###### Abstract  
Non-thermal plasma driven ammonia synthesis has great potential for future industrial applications due to its low theoretical energy requirements. To achieve technological advancement and environmental sustainability, it is crucial to boost the energy yield in plasma-assisted ammonia synthesis. Therefore, optimizing energy transfer and utilization are key strategies for enhancing energy efficiency. In this study, dielectric barrier discharge driven by a nanosecond pulsed power supply is used to enhance plasma-assisted ammonia synthesis by controlling the energy transfer through the addition of noble gases. It was found that the addition of noble gases changed the plasma characteristics, significantly improved the uniformity of the discharge, and achieved a high energy yield for ammonia synthesis. The effects of additive amounts of argon (Ar) and helium (He), as well as the pulse parameters including the pulse voltage, pulse repetition frequency, pulse width, and pulse rise time on the energy yield of ammonia synthesis are discussed. The inclusion of noble gases expanded the pathway for gas-phase reactions, with the active components of critical reactions examined through optical emission spectra. This analysis revealed an increased presence of both N2+ and N2+ particles in the reaction's rate-limiting step, attributed to the addition of noble gases. Finally, a zero-dimensional (0D) plasma chemical kinetic model was established to investigate the influence of Ar addition on the reaction mechanism of ammonia synthesis. ammonia synthesis; dielectric barrier discharge; non-thermal plasma; optical emission spectra; kinetic modelling 2024202  
activating molecules with strong bonds such as N\(\equiv\)N triple bonds [7]. The plasma can be initiated and halted at any moment and is flexible to intermittent renewable energy sources, including solar, wind, and hydropower [8]. Plasma ammonia synthesis reaction units are very small and can be adapted to practical conditions for decentralized, small-scale ammonia production. Based on these advantages, plasma-catalyzed ammonia synthesis has great application potential. To date, researchers have investigated NTP-assisted ammonia synthesis using various types of discharges, including glow discharges [9; 10], radio frequency discharges (RF) [11; 12] and microwave discharges [13; 14], arc discharges [15; 16; 17], and dielectric barrier discharges (DBD) [18; 19; 20]. [PERSON] et al. attempted the synthesis of ammonia by NTP using microwave discharges and RF plasma. These processes were performed at a pressure of about 650 Pa, well below atmospheric pressure [21]. However, to eliminate the need for a vacuum and allow for the continuous operation of the system, studies published in recent years have focused on ammonia synthesis using DBD. [PERSON] et al. described a ferroelectric packed-bed DBD reactor. Two planar electrodes and a filled catalyst form the main body of this reactor. In this study, the ferroelectric material acts as both the catalyst and the electrode [22]. However, in their most recent study using this DBD device coupled with a metal catalyst, although the discharge characteristics could be modified to produce a stronger plasma, ammonia decomposition or hydrogen exchange processes were promoted in the process, and the ammonia synthesis of this reactor was not significantly enhanced [23]. This structure of the DBD makes it easier to couple the plasma to the catalyst to support ammonia synthesis, and improves ammonia synthesis by changing the discharge characteristics of the plasma and adding new chemical kinetic reactions [24]. In addition to the addition of suitable catalysts, the addition of noble gases to gas-phase reactions can also improve plasma utilization. It has been discovered that the addition of noble gases alters the properties of the plasma, which accelerates the chemical reactions within it. Adding noble gases to the RF plasma resulted in much improved ammonia synthesis by [PERSON] et al. [25].