Measuring Impedance and Power in ICRF Antenna Feeding Lines with Voltage and Current Probes.

Usually the power measurement in a ICRF system is done using directional couplers. Directional couplers can be calibrated with moderate effort in 50 Ohm transmission lines, as the measurement equipment with this impedance is widely available. In transmission lines with a lower impedance like 30 or 25 Ohm, who are common in antenna feeding lines, makes calibration complicated as reflection on impedance transitions like connectors for the measurement equipments are unavoidable. In such transmission lines the use of voltage and current probes can be beneficial as their calibration procedure is easier. A way to calibrate these probes in a low-impedance transmission line is shown. The last part of this paper shows the first results of this kind of measurements at an ASDEX Upgrade antenna feeding line. [ABSTRACT FROM AUTHOR]