow is necessary to achieve satisfactory agreement of the model with the real plasma properties. The new simulation model for inductively coupled plasma sources adds new opportunities to the scientific field of plasma modeling. Plasma source design and optimization can be carried out on a virtual level now, surely not yet perfectly, but already very close to reality, as proven by plasmadiagnostic control measurements. Important trends will become visible in computational optimization processes and simplify and shorten new plasma source developments. Sample introduction has not yet been included into the simulation model, but its implementation will surely be suited to further improve the model.
Projektbezogene Publikationen (Auswahl)
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“Cooling of ICP Torches: A Model Investigation”, 2014 Winter Conference on Plasma Spectrochemistry, January 06–12, 2014, Amelia Island, Florida, USA
M. Voronov, V. Hoffmann, W. Buscher, C. Engelhard
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“Direct measurement of voltage and current in an ICP coil and corresponding calculation of power”, 2015 Winter Conference on Plasma Spectrochemistry, February 22–26, 2015, Münster, Germany
M. Voronov, V. Hoffmann, D. Birus, C. Engelhard, W. Buscher
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“ICP Diagnostics applying SHIP- and Fassel-type Torches”, 2015 Winter Conference on Plasma Spectrochemistry, February 22–26, 2015, Münster, Germany
M. Voronov, V. Hoffmann, D. Birus, C. Engelhard, W. Buscher
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“Investigation of the electrical properties of standard and low-gas-flow ICPs using novel probes for the direct measurements of RF voltage and current in the load coil and corresponding calculation of the ICP power”, J. Anal. At. Spectrom., 2015, 30, 2089–2098
M. Voronov, V. Hoffmann, D. Birus, C. Engelhard, W. Buscher
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“Plasma diagnostics with a novel Acousto-Optical Spectrometer”, 2nd International Workshop “Diagnostic Systems for Plasma Processes”, September 30, 2015, Lichtenwalde, Germany
M. Voronov, V. Hoffmann, C. Engelhard3, W. Buscher
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“Comparison of ICP modeling results and measured plasma properties”, 2016 Winter Conference on Plasma Spectrochemistry, January 11–16, 2016, Tucson, Arizona, USA
M. Voronov, V. Hoffmann, C. Engelhard, W. Buscher
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“Diagnostics and simulation of a low-argon-flow ICP followed by optimization of the torch”, 8th Nordic Conference on Plasma Spectrochemistry, Loen, Norway, June 5-8, 2016
M. Voronov, V. Hoffmann, C. Engelhard, W. Buscher
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“Computational model of inductively coupled plasma sources in comparison to experimental data for different torch designs and plasma conditions. Part I: experimental study”, J. Anal. At. Spectrom., 2017, 32, 167–180
M. Voronov, V. Hoffmann, C. Engelhard, W. Buscher
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“Computational model of inductively coupled plasma sources in comparison to experimental data for different torch designs and plasma conditions. Part II: theoretical model”, J. Anal. At. Spectrom., 2017, 32, 181–192
M. Voronov, V. Hoffmann, W. Buscher, C. Engelhard
