EFDA-JET-CP(03)01/34

Three-Dimensional Modelling of the JET A2 ICRH Antenna

Antenna codes developed by the ICRH community include fairly realistic descriptions of wave propagation in magnetized plasmas, but rather crude representations of the launcher. This may seriously limit the accuracy of the resulting input impedance matrix, which is an essential ingredient of coupling predictions. Successful quantitative predictive modelling of the coupling characteristics of RF structures as complex as the JET A2 arrays remains to be demonstrated (the experimental coupling resistance Rc of these antennae being less than their design estimate of the early nineties). The recent appearance of highly powerful and versatile commercial electromagnetic codes has brought hope to make decisive progress, although these products do not yet include a magnetized plasma. We have taken this approach, and report on recent three-dimensional electromagnetic modelling of the JET A2 ICRF antennae using the MICROWAVE STUDIO® (MWS) software [3]. This work was triggered by renewed interest in accurate predictions of ICRH antenna array coupling during the design activity of the JET ITER-Like antenna. Our goals are to validate the numerical simulations against available A2 experimental data, to understand the array RF characteristics in detail, and to improve confidence in predictions for future designs.
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EFDC030134 2.58 Mb