Influence of arc current modulation in plasma torch on jet oscillations

This paper presents the influence of arc current modulation in plasma torch on jet oscillations. The effect of interaction of various types of fluctuations on plasma fluctuations was studied on plasma torch with electric arc stabilized by combination of gas flow with water vortex. Oscillations of plasma jet radiation were recorded using a linear array of high frequency photodiodes. Spectra of oscillations, mean amplitudes and phase velocities were evaluated by statistical analysis of records in various spectral windows for several arc currents. Two types of power supply with current ripple frequencies 300 Hz and 30 kHz were compared.