简介:Alargemagnetizedplasmasheetwithsizeof60cmx60cmx2cmwasgeneratedbyalinearhollowcathodedischargeundertheconfinementofauniformmagneticfieldgeneratedbyaHelmholtzCoil.Themicrowavetransmissioncharacteristicoftheplasmasheetwasmeasuredfordifferentincidentfrequencies,incaseswiththeelectricfieldpolarizationoftheincidentmicrowaveeitherperpendicularorparalleltothemagneticfield.Inthismeasurement,parametersoftheplasmasheetwerechangedbyvaryingthedischargecurrentandmagneticfieldintensity.Intheexperiment,upperhybridresonancephenomenawereobservedwhentheelectricfieldpolarizationoftheincidentwavewasperpendiculartothemagneticfield.Theseresonancephenomenacannotbefoundinthecaseofparallelpolarizationincidence.Thisresultisconsistentwiththeoreticalconsideration.Accordingtotheresonancecondition,theelectrondensityvaluesattheresonancepointsarecalculatedundervariousexperimentalconditions.Thiskindofresonancephenomenacanbeusedtodevelopaspecificmethodtodiagnosetheelectrondensityofthismagnetizedplasmasheetapparatus.Moreover,itispointedoutthattheoperatingparametersofthelargeplasmasheetinpracticalapplicationsshouldbeselectedtokeepawayfromtheupperhybridresonancepointtopreventsignalsfrompolarizationdistortion.
简介:Alargediamondcrystalupto500μmindiameterwithasmooth(100)facetatitstophasbeensynthesizedonMosubstratethroughmicrowaveplasmachemicalvapordeposition(MPCVD).Itsmorphologyandqualitywerecharacterizedbyscanningelectronmicroscopy(SEM),andthegrowthmechanismwasroughlyillustratedfrombothmacroscopicandmicroscopicviewpoints.Itwasfoundthatmorphologicalinstabilitiesareamajorfactorresultinginsynthesisoflargediamondcrystals,moreover,highmicrowavepowerdensity(MPD),highCH4concentrations,highpressure,highsubstratesurfacetemperatureandtheadditionofasmallamountofO2werealsonecessaryforthesynthesisoflargediamondcrystals.