Inordertoimplementlarge-scaleandhigh-betatokamaksimulation,anewalgorithmoftheelectromagneticgyrokineticPIC（particle-in-cell）codewasproposedandinstalledontheGpic-MHDcode[GyrokineticPICcodeformagnetohydrodynamic（MHD）simulation].Inthenewalgorithm,thevorticityequationandthegeneralizedOhm’slawalongthemagneticfieldarederivedfromthebasicequationsofthegyrokineticVlasov,Poisson,andAmperesystemandareusedtodescribethespatio-temporalevolutionofthefieldquantitiesoftheelectrostaticpotentialφandthelongitudinalcomponentofthevectorpotentialAz.Thebasicalgorithmisequivalenttosolvingthereduced-MHD-typeequationswithkineticcorrections,inwhichMHDphysicsrelatedtoAlfvenmodesarewelldescribed.Theestimationofperturbedelectronpressurefromparticledynamicsisdominant,whiletheeffectsofothermomentsarenegligible.Anotheradvantageofthealgorithmisthatthelongitudinalinducedelectricfield,Etz=-■z/■t,isexplicitlyestimatedbythegeneralizedOhm’slawandusedintheequationsofmotion.Furthermore,theparticlevelocitiesalongthemagneticfieldareused（vz-formulation）insteadofgeneralizedmomentums（pz-formulation）,hencethereisnoproblemof’cancellation’,whichwouldotherwiseappearwhenAzisestimatedfromtheAmpere’slawinthepz-formulation.ThesuccessfulsimulationofthecollisionlessinternalkinkmodebythenewGpic-MHDwithrealisticvaluesofthelarge-scaleandhigh-betatokamaksrevealedtheusefulnessofthenewalgorithm.
