Enhancements in Laser-Direct-Drive Nuclear Performance with Target Radius

Area of Science:

• Nuclear fusion science
• Plasma physics
• Laser-matter interaction

Background:

• Inertial confinement fusion (ICF) requires advanced technology for large-target implosions at high energies.
• Previous studies may have underestimated the impact of target radius on ICF performance.

Purpose of the Study:

• To assess the impact of target radius on nuclear performance in direct-drive cryogenic implosions.
• To quantify the relationship between target radius and neutron yield and areal density.

Main Methods:

• Experiments were conducted on the OMEGA laser using direct-drive cryogenic implosions.
• Nuclear performance metrics (neutron yield, areal density) were measured as a function of target radius (R_{t}).

Main Results:

• Neutron yield scales as R_{t}^{5.0±0.2}, and areal density scales as R_{t}^{1.8±0.2}.
• These dependencies are stronger than previously assumed, indicating significant sensitivity to target radius.

Conclusions:

• Larger targets demonstrate superior relative quality and approach ignition criteria more rapidly.
• Multidimensional effects and instabilities significantly impact implosion performance, with larger targets showing greater relative improvement when imperfections are constant.