3D Simulations Capture the Persistent Low-Mode Asymmetries Evident in Laser-Direct-Drive Implosions on OMEGA.

Area of Science:

• Physics
• Plasma Physics
• Nuclear Fusion

Background:

• Spherical implosions in inertial confinement fusion (ICF) are highly sensitive to perturbations.
• Controlling low-mode (long-wavelength) perturbations is essential for enhancing ICF implosion performance.

Purpose of the Study:

• To investigate the impact of polarized crossed-beam energy transfer (XBT) on 3D radiation-hydrodynamic simulations of ICF implosions.
• To quantify the yield degradation caused by various asymmetries and explore mitigation strategies.

Main Methods:

• Conducted 3D radiation-hydrodynamic simulations incorporating an inline package for polarized crossed-beam energy transfer.
• Validated simulation results against experimental data for bang times, yields, and hot spot flow characteristics.
• Analyzed the effects of beam mispointing, imbalance, target offset, and XBT-induced asymmetry.

Main Results:

• Simulations accurately reproduced experimental bang times, yields, and hot spot flow velocities and direction.
• Polarized crossed-beam energy transfer was identified as a contributor to systematic flow orientation in OMEGA implosions.
• Current experimental imperfections, including XBT asymmetry, degrade ICF yields by over 40%.

Conclusions:

• Polarized crossed-beam energy transfer significantly influences ICF implosion dynamics and performance.
• Addressing low-mode perturbations, particularly those arising from XBT, is critical for achieving high-yield ICF.
• Further research into mitigation strategies is necessary to overcome performance limitations.