Diagnostic techniques for the interaction of non-thermal atmospheric pressure plasmas and targets

Abstract The interaction of non-thermal atmospheric pressure plasmas and targets of various properties is an interdisciplinary area of growing interest. The understanding of the interaction mechanisms between a cold atmospheric pressure plasma and the surface of a liquid or a solid target, as well as the modifications induced inside the target, requires in situ study of these phenomena. Techniques for characterizing the plasma above the target are very well developed but on their own they are not sufficient for understanding the interaction with the target because the target itself must be studied while being under direct exposure to the plasma. The topic of this review are the diagnostic techniques for the characterization of the target in a plasma-target system, performed in situ , while under plasma exposure, time-and space- resolved. Examples also include combining the existing gas-phase techniques with the techniques that traditionally characterize the target in absence of plasma. Many approaches stem from plasma science, but also chemistry, material science, mass transport and fluid dynamics. The possibilities and limitations of the in situ characterization techniques for liquid or solid targets are described, with examples of applications to atmospheric pressure non thermal plasma-target systems.