Numerical Simulation of Fusion Plasmas

The generation of energy by nuclear fusion is one of the most challenging goals of research of European Community. It is highly probable that the first fusion reactor with high power amplification with the acronym ITER-FEAT will be realized in 6th frame program. Austria participates in fusion research by the EURATOM/ ÖAW association which coordinates the research activities of the participating Ausrtian laboratories. The fusion physics group of Austrian Research Centers Seibersdorf deals with numerical simulation of fusion plasmas. Recently a regime has been discovered where the plasma confinement is enhanced by a particular plasma current profile. The hollow current profile creates an internal tranport barrier (ITB). The plasma current is produced partly by injection of radio frequency or of energetic particles and partly by a current produced - under certain conditions - by the plasma itself, referred to as bootstrap current. By this technique the pulsed generation of plasma current can be avoided and a steady state operation is possible. In order to apply this regime to ITER-FEAT, many reliable and realistic predictive numerical simulations are necessary. To accomplish that task it is imperative to dispose of computer codes with realistic physical models for energy and particle confinment in agreement with the experiment. The most important experimental installation is the JET tokamak in UK, operated by EC. Tore-Supra in France (CEA Cadarache) and ASDEX-Upgrade (IPP, Garching) in München/Garching are important national plasma research devices. The main interest of the ARCS group is the modeling of plasma fuelling. One promising method is the injection of frozen fuel spheres (consisting of deuterium and tritium) referred to as pellets, which are launched with high velocities into the hot plasma. By interaction with the plasma the pellets are dissolved and tranformed into plasma replacing the losses due to fusion reactions and diffusion. It is the goal of the proposed project to improve the models in the existing computer codes and to validate them with experimental evidence. Especially the influence of the ITB on fuelling effectivity is of high interest. Above all, it must be clarified, if the presently technically available pellet injection velocities are sufficient to attain the required penetration depth in the fucion device. The results will be useful for predictive simulations for ITER-FEAT. The project will be accomplished in cooperation with our partners from JET, IPP and Cadarache.