Plasma breakdown of low-pressure gas discharges Citation for published version (APA): Wagenaars, E. (2006). Plasma breakdown of low-pressure gas discharges. Technische Universiteit Eindhoven. https://doi.org/10.6100/IR614696 DOI: 10.6100/IR614696 Document status and date: Published: 01/01/2006 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. 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If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, please follow below link for the End User Agreement: www.tue.nl/taverne Take down policy If you believe that this document breaches copyright please contact us at: [email protected] providing details and we will investigate your claim. Download date: 06. Oct. 2021 Plasma Breakdown of Low-Pressure Gas Discharges PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Technische Universiteit Eindhoven, op gezag van de Rector Magnificus, prof.dr.ir. C.J. van Duijn, voor een commissie aangewezen door het College voor Promoties in het openbaar te verdedigen op donderdag 30 november 2006 om 16.00 uur door Erik Wagenaars geboren te Schaijk Dit proefschrift is goedgekeurd door de promotor: prof.dr.ir. G.M.W. Kroesen Copromotoren: dr. M.D. Bowden en Dr.rer.nat.habil. H.-E. Wagner This research was financially supported by the Dutch Technology Foundation STW (ETF5856) CIP-DATA LIBRARY TECHNISCHE UNIVERSITEIT EINDHOVEN Wagenaars, Erik Plasma breakdown of low-pressure gas discharges / by Erik Wagenaars. - Eindhoven : Technische Universiteit Eindhoven, 2006. - Proefschrift. ISBN-10: 90-386-2112-4 ISBN-13: 978-90-386-2112-8 NUR 926 Trefwoorden: plasmafysica / gasontladingen / plasma doorslag / laserspectroscopie / plas- madiagnostiek / Stark effect Subject headings: electric discharges / electric breakdown / atomic emission spectroscopy / plasma diagnostics / Stark effect Copyright C 2006 E. Wagenaars Typeset in LATEX2ε. Printed by PrintPartners Ipskamp, Enschede. Contents 1 General introduction 1 1.1Gasdischarges.................................. 2 1.1.1 Steady-statedischargesbetweenparallelelectrodes......... 3 1.2Plasmabreakdown............................... 6 1.3Scopeofthisthesis............................... 8 1.4Thesisoutline.................................. 9 References....................................... 10 2 Background on plasma breakdown 15 2.1 Fundamental processes ............................. 16 2.1.1 Electronavalanches........................... 16 2.1.2 Secondaryelectronemission...................... 18 2.2Townsendtheory................................ 20 2.2.1 Breakdowncriterion.......................... 20 2.2.2 Non-self-sustainingdischarges..................... 22 2.2.3 Self-sustainingdischarges........................ 23 2.3Streamerandleaderbreakdown........................ 27 References....................................... 28 3 Plasma emission imaging of a low-pressure argon breakdown 31 3.1Introduction................................... 32 3.2Experimentalarrangement........................... 33 3.2.1 Dischargeapparatus.......................... 33 3.2.2 ICCDmeasurementsystem...................... 35 3.3Imagingofthebreakdownprocess....................... 36 3.3.1 Breakdowncycleoverview....................... 37 3.3.2 Pre-breakdownlightflash....................... 38 3.3.3 Crossingoflightfront......................... 41 iii 3.4Timedelayinvestigations............................ 46 3.5Conclusions................................... 50 References....................................... 51 4 Pre-breakdown light emission phenomena in low-pressure argon between parabolic electrodes 53 4.1Introduction................................... 54 4.2Experimentalarrangement........................... 55 4.3Behaviourandoriginofpre-breakdownphenomena............. 56 4.3.1 Fullbreakdowncycle.......................... 56 4.3.2 Frequencydependenceofpre-breakdownemission.......... 57 4.3.3 Originofpre-breakdownlightemission................ 59 4.4Effectsofstartingconditionsonbreakdownbehaviour............ 62 4.4.1 Separation of pre-breakdown phenomena from the main breakdown 62 4.4.2 Effectonmainbreakdownbehaviour................. 64 4.5Conclusions................................... 66 References....................................... 67 5 The Stark effect 69 5.1DiscoveryoftheStarkeffect.......................... 70 5.2Starkeffectsinhydrogen............................ 70 5.3NoblegasRydbergatoms........................... 74 5.4 Calculation of Stark effects by matrix diagonalization . ......... 76 5.4.1 Zero-fieldenergylevels......................... 77 5.4.2 Off-diagonal elements . ....................... 78 5.4.3 Diagonalization of total Hamiltonian . ................ 80 5.4.4 Transition probabilities . ....................... 80 5.5Starkeffectscalculatedbymultichannelquantumdefecttheory....... 81 References....................................... 82 6 Investigations of Stark effects in xenon Rydberg states by laser-induced fluorescence-dip spectroscopy 85 6.1Introduction................................... 86 6.2Experimentalinvestigations.......................... 87 6.2.1 Experimentalarrangement....................... 87 6.2.2 Experimentalresults.......................... 88 6.3Theoreticalcalculations............................ 89 6.3.1 Calculationmethodandprocedure.................. 90 iv 6.3.2 Calculationresults........................... 93 6.3.3 Comparisonoftheoreticalandexperimentalresults......... 95 6.4 Feasibility for use as electric field diagnostic . ................ 96 6.5Conclusions................................... 98 References....................................... 99 7 Measurements of electric field strengths in ionization fronts during plasma breakdown 101 7.1Introduction................................... 102 7.2Experimentalarrangementandmethods................... 102 7.3Resultsanddiscussion............................. 105 7.4Conclusionsandoutlook............................ 109 References....................................... 109 8 Experimental and modelling investigations of a dielectric barrier dis- charge in low-pressure argon 111 8.1Introduction................................... 112 8.2Experimentalarrangement........................... 113 8.2.1 Dischargeapparatus.......................... 113 8.2.2 Diagnosticsystem............................ 115 8.3Two-dimensionalfluidmodel.......................... 117 8.3.1 Modelequations............................ 117 8.3.2 Speciesandreactions.......................... 119 8.3.3 Dischargegeometry........................... 119 8.4 Experimental and modelling results ...................... 121 8.4.1 Transientglow-likedischarge...................... 121 8.4.2 Effectofreducingtheappliedvoltageamplitude........... 130 8.5Discussion.................................... 134 8.5.1 Effectsofdielectricsandplasmabreakdown............. 134 8.5.2 Comparisonwithotherdischargetypes................ 136 8.6Summary.................................... 136 References....................................... 137 9 General discussion and conclusions 141 9.1Introduction................................... 142 9.2Overviewofthethesis............................. 142 9.2.1 ICCDimaging.............................. 142 9.2.2 Measurementsofelectricfieldstrengths................ 143 v 9.2.3 Low-pressuredielectricbarrierdischarge............... 143 9.3Breakdownprocesses.............................. 144 9.4Initialconditions................................ 145 9.5Electricfielddiagnostic............................. 147 9.6Generalconclusionsandoutlook........................ 150 References....................................... 151 Summary 155 Samenvatting 159 Related publications 163 Dankwoord 167 Curriculum Vitae 169 vi Chapter 1 General introduction Abstract. This thesis deals with investigations of breakdown processes in gas dis- charges. Plasma breakdown can generally be defined as the transition process from an insulating, neutral gas to a conducting, (partially) ionized state. The fundamen- tal processes involved in this phenomenon are the subject of this thesis. This chapter is intended as a general introduction to gas discharges and more specifically, plasma breakdown. Further, it describes the scope of the thesis and the content