摘要： Application of nonequilibrium atmospheric-pressure plasma has been proven as a medium for silver particle formation in slug flow reactor systems. Argon gas was introduced in the slug flow reactor system in the gas phase. In the liquid phase, silver nitrate (AgNO3) with and without the addition of starch was dissolved in distilled water. The flow rates of the liquid and gas phases were 1.5 and 0.15 ml min?1, respectively. A yellow-colored solution product was obtained when the feed solution containing starch was fed. The optical emission spectrum showed that silver atoms were detected clearly at 328 nm. The ultraviolet–visible spectroscopy analysis showed that the solution products seemed to absorb light between 380 and 440 nm, corresponding to silver nanoparticle generation. Transmission electron microscopy revealed that the monodispersed silver nanoparticles were formed in a spherical morphology with diameter less than 10 nm on average. ? 2018 The Japan Society of Applied Physics