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This paper presents a dedicated study of plasma-antenna (PA) coupling withthe Alfven Eigenmode Active Diagnostic (AEAD) in JET. Stable AEs and theirresonant frequencies f, damping rates $\gamma$ < 0, and toroidal mode numbers nare measured for various PA separations and limiter versus X-point magneticconfigurations. Two stable AEs are observed to be resonantly excited atdistinct low and high frequencies in limiter plasmas. The values of f and n donot vary with PA separation. However, $\vert\gamma\vert$ increases with PAseparation for the low-f, but not high-f, mode, yet this may be due to slightlydifferent edge conditions. The high-f AE is detected throughout the transitionfrom limiter to X-point configuration, though its damping rate increases; thelow-f mode, on the other hand, becomes unidentifiable. The linear resistive MHDcode CASTOR is used to simulate the frequency scan of an AEAD-like externalantenna. For the limiter pulses, the high-f mode is determined to be an n = 0GAE, while the low-f mode is likely an n = 2 TAE. During the transition fromlimiter to X-point configuration, CASTOR indicates that n = 1 and 2 EAEs areexcited in the edge gap. These results extend previous experimental studies inJET and Alcator C-Mod; validate the computational work performed by Dvornova etal 2020 Phys. Plasmas 27 012507; and provide guidance for the optimization ofPA coupling in upcoming JET energetic particle experiments, for which the AEADwill aim to identify the contribution of alpha particles to AE drive during theDT campaign.

Experimental studies of plasma-antenna coupling with the JET Alfven Eigenmode Active Diagnostic