ITER relevant ICRF heating scenarios with large ion heating fraction

The merits of a large ion heating fraction for the performance of a tokamak reactor are investigated. The abilities of different ICRF heating scenarios in providing significant ion heating are discussed. The 3He minority scenario is found to be the most suitable scenario for a reactor. Simulations of ITER relevant scenarios suggest that the bulk ion heating fraction is in the range of 70% for most of the heating phase. The benefits of a large ion heating fraction are then discussed in the framework of transport simulations. In particular, a large ion heating fraction is shown to lead to an improved control over the path to ignition. Finally, the implications of a reduced size ITER are discussed. The steady state performance with 3He minority scenario is improved by 30% as compared with pure electron heating schemes. (author)