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The objectives work package 1 on pulsed discharges are the characterisation of different RF generators, sources and pulsing regimes; identification of influence of light elements on the electrical discharge parameters, accurate sputtering rate measurements as well as temporal and spatial resolved light intensity measurements for the development of improved RF-GD-OES quantification models; Quantification of influence of molecules originated by impurities of source and sample or as components or products of the layer; Investigation of Hollow Cathodes with pulsed discharges with respect to the influence of the hydrogen concentration on sputtering rate, ions intensities, processes in the afterglow and the influence of pulse frequency and pulse duration. Monte-Carlo Modelling to estimate crater shape for different experimental condition and the influence of some discharge gas admixtures - hydrogen, oxygen etc on the ionic spectrum.
Situation at mid-term:
Project 1In IFW Dresden Varvara Efimova adapted an existing device for the characterization of the electrical behaviour of rf discharge and measured the voltage-current characteristics of both continuous and pulsed DC and RF discharges. She observed that the current-voltage characteristics depend on the duty cycle of the pulsed discharge and attributed this effect to the cathode heating. Petr Å mÃd investigated the influence of light elements upon the electrical parameters of analytical glow discharges using the apparatus developed at Dresden. Interestingly, no changes in the ionic part of the I-V characteristic were observed, but the electronic part revealed remarkable differences. Varvara Efimova also worked together with Maxim Voronov and tested different pulsed power supplies on a lab made dc source. They found that difference in the electronic circuit leads to a difference in the current and voltage signal behaviour too.
Project 2
At SPSU, the analytical performance of a new combined hollow cathode source has been studied in conjunction with a ToFMS system. They found that changing the repelling pulse delay and gas pressure affects the transport dynamics of ion clusters and therefore leads to discrimination between different ion clusters. These results allow us to solve the problem of interference partially in time-of-flight mass-spectrometry with pulsed glow discharge in combined hollow cathode. The effect of hydrogen in the pulsed hollow cathode discharge has also been studied. While hydrogen suppressed the gas components by a large factor, it affected analyte ion intensities only slightly.
