The Power Measurement System of the Tore Supra Ecrh Transmitter at 118 GHZ

The E.C.R.H. (Electron Cyclotron Resonance Heating) generator on T.S. (Tore Supra) consists of six 500 kW-5 s and 400 kW up to 600 s gyrotrons at 118 GHz [1],[2]. It will be connected to its antenna by six 20 meter long transmission lines. Due to the very long pulse capability, this system is significant in view of the ITER transmitter. In order to measure the 12 different powers (6 forward and 6 reflected) in circular oversized corrugated waveguides carrying the HE1 1 mode at 118 GHz and to protect the tube against excessive reflected power and internal breakdowns, a specific measurement system is needed. In this way the T.S. measurement system has been designed to be reliable in a tokamak environment and to be easily extrapolated to ITER. Our measurement and calibration technique will be described, as well as various features of the whole system.