Automatic evaluation of plasma density profiles from microwave reflectometry on ASDEX upgrade based on the time-frequency distribution of the reflected signals
P. Varela et al., Automatic evaluation of plasma density profiles from microwave reflectometry on ASDEX upgrade based on the time-frequency distribution of the reflected signals, REV SCI INS, 70(1), 1999, pp. 1060-1063
A new data analysis technique has been developed for the evaluation of the
density profiles from broadband reflectometry in the presence of plasma tur
bulence. The method is based on the spectrogram of the reflected signals an
d uses the complete information of the beat frequency spectrum. The applica
tion of the Floyd best path algorithm, that takes into account the history
of the beat frequency curve, enables us to extract the slow component due t
o the plasma profile. The statistics of the group delay data points is also
considered to validate (or reject) data with great confidence. The results
obtained in a wide range of plasma regimes show that accurate and detailed
profiles can be measured automatically. One and two dimensional moving ave
raging over consecutive sweeps is also available to reduce the variance of
the inverted profile while retaining a good temporal resolution. (C) 1999 A
merican Institute of Physics. [S0034-6748(99)71001-4].