## 3 Results and Discussion
### Spatially Resolved Spectra of LS-APPJ  
To understand the dynamic behavior of the LS-APPJ and the spatial distribution of the excited active species, Figure 8 shows the effect of the distance from the plasma jet nozzle on the emission intensities of the N\({}_{2}\) (C\({}^{3}\Pi_{\rm u}\to\) B\({}^{3}\Pi_{\rm g}\)), N\({}_{2}\)\({}^{+}\) (B\({}^{2}\Sigma_{\rm u}^{+}\to\) X\({}^{2}\Sigma_{\rm g}^{+}\)), He (3s\({}^{3}\)S \(\to\) 706.5 nm), emitted from BPPJ and PPJ, varying with pulse peak voltage. ### Spatially Resolved Spectra of LS-APPJ  
To understand the dynamic behavior of the LS-APPJ and the spatial distribution of the excited active species, Figure 8 shows the effect of the distance from the plasma jet nozzle on the emission intensities of the N\({}_{2}\) (C\({}^{3}\Pi_{\rm u}\to\) B\({}^{3}\Pi_{\rm g}\)), N\({}_{2}\)\({}^{+}\) (B\({}^{2}\Sigma_{\rm u}^{+}\to\) X\({}^{2}\Sigma_{\rm g}^{+}\)), He (3s\({}^{3}\)S \(\to\) 706.5 nm), emitted from BPPJ and PPJ, varying with pulse peak voltage. \begin{table}
\begin{tabular}{c c c c} \hline No. & Reaction & Reaction Rate Constant \({}^{*}\) & Reference \\ \hline
1 & e + N\({}_{2}\to\) N\({}_{2}\) (C) + e & \(f\)(E/N) & [26] \\
2 & e + N\({}_{2}\to\) N\({}_{2}\)\({}^{+}\) + e & \(f\)(E/N) & [26] \\
3 & e + He \(\to\) He \({}^{*}\) + e & \(f\)(E/N) & [26] \\
4 & He \({}^{*}\) + He \({}^{*}\) \(\to\) e + He\({}^{*}\) + He & 8.7 \(\times\) 10\({}^{-10}\) cm\({}^{3}\)/s & [27] \\
5 & He \({}^{*}\) + He \({}^{*}\)\(\to\) e + He\({}_{2}\)\({}^{+}\) & 2.03 \(\times\) 10\({}^{-9}\) cm\({}^{3}\)/s & [27] \\
6 & He \({}^{*}\) + N\({}_{2}\to\)N\({}_{2}\)\({}^{+}\) + He + e & 7 \(\times\) 10\({}^{-11}\) cm\({}^{3}\)/s & [27] \\
7 & He \({}^{*}\) + He + H\({}_{2}\)O \(\to\) 2 He + & 2 \(\times\) 10\({}^{-29}\) cm\({}^{6}\)/s & [27] \\
8 & He \({}^{*}\) + 2 He + He\({}_{2}\) (a) + He & 3 \(\times\) 10\({}^{-34}\) cm\({}^{6}\)/s & [27] \\
9 & He\({}_{2}\) (a) + H\({}_{2}\)O \(\to\) 2 He + & 6 \(\times\) 10\({}^{-10}\) cm\({}^{3}\)/s & [27] \\
10 & He\({}_{2}\)\({}^{+}\) + H\({}_{2}\)O \(\to\) OH + HeH\({}^{*}\) & 1.3 \(\times\) 10\({}^{-10}\) cm\({}^{3}\)/s & [27] \\
11 & H\({}_{2}\)O\({}^{+}\) + e \(\to\) OH + H & 3 \(\times\) 10\({}^{-7}\) cm\({}^{3}\)/s & [27] \\
12 & He\({}_{2}\) (a) +O\({}_{2}\)\(\to\) 2 He + O\({}_{2}\)\({}^{+}\) + e & 1 \(\times\) 10\({}^{-10}\) cm\({}^{3}\)/s & [28] \\
13 & He \({}^{*}\) +O\({}_{2}\)\(\to\) He + O\({}_{2}\)\({}^{+}\) + e & 2.54 \(\times\) 10\({}^{-10}\) cm\({}^{3}\)/s & [28] \\
14 & He\({}_{2}\)\({}^{+}\)O\({}_{2}\)\(\to\) 2 He + O\({}_{2}\)\({}^{+}\) & 1 \(\times\) 10\({}^{-9}\) cm\({}^{3}\)/s & [28] \\
15 & O\({}_{2}\)\({}^{+}\) + e \(\to\) 2O & 1.2 \(\times\) 10\({}^{-8}\) Te\({}^{-0.7}\) cm\({}^{3}\)/s & [29] \\ \hline \end{tabular} \({}^{*}\)The reaction rate constants are calculated when the gas temperature is 300 K.  
\end{table} 
Table 1: The main physiochemical processes and their rate constants in a helium plasma jet. 2p\({}^{3}\)P, 706.5 nm), OH (A\({}^{2}\Sigma\rightarrow\) X\({}^{2}\Pi\)) and O (3p\({}^{5}\)P \(\rightarrow\) 3s\({}^{5}\)S\({}^{\circ}\), 777.4 nm) emitted from the BPPJ, PPPJ, and NPPJ. The pulse peak voltage, pulse repetition rate, and gas flow rate are kept at 24 kV, 150 Hz, and 3.5 L/min, respectively. The active species produced by the BPPJ have the highest emission intensity and the widest spatial distribution compared with the PPPJ and NPPJ. Regarding the spatial distribution of He (3s\({}^{3}\)S), it exhibits the maximum emission intensity at the position of the jet nozzle, and the emission intensity decreases with the increase in the distance from the nozzle. Regarding the emission intensities of N\({}_{2}\) (C\({}^{3}\Pi_{\rm u}\rightarrow\) B\({}^{3}\Pi_{\rm g}\)) and N\({}_{2}\)\({}^{+}\) (B\({}^{2}\Sigma_{\rm u}^{+}\rightarrow\) X\({}^{2}\Sigma_{\rm g}^{+}\)), the maximum values occur at distances of 0 cm and 2 cm from the jet nozzle, respectively, and then decrease with the increase in the distance from the jet nozzle.