Modeling ICRH and ICRH-NBI synergy in high power jet scenarios using european transport simulator (ETS)

Abstract : In ITER, Neutral Beam Injection (NBI) and Ion Cyclotron Resonance Heating (ICRH) will be used to increase the temperatures beyond what is achieved by ohmic heating. To be able to predict how ITER discharges will behave it is necessary to have numerical tools capturing the dynamics sufficiently realistically. The European Integrated Modelling effort (EU-IM) provides the European Transport Simulator (ETS) [1] which was designed to simulate arbitrary tokamak plasma discharges. A first verification of ICRF full-wave codes was done in [2] but a detailed study of the Fokker-Planck codes, that describe the collisional power redistribution of the heated ions to the bulk plasma (via Coulomb collisions) was not done. Two 1D Fokker-Planck solvers for arbitrary distributions functions have recently been implemented within ETS: StixRedist [3] and FoPla [4]. To ensure the CPU time remains acceptable, the latter was parallelized. We discuss the integration and verification/validation of these modules in the heating and current drive (H&CD) ETS workflow in high power JET-ILW discharges, drawing special attention to the importance of the nonlinear collision operator when solving a set of coupled Fokker-Planck equations for cases when majority species play a key .