Abstract: A thruster comprising: a chamber to contain a fluid; a plurality of nozzles to exhaust neutral particles derived from the fluid in the chamber, wherein each nozzle has a converging section and the converging section includes a first electrode; a second electrode located distal to the first electrode to provide a voltage differential between the first and second electrodes sufficient to create plasma ions from the fluid and the voltage differential accelerates the plasma ions on a flow path through the converging section, and wherein at least one or more of the accelerated plasma ions are neutralised to form the neutral particles by charge exchange with other neutral particles, or by recombination with electrons, on the flow path.

Abstract: A method of computerized color matching for articles where articles are photographed, using a still video camera, against a set of reference colors. The photographs are stored on a diskette (34) which is read on a recorder (54). The computer (55) compares the set of reference colors against an absolute set of colors and generates a compensation factor which is applied to the photographed colors to produce a corrected photograph. Areas of the corrected photograph may be selected for computer enhancement and a computer generated map may be produced to enable the color of other articles to be matched to the photographed articles.