Modeling of RF Heating in the JET Tokamak

Abstract: Fusion reactors need methods to couple externalpower to confined plasmas. Ion cyclotron resonance heating(ICRH) is a method to radiate electromagnetic waves to couplepower to the kinetic motion of gyrating ions in a plasma. In thisreport we study ICRH with regard to the dispersive effects ofthe confined plasma in the JET tokamak. We study this witha division of the electric field with regard to toroidal modenumbers. Specifically we examine where dispersive effects arelocated in the plasma and if they have any importance. We alsostudy the ion-ion hybrid layer, where according to the dispersionrelation a singularity can occur. To do the analysis, we use thecode FEMIC to simulate fusion scenarios.The results show that ion absorption is stronger and morelocalized for low toroidal mode numbers. This is true for toroidalmode numbers n 10, and for n < 6 the resolution ofthe solutions does not suffice for a meaningful analysis. Anexamination of the effects of the singularity in the dispersionrelation at the ion-ion hybrid layer shows that the amount ofabsorbed power in the ion-ion hybrid layer is significantly smallerthan for the central region of absorption. This means that thesingularity does not affect ICRH heating in our scenarios in anymajor sense.