Process control for atmospheric plasma treatment of surfaces

A method of delivering a predetermined dose distribution of reactive species from a plasma to a treatment area with a predetermined treatment boundary, the method comprising the steps of:

• providing a plasma array, the plasma array comprising a linear array of at least two plasma elements stacked linearly along an array axis, wherein each plasma element is an atmospheric plasma source and wherein each plasma element has an on state producing a reactive species output and an off state wherein the reactive species output is zero;
• performing a calibration measurement, wherein the calibration measurement comprises:
• activating the plasma elements to produce the reactive species output;
• measuring a reactive species concentration for each one of the plasma elements;
• and,
• deriving an element scaling factor for each one of the plasma elements, wherein each element scaling factor is inversely proportional to the corresponding reactive species concentration;
• scanning the plasma array across the treatment area with one or more scans in a back-and-forth scan direction perpendicular to the array axis;
• and,
• controlling each plasma element during the scanning with a uniformity modulation and a dose modulation, wherein the uniformity modulation controls the reactive species concentration of each plasma element to be proportional to the corresponding element scaling factor, and wherein the dose modulation controls the on state and the off state of each plasma element to deliver the predetermined dose distribution.