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

The influence of microwave power, magnetic field, neutral gas pressure and gas mixture on the ion charge state distribution (CSD) of an electron cyclo tron resonance (ECR) plasma was investigated by did-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 alt ers 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 mea sured CSD are significantly different. Additionally, the transmission of th e ions to the beam stop depends on the q/A ratio of the ion species and cal l 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. I n comparison to the q/A analysis it provides the true distribution and, mor eover, different plasma regions can be examined. (C) 2000 Elsevier Science B.V. All rights reserved.