The broadband FMCW reflectometry system on ASDEX Upgrade has had significant improvements
extending its measuring capabilities both on high and low density plasmas: (i) the upgrade of the W
band to probe electron densities up to 12.4*1019 m−3 with O mode, (ii) Q and V frequency bands
operating in X mode to probe the edge plasma and to provide information for O-mode profile
initialization, and (iii) a new dynamic frequency calibration method to take into account all existing
delays in the hyperabrupt varactor-tuned oscillator (HTO) tuning port and driver electronics. These
improvements are particularly important to measure accurately the edge pedestal region of high
density ITER relevant discharges. Density profiles obtained in high density discharges are presented
and compared with results from both Li-beam and Thomson scattering diagnostics. |