Incoherent Thomson scattering : reliable access to electron properties in plasma sources

Sedina Tsikata (CNRS – ICARE, Orléans, France)

For a large number of plasma devices, complete modeling has been limited by a lack of insight into particle properties and fundamental phenomena. This difficulty arises, in part, due to the source geometries (often closed and inaccessible to measurement) and other features which restrict the application of conventional diagnostic tools.

Optical diagnostics optimized for these environments can overcome certain limitations. One example is incoherent Thomson scattering, which in recent decades has been increasingly used for studies in various low temperature plasmas. This diagnostic, based on electromagnetic wave scattering on free electrons, can provide access to electron properties non-invasively : density, energy distribution functions and even global drift. In recent years, we have developed and applied a diagnostic of this type, known as THETIS, to investigations across a range of low-temperature plasmas, including an ECRIS for the generation of light ions. A possible future implementation on PK-GENESA could provide much-needed information on electron properties and an improved understanding of the device performance under various configurations.

This talk covers the main diagnostic principles, key features, limits and requirements for implementation, with discussion of aspects specific to ECRIS investigations.