A Fabry-Perot interferometer for plasma diagnostics

A Fabry-Perot interferometer for the measurement of tokamak plasma electron cyclotron emission is described. The interferometer operates in either a static or a scanning mode. In the static mode the resolving power is typically 30 and the time resolution (limited by the detector bandwidth) typically 1 μs. In the scanning mode, the emission in narrow regions of the spectrum - usually the second harmonic of the electron cyclotron frequency typically covering the range 120 to 170 GHz - can be measured in 2.5 ms with a resolving power >25. Results obtained on the DITE tokamak are presented. (author)