The response of a collisionless plasma to global electromagnetic perturbations of an axisymmetric toroidal equilibrium is derived. By adopting a variational formulation for guiding center motion, the perturbed distribution function is expressed in terms of the linearized guiding center Lagrangian. Finite orbit widths are retained. In particular, the high particle energy limit where mirror-trapped banana orbits are distorted into ‘‘potato-shaped’’ orbits is considered. In this limit, the time scales associated with the drift and bounce motions of a mirror-trapped orbit become comparable, yielding important consequences on plasma stability. Quadratic forms are constructed in the context of kinetic-magnetohydrodynamic (MHD) models of plasmas composed of a thermal component obeying fluid-like equations and a high-energy component described in terms of the collisionless drift-kinetic equation. Relevant applications include improved modeling of energetic ion effects on toroidicity-induced Alfvén gap modes and internal kinks.

Scenario modelling for the demonstration fusion reactor (DEMO) has been carried out using a variety of simulation codes. Two DEMO concepts have been analysed: a pulsed tokamak, characterised by rather conventional physics and technology assumptions (DEMO1) and a steady-state tokamak, with moderately advanced physics and technology assumptions (DEMO2). Sensitivity to impurity concentrations, radiation, heat transport models has been investigated. For DEMO2, the impact of current driven non-inductively by Neutral Beams has been studied by full MonteCarlo simulations of the fast ion distribution. The results obtained are a part of a more extensive R&D effort carried out in the EU in order to develop a viable option for a DEMO reactor, to be adopted after ITER for fusion energy research.

Abstract.A selection of achievements and first physics results are presented of the European Integrated Tokamak Modelling Task Force (EFDA ITM-TF) simulation framework, which aims to provide a standardized platform and an integrated modelling suite of validated numerical codes for the simulation and prediction of a complete plasma discharge of an arbitrary tokamak. The framework developed by the ITM-TF, based on a generic data structure including both simulated and experimental data, allows for the development of sophisticated integrated simulations (workflows) for physics application. The equilibrium reconstruction and linear MHD stability simulation chain was applied, in particular, to the analysis of the edge MHD stability of ASDEX Upgrade type-I ELMy Hmode discharges and ITER hybrid scenario, demonstrating the stabilizing effect of an increased Shafranov shift on edge modes. Interpretive simulations of a JET hybrid discharge were performed with two electromagnetic turbulence codes within ITM infrastructure showing the signature of trapped-electron assisted ITG turbulence. A successful benchmark among five EC beam/ray-tracing codes was performed in the ITM framework for an ITER inductive scenario for different launching conditions from the Equatorial and Upper Launcher, showing good agreement of the computed * See the Appendix.

The reduction in divertor target power load due to radiation of sputtered and externally seeded impurities in tokamak fusion reactors is investigated. The approach is based on integrated numerical modelling of DEMO discharges using the COREDIV code, which self-consistently solves 1D radial transport equations of plasma and impurities in the core region and 2D multifluid transport in the SOL. Calculations are performed for inductive DEMO scenarios and for DEMO steady-state configurations with tungsten walls and Ar or Ne seeding. For all considered DEMO scenarios significant fusion power can be achieved. Increase in seeded impurity influx leads to the reduction in fusion power and Q-factor (defined as the ratio of fusion power to auxiliary heating power) due to plasma dilution. Total radiation appears to be almost independent of the puffing level and is dominated by core radiation (>90%). The radiation due to seeding impurity is small and the type of seeded impurity weakly affects the results. For pulsed DEMO concepts, the accessible seeding level is limited. There is no steady-state solution for stronger puffing. The solution terminates due to helium accumulation, and if confirmed by more detailed investigations, might strongly affect DEMO design.

The "European Transport Simulator" (ETS) [1,2] is the new modular package for 1-D discharge evolution developed within the EFDA Integrated Tokamak Modelling (ITM) Task Force. It consists of precompiled physics modules combined into a workflow through standardized input/output data-structures. Ultimately, the ETS will allow for an entire discharge simulation from the start up until the current termination phase, including controllers and sub-systems. The paper presents the current status of the ETS towards this ultimate goal. It discusses the design of the workflow, the validation and verification of its components on the example of impurity solver and demonstrates a proof-of-principles coupling of a local gyrofluid model for turbulent transport to the ETS. It also presents first results on the application of the ETS to JET tokamak discharges with ITER like wall. It studies the correlations of the radiation from impurity to the choice of the sources and transport coefficients. ETS transport solver and workflow designThe ETS adopts a modular approach, where standalone precompiled physics modules ('actors' in the context of the workflow) are coupled into the workflow through standardised interfaces linked with the ITM data-structure. In view of allowing collective development of