## 3 Calculations  
We conducted atomic calculations and plasma spectroscopy simulations of highly charged Xenon using the Flexible Atomic Code (FAC) package developed by [PERSON] [74; 75; 76]. Calculations about atomic levels and transitions in FAC were performed employing the Dirac-Coulomb-Breit Hamiltonian to adequately account for relativistic effects and treating electron-correlation effects within the framework of relativistic configuration interaction (RCI) approach. Additionally, FAC utilizes the distorted-wave (DW) approximation to compute collision cross-section and other parameters for electron-impact excitation (EIE), enabling us to perform simulations of electron-ion interaction in plasma. In our calculations, for Ne-like Xe\({}^{44+}\), a total of 293 energy levels were included, originating from the ground 1s\({}^{2}\)2\({}^{8}\) and single-excitation configuration groups 1s\({}^{2}\)2\(l^{7}\)3\(l\) (\(n_{\text{max}}\) = 7 and \(l_{\text{max}}\) = 4). The selection of configurations was guided by the discussions in Refs. [14; 47] on the convergence with respect to principal quantum number \(n\) and the consideration of double excitations, while balancing computational efficiency and accuracy. Furthermore, xenon ions with near charge states were also included in the calculations. For Na-like Xe\({}^{43+}\), a total of 1509 energy levels were included, originating from single-excitation configuration groups 1s\({}^{2}\)2s\({}^{2}\)2p\({}^{6}\)\(nl\) (\(n\) = 3-10 and \(l_{\text{max}}\) = 3) and double-excitation configuration groups 1s\({}^{2}\)2\(l^{7}\)\(n^{\prime}\)\(l^{2}\) (\(n^{\prime}\) =3-7 and \(l_{\text{max}}\) = 3). For Mg-like Xe\({}^{42+}\), a total of 3899 energy levels were included, originating from configuration groups 1s\({}^{2}\)2s\({}^{2}\)2p\({}^{6}\)\(nl\) (\(n\) = 3-5 and \(l_{\text{max}}\) = 2) and 1s\({}^{2}\)2s\({}^{2}\)2p\({}^{5}\)3\(l^{2}\)\(n^{\prime}\)1 (\(n^{\prime}\) = 3-4 and \(l_{\text{max}}\) = 2). The collisional-radiative model (CRM) incorporated in FAC allows us to simulate spectra of above ions based on computed atomic parameters. CRM has been widely used in the simulation and interpretation of spectra observed from low-density, optically thin plasma, like EBIT [77; 78], magnetic confinement fusion [79; 80; 81], astrophysical plasma [53; 82], and so on. In the simulation, the processes inside EBIT plasma, which significantly influence the level populations, such as radiation transition, collisional excitation, and collisional de-excitation, are primarily considered [77]. Processes concerned about population transfers between different ions are neglected, such as radiative recombination, impact ionization, dielectronic recombination, and charge exchange. Under this assumption, the following rate equation can be used to describe the differential rate for the population of level \(i\):  
\[\frac{dN_{i}}{dt}=\sum_{j>i}(A_{ji}\cdot N_{j})+\sum_{j<i}\left(C_{ji}^{e}\cdot N _{j}\right)+\sum_{j>i}\left(C_{ji}^{d}\cdot N_{j}\right)-\sum_{j<i}\left(A_{ ij}\cdot N_{i}\right)-\sum_{j<i}\left(C_{ij}^{e}\cdot N_{i}\right)-\sum_{j<i} \left(C_{ij}^{d}\cdot N_{i}\right), \tag{1}\]  
where \(N\) is the population for each level, and \(A\), \(C^{e}\), and \(C^{d}\) stand for the radiative transition rate, electron-impact excitation rate, and electron-impact deexcitation rate, respectively. The subscripts \((i,j)\) represent the initial or the final levels, respectively. For EBIT plasma with monoenergetic electrons, electron-impact excitation rate \(C^{e}=n_{e}\sigma v\), where \(n_{e}\) is electron