Laser-Powered Fusion Experiment More Than Doubles Its Power Output

The world’s only net-positive fusion experiment has been steadily ramping up the amount of power it produces, TechCrunch has learned.

In recent attempts, the team at the U.S. Department of Energy’s National Ignition Facility (NIF) increased the yield of the experiment, first to 5.2 megajoules and then again to 8.6 megajoules, according to a source with knowledge of the experiment.

The new results are significant improvements over the historic experiment in 2022, which was the first controlled fusion reaction to generate more energy than the it consumed.

The 2022 shot generated 3.15 megajoules, a small bump over the 2.05 megajoules that the lasers delivered to the BB-sized fuel pellet.

None of the shots to date have been effective enough to feed electrons back into the grid, let alone to offset the energy required to power the entire facility — the facility wasn’t designed to do that. The first net-positive shot, for example, required 300 megajoules to power the laser system alone. But they are continued proof that controlled nuclear fusion is more than hypothetical.

The NIF uses what’s known as inertial confinement to produce fusion reactions. At the facility, fusion fuel is coated in diamond and then encased in a small gold cylinder called a hohlraum. That tiny pellet is dropped into a spherical vacuum chamber 10 meters in diameter, where 192 powerful laser beams converge on the target. 

The cylinder is vaporized under the onslaught, emitting X-rays in the process that bombard the fuel pellet inside. The pellet’s diamond coating receives so much energy that it turns into an expanding plasma, which compresses the deuterium-tritium fuel inside to the point where their nuclei fuse, releasing energy in the process.

The other main approach to fusion, magnetic confinement, uses powerful superconducting magnets to compress and contain plasma in a space tight enough to create the conditions necessary for fusion. While no magnetic confinement experiments have produced net-positive results, several are being constructed or designed with the expectation that they’ll hit that milestone.

Several startups are pursuing inertial confinement, including Xcimer Energy and Focused Energy.

Understanding Nuclear Fusion

Nuclear fusion is the process that powers the sun and other stars. It involves forcing two light atomic nuclei to combine into a single, heavier nucleus. This process releases a tremendous amount of energy because the mass of the new nucleus is slightly less than the sum of the masses of the original nuclei. This mass difference is converted into energy according to Einstein's famous equation, E=mc².

Inertial Confinement Fusion (ICF)

Inertial Confinement Fusion (ICF) is one of the primary methods scientists are using to achieve fusion on Earth. The National Ignition Facility (NIF) employs this method. Here’s a breakdown of how it works:

• Fuel Target: A tiny pellet, about the size of a BB, contains deuterium and tritium, which are isotopes of hydrogen.
• Hohlraum: The fuel pellet is encased in a small gold or uranium cylinder called a hohlraum.
• Laser System: The NIF uses 192 powerful lasers that converge on the hohlraum.
• X-ray Emission: The lasers vaporize the hohlraum, causing it to emit intense X-rays.
• Implosion: The X-rays bombard the fuel pellet, causing its outer layer to turn into plasma and compress the fuel inward.
• Fusion: The compression heats the fuel to temperatures exceeding 100 million degrees Celsius, causing the deuterium and tritium nuclei to fuse and release energy.

Magnetic Confinement Fusion (MCF)

Magnetic Confinement Fusion (MCF) is the other leading approach to achieving fusion. Instead of using lasers to compress the fuel, MCF uses powerful magnetic fields to contain and compress a plasma. Here’s how it generally works:

• Plasma Creation: Hydrogen isotopes are heated to extreme temperatures, turning them into plasma.
• Magnetic Confinement: Strong magnetic fields, often generated by superconducting magnets, confine the plasma, preventing it from touching the reactor walls.
• Compression and Heating: The magnetic fields compress the plasma, further increasing its temperature and density.
• Fusion: At sufficiently high temperatures and densities, the hydrogen nuclei fuse, releasing energy.

The Significance of NIF's Recent Achievements

The recent experiments at NIF, yielding 5.2 and 8.6 megajoules, represent a significant leap forward in fusion research. These results build upon the historic 2022 experiment, which was the first to achieve net energy gain, producing 3.15 megajoules of energy output from 2.05 megajoules of laser energy input. While these experiments have not yet achieved the energy levels required to power the facility itself or feed energy back into the grid, they provide crucial data and validation for the inertial confinement approach.

Key Implications

• Proof of Concept: These results reinforce the feasibility of controlled nuclear fusion as a viable energy source.
• Advancement in Technology: The improvements in energy output demonstrate advancements in laser technology, target design, and experimental techniques.
• Future Research: The data collected from these experiments will guide future research and development efforts, helping scientists optimize the fusion process.

Challenges and Future Directions

Despite the progress, significant challenges remain before fusion energy can become a practical reality.

Energy Efficiency

One of the biggest challenges is improving the overall energy efficiency of the fusion process. The NIF experiments still require a large amount of energy to power the lasers, far exceeding the energy produced by the fusion reactions. Future research will focus on:

• More Efficient Lasers: Developing lasers that require less energy input to deliver the same amount of energy to the target.
• Target Optimization: Designing fuel pellets and hohlraums that maximize energy absorption and compression.
• Recirculation: Creating systems that can capture and reuse some of the energy produced by the fusion reactions to power the facility.

Cost Reduction

The cost of building and operating fusion facilities is another major hurdle. The NIF, for example, is a multi-billion-dollar facility. Reducing the cost of fusion energy will require:

• Innovative Materials: Developing cheaper and more durable materials for reactor components.
• Simplified Designs: Creating simpler and more scalable reactor designs.
• Economies of Scale: Building multiple fusion facilities to reduce manufacturing and operating costs.

Startup Involvement

Several startups are actively involved in advancing fusion technology. Companies like Xcimer Energy and Focused Energy are pursuing inertial confinement fusion, while others are exploring magnetic confinement and other innovative approaches. These startups bring fresh ideas, entrepreneurial spirit, and private investment to the field, accelerating the pace of innovation.

The Promise of Fusion Energy

If the challenges can be overcome, fusion energy holds the promise of a clean, abundant, and sustainable energy source. Fusion reactions produce no greenhouse gases and generate far less radioactive waste than nuclear fission. The fuel for fusion, deuterium, can be extracted from seawater, and tritium can be produced from lithium, both of which are abundant resources.

Potential Benefits

• Clean Energy: Fusion produces no greenhouse gas emissions, helping to mitigate climate change.
• Abundant Fuel: The fuel for fusion is readily available and virtually inexhaustible.
• Low Waste: Fusion produces less radioactive waste than fission, and the waste is shorter-lived.
• Energy Security: Fusion could reduce dependence on fossil fuels and enhance energy security.

Conclusion

The recent progress at the National Ignition Facility represents a major step forward in the quest for fusion energy. While significant challenges remain, the increasing energy output and growing involvement of startups demonstrate the potential of fusion to transform the world’s energy landscape. With continued research, development, and investment, fusion energy could become a reality in the coming decades, providing a clean, abundant, and sustainable energy source for future generations.