A novel method with periodic heat excitation to improve self-heating fuel layers

Achieving ignition and initiating a self-sustaining reaction in inertial confinement fusion (ICF) demands continuous improvement in the net energy gain. The quality of fusion fuel obtained in a cryogenic and confined space, subjected to internal β-decay heating, governs the fusion energy yield. Based on the thermal breathing technology, this study proposes periodic thermal excitation with spatial selectivity to improve the quality of self-heating fuel layers. A one-dimensional analytical solution under periodic boundary conditions establishes the theoretical objective function, while a coupled heat transfer model of a typical cylindrical hohlraum is numerically reconstructed and integrated with a genetic algorithm for inverse identification and correction of control parameters. The effectiveness of the strategy is validated under experimental conditions through a reduction in defect density within spatially targeted regions. The results reveal that periodic thermal excitation induces spatially varying temperature oscillations along the capsule's equator-to-pole direction. The spatial temperature difference depends linearly on the amplitude and exhibits a maximum value with respect to frequency at 34 Hz. Experimental validation confirms that the strategy successfully eliminates grooves of ∼3 μm depth in the equatorial region, thereby demonstrating the proposed 'analytical-numerical-optimization' framework as an effective inverse thermal design tool for cryogenic targets. The findings highlight the engineering applicability of periodic thermal excitation in enhancing morphology and uniformity of fuel layer during ICF target fabrication.