Process and apparatus for carrying out a reaction, such as etching aluminum, in the glow discharge of a gas plasma. The plasma is formed between a pair of closely spaced electrodes, and a distributed impedance is provided in series with the plasma to assure uniform distribution of the ionizing current...http://www.google.com.au/patents/US4148705?utm_source=gb-gplus-sharePatent US4148705 - Gas plasma reactor and process
