In laser-driven inertial confinement fusion (ICF) research, microstructures (e.g., micropores, bubbles) on capsule surfaces critically impact fusion performance, with slit structures at hemispherical shell joints in double-shell volume ignition targets being particularly crucial. These microstructures induce ablation non-uniformity, hydrodynamic instabilities, and jets during radiation ablation, altering shock wave propagation and compromising converging shock front integrity in imploding shells, thereby degrading implosion performance. Under certain conditions, preheating may elevate sample temperature before radiation ablation, causing expansion and potential defect closure that significantly affects ablation dynamics. To address this,  we propose using one short-pulse laser to generate charged particle beams for sample preheating, employing multi-beam nanosecond lasers to produce radiation for sample ablation, and utilizing another short-pulse laser to generate micro-focus high-energy X-rays for backlighting radiography, thereby establishing the "preheating + radiation ablation" experimental technique. Experiments at the Shenguang-II Upgrade facility diagnosed dynamic evolution in planar slits (varying aspect ratios) under preheated/non-preheated conditions, capturing high-resolution images (average spatial resolution: 7.6 μm ± 0.5 μm; peak SNR: 33.9). Geometric feature extraction from these images revealed temporal evolution of slit dimensions, experimentally confirming that preheating significantly mitigates slit impacts on shock fronts and that longer preheating-ablation intervals enhance suppression efficacy on shock front morphology.

hard x-ray; radiography; plannar slit; preheating; radiation