Seeing the light

When scientists first glimpsed the possibility of opening up new knowledge about the universe through ultra-powerful lasers, they faced a challenge: no laser at the time was remotely powerful enough. But ten years later, Thales has brought them to the verge of realising their vision.

 

The pioneering laser system Thales has developed promises to push back the frontiers of physics. And it holds the key to breakthroughs in many other fields, from cancer treatments and imaging to nuclear waste disposal.

 

To get to this point, Thales built a close relationship with its client to overcome the challenges that inevitably come with breaking new ground. And the team focused all their ingenuity on helping the client achieve their ambition on time, and on budget.

 

Setting a bold vision

Around a decade ago, scientists saw the opportunity to push back the boundaries of fundamental physics by using extreme light to interact with matter. By using lasers to generate up to a tenth of the power of the sun, they hoped to replicate the energy behind the big bang.

 

The result they envisaged would be nothing less than new knowledge about the origins of the universe. It would also be a much smaller and less costly alternative to the largest particle colliders. Instead of accelerating particles over tens of kilometres, they’d have light acting on matter over a few centimetres.

 

Professor Nicolae-Victor Zamfir and his team at the Institute of Nuclear Physics in Romania successfully bid for around €300m in European Union funding to realise the vision. With extra support from the Romanian government, they launched Extreme Light Infrastructure Nuclear Physics (ELI-NP). In the process, they catapulted their country to the centre of this scientific world.

 

Setting a new standard

At about the same time as Prof Zamfir and his team were bidding for their funding, in labs at Berkeley in the US, Thales experts led by Francois Lureau were working on a new laser system. In 2012, it would set a world record. For a femtosecond – a millionth of a billionth of a second – it generated 1 PetaWatt of power – equivalent to over 1,200 times the electrical generating capacity of the US.

 

Rethinking possibilities

But ELI-NP’s target was a laser ten times more powerful than even this. So Thales worked with them and other international scientists and laser experts to define what was possible, and how to make it happen. Hundreds of scientists from labs all over the world helped to shape the brief for the new system. And Thales helped point the way to building it.

 

Then, in 2013, Thales won the competitive bid for the chance to put their ideas into action.

 

Prof Zamfir says: ‘It needed a big company with big expertise. If anyone in the world could do it, it was Thales.’

 

The journey

Thales designed and developed the system in France. It’s made up of several elements. An OPCPA front end generates a high-quality laser pulse, but with low energy. The laser pulse is then amplified through several stages of high-energy ‘pump’ lasers and titanium sapphire crystals. These crystals absorb the light coming from the pump lasers, storing its energy and transferring it to the laser pulse. Once the energy level is high enough and the laser pulse has been compressed by refractive optical gratings, the system can create the ultra-short pulses of peak power that ELI-NP needs.

 

New results need new components

The new system needed groups of larger-than-ever pump lasers, which Thales developed specially for the job. And it needed new larger optical gratings up to 1 metre wide.

 

But most urgently, it needed a 200mm diameter titanium sapphire crystal - twice as big as its US supplier had ever produced. Without such a large crystal, Thales wouldn’t be able to generate enough energy. From the time Thales was awarded the ELI-NP work in 2013, the team  worked intensively with their supplier on how to overcome the challenge of growing the crystal. That included building a strong team spirit between Thales and the supplier's scientists. ‘I travelled to the supplier’s factory every three months until 2018, when the crystals were ready,’ says Francois Lureau.

 

A new system needs a new kind of home

ELI NP created its purpose-built centre near Bucharest with detailed input from Thales. Across the laser system’s 200m length, vibration can’t vary by more than 1 micron. So the laser platform is underpinned by springs and dampers that decouple it from the building. But the system is still so sensitive to vibration that high-heeled shoes aren’t allowed in the laser hall.

 

The facility also needs an unusual amount of power, which comes from its own 5 megawatt geothermic power station. It uses heat pumps to draw energy from springs 120m underground.

 

As well as this, the centre has protection to keep radioactivity, and electro-magnetic waves, in. The 2,400m2 laser hall needs precisely controlled temperature and humidity, as well as two hours a day of cleaning to stop dust reaching the laser optics. Testing alone took four months.

 

 

A new field needs new experts

With the Thales system in place from 2016, ELI-NP needed a local team to prepare it for its task. ‘We looked for graduates with potential, who we could train in France,’ said Francois Lureau. The local laser team is now five-strong, including a software engineer and two people working on the transport of the beam to its target.

 

Thales is now working with ELI-NP on how to recruit and train the larger team to operate the system after it goes live in 2019. It’s no simple task, says Prof Zamfir: ‘We can’t hire ten experts in 10 PetaWatt lasers, because they don’t exist. Instead, we must decide what background they should have, and how to train them. It’s new territory for Thales too, and together we have to find the solution to meet our common goal.’

 

Reaping rewards

In May 2018, five years into the partnership with ELI NP, the Thales team successfully generated 3 PetaWatts of power. They expect to reach 10 PetaWatts later in the year, by bringing the full system online. And the facility will welcome the first international researchers in 2020.

 

Seeing the future

What happens next is down to the results of early experiments, and where the research community wants to focus its work. ‘It’s difficult to be Jules Verne and have the imagination to see what will happen with a tool that doesn’t yet exist,’ says Prof Zamfir. But he’s excited by the prospect, especially the idea that new discoveries could turn his own field of nuclear physics on its head.

 

‘It’s possible that everything I’ve learned about nuclear reactions won’t be valid anymore,’ he says. ‘This is a completely new toy, a new method of investigating. That’s why there’s so much excitement.’

 

There’s much more potential besides, particularly where lasers could take over from particle colliders and ‘where there’s a societal interest’, says Prof Zamfir. That could mean smaller, cheaper proton treatments for cancer, where beams attack tumours but minimise damage to healthy tissue. It could also mean much better management of radioactive waste, reducing isotopes’ lives from thousands of years to a matter of days. And it could mean new ways to test materials for space missions.

 

The new centre is also likely to halt the brain drain of scientists from behind the former iron curtain. Research infrastructure on this scale puts Romania at the heart of international scientific collaboration. ‘Every young student wants to go where there’s the biggest chance of winning a Nobel Prize, and that chance is in the biggest laboratories,’ says Prof Zamfir.

 

It’s a prospect many may find hard to resist: ‘As kids, we probably all try to start a fire concentrating light on dried leaves with a magnifying glass. Here we’re doing that with 10% of the sun’s power.’

 

Working together today and tomorrow

Prof Zamfir says ElI NP and Thales are a ‘perfect couple’. He adds: ‘We had the courage to think of building a 10 PetaWatt laser. Thales had the courage to take on the challenge of creating it and solving the bottlenecks, and they did it on time.

 

‘Ten years ago, a high-powered laser like this was a dream. Now it’s working.’