The impact of current-limiting resistors on NOx synthesis in a plasma-based process with a gliding arc reactor

Plasma-based nitrogen fixation presents a promising alternative to conventional methods for NOx synthesis, with gliding arc reactors demonstrating high efficiency under ambient conditions. Current-limiting resistors (CLRs) are commonly used in experimental research to ensure stable discharge operation; however, most reported studies focus solely on reactor performance, overlooking the impact of these resistors on the overall process. This study systematically investigates the influence of resistors in the circuit on NOx concentration and energy consumption (EC) in a 2D gliding arc system. Three CLRs and two current viewing resistors were tested, and the case with a 20 kΩ CLR achieved the highest NOx concentration of 5.80 vol%. A key reason is that the CLRs maintained a stable glow-like discharge regime, suppressing undesired transitions of the discharge mode in a gliding arc. Optical emission spectroscopy measurements indicated that increased CLR values reduced the electron density and plasma temperature, potentially explaining variations in the achieved NOx concentration. Additionally, a significant disparity in EC was observed when accounting for total dissipated power, leading to a maximum EC increase of 5.65 MJ molN–1. These findings highlight the need to report the EC of both the reactor and CLR when evaluating plasma-based NOx synthesis efficiency.