In indirect-drive inertial confinement fusion (ICF) research, the meticulous design and optimization of laser parameters are crucial for achieving high-gain ignition. The intensity of the toe laser, used for ablating the hohlraum sealing membrane, is a subtle but equally critical parameter. This study introduces a novel experimental approach using the Velocity Interferometer System for Any Reflector (VISAR) to assess the impact of toe laser intensity on the compression of fusion capsules. By tracking the reflectivity of tracer layers and shock velocities in liquid deuterium, the adverse effects of insufficient toe laser intensity on capsule compression have been unveiled for the first time. From a comparison with hydrodynamic simulations, we show that below a critical threshold of 0.23 × 1014 W cm−2, the adiabat, a measure of the fuel's compression efficiency, increases markedly with the toe laser intensity decreases, whereas it remains stable within the range of (0.23 ∼ 7) × 1014 W cm−2. Our findings provide critical insights on toe laser parameter design, enhancing our understanding of the role of toe laser intensity in ICF experiments. This research not only refines the parameters for laser operation but also underscores the importance of precision in achieving the desired implosion efficiency, contributing to the development of nuclear fusion as a clean energy source.
This paper investigates how the intensity of the 'toe' laser, used to ablate the hohlraum membrane, affects the compression of fusion capsules in indirect-drive inertial confinement fusion (ICF) experiments. The study uses VISAR to track reflectivity and shock velocities, revealing that insufficient toe laser intensity can adversely impact compression efficiency. The findings provide critical insights for optimizing toe laser parameters to enhance implosion efficiency, contributing to the development of fusion as a clean energy source.