Large-scale spatially extended atmospheric pressure plasma

This thesis presents experimental studies of low-temperature atmospheric pressure plasma sources with generic ability to effectively treat large-scale three-dimensional (3D) objects. The reported large-scale plasma sources are developed through parallelisation of single plasma jets. This strategy outshines the other reported strategies for treatment of uneven surfaces by being able to produce spatially extended plasma directly onto the surface of heavily three-dimensional objects. Comparable studies of the design of elemental plasma jets bring out a hybrid electrode configuration, the capillary-ring jet, as the best elemental jet to be used in the parallelisation. It is found that the introduction of a ballast resistor to the individual jet circuit or built-in capacitance is important to assure the jet-to-jet synchronism, stability and uniformity. Electrical and optical analyses of one-dimensional (1D) array of atmospheric pressure plasma jets demonstrate robust temporal and spatial jet-to-jet uniformity both for flat and sloped surfaces. Hexagonally-arranged two-dimensional (2D) arrays of atmospheric pressure plasma jets show good level of insusceptibility to variations of the downstream samples in their physical dimensions as well as structural and material properties. The reaction chemistry impact area of a 2D 37-jet array is estimated to be 18.6 cm2. These confirm the plasma jet arrays as a viable option as large-scale atmospheric plasma sources, well suited for many processing applications including plasma medicine. The spatially separated dual-frequency excitation further benefits the plasma jet in that separate control of different important plasma parameters is possible. Enhanced plasma properties achieved by the dual-frequency offer greater potential to the jet arrays.