Phase Resolved Optical Emission Spectroscopy (PROES): A powerful diagnostic for non-thermal plasmas

Low and atmospheric pressure non-thermal plasmas are used for a wide range of applications. Electrons energized through electric fields play a vital role in plasma sustainment and plasma-generated chemistry. Therefore, electron heating and dynamics are crucial for understanding plasma behavior. Phase-resolved optical emission spectroscopy (PROES) is a powerful diagnostic technique that allows the non-intrusive measurement of space and time-resolved excitation, which reflects the energetic electron dynamics. In addition to space and time-resolved excitation, PROES can be used to evaluate space and time-resolved plasma parameters such as the electron temperature, electron density etc. Also, it can be utilized to assess quenching coefficients of excited states and the secondary electron emission coefficient of surface materials. In this talk, the experimental setup and method of PROES will be reviewed. Several examples of its application in both low pressure (capacitively and inductively coupled plasmas) and atmospheric pressure (jets and dielectric barrier) discharges will be presented. Finally, the limitations of PROES and future interest areas will be discussed.