TY - JOUR

T1 - The effect of the gap distance between an atmospheric-pressure plasma jet nozzle and liquid surface on OH and N2 species concentrations

AU - Ghimire, Bhagirath

AU - Sornsakdanuphap, Jirapong

AU - Hong, Young Jun

AU - Uhm, Han Sup

AU - Weltmann, Klaus-Dieter

AU - Choi, Eun Ha

PY - 2017/6/28

Y1 - 2017/6/28

N2 - An argon plasma jet at atmospheric pressure was operated at various gap distances between the nozzle of the plasma jet and the water surface in order to study the formation of OH and N2 species in the vicinity of the water surface. Plasma was generated using a 24 kHz sinusoidal power supply at a steady gas flow-rate of 200 sccm. The electron temperature and rotational temperature of gas species were measured using optical emission spectroscopy and found to decrease with increasing gap distance. Meanwhile, the electron density calculated from jet current measurement increased with increasing gap distance. The average OH concentration reduced from 6.10 × 1015 cm−3 to 1.35 × 1015 cm−3, as the gap distance increased from 1 to 4 mm. The 337 nm N2 second positive system studied by optical emission spectroscopy and temporal emission signals increased with increasing gap distance. Plasma activated water was also made from various gap distances in order to confirm the presence of particular reactive oxygen or nitrogen species inside the water. The maximum observed absorbance corresponding to nitrogen oxide was in the spectral range of 230–250 nm from the 4 mm gap distance, while another maximum was recorded in the range of 250–260 nm corresponding to H2O2 from the 1 mm gap distance. Our experimental observations indicate that reactive oxygen and nitrogen species may be generated above the water surface or penetrate into some biological fluids, suggesting that their particular production can be tailored by the variation of the gap distance.I. INTRODUCTION

AB - An argon plasma jet at atmospheric pressure was operated at various gap distances between the nozzle of the plasma jet and the water surface in order to study the formation of OH and N2 species in the vicinity of the water surface. Plasma was generated using a 24 kHz sinusoidal power supply at a steady gas flow-rate of 200 sccm. The electron temperature and rotational temperature of gas species were measured using optical emission spectroscopy and found to decrease with increasing gap distance. Meanwhile, the electron density calculated from jet current measurement increased with increasing gap distance. The average OH concentration reduced from 6.10 × 1015 cm−3 to 1.35 × 1015 cm−3, as the gap distance increased from 1 to 4 mm. The 337 nm N2 second positive system studied by optical emission spectroscopy and temporal emission signals increased with increasing gap distance. Plasma activated water was also made from various gap distances in order to confirm the presence of particular reactive oxygen or nitrogen species inside the water. The maximum observed absorbance corresponding to nitrogen oxide was in the spectral range of 230–250 nm from the 4 mm gap distance, while another maximum was recorded in the range of 250–260 nm corresponding to H2O2 from the 1 mm gap distance. Our experimental observations indicate that reactive oxygen and nitrogen species may be generated above the water surface or penetrate into some biological fluids, suggesting that their particular production can be tailored by the variation of the gap distance.I. INTRODUCTION

U2 - 10.1063/1.4989735

DO - 10.1063/1.4989735

M3 - Journal article

VL - 24

JO - Physics of Plasmas

JF - Physics of Plasmas

SN - 1070-664X

IS - 7

M1 - 073502

ER -