A new type of DC-powered plasma source (LARGE) was developed and evaluated for continuous plasma-enhanced (PE) CVD under atmospheric pressure. The linear extended emanating plasma sheet was scaled-up to various working widths with the result that a half meter range has already been achieved. A CVD reactor was designed for continuous deposition of non-oxide materials. The reactor operates in a remote atmospheric pressure (AP) PECVD configuration with typical deposition rates of 5±50 nm s ±1 (static) and 0.1±1.0 nm m s ±1 (dynamic).The potential application range of the ArcJet-CVD technology was evaluated by screening studies with various substrates, (stainless steel, glass, silicon wafers) and coating materials (silica, carbon, silicon nitride). In-situ process characterization has been provided by both optical emission and Fourier transform infrared (FTIR) spectroscopy. A range of atomic and molecular intermediates, precursor fragments, and reaction products were identified, leading to the conclusion that a complete conversion of the element-organic precursors into an inorganic layer takes place.

Coating production by thermal plasma spray is dependent on the residence time of particles in the plasma jet produced by the gas flow inside a plasma torch. To ensure a high fraction of well-molten particles to be accelerated towards the substrate a long reproducible residence time is needed. This can be achieved by a long plasma jet with little or no temporal variation in length and temperature. While single electrode plasma torches need an unstable attachment of the anodic arc root in order to avoid excess erosion, which also causes an unstable plasma jet, multi-electrode torches allow operation with fixed anode attachments by subdividing the anode current by the number of electrodes used, and thereby thus reducing the power input for each separated arc root. Once the steady anode attachment has been obtained the produced plasma jet exhibits a steady characteristic, but also looses rotational symmetry. The separation can be achieved by using either multi anode or multi cathode geometry with appropriate electrical control. Both version have been produced with 3 electrodes each resulting in two systems known as the Delta Gun (3 anodes) and Triplex (3 cathodes).

Recent advances in the development of new plasma torches rely on the use of multiple electrodes to improve plasma jet stability. Examples are the Triplex, employing three cathodes and a single anode, and the Delta, which uses three anodes with a single common cathode. To characterize the plasma jet produced by these plasma torches, initial experiments have been performed using tomography in the visible range. Due to the improved stability of the plasma jet in the multielectrode configuration it is possible to carry out tomography by means of a regular charge-coupled device (CCD) camera, which is rotated around the plasma jet axis. The two-dimensional information obtained by the CCD camera is subsequently processed to produce an image of the three-dimensional emission distribution. The tomographic analysis is mated with a simple but effective simulation tool, which can be used as a basis for parameter-dependent multielectrode plasma torch design.

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