[优秀毕业设计精品] 霍尔推力器高频电磁辐射的实验研究.doc

学位论文-I-摘要霍尔推力器由于其具有比冲高、质量轻、体积小、结构紧凑、控制精度高、寿命长等特点，在卫星的精确定位、轨道保持、姿态控制等方面得到了广泛的应用。霍尔推力器作为一种典型的磁约束等离子体放电装置，在其放电过程中，必然会伴随着等离子体振荡现象，从几十KHz到十几GHz都测量得到振荡信号。其中，频率范围在100MHz量级的高频振荡，影响着霍尔推力器内放电等离子体的微观物理过程，其辐射的电磁波可能干扰卫星与地面的通讯。本文主要针对高频辐射系统的建立进行研究，并对负梯度区和等离子体桥区高频辐射进行了相关测量。本文的主要工作有：对霍尔推力器振荡问题研究现状进行综述。霍尔推力器内振荡按照频率范围可以分为低频、高频和超高频振荡，各个频段的振荡由于其产生机理不同，对发动机的影响也不同。综述应阐明各个频段振荡产生的物理机理，给出国内外对振荡问题研究的方法，指明目前振荡研究存在的问题；建立霍尔推力器内高频辐射实验测量系统。以同轴传输线内导体制作的电磁波探针为前端测量工具，以高频半柔同轴电缆为传输介质，通过合理设计保证真空背压的密封同轴连接器，利用TEKRSA3308A实时频谱分析仪为采集终端，制定出霍尔推力器内高频辐射的实验方案。实验研究推力器放电参数对负梯度区高频辐射效应的制约关系。实验结果表明负梯度区高频辐射的频率分布在250MHz以下，最大幅值频率为100MHz左右。放电电压、阳极质量流量和磁场分别影响负梯度区的电子运动能量、电子的等离子体频率和电子回旋频率，进而对负梯度区的高频辐射信号产生影响；实验研究推力器放电参数对等离子体桥区高频辐射的影响。实验结果表明，等离子体桥区高频辐射频率分布在750MHz频率范围内，并且在250MHz以下（以下称为低频段辐射）及250MHz-750MHz（以下称高频段辐射）分别存在着幅值较大的频段，在低频段对应幅值最大的频率在60MHz左右，而高频段该频率在310MHz左右。工作参数对低频段辐射的影响与负梯度区类似。在高频段，工作参数是通过影响桥区的等离子体密度影响辐射信号的；实验研究阴极工作参数对等离子体桥区高频辐射信影响。实验结果表明，学位论文-II-阴极加热功率及阴极质量流量对等离子体桥区低频段辐射和高频段辐射的频率和幅值、以及总功率影响均较小。经过对实验结果的分析认为，这是因为阴极工作参数，特别是阴极发射功率只影响发射体热辐射电子数，而对阴极出射电子的能量没有影响，因而对与电子能量密切相关的低频段辐射和高频段辐射影响较小。本文的创新工作体现在建立霍尔推力器高频辐射测量系统，目前，国内对霍尔推力器的研究工作中尚未见到类似的测量系统。该系统的建立为国内开展霍尔推力器高频振荡的研究建立了一个基础平台。关键词霍尔推力器；辐射测量系统；等离子体振荡；高频辐射学位论文-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学位论文-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