Plasma cleaning of “endless” substrates by use of a tandem dielectric barrier discharge

In this work a tandem dielectric barrier discharge plasma source for cleaning of elongated (“endless”), electrically conducting substrates is presented. It is powered by novel resonant power supply allowing high power densities up to 50 W/cm3. In investigated configuration, the conducting material is part of the plasma source. Even though no electrical currents leave the system. The used gases are helium or argon based mixtures. As an application example, the removal of organic films from wires is investigated. The removal rate is determined gravimetrically and investigated as a function of power coupled into plasma, gas mixture and gas flow. An optimum for the treatment time, the gas mixture and the flux is found and presented. The maximum removal rate of 1400 ng/J (this corresponds to 4.5 μm/min at 100 W) of the polyurethane coating is achieved for an insulated wire treated in the gas mixture of argon with 5% admixture of oxygen. To get the value of the power coupled effectively into the plasma, thermal and electrical investigations are made and discussed.