Eur. Phys. J. Appl. Phys. (2017) 77: 10801
https://doi.org/10.1051/epjap/2016160280

Regular Article

Influence of argon fraction on plasma parameters in H₂-N₂ mixture discharge with cathodic cage

¹ Department of Physics, Quaid-i-Azam University, 45320 Islamabad, Pakistan
² Department of Physics, Faculty of Science, Jazan University, P.O. Box 114, Jazan, Saudi Arabia

^a e-mail: mzakaullah@qau.edu.pk

Received: 1 July 2016
Revised: 20 October 2016
Accepted: 5 December 2016
Published online: 27 January 2017

Abstract

Low-pressure H₂-N₂ mixture pulsed DC plasmas with a cathodic cage (active screen) are widely used for plasma nitriding applications. In this study, the low-pressure H₂-N₂ mixture plasma with a cathodic cage generated by 50 Hz pulsed DC source is investigated with triple Langmuir probe and optical emission spectroscopy. The electron temperature (T_e^LP) and electron number density (n_e) are measured using a triple Langmuir probe (TLP). The excitation temperature (T_exc^OES) is calculated spectroscopically using Boltzmann plot method whereas nitrogen dissociation fraction is estimated using actinometry as well as the intensity ratio method (I_N (746.83 nm)/I_N2(337.1 nm)). The results show that the electron and excitation temperatures, electron density and nitrogen atomic species density [N] all increase with the argon admixture, however, the important molecular ionized species density [N₂⁺] significantly decreases beyond 30% addition. This study provides useful information about the influence of the argon addition on plasma parameters and active species generation. As a result it helps to optimize the plasma nitriding system as a function of argon admixture to avoid random trials in the processing.