Characterization of High-energy electrons by OES in the negative glow

ISOLA, L M; LOPEZ, M; GOMEZ, B J; GUERRA, V; FERREC, A; DJOUADI, A; JOUAN, P.-Y

Nantes

Congreso; The 18th International Colloquium on Plasma Processes (CIP); 2011

Institut des Materiaux Jean Rouxel

Ar plasmas have been widely studied for different conditions of pressure, type and discharge zone. In particular, these plasmas are of great interest because they are the commonly used in numerous treatment techniques and generation of thin films and multilayer systems. Optical emission spectroscopy (OES) is a non-intrusive and relatively easy-to-use plasma diagnostic, which makes it widely applied to characterize these plasmas, although the spectra interpretation is not straightforward. The absence of Maxwellian electron energy distribution (EEDF) is a frequent complication in the spectra interpretation of the processing plasmas. In particular, the DC negative glow EEDF is strongly non-Maxwellian distribution, it consists of a very small fraction of high-energy electrons generated in the cathode sheath, and of the main body of cold electrons with their temperature close to the room temperature [1]. OES has been used to determine the EEDF non-Maxwellian in different conditions and types of discharges. For instance, in the work [2] of Behringers et. al. the EEDF was determined in the Ar-He-N2 positive column of a stationary DC glow discharge, Vinogradov [3] measuring in the positive column of dc glow discharge and electron cyclotron resonance discharge (ECR) in He-N2 and Boffard et. al. [4] measured on the inductively coupled Ar plasma. However, these methods can not be directly applied in DC pulsed negative glow. In this work, we have studied the high-energy electrons part of the Ar negative glow EEDF, in DC pulsed discharge, through the measure the Ar, Ar+, Ar++ line intensities and their ratios, for different argon pressures.