Kinetic processes in the initial (nanosecond range) stage of the double?arcing instability in oxygen plasmas

BEATRIZ MANCINELLI; LEANDRO PREVOSTO; JUAN CAMILO CHAMORRO GARCÉS; FERNANDO MINOTTI

CABA

Congreso; XV Reunión de fluidos y sus aplicaciones (FLUIDOS 2018); 2018

A numerical study of the relevant kinetic processes in the initial (nanosecond range) stage of the double?arcing instability occurring at the plasma?sheath boundary region of an oxygen?operated cutting torch was considered. The model takes into consideration a quite comprehensive kinetic block describing the gas energy balance and charged particles kinetic processes in the discharge. It is shown that the double?arcing instability is a swift glow?to?arc transition arising from a field?emission instability. A critical electric field value of  107 volts/m was found at the cathodic part of the nozzle wall under the conditions considered. A fast electronic?to?translational energy relaxation mechanism induced by the field?emission instability drives in turn a very fast gas heating rate of at least109 K/s.