Current-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding

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creativework.publisherAmerican Institute of Physics Inc.subs@aip.orgen
dc.contributor.authorTrushnikov D.
dc.contributor.authorMladenov G.
dc.contributor.authorBelenkiy V.
dc.contributor.authorKoleva E.
dc.contributor.authorVarushkin S.
dc.date.accessioned2024-07-10T14:27:03Z
dc.date.accessioned2024-07-10T14:48:03Z
dc.date.available2024-07-10T14:27:03Z
dc.date.available2024-07-10T14:48:03Z
dc.date.issued2014-01-01
dc.description.abstractMany papers have sought correlations between the parameters of secondary particles generated above the beam/work piece interaction zone, dynamics of processes in the keyhole, and technological processes. Low- and high-frequency oscillations of the current, collected by plasma have been observed above the welding zone during electron beam welding. Low-frequency oscillations of secondary signals are related to capillary instabilities of the keyhole, however; the physical mechanisms responsible for the high-frequency oscillations (>10 kHz) of the collected current are not fully understood. This paper shows that peak frequencies in the spectra of the collected high-frequency signal are dependent on the reciprocal distance between the welding zone and collector electrode. From the relationship between current harmonics frequency and distance of the collector/welding zone, it can be estimated that the draft velocity of electrons or phase velocity of excited waves is about 1600 m/s. The dispersion relation with the properties of ion-acoustic waves is related to electron temperature 10 000 K, ion temperature 2 400 K and plasma density 1016 m-3, which is analogues to the parameters of potential-relaxation instabilities, observed in similar conditions. The estimated critical density of the transported current for creating the anomalous resistance state of plasma is of the order of 3 A·m-2, i.e. 8 mA for a 3-10 cm2 collector electrode. Thus, it is assumed that the observed high-frequency oscillations of the current collected by the positive collector electrode are caused by relaxation processes in the plasma plume above the welding zone, and not a direct demonstration of oscillations in the keyhole. © 2014 Author(s).
dc.identifier.doi10.1063/1.4870944
dc.identifier.issn2158-3226
dc.identifier.scopusSCOPUS_ID:84898473215en
dc.identifier.urihttps://rlib.uctm.edu/handle/123456789/306
dc.language.isoen
dc.source.urihttps://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84898473215&origin=inward
dc.titleCurrent-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding
dc.typeArticle
oaire.citation.issue4
oaire.citation.volume4
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