Non-Uniformity of Non-Thermal Plasma Formation: Using FBG as Temperature Sensors

This research investigates fiber Bragg grating (FBG) temperature sensing performance in monitoring non—uniformity of non-thermal plasma (NTP) formation in a packed-bed reactor using FBG operating at atmospheric pressure. Two FBGs made from germanium doped fiber were embedded inside and outside the PBNTP reactor to allow for comparison between the temperatures inside and outside of the reactor to be made. Each FBG comes with three grating series, which allow the reactor temperatures at three different locations inside or outside the reactor to be measured and compared. Two types of plasma, namely nitrogen (N2) and argon (Ar) were generated in the reactor at a gas flow rate in the range of 2 - 7 L/min and applied voltage in the range of l - 20 kV. It was found that the PBNTP reactor temperature varies up to 20 oC at different positions inside and up to 40 oC outside of the reactor. This finding shows the non-uniformity of plasma formation and the nature of the plasma's localized thermodynamic equilibrium (LTE). The sensitivity of the FBG temperature sensor used in this study is estimated at 10.36 - 10.50 pm/oC.