## 5 Discussion of Results
The contributions of these sources to the total number of particles, with allowance for different particle lifetimes for each source, are shown in Figure 4b. It can be seen that a rather large particle flux \(S_{sep}\) from the divertor region (Figure 4a) makes a minor contribution to the total number of particles (Figure 4b). This can be explained by the peripheral localization of this source and, accordingly, by the short lifetime of the particles coming from it. In this case, in the range of the \(n_{e}\) and \(D/\chi_{e}\) parameters under consideration, the total flux \(S_{pel}{}^{D}+S_{pel}{}^{T}\) varies in the range of \(\sim\)10\({}^{20}\)-10\({}^{21}\) s\({}^{-1}\). Figure 3: Maximum possible fraction of tritium \(f_{core}{}^{T}(max)\) as a function of the \(n_{e}\) and \(D/\chi_{e}\) parameters for the (**a**) D + T and (**b**) D beams. The scale on the right shows the correspondence of the color and \(f_{core}{}^{T}(max)\) values. For both types of beams, the \(S_{neut}\) intensities as functions of the \(n_{e}\) and \(D/\chi_{e}\) parameters are shown in Figure 5. In this case, the fractions of tritium are maximal, \(f_{core}{}^{T}=f_{core}{}^{T}(max)\), which provides the maximum possible neutron yield in the entire range of the parameters under consideration. It can be seen that the dependencies of the \(S_{neut}\) intensities on the parameters are different for the scenarios with the D + T and D beams (see Figure 5a,b). In this case, in the range of the tritium fractions \(f_{core}{}^{T}(max)>0.5\), the ranges of neutron yield variation turn out to be comparable for both types of beams. However, the maximum values are reached in different ranges of the \(n_{e}\) and \(D/\chi_{e}\) parameters. For the D beam, the \(S_{neut}\) intensity is noticeably lower compared with the D + T beam in the range of parameters where \(f_{core}{}^{T}(max)<0.5\). This is an indirect consequence of the fact that the dependence \(S_{neut}(f_{core}{}^{T})\) shown in Figure 2 for the central point of the parameter plane (\(n_{e}\), \(D/\chi_{e}\)) is steeper for the D beam than for the D + T beam. Figure 4: (**a**) Sources of deuterium and tritium in the plasma core, originating from the neutral beam \(S_{NB}\), pellet injection \(S_{pel}\), and divertor region \(S_{sep}\) for the D + T (**top**) and D (**bottom**) beams. The absolute values of the particle flux sources are given. \(n_{e}\) = 8.5 \(\times\) 10\({}^{19}\) m\({}^{-3}\), \(D/\chi_{e}\) = 0.4. For the D + T and D beams, \(f_{core}{}^{T}\) = 0.75 and 0.5, respectively. (**b**) Fractions of particles from different sources with allowance for their lifetimes. The amounts of tritium accumulated at the site as functions of the \(n_{e}\) and \(D/\chi_{e}\) parameters are shown in Figure 6. For the D + T beam, the simulations of the operating regimes show that the amount of tritium accumulated in the FC of the facility is quite noticeable; nevertheless, it was lower than that estimated previously in [4]. One can see that the accumulation of tritium in the FC depends directly on the fraction of tritium \(f_{conv}\). For the D beam, the total amount of tritium turns out to be lower than for the D + T beam. Primarily, this is due to the absence of tritium in the neutral beam injectors (in the case of the D + T beam, each of them accumulates up to 100 g of T\({}_{2}\)), as well as due to the smaller amount of tritium in the hydrogen isotope separation system. By comparing Figures 5 and 6, we can decide what regimes are most reasonable from the point of view of neutron generation and the amount of accumulated tritium at the site. For the D + T beam, to obtain the maximum neutron yield of 4.5-5.5 \(\times\) 10\({}^{17}\) s\({}^{-1}\), it would  
Figure 5: Neutron intensity \(S_{neut}\) as a function of the \(n_{e}\) and \(D/\chi_{e}\) parameters for the (**a**) D + T and (**b**) D beams. The scale on the right shows the correspondence of the color and \(S_{neut}\) values.