As hero experiments go, the US Department of Energy's $4 bn (€3.1 bn) National Ignition Facility (NIF) is right up there with the biggest and best of them. When it's operating at full belt, the world's largest optical instrument – it's roughly the size of three football pitches – will combine 192 laser beams to generate a peak power of 500 trillion watts – 1000 times the electrical generating power of the US – and a pulse energy of 1.8 MJ of UV light.

By focusing the super laser onto a tiny pellet of hydrogen isotopes (deuterium and tritium), NIF scientists hope to initiate and study nuclear fusion reactions in the laboratory. In doing so, they will recreate the temperatures and pressures found in the cores of stars and giant planets, opening up the possibility for ground-breaking discoveries in planetary science and astrophysics. Those same fusion reactions are also the basis of the hydrogen bomb, which means that NIF will enable researchers to study nuclear weapons without actually testing any weapons.

The final element of NIF's remit, and some think the most important, is to carry out proof-of-principle research into energy generation from laser-driven fusion, work that could one day yield a limitless supply of carbon-free electric power. With experiments scheduled to begin next year to realize the critical step of scientific "breakeven" – the elusive goal of producing more fusion energy out than laser energy in – Breck Hitz met up with NIF director Edward Moses at the Lawrence Livermore National Laboratory in California to hear more about NIF's research programme and the benefits that could flow from it.

BH: Why is breakeven important?

EM: Breakeven is a major milestone on the path to fusion power for mankind. Fusion energy has a practically inexhaustible source of fuel – hydrogen, as in water – and produces negligible radioactive waste.
Ignition
Ignition

Most of the energy in the universe is the result of hydrogen fusion. Controlled fusion has never been performed on Earth in a manner that could be useful for energy generation, fundamental science or national security. NIF will be the first place, if everything goes as we think it will, that will demonstrate controlled nuclear burn.
"If everything goes as you think it will." So what might go wrong?

Controlled fusion has been a grand challenge for decades. People first started to think that it might be possible during the speculation era in the middle of the previous century. Then there was the evaluation era, when people started figuring out what kind of laser would be necessary to create controlled fusion. Thirty years ago, some people thought carbon-dioxide lasers might offer the best approach, because their photons are so inexpensive. We now know that the 10 µm wavelength is wholly unsuitable for fusion.

Today at Lawrence Livermore [the US government lab that is home to NIF], we have an operational facility that meets all of the requirements, as we understand them. We have targets that meet the specifications, we have all the diagnostics and cryogenics, we have the UV laser energy, and we are ready to begin an experimental campaign. When you look at all that, we believe we're on track. But there are still some physics issues to deal with.

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