By building the heart of a star, humans are getting closer to net zero

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The writer is a science commentator

The fireball at the heart of our solar system is fueled by nuclear fusion. The overwhelming pressures in the sun’s core squeeze the hydrogen nuclei together so powerfully that they overcome their natural repulsion and merge. These nuclear corpses generate larger particles with masses that are not quite the sum of their parts.

The missing mass becomes energy, a fiery embodiment of Einstein’s equation E = mc2. The equation shows that in terms of energy production, a tiny mass goes very far thanks to the colossal multiplier of c, the speed of light (300,000 km per second), squared.

Scientists, drawn to the prospect of almost unlimited power from minimal fuel, have long dreamed of reproducing nuclear fusion in the laboratory. This month, researchers in the United States dramatically altered the dial as it neared “ignition,” where a tiny pellet of hydrogen plasma fuel, bombarded by 192 lasers, began to fuse, producing enough energy to continue heating the rest of the fuel in a self- sustainable manner.

Professor Jeremy Chittenden of Imperial College London hailed the National Ignition Facility’s breakthrough in California as the most significant in nearly half a century. Chittenden, who works with the NIF, likened the challenge of achieving ignition to that of striking a match so that it produces a flame. “Ignition is the key process by which we can produce significant energy gains, because it is a self-sustaining process – as long as we can keep the plasma burning.”

Which, currently, is only a tenth of a billionth of a second. This is because of the extraordinary process that the fuel pellet goes through. First, it is targeted by lasers – collectively the most powerful in the world. The rapidly heated outer surface explodes, causing the reactive collapse of the plasma fuel inside. The peppercorn-sized pellet implodes the width of a human hair, reaching a pressure of hundreds of billions of atmospheres and 100 m degrees Celsius, triggering fusion. Scientists at NIF managed to hold the pellet long enough to burn about 2% of the available fuel.

The energy produced, 1.3 megajoules, was about 70 percent of the energy used by lasers and several times the power of previous attempts. Importantly, it was considered sufficient to be on the threshold of inflammation (there is active debate on the definition). The next hurdle is reaching the “breakeven point,” where the energy produced by fusion is the energy expended to initiate the process.

The ultimate goal is for the outgoing energy to exceed the incoming energy, creating a clean and abundant source of energy (the fusion itself is emission-free and the associated nuclear waste is less than that produced by nuclear fission reactors. current, which divide atoms rather than merging them).

The NIF approach is one of many fusion technologies being explored. The best known is magnetic confinement fusion, in which combustible hydrogen is trapped and compressed by strong magnetic fields. The international thermonuclear experimental reactor in France is a collaboration of 35 countries to build the world’s largest tokamak – a magnetic containment device. This is considered to be a more stable and controllable way to generate fusion energy over the long term. It has not yet reached equilibrium but optimism remains strong, especially as we get closer to net zero.

The UK government has pledged to build its own prototype tokamak-based fusion power plant by 2040. Scaling-up won’t be easy: a viable plant needs high-performance production. energy equivalent to hundreds or thousands of the energy produced by the NIF experiment, each second.

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Plugging it into national grids and regulating a new form of nuclear power also present bear traps. But the high risks are outweighed by the potentially astronomical rewards. Investors, including Amazon founder Jeff Bezos, invested around $ 300 million in private merger companies in 2020.

Chittenden points out that the NIF is geared towards basic science rather than energy production: proving that it is possible to build a star’s heart in a laboratory to help understand nuclear processes, including nuclear weapons . “It’s a much more extreme state of matter than ever before,” he says. “We can study material under conditions comparable to the first few minutes after the Big Bang.”

The intensity of electromagnetic radiation is such that it may even be possible to observe the spontaneous creation of matter, when energy becomes mass. Nuclear fusion, by illuminating a path to the future, could one day illuminate our distant cosmic past.