EFDA-JET-CP(14)03/23
Mode Coupling in Hybrid Discharges at JET
Multiplemagneto-hydrodynamic(MHD)instabilitiesmaycontemporarilyappearinaTokamakdischarge,andinteractwithoneanotherifcertainspatialandtemporalconditionsaresatisfied.EachMHDmodeproducesaperturbedmagneticfieldoverthewholeplasmawithagivenspatialperiodicity(K)thatsatisfies:K*B=0(1)WiththemagneticfieldlinesBofagivenrationalsurface.Assumingthatmagneticislandsaredraggedbytheionpopulation[1],a(m,n)modewillappearatexternalmagneticcoilsasfluctuatingat:2fm,n=WD(2)whereWDistheionrotationattheq=m/nrationalsurface.PreprintofPapertobesubmittedforpublicationinProceedingsofthe41stEPSConferenceonPlasmaPhysics,Berlin,Germany23rdJune2014­27thJune2014