WAVELET ANALYSIS OF ADITYA EDGE TURBULENCE - EVIDENCE OF NONLINEAR-INTERACTION

The edge turbulence in the ADITYA tokamak [Phys. Rev. Lett. 69, 1375 ( 1992)] is examined using wavelet analysis techniques. The wavelet filt ers are used to separate low and high frequency components. The filter ed plasma density and floating potential fluctuations show leptokurtic non-Gaussianity (kurtosis, K>3) at high frequencies, whereas, the low frequency components are nearly Gaussian. The recently developed wave let bicoherence technique [Phys. Plasmas 2, 3017 (1995)] is extended t o the Mexican hat wavelet. When the data are examined using wavelet bi coherence technique, it is found that the turbulent density and potent ial signals exhibit episodes of quadratic interaction in which low and high frequency components are coupled. (C) 1996 American Institute of Physics.