Design and testing of a 5 GHz TE10–TE30 mode converter mock-up for the lower hybrid antenna proposed for ITER

The design and overall dimensions of a 5 GHz TE10–TE30 mode converter are presented. This mode converter is a RF element of a 20 MW CW lower hybrid system proposed for ITER. A low power mock-up of this device has been manufactured at CEA/IRFM and measured at low power. RF measurements indicate a return loss of 40 dB and a transmission loss of 4.78 dB ± 0.03 dB for the three outputs. The forward conversion efficiency from TE10 mode to TE30 has been measured from electric field probing to 99.9%. The good RF performances obtained validate the RF design of this element.