NIF Experiment Puts Researchers at Threshold of Fusion Ignition
This week everyone’s been talking about the news from the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory—their laser fusion experiment has achieved a fusion energy release of 1.3 mega joules (MJ). So, what have they done and why does it matter?
What have they done?
Scientists at NIF have made a significant step towards achieving “ignition”—this is when the fusion reaction become self-sustaining and you get more energy out of the reactions than is put in to trigger them. It’s a bit like lighting a fire. You can strike a match and get a flame, but you really want to get enough energy concentrated in the centre that it will get the logs to burn and keep burning.
Why is the NIF result impressive?
They have got 1.3MJ of energy out of the fuel pellet, which they say is an energy gain of 0.7 (energy out/energy in). This is about the same gain as the JET tokamak achieved in 1997. But they have been making really fast progress. This result is an 8-fold improvement over experiments they did just this Spring. If they keep it up, they could be achieving ignition sometime soon (whenever they do their next experiments).
Why is it important?
Demonstrating ignition, or getting more energy out of fusion reactions than is put in, is an important stepping stone on the path to developing and commercialising fusion as a clean energy source. Fusion would produce reliable, non-variable, abundant energy without greenhouse gases, so it’s pretty important to our security on this planet that we develop it.
There’s still a lot to do. These measurements look at the amount of energy going into the fuel versus the energy coming out. It takes many times, perhaps hundreds of times, more energy to drive the huge lasers that initiate the fusion. Justin Ball showed a good graphic about this in a recent tweet, and how the numbers compare to JET. And then it's just a step on the pathway towards commercialisation and actually building a power station. But it's an important one, so it's really exciting!
The community has a plan for how to move from the demonstration of ignition to fusion energy, which includes increasing the energy of the lasers, improving understanding of the fusion physics to increase efficiency, etc. The UK community has a roadmap that gives some details of their recommendations to 2035.
Demonstrating that fusion energy can work, by demonstrating ignition, is an important step on the way to commercial fusion energy. We look forward to seeing more progress!