Nuclear fusion succeeded: "This is comparable to the first flight of the Wright brothers"

Created: 2022-12-14 07:13

By: Dominik Goettler

To put it in the word of the year, a turning point has been achieved in the USA.

For the first time ever, nuclear fusion has generated more electricity on Earth than was supplied.

Munich – Professor Markus Roth, 57, is a physicist and an expert in laser fusion research at the TU Darmstadt.

He was involved in the construction of the laser system for the research project in the USA in the 1990s and has been in close contact with the local scientists ever since.

In an interview, he explains how the latest experiment went - and what the result means for the construction of a fusion power plant.

Mr. Roth, are we currently experiencing the big breakthrough in nuclear fusion?

Roth:

In science, we always have a hard time with the big breakthrough.

But it sure is a huge step forward.

After many decades of research, for the first time it has been possible to get more energy out of a controlled fusion than was put into it.

Many say: This is comparable to the first flight of the Wright brothers.

You knew beforehand that you could fly with wings.

But then it really worked for the first time.

Explain to us in simple terms: how does nuclear fusion work?

Roth:

In contrast to nuclear fission, fusion fuses two light atoms together, creating a heavy one.

This fusion can only work if the particles are held together under high temperatures.

And there are two ways: laser or magnet.

Roth:

Our colleagues from magnetic fusion try to hold together a very thin plasma with magnetic fields for a very long time.

And we at laser fusion are trying to compress a hot gas extremely hard so that the distances between the particles become very short.

And then the reaction happens so fast that the mass's own inertia keeps the particles together long enough to fuse.

Nuclear fusion in the USA: Energy gain by a factor of 1.5

How exactly did the current experiment in the USA work?

Roth:

A small plastic bead, two millimeters in diameter, was used.

There hydrogen was filled as fuel.

This bead is locked in a hollow cylinder made of a gold mixture.

Then 192 laser beams are radiated into this cylinder from both sides, thus heating up the furnace, so to speak.

The pellet gets so hot on the outside that it explodes.

And the recoil of that explosion accelerates the particles in the sphere inward.

When this mass meets inside the sphere, there are densities thousands of solid densities, pressures of 500 billion atmospheres, and a temperature of about 140 million degrees.

This is how the fusion reaction ignites.

And so the energy is released.

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To what extent did this succeed in the USA?

Roth:

In this case, it was three megajoules of energy, compared to two megajoules that you put in via the laser.

So you have achieved an energy gain of a factor of 1.5.

And that's a first.

What does this mean for further research on the way to a fusion power plant?

Roth:

There are still several steps to go before a power plant can be built.

The American process is excellent for experiments and basic research, but it is still too inefficient for a power plant.

The aim is to dispense with the furnace – i.e. the cylinder – and to irradiate the sphere directly.

In this way, 90 percent losses in the laser energy used can be saved.

Then there are already more efficient methods of ignition, which we are currently testing, as well as more modern lasers.

This also saves more energy.

And the laser systems in a power plant don't even have to fire every two hours, as they do in the USA, but ten times a second.

So there is still room for improvement.

But the technology is known.

And by the way, it is also developed in Germany.

Markus Roth from the TU Darmstadt, an expert in laser fusion.

© private

The first plant on the grid is planned for 2037/38

The experiments in the USA originally come from military research.

Roth:

Yes, the money would probably not have been spent on civilian research in the USA.

By when can we realistically expect a nuclear fusion power plant?

Roth:

We founded an American-German startup called “Focused Energy” here in Darmstadt, which is working on exactly this project.

Incidentally, also with former employees from the research team in the USA.

We have submitted a roadmap to the federal government.

We will still need a few test plants, but the goal is to have the first plant connected to the grid by 2037/38.

Only then will we have the chance to do something to combat climate change.

The big debate in current nuclear power plants is about safety.

What about fusion power plants?

Roth:

The first big difference: the radioactive material.

In nuclear fission, that's about 130 tons per reactor charge.

In laser fusion we use tritium, a radioactive gas that has already decayed in half after ten years.

There is a maximum of one to two milligrams of this in the reactor at any time.

The total radioactive inventory in a fusion power plant is between one and two kilograms.

So very small amounts.

The English government has therefore decided to completely remove future fusion power plants from nuclear law and to place them in the area of ​​health and the environment.

Because she says the potential danger corresponds to that of a tumor therapy facility.

What is left when a fusion power plant shuts down?

Roth:

The reactor itself.

It has become radioactive and must be temporarily stored for 50 to a maximum of 100 years.

After that, the radioactivity has decayed and the material can be reused.

And in case of an accident?

Roth:

Cannot trigger an uncontrolled chain reaction.

And there is no afterheat.

With the current nuclear power plants, the reactors have to be cooled for days, even when they are off.

In a fusion power plant, there is nothing that could give off heat.

That's what makes it so safe.

Has laser fusion won the race against magnetic fusion?

Roth:

The race is won by whoever connects the first power plant to the grid.

We're a bit ahead at the moment.

But I don't see us as competitors, but as partners.

The market is so big that we need both technologies.

I see this as friendly competition.

The interview was conducted by Dominik Göttler