A Multiplexer-Based Multi-Channel Microwave Doppler Backward Scattering Reflectometer On The Hl-2a Tokamak

The Doppler backward scattering DBS) reflectometer has become a well-established and versatile diagnostic technique for the measurement of density fluctuations and flows in magnetically confined fusion experiments. In this work, a novel multiple fixed-frequency array source with a multiplexer technique is developed and applied in the multi-channel DBS system. The details of the system design and laboratory tests are presented. Preliminary results of Doppler shift frequency spectra measured by the multi-channel DBS reflectometer systems are obtained. Characteristics of plasma rotation and turbulence before and after supersonic molecular beam injection are analyzed. Published by AIP Publishing.