Energy dispersive X-ray spectroscopy for ECR plasma diagnostics

Abstract

Electron-ion bremsstrahlung spectra down to 4 keV emitted from plasmas of the 7.25 GHz electron cyclotron resonance (ECR) ion source of the Forschungszentrum Rossendorf and of the 14.5 GHz ECR ion source of the Technische Universität (TU) Dresden were de-convoluted using a newly developed integration method. In the approximation of isotropy in velocity space this method yields the exact electron energy distribution function. The high energetic electrons are clearly separated into two Boltzmann distributed populations. Their densities and temperatures could be estimated. Higher frequencies of the microwave can increase the hot and warm electron densities by orders of magnitude. First results are obtained for the behaviour of this populations belonging to the mixture (argon — oxygen). Gas mixing increases the densities of these populations. The influence of the electron energy distribution function on X-ray line intensities is discussed.