Two-Plasmon Decay Mitigation in Direct-Drive Inertial-Confinement-Fusion Experiments Using Multilayer Targets

Area of Science:

• Physics
• Plasma Physics
• Fusion Energy

Background:

• Two-plasmon decay (TPD) is a significant source of hot-electron production in inertial confinement fusion (ICF) experiments.
• Hot electrons can reduce the efficiency of ICF implosions.

Purpose of the Study:

• To investigate the effectiveness of multilayer ICF targets in reducing TPD-driven hot-electron production.
• To maintain high hydrodynamic efficiency during ICF implosions.

Main Methods:

• Experiments were conducted on the OMEGA laser using multilayer targets with silicon layers.
• Three-dimensional simulations using the lpse laser-plasma interaction code were performed.
• Hot-electron generation was measured and compared between multilayer and pure CH targets.

Main Results:

• A factor-of-5 reduction in hot-electron generation (>50 keV) was observed with multilayer targets compared to pure CH targets.
• Simulations showed good agreement with experimental measurements.
• The reduction in hot-electron production is primarily attributed to increased electron-ion collisional damping.

Conclusions:

• Multilayer ICF targets offer a promising approach to mitigate hot-electron generation.
• This reduction in hot electrons can improve the efficiency of ICF implosions.
• Further research into collisional damping mechanisms in multilayer targets is warranted.