Benchmarking of electron cyclotron heating and current drive codes on ITER scenarios within the European Integrated Tokamak Modelling framework

Electron cyclotron resonance heating (ECRH) and electron cyclotron current drive (ECCD) are used to heat the plasma, to tailor the current profiles and to achieve different operating regimes of tokamak plasmas. Plasmas with ECRH/ECCD are characterized by non-thermal electrons, which cannot be described by a Maxwellian distribution. Non-thermal electrons are also generated during MHD activity, like sawteeth crashes. Quantifying the non-thermal electron distribution is therefore a key for understanding EC heated fusion plasmas. For this purpose a vertical electron cyclotron emission (V-ECE) diagnostic is being installed at TCV. The diagnostic layout, the calibration, the analysis technique for data interpretation, the physics potentials and limitations are discussed

Parallel universal access layer: A scalable I/O library for integrated tokamak modeling

The paper describes a parallel-I/O extension of the Universal Access Layer, a multi-language interface used for exchange of standardized data objects between Integrated Tokamak Modeling (ITM) codes. Although our evaluation focuses on Lustre, the general idea also applies to other parallel file systems. A snapshot of the current implementation is given, followed by an analysis of user and system requirements. The design derived from the serial version of the UAL is described, and emphasized features such as the ability to choose between serial and parallel I/O are explained. Performance tests comparing the implementation to other I/O methods are made to analyze the impact of the implementation. The outcome shows that the new implementation not only enables the I/O of datasets with several GB in size but also speeds up the write rate by a factor of 13 in the best case

Simulations of the edge plasma: the role of atomic, molecular and surface physics

Atomic, molecular and surface physics plays an important role in simulations of the edge plasma in present day tokamaks, and in the predictive simulations of new devices. The edge plasma-in this context, the Scrape-Off Layer (SOL), the Private Flux Region (PFR) and core region close to the separatrix (or Last Closed Flux Surface, LCFS)-provides the boundary conditions for the main plasma, and is the region where much of the power and all of the particle exhaust occurs. It is also the region where the plasma interacts with solid surfaces, puffed gases and gas arising from recycling. The results of plasma edge simulations can depend strongly on the availability and quality of the atomic, molecular and surface data (the peak plasma temperature at the divertor was found to vary by a factor of five dependent on the choice of atomic physics data in a recent sensitivity analysis). The current material choice for ITER with Plasma Facing Components (PFCs) consisting of C, Be and W also presents challenges, both in the availability of the necessary data for W, and in the plethora of charge states for W. Another challenge presented by the material choice is the likely presence of mixed materials formed by the migration of material from one surface to another. These introduce effects like alloying and preferential sputtering as well as new (much longer) time-scales in the problem. Efforts to incorporate a bundled charge state model within one of the present edge simulation codes, SOLPS, will he described, as well as efforts to address some of the questions raised by mixed materials. Some issues related to data consistency and traceability within the context of the European effort on Integrated Tokamak Modelling will also be addressed