6. Molecular Spectroscopy Techniques Applied for Processing Plasma Diagnostics

Abstract

Optical diagnostics are between the most commonly used tools for the characterization of plasmas and for the better understanding of physical and chemical processes controlling their time and space dependencies. In this review paper the most popular spectroscopy techniques are described and examples of their applications to plasmas are indicated. An special emphasis is given to power saturation phenomena, encountered in laser based diagnostics. Numerical applications show that with commonly available lasers a great care must be taken to avoid saturation and to be really non-intrusive, as expected for a diagnostic tool.

Time-resolved absolute OH density of a nanosecond pulsed discharge in atmospheric pressure He–H2O: absolute calibration, collisional quenching and the importance of charged species in OH production

“…The The recorded 1083 nm line is composed of three transitions, which are summarized in table 1. The He (2 3 S 1 ) metastable density is estimated from the surface S(t) of the absorption profile (GHz), given by [20] …”

Argon metastable dynamics in a filamentary jet micro-discharge at atmospheric pressure

“…where I(ν) and I 0 (ν) are the intensities of transmitted radiation with and without the presence of absorbing species, k(ν) is the absorption coefficient and l the path length through the absorbing medium [16]. The absorption coefficient is connected to the population density of metastable atoms by…”

Spatial dynamics of helium metastables in sheath or bulk dominated rf micro-plasma jets

“…I(ν) and I 0 (ν) are the intensities of transmitted radiation with and without the presence of absorbing species, k(ν) is the absorption coefficient and l the path length through the absorbing medium [12]. The absorption coefficient is connected to the population density of metastable atoms by…”