Effect of the ICRH Antenna Position on the Coupled Power in ITER and JET

Sammanfattning: Fusion energy has fascinated scientists for decades. One reason we do not see thispromising energy source powering today's society is the fact that the process requires extremeplasma temperatures. Plasmas can be heated to these temperatures by using radio waves, but to dothis efficiently, it is important to understand how the relative position of the antenna to the plasmaaffects the coupling. This thesis project studied the impact of the antenna's alignment with theplasma on the coupled power. To better understand the differences and similarities betweendifferent machines, results from ITER and JET were compared. The heating of the plasma wassimulated for different antenna positions using a finite element method-based code, which wasdeveloped at KTH, called FEMIC. A simplified theoretical model was also derived and compared withthe simulations. The antenna position was found to be important in both machines. The reason isthe evanescent behavior of the electric field in the region between the antenna and the plasma.Thus, the antennas' optimal positions were located where this distance was minimized. Even thoughthe antenna placement was determined to have an impact in both machines, the placement had agreater impact on the heating in ITER. The theoretical model showed similar behavior as thesimulations. However, it was better suited for JET.