Suppression of Instabilities in Thermal Plasma Jet by Additional Arc Current Modulation

Arc current in a dc thermal plasma torch was modulated by superimposed ac current with frequency 15 kHz. The plasma jet optical radiation was recorded by a matrix of fast photodiodes. The analysis of records using standard deviations and 3-D phase portraits has shown that the fluctuations in the plasma jet in the frequency range under 5 kHz were suppressed.