Diagnosis of Electron, Vibrational and Rotational Temperatures in an Ar/N₂Shock Plasma Jet Produced by a Low Pressure DC Cascade Arc Discharge

Abstract

In this paper, a low pressure Ar/N2 shock plasma jet with clearly multicycle alternating zones produced by a DC cascade arc discharge has been investigated by an emission spectral method combined with Abel inversion analysis. Plasma emission intensity, electron, vibrational and rotational temperatures of the shock plasma have been measured in the expansion and compression zones. The results indicate that the ranges of the measured electron temperature, vibrational temperature and rotational temperature are 1.1 eV to 1.6 eV, 0.2 eV to 0.7 eV and 0.19 eV to 0.22 eV, respectively, and it is found for the first time that the vibrational and rotational temperatures increase while the electron temperature decreases in the compression zones. The electron temperature departs from the vibrational and the rotational temperatures due to non-equilibrium plasma effects. Electrons and heavy particles could not completely exchange energy via collisions in the shock plasma jet under the low pressure of 620 Pa or so.

Discharge aspects of a snake‐like plasma plume generated by an atmospheric pressure plasma jet with variable argon flow rate

“…Herein, vibrational temperature ( T vib ) is calculated from N 2 (C 3 Π u ‐B 3 Π g ) by the Boltzmann's plot. [ 71,72 ] $$$\mathrm{ln}({I}_{{{\rm{\nu }}}^{^{\prime} }{{\rm{\nu }}}^{^{\prime\prime} }}/{v}_{{{\rm{\nu }}}^{\text{'}}{{\rm{\nu }}}^{^{\prime\prime} }}{A}_{{{\rm{\nu }}}^{\text{'}}{{\rm{\nu }}}^{^{\prime\prime} }})=C-\frac{{E}_{{{\rm{\nu }}}^{\text{'}}}}{k{T}_{\mathrm{vib}}}$$$where $${I}_{{{\rm{\nu }}}^{\text{'}}{{\rm{\nu }}}^{^{\prime\prime} }}$$ and $${A}_{{{\rm{\nu }}}^{\text{'}}{{\rm{\nu }}}^{^{\prime\prime} }}$$ are the emission intensity, and the Einstein spontaneous emission probability for the transition from the upper (quantum number ν ′) to the lower (quantum number ν ″) energy level. E ν′ is the molecular vibration energy, and C is a constant.…”

“…Herein, vibrational temperature (T vib ) is calculated from N 2 (C 3 Π u -B 3 Π g ) by the Boltzmann's plot. [71,72]…”

Determination of the number densities of CH(X2Π) and CH(A2Δ) radicals in a DC cascaded arc discharge plasma

“…For Ar excited states, they are produced by electron impact, heavy particle impact, and radiative processes [35]. They are in excitation equilibrium and follow the Boltzmann distribution [36]. We use T exc instead of T e to estimate ζ. ζ > 1 represents overpopulation of CH(A), while ζ < 1 represents the opposite.…”

Measurement of electron density and electron temperature of a cascaded arc plasma using laser Thomson scattering compared to an optical emission spectroscopic approach

“…In our work, OES is utilized to determine the electron excitation temperature. The electron excitation temperature (T exc ) can be determined by the Boltzmann-plot method, which employs the relative intensity of two or more spectral lines using the following equation [21]:…”