Testing the Use of the Principal Component Analysis Method to Detect Slight Changes in Nitrogen and Oxygen Spectra Induced by a Change in Discharge Conditions

TL;DR

This study uses principal component analysis to detect subtle spectral changes in nitrogen and oxygen plasmas caused by magnetic fields, revealing different plasma behaviors and polarization effects.

Contribution

It applies PCA to plasma spectra to identify magnetic field effects and distinguishes plasma responses of nitrogen and oxygen under these conditions.

Findings

Magnetic fields influence oxygen plasma particle movement more than nitrogen.

PCA reveals polarization effects in oxygen and nitrogen spectra due to magnetic fields.

Electron temperatures are estimated as 25000K for nitrogen and 5000K for oxygen.

Abstract

In this work, the influence of crossed magnetic fields (B=100 Gauss) on the UV-vis and NIR spectra and breakdown voltages of nitrogen and oxygen at a pair of parallel plane copper electrodes with a spacing d=2 cm and diameter R= 2.2 cm are studied. Working pressures of the gases are kept between 0.1 and 1 Torr. The breakdown voltage measurements across the electrodes are conducted by Tektronix P6015 high voltage probe connected to a Tektronix 2430A oscilloscope. The Spectra of discharge plasmas in the absence and presence of magnetic fields are recorded between 200-1100 nm. by AvaSpec-ULS3648. In order to analyse observed spectra of nitrogen and oxygen plasmas, one of the pattern recognition techniques of principal component analysis has been employed. Results of principal component analysis shows that the presence of magnetic field cause the plasma particles to move in condensed way for the oxygen but not for the nitrogen. Principal component spectra shows that small amount of the cross magnetic field results in the Stokes linear polarization of the most of the oxygen and NIII (337 nm) of the Nitrogen species in the plasmas. The non-local thermal equilibrium based spectroscopic modeling of nitrogen and oxygen plasma gives that the electron temperature of nitrogen and oxygen are Te=25000 and 5000 Kelvin respectively.