简介：Leaderpropagationisafundamentalissueinlightningphysics.Thepropagationcharacteristicsofpositiveleadersandnegativeleadersaresummarizedandcomparedbasedondatafromhigh-speedcameraandelectromagneticfieldinrocket-triggeredlightningandtower-initiatedlightningdischarges;availablechannelbasecurrentdatarecordedinrocket-triggeredlightningarealsoused.Thenegativeleaderspropagateinasteppedfashionaccompaniedbymanybranches.Thestemsaheadofthenegativeleadertipdeterminethemanneranddirectionoftheleaderpropagation,andeventhebranchingandwindingofthelightningchannel.Theimpulsivecurrent,electromagneticfield,andrelatedopticalimagessuggestthatthepositiveleadermaydevelopinastep-likefashionatitsinitialstageoftriggeredlightning.However,thesteppingprocessesofthepositiveleaderareobviouslydifferentfromthoseofthenegativeleader.Tower-initiatedlightningrevealedthatthemostconspicuouscharacteristicsofthestepwisepositiveleaderinvolvetheintermittentbrush-likecoronazoneinfrontoftheleadertipandtheluminosityenhancementofthechannelbehindthetip.Inrockettriggeredlightningflashes,thechargetransferredduringanindividualstepforthenegativeleaderwasnearlyanordergreaterthanforthepositivecounterpart.Thesuccessivestreamersaheadoftheleadertipareessentialforbothnegativeandpositiveleaderpropagation,andthestemscouldbeformedfromoneormorestreamersinthepreviousnegativestreamerzonewiththemainleaderchanneldim.High-resolutionobservationoftowerlightningalsorevealedanewtypeofbidirectionalrecoilleader,withpolaritycontrarytothetraditionalone,traversinginnegativechannelsassociatedwithtower-initiatedandrocket-triggeredlightning.

简介：Magneticlocalizedsurfaceplasmonmodesaresupportedonmetallicspiralstructures.Couplingmechanismsforthesemetamaterialresonators,whicharethejointactionofmagneticandelectriccoupling,arestudied.Basedonthestrongcoupling,spoofmagneticplasmonmodespropagatinginthebackwarddirectionareproposedalongachainofsubwavelengthresonators.Thetheoreticalanalysis,numericalsimulations,andexperimentsareingoodagreement.Theproposednovelrouteforachievingnegative-indexwaveguidinghaspotentialapplicationsinintegrateddevicesandcircuits.

简介：Opticalemissionspectroscopy(OES)usingthetraceraregasesofArandXehavebeencarriedoutinaradiofrequency(RF)drivennegativeionsourceatInstituteofPlasmaPhysics,ChineseAcademyofScience(ASIPP),inordertodeterminetheelectrontemperatureanddensityofthehydrogenplasma.Theline-ratiomethodsbasedonpopulationmodelsareappliedtodescribetheradiationprocessoftheexcitedstateparticlesandestablishtheirrelationswiththeplasmaparameters.Thespectrallinesfromtheargonandxenonexcitedstateatomswiththewavelengthof750.4and828.0nmareusedtocalculatetheelectrontemperaturebasedonthecoronamodel.Theargonionsemissionlineswiththewavelengthof480and488nmareselectedtocalculatetheelectrondensitybasedonthecollisionalradiativemodel.OEShasgiventhepreliminaryresultsoftheelectrontemperatureanddensitybyvaryingthedischargegaspressureandRFpower.Accordingtotheexperimentalresults,thetypicalplasmaparametersisTe2≈2-4eVandne≈1x1017-8x1017m^-3infrontofplasmagrid.

简介：Here,wereportthesynthesisofhardcarbonmaterials(RH)madefromnaturalricehuskthroughasinglepyrolysisprocessandtheirapplicationasananodeinsodium-ionbatteries.ThestudiesshowthattheelectrochemicalpropertiesofRHsareaffectedbythetreatmenttemperatures,whichdeterminethematerialsmorphology,inparticular,theirdegreeofgraphitizationandextentofcontinuouschannels(nanovoids).Thelatterareaccessibletosodiumionsandsignificantlycontributetochargestoragecapacityoftheproducedanodes.TheRHsobtainedat1600°Cdeliverthehighestreversiblecapacityof276mAhg-1mainlyduetoinsertionofsodiumionsintothenanovoids.Thisworkdeepensthebasicunderstandingoftheinfluenceofthecarbonizationtemperatureonthesodiumstoragemechanism.