Antenna Q Monitoring for Pulsed RF Heating Experiments

Low frequency wave heating experiments conducted on pulsed plasmas are often faced with the task of measuring low antenna resistance. This paper describes a method for monitoring the antenna-plasma Q during a plasma discharge. Knowledge of Q measured at low power can be helpful in the design of a high power antenna and its associated matching network. The concept of an effective Q is introduced and its importance in suppressing harmonics is noted. Q scans for a low frequency Alfvén wave heating experiment conducted on the PRETEXT tokamak are shown. Detailed circuitry of this diagnostic is included.