Apparently what a fusion power plant should look like

Less Than 10 Years? Commonwealth Fusion Systems Applies To Plug Into Grid In 2030s

June 7, 2026 by 40 Comments

Whenever the topic of fusion power comes up, someone will say it’s only 10 years away from commercialization in an excited tone, and someone older or more cynical will point out that it’s been 10 years away since Eisenhower was president. So it’s with a certain-sized crystal of sodium chloride that we share the news here that the US-based Commonwealth Fusion Systems is applying to feed 400MWe into the grid there by the early 2030s.

The early 2030s is, notably, less than ten years from now.

Commonwealth Fusion Systems isn’t a bunch of nobodies out to suck up venture capital; they’re a talented group of researchers from MIT’s well-known plasma laboratory out to suck up lots of venture capital and hopefully build reactors along the way. So far, the second part is going better than the first: they’ve raised a couple billion dollars, which has let them make great strides in building their SPARC reactor– like crafting the big magnet we told you about in 2021. As that article describes, SPARC is the precursor to the later, larger ARC reactor they hope to hook to the grid in slightly under a decade. Alas, SPARC remains under construction as of this writing. ARC is evidently in the final planning stages, with a physical location determined and grid-tie applied for at the “Fall Line Fusion Power Station” in Virginia.

CFS’s reactors are of the Tokamak type that has been favoured at universities since the 1970s. From China to Europe’s ITER who are also planning to produce power before another decade passes— though not, notably, into a power grid. While promising, Tokamaks aren’t the only game in town, either– steampunk startup General Fusion started making plasma last year, though while if it works it has some big advantages, that one is probably the traditional “ten years away” still.

What do you think? Will fusion power be in the grid before humans make it back to the moon? Add the flying-car potential of eVTOL and we might finally get close to the future we were promised.

A diagram of a neutron generator is shown in the top portion of the image, with the physical version below.

A Benchtop Neutron Generator For The Home Reactor

May 25, 2026 by 19 Comments

There are a surprising number of experiments an amateur nuclear physicist can perform, from making a Geiger counter to fusing hydrogen atoms in a fusor. One project which we haven’t seen before is a neutron generator, such as the benchtop neutron generator made by [Rapp Instruments] (translated).

This particular generator takes a feedstock of pure deuterium, which it ionizes and accelerates into a titanium target. The first deuterium nuclei to hit the target react with it to form titanium deuteride, immobilizing them until more ions strike them and they undergo nuclear fusion. The fusion reaction mostly forms helium-4, but sometimes forms helium-3 and a free neutron, which is radiated away. The radiated neutrons are slowed down by a block of high-density polyethylene, and a portion of them strike a silver or indium foil wrapped around a Geiger counter tube. The neutrons activate the silver or indium, and the Geiger counter detects the resultant increase in radioactivity.

The design is a linear particle accelerator built inside an evacuated glass tube. It uses two high-voltage power supplies: a 20 kV supply which ionizes the deuterium gas fed into the tube, and a 100 kV supply which accelerates ions emitted from the source into the target. The target itself is surrounded by a cup-shaped electrode to capture secondary electrons emitted during impact. To prevent arcing, the tube needs to be at a very low pressure, reached by extensive use of an oil diffusion pump.

Radioactivity measurements of the silver and indium foils showed that the generator did work; when irradiating the silver foil for five minutes, it generated 175 counts per second after the neutron source was turned off. Plotting the count rate versus time suggested that a mixture of two silver isotopes was being generated, Ag-110 and Ag-108, based on their half-lives. Irradiation of indium produced a similar exponential decay in radiation.

We recommend checking out the rest of the site; it’s a gold mine of projects, such as this mass spectrometer. For more background on neutron generators, we’ve covered their theory and some of the more common varieties.

View inside the vacuum vessel of Wendelstein 7-X in Greifswald, Germany. (Credit: Jan Hosan, MPI for Plasma Physics)

Wendelstein 7-X Sets New Record For The Nuclear Fusion Triple Product

July 15, 2025 by 36 Comments

Fusion product against duration, showing the Lawson criterion progress. (Credit: Dinklage et al., 2024, MPI for Plasma Physics)
Fusion product against duration, showing the Lawson criterion progress. (Credit: Dinklage et al., 2024, MPI for Plasma Physics)

In nuclear fusion, the triple product – also known as the Lawson criterion – defines the point at which a nuclear fusion reaction produces more power than is needed to sustain the fusion reaction. Recently the German Wendelstein 7-X stellarator managed to hit new records here during its most recent OP 2.3 experimental campaign, courtesy of a frozen hydrogen pellet injector developed by the US Department of Energy’s Oak Ridge National Laboratory. With this injector the stellarator was able to sustain plasma for over 43 seconds as microwaves heated the freshly injected pellets.

Although the W7-X team was informed later that the recently decommissioned UK-based JET tokamak had achieved a similar triple product during its last – so far unpublished – runs, it’s of note that the JET tokamak had triple the plasma volume. Having a larger plasma volume makes such an achievement significantly easier due to inherently less heat loss, which arguably makes the W7-X achievement more noteworthy.

The triple product is also just one of the many ways to measure progress in commercial nuclear fusion, with fusion reactors dealing with considerations like low- and high-confinement mode, plasma instabilities like ELMs and the Greenwald Density Limit, as we previously covered. Here stellarators also seem to have a leg up on tokamaks, with the proposed SQuID stellarator design conceivably leap-frogging the latter based on all the lessons learned from W7-X.

Top image: Inside the vacuum vessel of Wendelstein 7-X. (Credit: Jan Hosan, MPI for Plasma Physics)

General Fusion Claims Success With Magnetized Target Fusion

March 27, 2025 by 21 Comments

It’s rarely appreciated just how much more complicated nuclear fusion is than nuclear fission. Whereas the latter involves a process that happens all around us without any human involvement, and where the main challenge is to keep the nuclear chain reaction within safe bounds, nuclear fusion means making atoms do something that goes against their very nature, outside of a star’s interior.

Fusing helium isotopes can be done on Earth fairly readily these days, but doing it in a way that’s repeatable — bombs don’t count — and in a way that makes economical sense is trickier. As covered previously, plasma stability is a problem with the popular approach of tokamak-based magnetic confinement fusion (MCF). Although this core problem has now been largely addressed, and stellarators are mostly unbothered by this particular problem, a Canadian start-up figures that they can do even better, in the form of a nuclear fusion reactors based around the principle of magnetized target fusion (MTF).

Although General Fusion’s piston-based fusion reactor has people mostly very confused, MTF is based on real physics and with GF’s current LM26 prototype having recently achieved first plasma, this seems like an excellent time to ask the question of what MTF is, and whether it can truly compete billion-dollar tokamak-based projects.

Continue reading “General Fusion Claims Success With Magnetized Target Fusion” →

China Claims Commercial Nuclear Fusion By 2050 As Germany Goes Stellarator

March 5, 2025 by 49 Comments

Things are heating up in the world of nuclear fusion research, with most fundamental issues resolved and an increasing rate of announcements being made regarding commercial fusion power. China’s CNNC is one of the most recent voices here, with their statement that they expect to have commercial nuclear fusion plants online by 2050. Although scarce on details, China is one of the leading nations when it comes to nuclear fusion research, with multiple large tokamaks, including the HL-2M and the upcoming CFETR which we covered a few years ago.

Stellaris stellarator. (Credit: Proxima Fusion)

In addition to China’s fusion-related news, a German startup called Proxima Fusion announced their Stellaris commercial fusion plant design concept, with a targeted grid connection by the 2030s. Of note is that this involves a stellarator design, which has the major advantage of inherent plasma stability, dodging the confinement mode and Greenwald density issues that plague tokamaks. The Stellaris design is an evolution of the famous Wendelstein 7-X research stellarator at the Max Planck Institute.

While Wendelstein 7-X was not designed to produce power, it features everything from the complex coiled design and cooled divertors plus demonstrated long-term operation that a commercial reactor would need. This makes it quite likely that the coming decades we’ll be seeing the end spurt for commercial fusion power, with conceivably stellarators being the unlikely winner long before tokamaks cross the finish line.

Repeatable “One-Click” Fusion, From Your Cellphone

July 6, 2024 by 22 Comments

Sometimes you spend so much time building and operating your nuclear fusor that you neglect the creature comforts, like a simple fusion control profile or a cellphone app to remote control the whole setup. No worries, [Nate Sales] has your back with his openreactor project, your one-click fusion solution!

An inertial electrostatic confinement (IEC) fusor is perhaps the easiest type of fusion for the home gamer, but that’s not the same thing as saying that building and running one is easy. It requires high vacuum, high voltage, and the controlled introduction of deuterium into the chamber. And because it’s real-deal fusion, it’s giving off neutrons, which means that you don’t want to be standing on the wrong side of the lead shielding. This is where remote control is paramount.

While this isn’t an automation problem that many people will be having, to put it lightly, it’s awesome that [Nate] shared his solution with us all. Sure, if you’re running a different turbo pump or flow controller, you might have some hacking to do, but at least you’ve got a start. And if you’re simply curious about fusion on a hobby scale, his repo is full of interesting details, from the inside.

And while this sounds far out, fusion at home is surprisingly attainable. Heck, if a 12-year old or even a YouTuber can do it, so can you! And now the software shouldn’t stand in your way.

Thanks [Anon] for the tip!

Can We Ever Achieve Fusion Power?

June 29, 2024 by 51 Comments

Fusion power has long held the promise of delivering near-endless energy without as many unfortunate side effects as nuclear fission. But despite huge investment and some fascinating science, the old adage about practical power generation being 20 years away seems just as true as ever. But is that really the case? [Brian Potter] has written a review article for Construction Physics, which takes us through the decades of fusion research.

For a start, it’s fascinating to learn about the many historical fusion process, the magnetic pinch, the stelarator, and finally the basis of many modern reactors, the tokamak. He demonstrates that we’ve made an impressive amount of progress, but at the same time warns against misleading comparisons. There’s a graph comparing fusion progress with Moore’s Law that he debunks, but he ends on a positive note. Who knows, we might not need a Mr. Fusion to arrive from the future after all!

Fusion reactors are surprisingly easy to make, assuming you don’t mind putting far more energy in than you’d ever receive in return. We’ve featured more than one Farnsworth fusor over the years.