Continuous wavelet transform based time-scale and multi-fractal analysis of the nonlinear oscillations in a hollow cathode glow discharge plasma

摘要

Continuous wavelet transform (CWT) based time-scale and multi-fractalanalyses have been carried out on the anode glow related nonlinear floatingpotential fluctuations in a hollow cathode glow discharge plasma. CWT has beenused to obtain the contour and ridge plots. Scale shift (or inversely frequencyshift) which is a typical nonlinear behaviour, has been detected from theundulating contours. From the ridge plots, we have identified the presence ofnonlinearity and degree of chaoticity. Using the wavelet transform modulusmaxima technique we have obtained the multi-fractal spectrum for thefluctuations at different discharge voltages and the spectrum was observed tobecome a monofractal for periodic signals. These multi-fractal spectra werealso used to estimate different quantities like the correlation and fractaldimension, degree of multi-fractality and complexity parameters. Theseestimations have been found to be consistent with the nonlinear time seriesanalysis.