Diagnostics and application of the microhollow cathode discharge as an analytical plasma

Abstract

This paper focuses on the diagnostics and applications of the microhollow cathode discharge operated in Ar and He at high pressures. The gas temperature and electron number density in Ar and He are deduced from absorption and emission spectroscopy employing line profile analysis. Additionally, a collisional radiative model is used for the estimation of the electron number density in He. The gas temperature increases in Ar from 500 K at 100 mbar to 2000 K at 1000 mbar. The electron density also increases from 2 × 1015 to 9 × 1015 cm−3 in the same pressure range. In He, the gas temperature reaches values up to 800 K and the electron density does not exceed 5 × 1014 cm−3 at atmospheric pressure. The discharge was coupled with emission and mass spectrometry for analytical applications. The detection of organometallic compounds (ferrocene) reveals good detection limits of about 500 ppb for Fe.