Kinetic Simulations of Ion Transport in Fusion Devices [recurso electrónico] $c

This thesis deals with the problem of ion confinement in thermonuclear fusion devices. It is a topic of general interest, as it helps to understand via numerical simulations the ion confinement properties in complex geometries, in order to predict their behavior and maximize the performance of future fusion reactors. The main work carried out in this thesis is the improvement and exploitation of an existing simulation code called ISDEP. This code solves the so-called ion collisional transport in arbitrary plasma geometry, improving in this sense other existing codes. Additionally, it presents outstanding portability and scalability in distributed computing architectures, such as Grid or Volunteer Computing. The main physical results can be divided into two blocks. First, the study of 3D ion transport in ITER is presented. ITER is the largest fusion reactor (under construction) and most of the simulations so far assume the axis-symmetry of the device. Unfortunately, this symmetry is only an approximation because of the discrete number of magnetic coils used. ISDEP has shown, using a simple model of the 3D magnetic field, how the ion confinement is affected by this symmetry breaking. Secondly, ISDEP has been applied successfully to the study of fast ion dynamics in fusion plasmas. The fast ions, with energies much larger than the thermal energy, are a product of the device’s heating system. Thus, a numerical predictive tool can be used to improve the heating efficiency. ISDEP has been combined with the FAFNER2 code to study such ions in stellarator (TJ-II, LHD) and tokamak (ITER) geometries. It has also been validated by experimental results. In particular, comparisons with the CNPA diagnostic in the TJ-II stellarator are remarkable. During many years the grid computing efforts in Europe were focused at developing the technologies and demonstrating them in the field through pilot infrastructures. In time these infrastructures evolved to become production oriented services supporting a wide range of scientific applications. These international and regional infrastructures that exist today are still based on the same organizational and financial models. They are still much dependent on European funds and based on the individual participation of research organizations across Europe. Some of these infrastructures have found ways to continue operating without external funding usually this implies both a commitment from the partners to continue supporting them and a considerable reduction of the associated development and support activities. None of these models ensures the long term sustainability of these grid services. This is clearly one of the main obstacles to a wider adoption of these technologies. For new users the learning curve and the effort required to adopt the grid technologies is still high and frequently only makes sense when considered as part of a strategic investment. Such an investment requires confidence in the long-term availability of the grid services and technologies Introduction.- ISDEP.- 3D Transport in ITER.- Simulations of Fast Ions in Stellarators.- Simulations of NBI Ion Transport in ITER.- Overview and Conclusions.