Fig. 1. Different DD ice shapes obtained in cryogenic experiments for the same batch of targets, as viewed by x-ray phase contrast imaging.

Fig. 2. Sectional structure of the cryogenic target (the copper rod, sensors, heaters, and thermal shield are not shown).

Fig. 3. Radiation energy transport through the semitransparent LEH films.

Fig. 4. Details of the adhesive distribution types around the fill tube.

Fig. 5. Calculated temperature distributions on the outer surfaces of (a) the target and (b) the capsule for the AD1 case with fill tube.

Fig. 6. Temperature profiles around the capsule’s equator for different adhesive distribution types AD1, AD2, and AD3 and thermal conductivities k_a.

Fig. 7. Temperature profiles in the same cases as in Fig. 6 but without the fill tube.

Fig. 8. Temperature profiles around the capsule’s equator for different diameters d_t of the tube tip. In all cases, the tube’s thermal conductivity is k_t = 0.29 W/(mK).

Fig. 9. Temperature profiles around the capsule’s equator for different thermal conductivities k_t of the tube. In all cases, the diameter of the tube tip is d_t = 20 µm. (Note that the vertical scale is three times larger than in other similar figures.)

Fig. 10. Influence of the optical properties of the hohlraum and HCH films on thermal effects. (a) Temperature profiles around the capsule’s equator for different combinations of HCH transmissivity τ_HCH and the hohlraum’s inner surface emissivity ε_h,in. (b) Variation with the hohlraum’s inner surface emissivity ε_h,in of the maximum and minimum temperatures on the capsule’s outer surface and their difference.

Fig. 11. Calculated results for the thermal impact of fractional and unreliable connections between the hohlraum tori and the jacket. (a) Assumed circumferential contact points. (b) Temperature profiles around the capsule’s equator in the different scenarios.

Fig. 12. Temperature profiles around the capsule’s equator (local X–Z section) for different scenarios of location deviation.

Fig. 13. Temperature profiles around the capsule’s pole (local X–Y section) for different scenarios of location deviation.

Fig. 14. First simulated scenario of asymmetric thermal contact at arm–jacket interfaces. (a) Claws that are out of contact in the model. (b) Calculated thermal field on the outer components of the target. (c) Calculated thermal field on the capsule.

Fig. 15. Second simulated scenario of asymmetric thermal contact at arm–jacket interfaces. (a) Claws that are out of contact in the model. (b) Calculated thermal field on the outer components of the target. (c) Calculated thermal field on the capsule.

Fig. 16. Third simulated scenario of asymmetric thermal contact at arm–jacket interfaces. (a) Claws that are out of contact in the model. (b) Calculated thermal field on the outer components of the target. (c) Calculated thermal field on the capsule.

Fig. 17. Fourth simulated scenario of asymmetric thermal contact at arm–jacket interfaces. (a) The unconnected claws are the same as in the third scenario, but the jacket material is changed to oxygen-free copper (C10200). (b) Calculated thermal field on the outer components of the target. (c) Calculated thermal field on the capsule.

Fig. 18. Experimental snapshots showing the procedure of seed crystal preparation in previous and current targets. (a) The seed crystal could be preserved successfully in the fill tube of previous targets, in which the tube was always colder than the capsule. (b) The seed crystal cannot be preserved in current targets (before optimization), because the solid fuel in the fill tube melts earlier than that in the capsule.

Fig. 19. Structure of the fill tube thermal controller (the parts marked with blue labels).

Fig. 20. Calculated results for the sectional thermal field of the target with a tube controller. (a) Preliminary design with direct connection between tube and controller. (b) Optimized design with the addition of a copper sleeve around the external portion of the tube.

Fig. 21. Experimental comparison between two sample targets with aluminum and copper jackets, respectively. (a) Target with an aluminum jacket: the DD ice shell ruptures at the poles after 32 min. (b) Target with a copper jacket: the DD ice shell remains for longer than 1 h without obvious variation (part of the profile of the inner surface of the ice is indistinct because of polycrystal growth, but this does not influence the assessment of the retention time).

Fig. 22. Experimental comparison between targets with different deviations in capsule location, with (a)–(c) representing three different targets from the same batch. The numbers (units of μm) under the images are the deviations in capsule location (ΔX, ΔY, ΔZ) in the coordinate system shown in Fig. 5(b). The ice thicknesses (units of μm) on the side nearest to the fill tube and on the opposite side are marked on each image.

Table 1. Main material properties in the numerical models (temperature 18 K).

Table 2. Maximum temperature differences on the capsule for some typical scenarios of location deviation.