Technical Description of the Sources, Detection Systems and Data Acquisitions for Joint European Torus (JET) Multichannel Reflectometer

摘要

A multichannel reflectometer for the Joint European Torus (JET) to measure density fluctuations and ne(r) is described. It features 12 channels in the frequency range of 18 to 80 GHz (corresponding electron densities to be probed of 4 times 10 to the 18th to 8 times 10 to the 19th power m); measurement of plasma movements and determination of the direction of these movements in the fixed frequency mode (insensitive to signal amplitude variations); profile measurements with high resolution in the swept frequency mode (insensitive to signal amplitude variations); mode switching from fixed to swept frequency without restraint; raw interference signal outputs (homodyne) followed by computer controlled bandpass filters; automatic data recording and handling; high sensitivity (maximun acceptable loss 105 dB, with S/N = 25 dB, and Delta f = 1 MHz); and distance calibration using the inner wall of the vacuum vessel.