World’s Largest Laser Could Solve Our Energy Problems

Forbes

You’re probably familiar with lasers and you might even have a laser pointer lying around at home which fits nicely in your hands. But now, imagine a laser that is the size of three (American) football pitches. Pretty hard to imagine, right? This huge laser does exist though. It lives in the beautiful state of California in the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory. NIF is the largest laser facility in the world and has nearly 40,000 optics in it and 192 laser beams.

National Ignition Facility, LLNL

Part of the NIF laser system which leads into the target chamber.

National Ignition Facility, LLNL

The NIF facility is the size of three (American) football fields.

Why did scientists create such a powerful laser? Well, they want to create extreme conditions, just like the conditions within the core of the Sun. They want to harness the power of fusion, the process that powers our Sun and other stars, in order to create ‘clean’ energy to provide electricity for our world.

In a fusion reaction, small nuclei are joined together to form heavier nuclei. In the center of our Sun, there are types of hydrogen known as deuterium and tritium which combine to make helium, a neutron and some energy. Deuterium and tritium are just like hydrogen except they have an extra neutron or two.

Fusion for Energy

Deuterium and tritium fuse to form helium, a neutron and energy.

If you were to put the reactants and the products of a fusion reaction on a weighing scale you’d see that the reactants actually weighed more than the products. So, where is all this mass going? This is where Einstein’s famous equation, E = mc^2, comes in. This equation tells us that mass and energy are interchangeable. As a result, this ‘missing’ mass, is actually not missing, but has been converted into energy in the form of radiation. It is this energy that scientists want to harness and convert into electricity.

Recreating fusion in the lab is quite a challenge though. Fusion is a process that can only occur under extreme conditions of high temperatures and pressures. This is because nuclei are positively charged and repel each other. So, if you want them to fuse, you need to overcome this repulsive force known as the Coulomb force. Having conditions of high temperatures means the nuclei have sufficient kinetic energy to overcome this repulsion and fuse.

With lasers, scientists can recreate fusion reactions that occur within the center of the Sun and create the most extreme conditions on Earth. With the largest laser in the world, you can create temperatures of more than three million degrees Celsius. At this temperature, atoms can no longer exist. The electrons are stripped away from their respective nuclei and you’re left with a soup of ions and electrons – this is a plasma, the fourth state of matter.

At NIF, 192 high-power laser beams are focused onto a small target which vaporizes and turns into a plasma. This small cylindrical target, known as a hohlraum, contains deuterium and tritium, which, when heated with the 192 laser beams, turns into an x-ray oven. The target implodes and the deuterium and tritium are heated and compressed to incredible temperatures and pressures causing them to fuse. If done correctly, this fusion reaction could be self-sustaining and the energy produced from the reaction will be larger than the losses, a condition known as ignition. Hence why NIF is known as the National Ignition Facility.

National Ignition Facility, LLNL

A NIF hohlraum which contains the fusion fuel which is about the size of a pencil eraser.

Although NIF are yet to achieve ignition, scientists are working super hard to get there and maybe one day our electricity will come from ‘man-made’ fusion reactions . Watch this space.