The United States' National Ignition Facility at the Lawrence Livermore National Lab, California, has fired the most powerful laser in history, a record-breaking two-megajoule shot. The laser was originally designed to reach 1.875 megajoules, but it beat everyone's expectations, setting a new world record.
192 laser beams combined into a single shot, initially reaching 1.875 megajoules. By the time it passed through its final focusing lens, the laser reached 2.03 megajoules, making it the world's first two-megajoule ultraviolet laser. The damage to the laser optics was less than predicted, which allowed the facility to fire another shot just 36 hours after the 2.03-megajoule one.
How it works
It all starts with a single laser, which is split into 48 separate beams. The beams are then redirected using mirrors into amplifiers — previously pumped by a total of 7680 Xenon flash lamps. After four bounces, they are further split into 192 rays through all the facility — which is the size of three football fields. As they travel through those endless tubes they will be amplified again at an exponential rate.
The result: from a tiny one billionth of a joule laser, the scientists at the National Ignition Facility obtains rays "a foot on their side" with a combined "1.8 million joules of ultraviolet energy", 1000 times the energy of all the power plants in the United States combined. Five trillion watts.
This time, the facility wasn't firing into any target. This will come later in the year, as the facility — which is supported by the US Nuclear Weapons Complex — races to achieve ignition in its first nuclear fusion experiment.
When that happens, the lasers will compress this frozen hydrogen fuel cell, which will be enclosed in a gold-plated cylinder called the hohlraum. The hohlraum is located inside the 10m diameter ignition chamber, and it will transforms the lasers into extremely intense X-rays, compressing the hydrogen at one hundred billion atmospheres in just 1/1,000,000 of a second.
This will trigger a controlled nuclear fusion reaction that will create a small star, hopefully generating more power than the energy used to fire the laser and contain the intense heat inside the chamber.
According to Ed Moses — director of the National Ignition Faciliy — "it's a remarkable demonstration of the laser from the standpoint of its energy, its precision, its power and its availability." [National Ignition Facility via Nature via Physorg]