National Ignition Facility Announces Milestone in Quest For Nuclear Fusion
Posted on February 14, 2014
Researchers at the National Ignition Facility announced a successful step toward ignition in the quest for nuclear fusion. The NIF says it has reached an "alpha particle self-heating goal." The NIF Target Chamber is pictured above.
During experiments, NIF's 192 intense laser beams can focus over 1.8 million joules of ultraviolet laser energy and 500 trillion watts of power in billionth-of-a-second pulses on a small BB-size target inside the chamber. Pulses from the NIF's high-powered lasers race toward the Target Bay at the speed of light. The NIF says the set-up is designed to create "a miniature star on Earth" inside the chamber.
In the successful experiment, researchers zapped a pellet of fuel with the NIF's high-powered lasers. They managed to get more energy out of the fuel core than went into it. The energy generated through fusion reactions exceeded the amount of energy deposited into the fusion fuel. The scientists say this is the first time fuel gain has exceeded unity in an inertially confined fusion implosion. It is not ignition, which is when the reaction fuels itself, but it is a step toward it. Ignition is the ultimate goal of the NIF.
The breakthrough was reported in the Washington Post and published here in Nature.
The scientists say in the Nature paper, "These experiments show an order-of-magnitude improvement in yield performance over past deuterium-tritium implosion experiments. We also see a significant contribution to the yield from α-particle self-heating and evidence for the 'bootstrapping' required to accelerate the deuterium-tritium fusion burn to eventually 'run away' and ignite."
Omar Hurricane, lead author of the Nature paper, says in a release, "What's really exciting is that we are seeing a steadily increasing contribution to the yield coming from the boot-strapping process we call alpha-particle self-heating as we push the implosion a little harder each time."
The scientists say the experimental results this time matched computer simulations much better than previous experiments. This will give them a better benchmark for predicting the behavior of matter under conditions similar to that of a nuclear explosion.