Temperature behavior of atmospheric-pressure non-equilibrium microwave discharge plasma jets for poly(ethylene naptharate)-surface processing

To understand the mechanism of surface processing using an atmospheric-pressure non-equilibrium microwave discharge plasma jet, we used optical emission spectroscopy to measure the vibrational and rotational temperatures of plasma. A microwave (2.45 GHz) power supply was used to excite the plasma. The vibrational and rotational temperatures in the plasma were measured at approximately 0.18 eV and 0.22 eV. We also conducted plasma surface processing of polyethylene naphthalate (PEN) film to measure changes in the water contact angle before and after the PEN film was processed, as well as while the rotational temperature of the plasma increased. The hydrophilicity of the PEN film surface was found to improve as the rotational temperature of the plasma increased.