The tiny diamond sphere that is crucial to the future of nuclear fusion and clean energy

On Monday, December 5, 2022 at 1:03 a.m., an experiment that may be vital to the future of energy took place in California.

Scientists at the National Ignition Facility (NIF) aimed their laser with 192 beams at a cylinder of a small diamond capsule filled with nuclear fuel.

The powerful burst of laser light generated enormous temperatures and pressures by starting a fusion reaction, like the one that powers the sun.

The NIF, which belongs to Lawrence Livermore National Laboratory (LLNL), had conducted similar experiments, but this time the energy of the reaction was greater than that of the laser used to produce it.

Scientists have been trying to reach that threshold for decades.

a perfect atmosphere

The aim of the scientific community in the future is to build power plants that produce an abundant stream of carbon-free electricity.

But that is still a long way off, and in the meantime there is still a long way to go in developing the necessary technology.

One of the key components in the NIF is a synthetic diamond capsule the size of a peppercorn.

The properties of that spherical capsule, which contains the fuel, are crucial to conducting a successful fusion experiment.

The globe it must be perfectly smooth and free of contaminantsas any deviation could ruin the reaction.

Those precision-engineered spheres aren’t made in California, though; are the result of years of work by the company Diamond Materials, based in Freiburg, Germany.

The demand for this type of spherical capsule is very high, says Christoph Wild, together with Eckhard Wörner general manager of Diamond Materials.

“We work closely with the LLNL laboratory and try to do so minimize defects such as impurities, voids or irregular walls”.

The process

Diamond Materials’ 25-person team produces synthetic diamonds using a process called chemical vapor deposition.

It takes about two months to make each batch of 20 to 40 capsules.

To make them, tiny diamond crystals are placed around a silicon carbide core and polished repeatedly.

During the development process, they found that even the most precise polishing was insufficient, as the surface still showed holes and imperfections at the microscopic level.

In their work with the LLNL teams, they eventually discovered they could glaze a polished capsule with a new layer of diamond crystals to achieve the perfect finish they needed.

When the diamond capsules arrive at the lab, the silicon core is removed and the hollow sphere is filled with deuterium and tritium – heavy isotopes of hydrogen – with a small glass tube, which fuel the fusion reaction.

“Surrounding that fuel pill is a cylinder of gold and depleted uranium,” explained Mike Farrell, vice president of inertial fusion technology at General Atomics, the LLNL’s largest industrial partner.

The third and final layer of the capsule is an aluminum cylinder used to cool the contents before reaction.

Another critical area of ​​technology for NIF is optics: anything that enables the transmission, detection or use of light.

Operating the most powerful laser in the world, the NIF uses a lot of optical technology and its components are damaged every time the machine is turned on.

Since the early 1970s, NIF has worked closely with optical firms such as Zygo Corporation and specialty glass manufacturer SCHOTT to provide parts assembly, spare parts, and splinter and blast protection.

bring the future closer

Following the success of the December experiment, the NIF and its partners are taking on the new challenge of further refining the technology to mimic and improve the response.

Mike Farrell hopes this step forward will serve to promote support for future research.

“The experiment caused a paradigm shift in the scientific community. Ignition was considered almost unattainable or could not happen until 40 years in the future. The result in December was revealing.”

Back in Freiburg, Diamond Materials hopes to spend more time on research.

“About 20% of our team is involved in research and the two CEOs are physicists,” says Wild.

“Research at this level requires a lot of resources and we cannot neglect production. That is why we will probably continue to expand the team. After all, today’s research leads to tomorrow’s products.”

Teams of scientists from all over the world today strive to build a working fusion power plant, using a variety of techniques.

But reach the goal it will take many years and a multibillion-dollar investment.

Last year’s milestone in the NIF is likely to boost the industry, Farrell thinks: “Now that ignition has been shown to be possible, it might be easier to get government and corporate funding.”

This investment will be necessary to meet the major challenges of building a power plant, including finding materials that can withstand the extremely high temperatures released by the fusion process.

But Farrell says once the big first step is taken, the project can move forward quickly.