## 3 Results and Discussion
### Effect of Ar and He Addition on NH\({}_{3}\) Formation
The different optimal ratios observed with no noble gas addition and with different noble gas additions are due to the different sensitivities of the optimal gas ratios to the reduced field in the reaction and to the electron density in the reactor [37]. The addition of either Ar or He increased the energetic yield of NH\({}_{3}\) synthesis in all gas ratios. The introduction of noble gas improved the To study the effect of the amount of noble gas added on the synthesis of ammonia, we added different amounts of noble gas at different feed gas ratios. Figure 4a,b illustrate how different additions of Ar and He at different gas ratios affect the energy yield in ammonia synthesis. According to the data presented, optimal results were obtained with both Ar and He additions at a ratio of 40%. Beyond this point, the energy yield of ammonia synthesis begins to decrease as the additions increase. The diminished lifting effect observed at a gas ratio of H\({}_{2}\):N\({}_{2}\) = 3 stems from the shift in the optimal gas ratio caused by the incorporation of noble gases. This result indicates that moderate addition of noble gases is favorable for ammonia synthesis, while excessive addition of noble gases can have a negative effect on ammonia synthesis. In the previous analysis, we concluded that the addition of an appropriate amount of noble gas can optimize discharge uniformity, while the addition of noble gas adds more collision particles to the reaction, increasing the likelihood of inelastic collisions and thus increasing the production of intermediate reaction products. However, in the case of further ionization, the increase in metastable Ar* and He* helps to maintain the plasma for a longer period of time, a process that may promote ammonia decomposition [28; 39]. In a later section, we will discuss the fact that the number of active particles in the metastable state increases with the addition of noble gases. When the density of the reacting species reaches its optimum level, further addition of noble gas changes the properties of the plasma, leading to an increase in both electron density and electron energy. This enhancement triggers additional decomposition of the intermediate product NH\({}_{x}\) in the gas phase [31]. Additionally, More energy is wasted on ionization and excitation of Ar and He than the dissociation of N\({}_{2}\) and H\({}_{2}\) when noble gases are added at too high a concentration [40]. Figure 4 demonstrates that the energy yield from ammonia synthesis notably improves as the nitrogen content increases, whereas the optimal gas ratio remains unchanged with an increase in noble gas content. The addition of noble gases increases the average electron energy and electron density, making N\({}_{2}\) easier to dissociate. For a given energy input, the conversion of N\({}_{2}\) increases with the addition of Ar and He, thus shifting the optimum gas ratio to a higher nitrogen concentration by noble gas injection. Figure S2 illustrates that the discharge power escalates with an augmentation in N\({}_{2}\) content, aligning with the findings  
Figure 3: Effect on ammonia synthesis energy yield of adding noble gases at different feed gas ratios. of [PERSON] et al., who reported that incorporating Ar into the gas mix enhances the average electric field strength [41]. It should be noted that too much H\({}_{2}\) leads to a weakening of the ammonia synthesis. The increase in metastable H\({}^{*}\) in the plasma undergoes a quenching reaction, and the intensity of the plasma discharge weakens as the H\({}_{2}\) content increases [42].