Sensitivity of the dynamic-shell target to laser drive nonuniformities

Area of Science:

• Physics
• Plasma Physics
• Nuclear Fusion

Background:

• The dynamic-shell concept for inertial confinement fusion (ICF) utilizes a shaped laser pulse on a homogeneous target to create and implode a shell.
• This method involves a series of laser "pickets" that generate shocks, forming an expanding plasma before shell coalescence and implosion.

Purpose of the Study:

• To investigate the sensitivity of dynamic-shell ICF targets to imperfections in the laser drive.
• To quantify the impact of laser power imbalance, timing variations, and irradiation nonuniformities on fusion yield.

Main Methods:

• Radiation-hydrodynamic simulations were employed for the investigation.
• A one-dimensional (1D) model assessed mistiming and power variations in laser pickets.
• A two-dimensional (2D) model examined irradiation perturbations from laser-beam geometry.

Main Results:

• Dynamic-shell targets are robust, with less than ~2% power imbalance or 200 ps timing variation in pickets preserving over 90% of maximum fusion yield.
• Two-dimensional simulations indicate that 72 or more laser beams are necessary to minimize irradiation nonuniformities.
• Sufficient beams ensure fusion yields comparable to ideal one-dimensional simulations.

Conclusions:

• The dynamic-shell ICF approach demonstrates significant resilience to moderate imperfections in laser drive parameters.
• Careful control of laser power balance and timing is crucial but allows for a reasonable margin of error.
• Optimizing laser beam count is essential for achieving high-fidelity implosions and maximizing fusion energy output.