Development of quasi-optical microwave transmission lines in microwave diagnostics systems on Hefei tokamaks

Microwave technology has turned out to be vital for the study of high temperature plasmas especially in tokamak devices, High power (up to 10 MW), wide frequency range (from 0.01 GHz for ion cyclotron range frequency heating, several GHz for low hybrid wave current driving and up to 140 GHz for electron cyclotron resonance heating in plasma), continuous wave or long pulsed microwave power are the preliminary energy needs to heat plasmas to 10/sup 8/ K that is required for ignition of plasma fusion in tokamak plasmas. Meanwhile, low power, RADARs are widely employed to measure plasma parameters and study plasma properties. In the paper, wide frequency band was used to collect and transmit weak microwave signals emitted from tokamak plasmas to microwave receivers; the transmission lines have the features of low transmission loss, wide working frequency band and effective polarization preservation and selection. The installation on HT-6B, HT-6M and HT-7 tokamaks successfully constructed electron cyclotron emission (ECE) diagnostics systems which have been measuring plasma properties.