Scientists have achieved self-sustaining fusion... but now they can't replicate it: ScienceAlert

Scientists confirmed that for the first time in the lab last year, they had a fusion reaction that perpetuates itself (rather than dies out) — bringing us closer to repeating the chemical reaction that powers the sun.

However, they are not quite sure how to recreate the experience.

nuclear fusion It occurs when two atoms combine to form a heavier atom, releasing a huge burst of energy.

This process is common in nature, but it is very difficult to replicate in a lab because it requires a high-energy environment to keep the reaction going.

the sun generates energy Using nuclear fusion – by breaking hydrogen atoms together to form helium.

Supernovae – Exploding Suns – Too Take Advantage of Nuclear Fusion Cosmic Fireworks. It is the force of these interactions that creates heavier particles such as iron.

However, in artificial places here on Earth, heat and energy tend to escape through cooling mechanisms such as X-rays and thermal conduction.

To make nuclear fusion a viable energy source for humans, scientists must first achieve something called "ignition," where self-heating mechanisms overcome all the energy loss.

Once inflammation is achieved, the fusion reaction fuels itself.

In 1955, physicist John Lawson created the set of criteria, now known as the "Lawson-like ignition criteria," to help determine when this inflammation occurred.

The ignition of nuclear reactions usually takes place in very dense environments, such as a supernova or nuclear weapons.

Researchers at Lawrence Livermore National Laboratory's National Ignition Facility in California spent more than a decade perfecting their method, now confirming that the historic experiment, conducted on August 8, 2021, actually led to the first-ever successful ignition of a nuclear fusion reaction. .

A recent analysis assessed the 2021 trial against nine different versions of the Lawson benchmark.

"This is the first time we've crossed the Lawson benchmark in the lab," said nuclear physicist Annie Kretcher of the National Ignition Facility. new world.

To achieve this effect, the team placed a capsule containing tritium and deuterium fuel in the center of a gold-lined chamber containing depleted uranium and fired 192 high-powered lasers at it to create a bath of intense X-rays.

The intense environment created by the internally directed shock waves created a self-sustaining fusion reaction.

Under these conditions, the hydrogen atoms underwent fusion, releasing 1.3 megajoules of energy for one hundred trillionths of a second, the equivalent of 10 quadrillion watts of energy.

In the past year, researchers have tried to replicate the finding in four similar experiences, but only managed to produce half the energy output produced in the record-breaking first experiment.

Critcher explains that the inflammation is very sensitive to small, barely noticeable changes, such as differences in the structure of each capsule and laser intensity.

“If you start from a microscopically worse premise, it will be reflected in a much larger difference in the final energy yield,” says plasma physicist Jeremy Chittenden at Imperial College London. The August 8 experience was the best-case scenario.

The team now wants to determine exactly what is needed to achieve ignition and how the experiment can be made more resilient to small errors. Without this knowledge, the process cannot be scaled up to create fusion reactors that can power cities, which is the ultimate goal of this type of research.

“You don't want to get into a situation where you have to get everything just right to ignite,” Chittenden says.

This article was published in physical assessment messages.