Time and spatially resolved spectroscopy during plasma etching of carbon surfaces

Samenvatting

With an increase in energy demand and a decrease in available traditional energy sources, the world is in need of new and durable energy sources. Dif- ferent kind of energy sources, i.e. wind, water and solar energy systems, are currently being developed. Another energy source for the future is nuclear fusion. The next generation experimental fusion reactor is currently in de- velopment. One of the challenges still to be resolved is the anomalous fast erosion of plasma-facing components due to plasma-surface interactions. The plasma-facing components are made of carbon-¯ber composites and these are etched away during fusion-plasma exposure. The etched hydrocarbons are redeposited on the reactor walls, incorporating the fusion fuels, i.e. the hy- drogen isotopes, which makes the wall radioactive. Plasma cleaning can be used to remove these layers. The aim of this study is to investigate the etch products formed and to deter- mine the e®ects of these products on the etching plasma. The etch products are determined to be methane, acetylene and ethene, by means of resid- ual gas analysis. In an interaction of the plasma particles with these etch products, CH radicals are formed, which are measured with optical emis- sion spectroscopy. To investigate their formation process the rotational and vibrational temperatures are determined in both time dependent and spa- tially resolved emission measurements. Rotational temperatures, in contrast to vibrational temperatures, are found to be decreasing in time, which is attributed to the °ow pattern in the plasma chamber.

Datum prijs	31 dec 2009
Originele taal	Engels
Begeleider	T.A.R. Hansen (Afstudeerdocent 1) & Richard A.H. Engeln (Afstudeerdocent 2)