The first antennas of the ASDEX Upgrade microwave reflectometer system were brought in-vessel by the summer 1991. Since then new channels have been added and several modifications and improvements were made to get better or add additional measuring capabilities. The system has four O-mode channels for measuring electron density profiles and fluctuations on the High Field Side (HFS sectors 5 & 6) covering the density range 0.3×1019 to 6.66×1019m-3. |