Study of a full coaxial atmospheric pressure plasma jet device and its application to the modification of polytetrafluoroethylene

In this article, a compact and portable microwave atmospheric pressure plasma jet (MW‐APPJ) generator based on a coaxial transmission line resonator (CTLR) was proposed. Based on the electromagnetic simulations, the jet generator was designed as a tapered inner conductor structure that ensures plasma generation at low power. A self‐igniting argon (Ar) plasma jet of 10 mm length was generated at an input power of ~20 W and maintained at 2 W. Thanks to the high efficiency of the CTLR structure, plasmas of mixed reactive gases were also realized. Intrinsic plasma parameters and active species were determined using optical emission spectroscopy. Furthermore, the MW‐APPJ device was used to modify the polytetrafluoroethylene surface, and improvement of hydrophilicity was achieved without thermal damage. A compact microwave atmospheric pressure plasma jet (MW‐APPJ) was developed. The MW‐APPJ can generate plasmas of multiple gases under low power owing to the high efficiency of the coaxial transmission line resonator structure. Using the MW‐APPJ, improving the surface hydrophilicity of polytetrafluoroethylene was achieved, and the underlying mechanism was revealed.