On the electron density of atmospheric pressure radio frequency dielectric barrier discharge and discharge with bare electrode

Atmospheric pressure radio frequency helium plasma with two different designs: dielectric barrier discharge (DBD) and discharge with bare electrode (DBE) were investigated by means of optical emission spectroscopy. Both DBD and DBE can work at relatively low temperature and produce abundant electrons facilitating production of reactive species through electron-impact reactions. Stark broadening method of Hydrogen Balmer beta (H-beta) line was employed to analyze the electron density. When electron density is below 10(20) m(-3), fine-structure fitting was used to improve the accuracy of electron density estimation. At power ranged 4-20 W, DBD and DBE showed electron density 4.1-6.1 x 10(19) m(-3), and 3.6-8.6 x 10(19) m(-3), respectively. The DBD is more suitable than DBE for biomedical applications due to the wider working power range and lower gas temperature in the range of 316-344 K, depending on the power. (C) 2020 The Japan Society of Applied Physics.