Fast multichannel heterodyne radiometer for electron cyclotron emission measurement on stellarator W VII‐A

An eight‐channel radiometer for simultaneous measurement of electron temperatures at different radii via electron cyclotron emission is described. It is divided into two parts, the interchangeable front end and the filter section. By replacing the front end, both first and second‐harmonic electron cyclotron emission measurements are possible in the range of 50–180 GHz. The instrument is absolutely calibrated with an accuracy estimated to be within ±10%. The spatial resolution ΔR/R is of the order 10−3, the temporal resolution 20 μs.