Ion charge state distributions in ECR-plasmas determined from mass spectrometry and X-ray spectroscopy

Abstract

The influence of microwave power, magnetic field, neutral gas pressure and gas mixture on the ion charge state distribution (CSD) of an electron cyclotron resonance (ECR) plasma was investigated by q/A-analysis of an ion beam extracted from the plasma and by X-ray spectroscopy of this plasma. As the ion beam expands from a limited plasma edge and the extraction process alters the plasma properties in this region a small plasma cone including the discharge core is investigated by the X-ray method. For this reason the measured CSD are significantly different. Additionally, the transmission of the ions to the beam stop depends on the q/A ratio of the ion species and can falsify the true, primary CSD. In this way, the analysis of ECR plasma X-rays represents a more accurate method to measure the CSD of a discharge. In comparison to the q/A analysis it provides the true distribution and, moreover, different plasma regions can be examined.