Spectroscopic study of a supersonic plasma jet generated by an ICP torch with a convergent-divergent nozzle

Abstract

A supersonic argon and argon-hydrogen (3-5{%}) plasma jet generated by an induction plasma torch is studied by means of the methods of optical emission spectroscopy. The torch was operated at the input power of 20 kW and near atmospheric pressure. The supersonic jet with a periodic structure of expansion and compression zones is created by expanding the plasma through the Laval nozzle into a chamber maintained at the pressure around 1.8 kPa. Atomic argon lines with the upper level energies ranging from 13.3 to 15.5 eV, continuum emission and Hβ line profile are used to evaluate plasma parameters such as temperature and electron number density. Analysis based on the Boltzmann diagram, line-to-continuum ratio, population of continuum extrapolated level and Stark broadening reveals various stages of departure from thermodynamic equilibrium in the plasma flow. It is shown, among others, that the temperature derived from Boltzmann diagram does not follow the jet structure and reliable determination of electron temperature is questionable. An addition of several percent of hydrogen results in a significant quenching of populations of atomic states and nonequilibrium behaviour of continuum radiation.

Numerical Modeling of Hybrid Stabilized Electric Arc With Uniform Mixing of Gases

“…An overpressure minimum at the axial position of 48.6 mm is accompanied by the Mach number, axial velocity maxima, and a slight temperature minimum. This detects a beginning of compression and expansion waves generation reported in papers dealing with supersonic plasma jets; see for example, [44]- [46].…”

Parametric study on excitation temperature and electron temperature in low pressure plasmas

“…The relationship between T exc and T e has been investigated over the past few decades, and the resulting studies reported the comparisons performed in microwave discharge [2,3,9], plasma jet [10], or theoretically [11] at atmospheric pressure. However, few studies have been attempted in high electron density at low pressure plasmas such as industrial processing plasmas in which various plasma sources are needed for advanced technology.…”

Degradation of Methylene Blue by RF Plasma in Water

“…For the estimation of electron density, the measured H b line profile was compared with a calculated one. Since the lines H b profile is broadened mainly due to Stark effect and the effect depends on electron density, this method has often been employed for the estimation of electron density when plasma contains hydrogen [19,20]. We employed the tables [21] to obtain the theoretical one.…”