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Investigation of Water-Vapor Plasma Excited by Microwaves as Ultraviolet Light Source Oh, Jun-Seok Kawamura, K. Pramanik, B.K. Hatta, A. © 2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Absolute spectrum calibration OH radical microwave optical-emission spectroscopy (OES) rotational temperature saturated water-vapor pressure ultraviolet (UV) water-vapor discharge The potential of using water-vapor plasmas excited by microwaves as a ultraviolet (UV) light source has been investigated by using various pressures and input powers. The UV irradiation power increased and saturated at a pressure range dependent on the input power. On the other hand, other visible and infrared emissions corresponding to four atomic lines, i.e., the Balmer series of hydrogen at 486.1 nm (Hβ) and 656.3 nm (Hα) and oxygen atoms at 777.2 and 844.6 nm, were clearly decreased with an increase in the total gas pressure. It was found that pressures (1.4–2.0 kPa) near the saturated water-vapor pressure were found to give the most intense UV irradiation. With a vapor pressure of 1.6 kPa and a total microwave power of 300 W, the power density of UV (Γuv) was measured to be 10.5 μW · cm−2 at a distance of 30 cm from the center of the discharge tube as measured through an optical viewing port on the cavity discharge applicator. This value for (Γuv) is comparable to that for a mercury lamp. However, the (ηuv) efficiency was estimated to be considerably lower than that of a mercury lamp. Institute of Electrical and Electronics Engineers (IEEE) 2009-01 eng journal article VoR http://hdl.handle.net/10173/594 https://kutarr.kochi-tech.ac.jp/records/75 10.1109/TPS.2008.2007732 AA0066803X 0093-3813 IEEE Transactions on Plasma Science 37 1 107 112 https://kutarr.kochi-tech.ac.jp/record/75/files/IEEE_TPS_37-1_107.pdf application/pdf 520.4 kB 2019-02-13