Electrical model of the Alfvén eigenmode exciter on JET

The TAE antenna system on JET is used to drive intermediate and high n Alfvén Eigenmodes (AEs) into the plasma so as to study their properties and estimate their stability by measuring their damping rates as a function of the various plasma parameters. In order to bring the system to full and optimized operation in terms of driving higher current into the antennas and hence higher magnetic perturbations into the plasma, the design of a matching unit was considered. The latter required a complete and accurate electrical circuit representation of the system. The construction of such an electrical model of the system involved the development of equivalent transformer circuits in the frequency range of interest and the use of impedance measurements as a benchmark in order to test its validity. The potential of the possible matching solutions was assessed and the effects of the inductive coupling between the antennas were investigated.