A Compact and Broadband Feeding Structure for In-Situ Plasma Probe Measurements

Christian Schulz, Ilona Rolfes

IEEE Asia Pacific Microwave Conference (APMC), pp. 540-542, doi: 10.1109/APMC.2017.8251501, Kuala Lumpur, Malaysia, Nov 13-16, 2017


A compact and broadband symmetrization for insitu plasma diagnostics is presented in this paper. Based on the maximum dimensions of the applied multipole resonance probe (MRP), a 5.8 mm by 33 mm stepped tapered balun is integrated into the holder of the probe. It possesses a return loss better than 30 dB and an insertion loss below 0.25 dB in conjunction with a high symmetry from 0.2 to 6 GHz. Hence, an undisturbed resonance behavior can be evaluated to calculate internal plasma parameters by one reflection measurement. The balun is investigated by detailed simulations in CST Microwave Studio and by measurements of a back-to-back transition. Additional measurements within an argon-oxygen plasma prove the suitability of the integrated balun.

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