Summary and results of the study of the hybrid matching option implementation of the ITER ICRH system

The hybrid option has been chosen for the load-resilient matching of the ITER ICRH system. The corresponding 3 dB hybrid matching circuit has been developed and fully implemented on a low-powered scaled mock-up at the LPP-ERM/KMS. The circuit features 23 simultaneously active feedback loops to minimize reflections on the 8 triplet lines, reduce the mutual coupling between the triplets and control the antenna array strap current distribution. The article discusses the employed methods for the implementation on a test-bench of the matching system including the derivation of closed-form analytical matching solutions for the tuners, the development of real-time control algorithms and the feedback systems. Furthermore, the achieved results are compared to numerical simulations of the ideal transmission line model of the matching system and the significance of these results for the extrapolation to the ITER case is discussed.