[優(yōu)秀畢業(yè)設(shè)計精品] 霍爾推力器高頻電磁輻射的實驗研究.doc

學(xué)位論文-I-摘要霍爾推力器由于其具有比沖高、質(zhì)量輕、體積小、結(jié)構(gòu)緊湊、控制精度高、壽命長等特點，在衛(wèi)星的精確定位、軌道保持、姿態(tài)控制等方面得到了廣泛的應(yīng)用。霍爾推力器作為一種典型的磁約束等離子體放電裝置，在其放電過程中，必然會伴隨著等離子體振蕩現(xiàn)象，從幾十KHz到十幾GHz都測量得到振蕩信號。其中，頻率范圍在100MHz量級的高頻振蕩，影響著霍爾推力器內(nèi)放電等離子體的微觀物理過程，其輻射的電磁波可能干擾衛(wèi)星與地面的通訊。本文主要針對高頻輻射系統(tǒng)的建立進行研究，并對負(fù)梯度區(qū)和等離子體橋區(qū)高頻輻射進行了相關(guān)測量。本文的主要工作有：對霍爾推力器振蕩問題研究現(xiàn)狀進行綜述。霍爾推力器內(nèi)振蕩按照頻率范圍可以分為低頻、高頻和超高頻振蕩，各個頻段的振蕩由于其產(chǎn)生機理不同，對發(fā)動機的影響也不同。綜述應(yīng)闡明各個頻段振蕩產(chǎn)生的物理機理，給出國內(nèi)外對振蕩問題研究的方法，指明目前振蕩研究存在的問題；建立霍爾推力器內(nèi)高頻輻射實驗測量系統(tǒng)。以同軸傳輸線內(nèi)導(dǎo)體制作的電磁波探針為前端測量工具，以高頻半柔同軸電纜為傳輸介質(zhì)，通過合理設(shè)計保證真空背壓的密封同軸連接器，利用TEKRSA3308A實時頻譜分析儀為采集終端，制定出霍爾推力器內(nèi)高頻輻射的實驗方案。實驗研究推力器放電參數(shù)對負(fù)梯度區(qū)高頻輻射效應(yīng)的制約關(guān)系。實驗結(jié)果表明負(fù)梯度區(qū)高頻輻射的頻率分布在250MHz以下，最大幅值頻率為100MHz左右。放電電壓、陽極質(zhì)量流量和磁場分別影響負(fù)梯度區(qū)的電子運動能量、電子的等離子體頻率和電子回旋頻率，進而對負(fù)梯度區(qū)的高頻輻射信號產(chǎn)生影響；實驗研究推力器放電參數(shù)對等離子體橋區(qū)高頻輻射的影響。實驗結(jié)果表明，等離子體橋區(qū)高頻輻射頻率分布在750MHz頻率范圍內(nèi)，并且在250MHz以下（以下稱為低頻段輻射）及250MHz-750MHz（以下稱高頻段輻射）分別存在著幅值較大的頻段，在低頻段對應(yīng)幅值最大的頻率在60MHz左右，而高頻段該頻率在310MHz左右。工作參數(shù)對低頻段輻射的影響與負(fù)梯度區(qū)類似。在高頻段，工作參數(shù)是通過影響橋區(qū)的等離子體密度影響輻射信號的；實驗研究陰極工作參數(shù)對等離子體橋區(qū)高頻輻射信影響。實驗結(jié)果表明，學(xué)位論文-II-陰極加熱功率及陰極質(zhì)量流量對等離子體橋區(qū)低頻段輻射和高頻段輻射的頻率和幅值、以及總功率影響均較小。經(jīng)過對實驗結(jié)果的分析認(rèn)為，這是因為陰極工作參數(shù)，特別是陰極發(fā)射功率只影響發(fā)射體熱輻射電子數(shù)，而對陰極出射電子的能量沒有影響，因而對與電子能量密切相關(guān)的低頻段輻射和高頻段輻射影響較小。本文的創(chuàng)新工作體現(xiàn)在建立霍爾推力器高頻輻射測量系統(tǒng)，目前，國內(nèi)對霍爾推力器的研究工作中尚未見到類似的測量系統(tǒng)。該系統(tǒng)的建立為國內(nèi)開展霍爾推力器高頻振蕩的研究建立了一個基礎(chǔ)平臺。關(guān)鍵詞霍爾推力器；輻射測量系統(tǒng)；等離子體振蕩；高頻輻射學(xué)位論文-III-AbstractDuetotheirhighspecificimpulse,lightweight,smallsize,compactstructure,highcontrolingprecisionandlonglifecharacteristics,HallThrusteriswidelyused,suchasprecisionofsatellitepositioning,orbitmaintenanceandattitudecontroling,Hallthruster,atypicaldischargeplasmamagneticconfinementdevice,inevitablyaccompaniedbythephenomenonofplasmaoscillationinitsdischargeprocess,andtheoscillationmeasurementsignalfromthetensofKHztoadozenGHzorso.Thefrequencyrangeof100MHzhigh-frequencyamongthemcouldimpactthemicro-physicalprocessesofHallthrustersplasmadischarge,andtheirelectromagneticradiationcouldalsointerferesatellitescommunicationswiththeground.Thisarticleaimsatresearchingthehigh-frequencyradiationsystemsbuildingandmeasuringanegativegradientareasandplasmahigh-frequencyradiationtobridge.Themainworkinthisarticleincludes:TheoscillationofHallthrusterresearchingissueswerereviewed.TheoscillationinHallthrustercanbedividedintolow-frequency,high-frequencyandultrahighfrequencyoscillationinaccordancewiththefrequencyrange；andduetothevariousmechanismofallkindsoffrequency,theoscillationmakesdifferenteffectsondifferentengines.Thesummaryofvariousoscillationshouldhaveaclearphysicalmechanismofoscillation,givetheresearchmethodsissuefromdomestictoforeignandindicatetheexistenceofcurrentproblemsofoscillations；TheestablishmentofHallthrusterexperimentsystemtomeasurehigh-frequencyradiation.Acoaxialtransmissionlineconductorofelectromagneticwavesproducedbythefront-endprobeformeasurementtoolstosemi-softhigh-frequencycoaxialcableforthetransmissionmedium,throughtherationaldesigningofvacuumpressuretoensurethatthesealcoaxialconnector,andusingtheTEKRSA3308AforReal-TimeSpectrumAnalyzercollectionterminals,makingtheexperimentalprogramofhigh-frequencyradiationofHallthrusters.ReseachingtheconstraintsrelationshipbetweenHallthrustersdischarge學(xué)位論文-IV-parametersandthenegativegradientareasofhighfrequencyradiationeffectinexperiment.Theresultsshowethatthedistributionofhigh-frequencyradiationinthenegativegradientareasisbelowthe250MHz,andthemaximumamplitudefrequencyis100MHZ.Dischargevoltage,anodemassflowandmagneticfieldgradient,respectively,thenegativeimpacttheelectronicmovementareasofenergy,electronplasmafrequencyandelectroncyclotronfrequency,andthusthenegativegradientareashaveanimpactonhigh-frequencyradiation；Theexperimentalstudyofthrusterplasmadischargeparametersonthebridgeoftheimpactofhigh-frequencyradiation.Thelresultsshowthat,BridgeDistrictplasmafhigh-frequencyradiationinthefrequencyrangeof750MHz,below250MHz(referredtoasthelow-frequencyradiation),andbetween250MHz-750MHz(referredtohigh-frequencyradiation),havealargerbandamplituderespectively.Inlow-frequencybandcorrespondingtothemaximumamplitudeinthefrequencyofaround60MHz,but310MHzinhigh-frequencyradiation.Workingparametersoflow-frequencyradiationsimilarwithnegativegradientzone.Inhigh-frequencyband,theworkingparametersofthebridgebytheimpactofplasmadensityimpactzoneoftheradiationsignal.Experimentalstudyontheworkparametersofthecathodehaveimpactonplasmaridgeareaofhighfrequencyradiation.Theresultshow,Cathodeheatingpowerandmassflowofcathodehavesmallerimpacttoplasmabridgeareaoflowradiationradiatioandhigh-frequencybandradiatioofthefrequencyandamplitude,aswellasontotalpower.Aftertheanalysisofexperimentalresultsthat,Thisisbecausethecathodeoperatingparameters,inparticularthecathodeemissionpoweronlyimpactthermalradiationemissionelectrons,anddoesnotaffecttheelectronicenergyexitofthecathode,andthusiscloselyrelatedwiththeelectronenergyspectrumoflowradiationandhigh-frequencyradiationwaslessaffected.ThisarticleembodiestheinnovativeworkofH