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1、AIAA99-2284OpticalStudyofAnomalousElectronTransportinaLaboratoryHallThrusterN.B.Meezan,D.P.Schmidt,W.A.Hargus,Jr.,andM.A.CappelliDepartmentofMechanicalEngineeringThermosciencesDivisionStanfordUniversityStailford,CA,94305-303235thAIAA/ASME/SAE/ASEEjoint‘pro
2、pulsionConferenceandExhibit20-24June1999L,os.Angeles,CaliforniaForpermissiontocopyortorepublish,contacttheAmericanInstituteofAeronauticsandAstronautics,1801AlexanderBellDrive,Suite500,Reston,VA,20191-4344.”.’AIAA-99-2284OpticalStudyofAnomalousElectronTrans
3、portinaLaboratoryHallThrusterN.B.Meezan“.W.A.Hargus.Jr.‘,D.P.Schmidt;‘:,andM.A.Cappelli’DepartmentofMechanicalEngineeringThermosciencesDivisionStanfordUniversityStanford,CA943053032AbstractAnopticalemissionexperimentisusedtoexploreplasmafluctuationsasamech
4、anismforanomalouselectrontransportinHalldischarges.EmissionisdetectedfrominsidethechannelofamodifiedlaboratoryHallthruster.Threeupperstatesarestudied-twoinXeIandoneinXeII.EmissionfromtheXeIItransitionagreeswellwithfluctuationdatafromnegatively-biasedelectr
5、ostaticprobes.EmissionfromoneXeIupperstatediffersgreatlyfromtheion-lineandprobemeasurements,suggestingfluctuationsinaplasmapropertyotherthanelectrondensity.Asimplecollisional-radiativemode1(coronamodel)isappliedtocalculatetheplasma’selectron“temperature.”T
6、emperaturesinthe2-4eVrangearemeasured,withfluctuationsupto30%ofthemean.Thetemperaturedropssignificantlyinthechannelionizationregion,aresultnotseeninprobemeasurements.Anon-Maxwellianelectronenergydistributionisofferedasanexplanationforthisobservation.Anomal
7、ouselectrontransportisdiscussedintermsofaneffectiveHallparameter.ClassicalestimatesoftheHallparameterarecomparedtoexperimentalresults.Therelativestrengthofplasmafluctuationsisfoundtocorrelatewithenhancedelectrontransport.I.Introductionwhereu,istheelectronv
8、elocityandv,,isthemomentum-transfercollisionfrequencyforneutral-Halldischargeaccelerators,alsocalledHallelectroncollisions.Thisequationcanbesolvedforthethrusters,arehighspecific-impulseplasmathrustersaxialele