Plasma contactor performance characterization

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1、N86-28429PLASMACONTACTORPERFORMANCECHARACTERIZATIONPaulWilbur1.SimplifiedschematicofPlasmaCouplingprocessunderconditionswhereexcessivecurrentsarebeingdemandedandadoublesheathregiondevelopswithattendanthighvoltagedrops.Thisconditionshouldbeavoidedbydesig

2、ningtheplasmasource(plasmacontactor)soitproducesadequateplasma.Thekeytohighplasmadensitiesisahighionproduc-tionrate.2.Plasmacontactorperformanceobjectives-Thistransparencyshouldbeself-explanatory.3.Thebasicelementsofthehollowcathodeareshown.Electronsare

3、drawnfromtheinsertbyfield-enhancedthermionicemissionandfromthebulkplasmabymultistepionizationprocesses.Thebulkplasmaissus-tainedbytheexpellantgasflowthroughthecathodetubeandorificeplateinthepresenceoftheelectricaldischargebetweenthecathodeinsertandanode

4、.Electronsescapefromthecathodeinteriorthroughtheorifice;ionsaredrawntotheinsertandorificeplacesurfaceswheretheydepositeenergy,heatingthesesurfaces.Someionsareproduceddownstreamoftheorificeasaresultofelectroncollisionswithneutralatomsclosetotheorifice.El

5、ectronorioncurrents(J)canbedrawn6fromthisplasmadownstreamoftheorificetoaplasmafurtherdownstreamofthehollowcathodeassemblyondemandanddependinguponthecathodetodownstreamplasmapotentialdifference.Forpresenttestsa0.6cmdiametercathodewith0.6mmdiameterorifice

6、wasused.4.Inordertoaugmenttheproductionofionsthehollowcathodebasedplasmasourcewasdesignedandbuilt.Keyfeaturesofthisdeviceare:oahollowcathodeoananodemoveddownstreamfromthelocationusedforthebasichollowcathodeoanenclosurethatconfinestheneutralgas4836^&8*S*

7、^8^oareversefeedexpellantflowplenumoaringcuspmagneticfieldconfigurationForthetestresultspresentedthebasichollowcathodeandthehollowcathodebasedplasmasourceusedanidenticalhollowcathode.5.Theionfilingsmapforthehollowcathodebasedplasmasource.Themagneticfiel

8、disusedtoconfineionsandelectronsandtherebyimproveionproductionperformance.6.Themechanicalschematicofthesystembeingusedtostudytheionandemissioncharacteristicsofthehollowcathode(shown)orthehollowcathodebasedplasmasource.7.Thesystem