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Initiation and progress of breakdown in range to the left of the paschen minimum.

dc.contributor.advisorOsmokrović, Predrag
dc.contributor.otherCvetić, Jovan
dc.contributor.otherVasić-Milovanović, Aleksandra
dc.contributor.otherVujisić, Miloš
dc.contributor.otherStanković, Koviljka
dc.creatorJovanović, Bojan
dc.date.accessioned2016-07-16T13:12:45Z
dc.date.available2016-07-16T13:12:45Z
dc.date.available2020-07-03T10:13:51Z
dc.date.issued2013-11-23
dc.identifier.urihttp://eteze.bg.ac.rs/application/showtheses?thesesId=3264
dc.identifier.urihttp://nardus.mpn.gov.rs/handle/123456789/5905
dc.identifier.urihttps://fedorabg.bg.ac.rs/fedora/get/o:11667/bdef:Content/download
dc.identifier.urihttp://vbs.rs/scripts/cobiss?command=DISPLAY&base=70036&RID=45420559
dc.description.abstractPašenovom krivom se prikazuje zavisnost vrednosti probojnog napona dvoelektrodnog sistema izolovanog gasom od proizvoda pritiska (p) i meĊuelektrodnog rastojanja (d). Jednoznaĉna zavisnost vrednosti dc probojnog napona od proizvoda pd direktna je posledica vaţenja zakona sliĉnosti za elektriĉno praţnjenje u gasovima. Pašenova kriva ima oblik asimetriĉne U-krive sa izrazitim minimumom koji se naziva Pašenovim minimumom. Pašenov minimum je odreĊen vrednošću pritiska gasa (tj. gustine) pri kojoj Tausendov jonizacioni koeficijent ima maksimalnu vrednost u zavisnosti od odnosa meĊuelektrodnog rastojanja srednje slobodne duţine puta elektrona. U taĉkama desno od Pašenovog minimuma dc probojni napon se moţe, uslovno, smatrati deterministiĉkom veliĉinom tj. veliĉinom prilikom ĉijeg odreĊivanja je dominantna merna nesigurnost tip B. To je posledica ĉinjenice da se u taĉkama desno od Pašenovog minimuma dc proboj odvija samoodrţavajućim gasnim multiplikativnim procesom uz vremensku konstatu promene napona mnogo veću od vremena karakteristiĉnog za odvijanje elementarnih procesa gasnog praţnjenja. U taĉkama levo od Pašenovog minimuma dc proboj se odvija kombinacijom gasnih mehanizama i vakuumskih mehanizmima, a javlja se i takozvani anomalni Pašenov efekat. To uslovljava da dc probojni napon u taĉkama levo od Pašenovog minimuma bude statistiĉka veliĉina tj. veliĉina prilikom ĉijeg odreĊivanja je dominantna merna nesigurnost tip A. Vrednost impulsnog probojnog napona je stohastiĉka veliĉina i levo i desno od Pašenovog minimuma. To je posledica ĉinjenice da je vremenska konstanta promene impulsnog napona istog reda veliĉine kao vreme karakteristiĉno za odvijanje elementarnih proces gasnog praţnjenja. U radu se razmatraju mehanizmi iniciranja i razvoja proboja gasova u taĉkama levo od Pašenovog minimuma. Statistiĉkom analizom eksperimentalnih rezultata, dobijenih pod dobro kontrolisanim laboratirijskim uslovima, pokazano je da se oblast levo od Pašenovog minimuma moţe, uslovno, podeliti na tri podoblasti. Pokazano je da se u prvoj podoblasti, neposredno uz Pašenov minimum proboj odvija se iviĉnim mehanizmima ĉesto tumaĉenim kao anomalni Pašenov efekat. U sledećoj podoblasti do proboja dolazi vakuumskim mehanizmom lavinskog tipa, a u trećoj podoblasti proboj se odvija vakuumskim emisionim mehanizmom katodnog tipa.sr
dc.description.abstractPaschen curve illustrates the dependence of the breakdown voltage of a gas insulated two-electrode system on the product of pressure (p) and inter-electrode distance (d). The validity of the similarity law for gas electrical breakdown produces direct dependence of the dc breakdown voltage on the pd product. Paschen curve is an asymmetrical U shape with a prominent minimum, called the Paschen minimum. The Paschen minimum corresponds to the gas pressure (i.e. density) at which the Townsend ionization coefficient is largest, with respect to the ratio between the inter-electrode distance and the electron mean free path. The dc breakdown voltage which occurs in the region to the right of the Paschen minimum, can be regarded as a deterministic quantity, i.e. a quantity for which type B uncertainty dominates its measurement. This results from the fact that to the right of the Paschen minimum dc breakdown occurs via self-sustained multiplication process in the gas, where the time constant of voltage change is much greater than the time characteristic of elementary gas discharge processes. In the range to the left of the Paschen minimum, dc breakdown occurs through a combination of gas mechanisms and vacuum mechanisms, and also as the so called anomalous Paschen effect. Because of this, in the range to the left of the Paschen minimum the dc breakdown voltage is a stochastic quantity, i.e. a quantity for which type A measurement uncertainty is dominant. The impulse breakdown voltage value is stochastic both to the left and to the right of the Paschen minimum. This derives from the fact that the time constant of a voltage pulse change is on the same order of magnitude as the time characteristic of elementary gas discharge processes. Mechanisms of gas breakdown initiation and development in the range to the left of the Paschen minimum are investigated in this paper. Experiments were conducted for gas pressures from 10-9 to 10-1 bar and interelectrode gaps from 0.1 to 1 mm. The statistical analysis shows that the region left of the Paschen minimum can be divided into three subregions. It is established that the so called anomalous Paschen effect refers to breakdown occuring by way of the edge mechanisms in the first subregion, just next to the Paschen minimum. In the second subregion, breakdown emerges through the vacuum avalanche mechanism, and in the third subregion it occurs through the vacuum cathode emission mechanism.en
dc.formatapplication/pdf
dc.languagesr
dc.publisherУниверзитет у Београду, Хемијски факултетsr
dc.rightsopenAccessen
dc.sourceУниверзитет у Београдуsr
dc.subjectPašenov minimum - anomalni Pašenov efekat - vakuumski mehanizam lavinskog tipa - vakuumski emisioni mehanizam katodnog tipa.sr
dc.subjectGas breakdownen
dc.subjectPaschen minimumen
dc.subjectanomalous Paschen effecten
dc.subjectvacuum avalanche mechanismen
dc.subjectvacuum cathode emission mechanismen
dc.titleIniciranje i razvoj proboja u tačkama levo od Pašenovog minimumasr
dc.titleInitiation and progress of breakdown in range to the left of the paschen minimum.en
dc.typedoctoralThesis
dc.rights.licenseBY
dcterms.abstractОсмокровић, Предраг; Цветић, Јован; Васић-Миловановић, Aлександра; Вујисић, Милош; Станковић, Ковиљка; Јовановић, Бојан; Иницирање и развој пробоја у тачкама лево од Пашеновог минимума; Иницирање и развој пробоја у тачкама лево од Пашеновог минимума;
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/29609/Disertacija3819.pdf


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