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1、电弧焊基础（Arcweldingfoundation）A,1inthecathodeconductivecharacteristicsofcathodefunctions:acceptpositiveionsandemissioncathodeelectronicinstitutions:thethermionicemissionofcathodesurface,fieldemission,thermalionizationcollisionlocalplasmaemissioncathode.Hotcathode(tungsten,car
2、bon,etc.):hotemissioncoldcathode(iron,aluminum,etc.):electricfieldemissioncollisionemissionplasmacausedthethermalpowertoleave.Theelectricconductioncharacteristicofthearccolumnisdisorganizedandtheaveragekineticenergyisincreased,resultinginhightemperature.Themolecules,theato
3、ms,willgenerateathermoelectricshock,formingaplasma.Thenarccolumniselectricallyneutral(theunitvolumeispositiveandnegativewithpointparticlesThechargedparticlesaredirectedtomoveandareessentiallyfreefromtherepulsiveactionofthespaceelectricfield,sotheycantransmitalargecurrentun
4、derlowvoltageconditions.Narccolumnlengthisarclength,arccolumnlengthVoltagedropbecomestheelectricfieldintensityofarccolumn.Theintensityofelectricfieldinthearccolumnislow:usuallyonly5~10v/cm.Theroleofanodesintheconductivecharacteristicofthe3anodearea:toaccepttheelectronandpr
5、ovidethepositiveiontothearccolumn.Theproductionmechanismofpositiveions:?Ionizationundertheactionoftheanodefield:inthecaseofsmallcurrent,thethermalpowerisdifficulttogetout.Formingananodepressuredrop?Electronkineticenergy?Collisionionization?Untiltheanodevoltageisstable.?The
6、rmoelectriccurrentintheanodearea:inthecaseoflargecurrent,theanodepressuredropisapproximatelyzero,andthemetalevaporatesduetohighelectrodetemperature.Thermalionization?Doesthecurrentnotformananodewhenitislargeenough?Theanodepressuredropisalsorelatedtotheelectrodematerialchar
7、acteristics,thethermalconductivityisgoodandtheanodepressuredrops.2.Theformingconditionsofcathodespots:1)theconditionsofemissionelectron(fieldemissionandthermalemission)2)thearccolumnenergydissipationisminimizedbythispoint.Thecharacteristicsofcathodespots:1)thehotcathodeisi
8、nthecaseofsmallcurrent,whilethecoldcathodespotsthecathodespotinthelargercurrent.2)toremov
