# In-Line Target Production for Laser IFE
## 2 Modeling Results
### FST-Layering Method for Classical High Gain Targets
Double-spiral LC:
* Specifications (baseline design: Spiral 1 + Spiral 2): angle of each spiral \(-\alpha=11.50\), radius of each spiral \(-21\) mm, height of each spiral \(-450\) mm, length of each spiral \(-2.261\) m, total spiral length \(-4.52\) m, total time of target rolling \(-23.49\) s;
* \(\mathrm{T_{in}}\sim\mathrm{T_{d}}\rightarrow\) the double-spiral LC specifications are those at which the TIP criterion (2) is valid for both D2 and D\({-}\)T fuel;
* \(\mathrm{T_{in}}\sim\mathrm{T_{s}}\rightarrow\) the TIP criterion is valid for D\({}_{2}\) fuel;
* \(\mathrm{T_{in}}\sim\mathrm{T_{s}}\rightarrow\) the TIP criterion is not valid for D\({-}\)T fuel. Nevertheless, the double-spiral LC can work in the latter case, as well, because the length of Spiral 2 can be extended on \(\sim\)2 m to meet the TIP criterion (Figure 2). Generally, this approach is workable for any spiral LC because several interchangeable spirals with different parameters can be joined to a baseline LC that depends on the experimental goals. For the CHGT-2 we have considered a three-fold-spiral LC, as well. The obtained results are presented below. 2. Tree-fold-spiral LC:  
Figure 2: Test mockup of a double-spiral LC with an extra working spiral having a different inclination angle. * Specifications #1 (baseline design: Spiral 1 + Spiral 2 + Spiral 3): angle of each spiral \(-\)\(\alpha\) = 16.70, radius of each spiral \(-\) 21 mm, height of each spiral \(-\) 88 cm, length of each spiral \(-\) 3.066 m, total spiral length \(-\) 9.187 m, total time of target rolling \(-\) 33.29 s;
* Specifications #2 (Specifications #1 + Spiral 4). Spiral 4: angle \(-\)\(\alpha\) = 30, radius \(-\) 21 mm, height \(-\) 10.8 cm, length \(-\) 2.070 m, total length of Spiral 3 and Spiral \(4-5.136\) m. Other words, this 3-fold LC is designed in a special configuration with an extra short Spiral 4 (combined LC). The modeling has shown that, in \(\sim\)5 s after a start, the target motion is carried out with a constant velocity V\({}_{\rm max}\) = 0.3 m/s. The total rolling time for Specifications #1 is 33.29 s. Thus, we can realize the rolling conditions for the CHGT-2 and satisfy the TIP criterion in the case of 3-fold-spiral LC, even with a certain time margin. Note also that the proposed 3-fold-spiral LC (Specifications #1) can have an extra spiral (Specifications #2) so that two spirals \"Spiral 3 + Spiral 4\" make a combined LC in which the Spiral 4 parameters differ considerably from those of Spiral 3. Such combined LC consists of these spirals assembled one after another: \"acceleration Spiral 3 + deceleration Spiral 4\" for controlling the target velocity at the output. For example, in our case, it will take no more than 1.5 s at \(\alpha\) = 30 to zero the target velocity. The obtained results are summarized in Table 3 in which \(\tau_{\rm zrol}\) and \(\tau_{\rm 3 rol}\) are the rolling times for the double-spiral LC and for the tree-fold-spiral LC, respectively. A few comments should be made regarding the gold-coated CH shell. In this case for both D\({}_{2}\) and D\(-\)T fuel the layering time \(\tau_{\rm form}\) \(<\) 0.5 s. This means that in order to have a uniform layer, a temperature profiling along the LC becomes a necessary condition for increase in time of \(\tau_{\rm roll}\) at temperatures more than the triple point one. In this case T\({}_{\rm in}\) can be \(\sim\)21 K as the hydrogen isotope vapor pressures near the triple point determine the minimum operating pressures (do not exceed 0.2 atm [19]) that allows one to consider an injection filling procedure. Filling of the CH shells with a cryogenic liquid fuel is suitable for the FST layering method because the fuel in the shell directly before the layering has a two-phase state \"Liquid + Vapor\" (Figure 1c). Thus, in the IFE, the FST layering is a credible pathway to a reliable, consistent, and economical target supply. Currently, our studies on the creation of FST-LM lie in the field of compatibility of its work with a noncontact method for delivering targets to the reactor.