Photo: The KSTAR tokamak at the Korea Institute of Fusion Technology created its first plasma in 2008. Credit: ITER
Last year, I wrote an open letter to the fusion industry outlining six fusion energy milestones every company must pass to succeed to commercialize this technology. My goal is to help investors, policymakers, journalists, analysts, and tech enthusiasts better understand what can be baffling science and technology. No one should need a plasma physics PhD to understand our industry.
With venture funding flowing into fusion, now is an important time to keep cutting through the hype and tracking what actually matters. Over the coming weeks, I’ll dig deeper into each milestone in the letter to help explain this.
Here’s a closer look at the first milestone:
Can you produce a stable plasma?
When you make a gas hot enough, the energy rips electrons and nuclei apart to form a plasma. Now you have a new state of matter — and new effects. One major effect is that the plasma is usually unstable. Holding it together is like holding jello with rubber bands. It wants to wriggle and squirt.
For fusion to work in a plasma, it has to be stable enough to do the things you want to do with it, for example insulate it and study it and have it make enough energy to be useful. A transient plasma blip or spark just one time doesn’t cut it. The first 20 years of fusion research from the 1940s to the 1960s focused on creating plasmas that could exist for more than a microsecond and on doing that over and over so we could get an understanding of them. Based on this learning of what plasmas like and don’t like, we now have a much better framework, and we can predict plasma stability with high accuracy using computer software. These principles are taught in the first year of grad school courses.
Some plasma shapes are more stable than others, some are stable enough to compress, and some are stable enough to last for minutes. Ultimately, this is the threshold where a fusion “architecture” is now a candidate for further experimentation.
Making a plasma stable enough for experiments
So how stable is stable enough for this first milestone? It must be stable enough to measure and experiment on. A plasma concept goes from a paper exercise to reality when it’s repeatable, measurable, and stable enough for the next step — heating it up even more. This doesn’t need to be super long. Even a fraction of a second suffices. But if the plasma you sketched on a napkin fizzles out in a microsecond, you’re not going to be able to make it hot enough to study.
The type of fusion device we’ve chosen at Commonwealth Fusion Systems, called a tokamak, first produced a stable plasma in 1968. Other fusion machines also have passed this milestone, including stellarators, mirrors, field-reverse configuration (FRC) devices, laser-imploded pellets, and recently the Z-pinch. Once researchers show a fusion machine architecture to be stable, many people can use it and study it.
We used to watch plasmas go unstable in microseconds. Not any longer!
It’s a testament to the scientific endeavor that in a single working lifetime, we went from no plasma stable enough to form fusion architectures to about a dozen. This gives fusion its many options.
Provide the proof
If your plasma architecture has passed the first milestone, it’s on you to prove it. That means photos and other high-quality diagnostics documented in research papers that independent experts can assess. When you do this, you’ll get the applause you deserve.
A recent example of passing this milestone is the University of Wisconsin’s WHAM experiment getting its first plasma — a repeatable process with plasma that was stable enough to measure and improve. And the team had the data to prove it. Other researchers pursuing this magnetic mirror approach had cleared this milestone a long time ago, but this new experiment clears the way for their next step.
Stay tuned for details on that second milestone: getting that plasma seriously hot.
