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Energy Principles of Scientific Breakeven in an Inertial Fusion Experiment
O A Hurricane1, D A Callahan1, D T Casey1
1Lawrence Livermore National Laboratory, P.O. Box 808, L-472, Livermore, California 94550, USA.
Physical Review Letters
|February 23, 2024
Summary
Achieving fusion "scientific breakeven" for the first time, this study reports on design changes enabling a target gain greater than unity. Key factors included reducing coast time and maximizing hot spot energy for controlled fusion energy output.
Area of Science:
- Nuclear Fusion
- Plasma Physics
- Laser-driven Inertial Confinement Fusion
Background:
- Fusion energy research aims for
- scientific breakeven,
- defined as achieving a target gain (Gtarget) greater than unity.
- Previous experiments approached but did not surpass this threshold.
Purpose of the Study:
- To report the first achievement of fusion scientific breakeven (Gtarget > 1) using laser indirect drive.
- To detail the physics principles and design modifications enabling this breakthrough.
- To explain the relationship between coast time, hot spot energy, and fusion yield.
Main Methods:
- Utilized laser indirect drive on the National Ignition Facility.
- Implemented design changes focused on reducing "coast time" between laser pulse and implosion.
- Optimized energy delivery to the
- hot spot
- for maximum fusion fuel compression.
Main Results:
- Achieved a target gain (Gtarget) of approximately 1.5, surpassing the unity threshold for scientific breakeven.
- Demonstrated controlled fusion energy output exceeding laser energy input.
- Established a key relationship linking hydrodynamic mixing and implosion asymmetry to kinetic energy costs.
Conclusions:
- The study marks the first controlled fusion experiment to achieve scientific breakeven.
- Reducing coast time and maximizing hot spot energy are critical for ignition.
- A modified Lawson criterion accounting for mixing and asymmetry is essential for future fusion designs.
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