On the use of sweeping Langmuir probes in cutting-arc plasmas - Part II: Interpretation of the results

A semiempirical Langmuir probe model is introduced that is particularly adapted to high-energy-density cutting arcs, for which, as we have shown in Part I, the ion current collected by negatively biased probes shows no plateau in the ion branch of the current-voltage (I-V) probe characteristic, and...

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Autores principales:	Kelly, Héctor Juan, Minotti, Fernando Oscar
Publicado:	2008
Materias:	Cutting arcs Langmuir probes Plasma diagnostic Computer simulation Current voltage characteristics Mathematical models Perturbation techniques Plasma diagnostics Plasma sheaths High-energy-density cutting arcs Space-charge sheath Plasma arc cutting
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00933813_v36PART2_n1_p271_Prevosto http://hdl.handle.net/20.500.12110/paper_00933813_v36PART2_n1_p271_Prevosto
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_00933813_v36PART2_n1_p271_Prevosto
record_format	dspace
spelling	paper:paper_00933813_v36PART2_n1_p271_Prevosto2023-06-08T15:08:40Z On the use of sweeping Langmuir probes in cutting-arc plasmas - Part II: Interpretation of the results Kelly, Héctor Juan Minotti, Fernando Oscar Cutting arcs Langmuir probes Plasma diagnostic Computer simulation Current voltage characteristics Langmuir probes Mathematical models Perturbation techniques Plasma diagnostics Plasma sheaths High-energy-density cutting arcs Space-charge sheath Plasma arc cutting A semiempirical Langmuir probe model is introduced that is particularly adapted to high-energy-density cutting arcs, for which, as we have shown in Part I, the ion current collected by negatively biased probes shows no plateau in the ion branch of the current-voltage (I-V) probe characteristic, and the signal amplitude is independent of the probe radius. According to the model, the ion drag due to the high-velocity plasma flow around the probe limits the effectively collecting area to a small fraction of the probe surface. If, according to the experimental evidence, this fraction is made independent of the probe radius, then its value results proportional to the probe bias, and so no plateau is found, at least as long as the collecting area is less than (half) the probe surface, which happens only at rather high probe bias. The model requires the determination of the function relating the electric field (in the region between the unperturbed plasma and the space-charge sheath close to the probe) to the parameters of the problem. Dimensional analysis together with empirical information allow to restrict the form of this function to leave only an auxiliary dimensionless function, which can be argued to be practically constant and whose value can be determined between rather tight bounds. As an example, radial profiles of plasma temperature and density are obtained by applying the proposed model to the experimental values of a I-V probe characteristic obtained in Part I. The derived temperature profile is in good agreement with a previous published numerical simulation for a similar cutting torch. © 2008 IEEE. Fil:Kelly, H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Minotti, F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2008 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00933813_v36PART2_n1_p271_Prevosto http://hdl.handle.net/20.500.12110/paper_00933813_v36PART2_n1_p271_Prevosto
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Cutting arcs Langmuir probes Plasma diagnostic Computer simulation Current voltage characteristics Langmuir probes Mathematical models Perturbation techniques Plasma diagnostics Plasma sheaths High-energy-density cutting arcs Space-charge sheath Plasma arc cutting
spellingShingle	Cutting arcs Langmuir probes Plasma diagnostic Computer simulation Current voltage characteristics Langmuir probes Mathematical models Perturbation techniques Plasma diagnostics Plasma sheaths High-energy-density cutting arcs Space-charge sheath Plasma arc cutting Kelly, Héctor Juan Minotti, Fernando Oscar On the use of sweeping Langmuir probes in cutting-arc plasmas - Part II: Interpretation of the results
topic_facet	Cutting arcs Langmuir probes Plasma diagnostic Computer simulation Current voltage characteristics Langmuir probes Mathematical models Perturbation techniques Plasma diagnostics Plasma sheaths High-energy-density cutting arcs Space-charge sheath Plasma arc cutting
description	A semiempirical Langmuir probe model is introduced that is particularly adapted to high-energy-density cutting arcs, for which, as we have shown in Part I, the ion current collected by negatively biased probes shows no plateau in the ion branch of the current-voltage (I-V) probe characteristic, and the signal amplitude is independent of the probe radius. According to the model, the ion drag due to the high-velocity plasma flow around the probe limits the effectively collecting area to a small fraction of the probe surface. If, according to the experimental evidence, this fraction is made independent of the probe radius, then its value results proportional to the probe bias, and so no plateau is found, at least as long as the collecting area is less than (half) the probe surface, which happens only at rather high probe bias. The model requires the determination of the function relating the electric field (in the region between the unperturbed plasma and the space-charge sheath close to the probe) to the parameters of the problem. Dimensional analysis together with empirical information allow to restrict the form of this function to leave only an auxiliary dimensionless function, which can be argued to be practically constant and whose value can be determined between rather tight bounds. As an example, radial profiles of plasma temperature and density are obtained by applying the proposed model to the experimental values of a I-V probe characteristic obtained in Part I. The derived temperature profile is in good agreement with a previous published numerical simulation for a similar cutting torch. © 2008 IEEE.
author	Kelly, Héctor Juan Minotti, Fernando Oscar
author_facet	Kelly, Héctor Juan Minotti, Fernando Oscar
author_sort	Kelly, Héctor Juan
title	On the use of sweeping Langmuir probes in cutting-arc plasmas - Part II: Interpretation of the results
title_short	On the use of sweeping Langmuir probes in cutting-arc plasmas - Part II: Interpretation of the results
title_full	On the use of sweeping Langmuir probes in cutting-arc plasmas - Part II: Interpretation of the results
title_fullStr	On the use of sweeping Langmuir probes in cutting-arc plasmas - Part II: Interpretation of the results
title_full_unstemmed	On the use of sweeping Langmuir probes in cutting-arc plasmas - Part II: Interpretation of the results
title_sort	on the use of sweeping langmuir probes in cutting-arc plasmas - part ii: interpretation of the results
publishDate	2008
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00933813_v36PART2_n1_p271_Prevosto http://hdl.handle.net/20.500.12110/paper_00933813_v36PART2_n1_p271_Prevosto
work_keys_str_mv	AT kellyhectorjuan ontheuseofsweepinglangmuirprobesincuttingarcplasmaspartiiinterpretationoftheresults AT minottifernandooscar ontheuseofsweepinglangmuirprobesincuttingarcplasmaspartiiinterpretationoftheresults
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On the use of sweeping Langmuir probes in cutting-arc plasmas - Part II: Interpretation of the results

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