First Inertial Confinement Fusion Implosion Experiment in Octahedral Spherical Hohlraum.

Area of Science:

• Physics
• Nuclear Fusion
• Laser-Plasma Interactions

Background:

• Achieving high gain in inertial confinement fusion (ICF) is hindered by target implosion asymmetry.
• Traditional ICF approaches require supplementary symmetry control for uniform target irradiation.
• A proposed octahedral spherical hohlraum offers a potential solution for naturally achieving spherical irradiation.

Purpose of the Study:

• To experimentally validate the proof-of-concept for the novel octahedral hohlraum geometry.
• To assess the implosion performance of a target using the octahedral hohlraum without symmetry control.
• To evaluate the feasibility of using existing laser facilities for octahedral hohlraum experiments.

Main Methods:

• Conducted a proof-of-concept experiment on the SGIII laser facility using the octahedral hohlraum.
• Employed a cylindrically configured laser facility without supplementary symmetry control.
• Utilized both square and shaped laser pulses for target irradiation.
• Captured polar and equatorial self-emission images of the compressed target.

Main Results:

• Observed near-round target shapes with a convergence ratio of 15.
• Demonstrated effective spherical target irradiation without supplementary symmetry control.
• Achieved implosion performances that align well with ideal spherical implosion simulations.
• Identified limitations of current laser facilities for octahedral hohlraum experiments.

Conclusions:

• The octahedral hohlraum geometry is a viable approach for achieving spherical target irradiation in ICF.
• Experimental results support the potential of this novel hohlraum design for fusion energy research.
• The findings highlight the need for spherical port geometry in future ignition laser facilities to fully realize the potential of the octahedral hohlraum.