3 Key Insights - Enabling Technologies for Fusion
In our second member Q&A session of 2024 on the 17th April, we discussed enabling technologies for fusion – what are they and what recent progress has been made. Our experts were Rajesh Maingi and Michael Ford from the Princeton Plasma Physics Laboratory (PPPL), with a focus on magnetic confinement fusion.
Rajesh and Michael spoke about how we are edging closer to realised fusion power, but that there are critical ‘game changing’ technologies which will enable fusion power plants.
Here are three key insights from the event.
1. There are 4 identified Transformative Enabling Capabilities that could be game-changers for fusion energy development
The 4 Transformative Enabling Capabilities (TECs) are:
· Advanced algorithms
· High critical-temperature superconductors
· Advanced materials
· Novel technologies in tritium fuel cycle control
And a Tier II fifth one, which is Fast flowing liquid metal plasma-facing components.
2. One important knowledge gap when it comes to building smaller magnetic confinement fusion systems is how to deal with the amount of power on the machine walls
Rajesh says: “You might be able to increase the confinement in the plasma. And basically, the confinement is—if I put heat in, how long does the plasma hold on to that heat before it leaks out? And the longer you hold on to the heat, then the less auxiliary heat that you need to put in and the smaller you can make your system because of the way that the fusion reactors work. So if you're successful at doing that, and you can create a more compact system, (if you're generating, in essence, close to the same amount of power) you end up putting more of a stress on the components on the wall.”
Fusion device designs favoured by private companies are smaller, more compact systems, so this will be an issue.
Rajesh says: “If you do nothing to mitigate the heat flux, and all of it goes to the wall, it tends to concentrate, and the numbers that you get are 500 to 1500 megawatts per meter squared—that's 50 to 150 times what we think can be handled by pristine solids like tungsten.”
He continues that if we put impurities into the plasma we can radiate power away, which is desirable for technical reasons. But it’s important to radiate power from the edge of the plasma, not the centre, because radiating power from the centre of the plasma will cool it down and slow the fusion reactions.
“So the question is,” asks Rajesh, “how much [impurity] do you have to put in? And can you have a self-consistent system that lets you generate the power in the core and radiate the power in the edge, and it all hangs together? We call this a core-edge integration problem. And that's what I think is one of the biggest challenges that we've got in fusion.”
3. There is potential to use AI and machine learning to accelerate materials selection and development for fusion
Mike talked about the Workshop for Applied Nuclear Data Activities (WANDA)—a US led effort that tries to collect the data on all materials testing, with a heavy emphasis on radiation effects. Most of their efforts so far have been tied to fission and space, but this year’s workshop was all about nuclear data for fusion.
According to Mike, an assessment from WANDA was that “there is an avenue for taking some of our understanding, that came from prior tests, and perhaps accelerating the pace of the development and understanding through use of AI/ML. But ultimately, it's still going to require some experimental validation and test that we're going to have to have.”
Mike relayed that people within the nuclear data community felt that there were test devices around the world that could be brought to bear to help accelerate the pace of experimentation in this area.
They couldn't do testing with 14 MeV fusion neutrons, but, says Mike, “there are other, more limited, testing that you could do to get some idea that would be a pointer, and then you could apply these AI/ML methods to say which things could I perhaps work with as my first generation.”
It's likely that companies will follow a generational way of development for fusion devices—starting with materials that scientists think would be the best to use today, and building with those materials with an understanding that there’ll be subsequent, improved, generations as more data is collected and understanding increases.
“That's the method I think we're going to have to follow,” says Mike. “Because if we wait until we have absolute certainty that the material is going to last for, you know, 30 years, we'll wait 30 years to build anything, and we can't do that. So we should build early, test, maybe accept the lower availability.”
And finally…
Rajesh and Mike stated that we are closer to fusion than ever before: “harnessing fusion energy is now within reach more than ever, this is due to continuous worldwide public efforts and… ‘exploding’ private efforts.” But transformative enabling capabilities can accelerate the progress to fusion energy realisation and there should be continued focusing of resources in these areas for further progress.