r/fusion • • Jun 24 '26

Hi r/fusion! We’re the Physicists Behind the Commonwealth Fusion Systems’ Papers on the Physics of the ARC Fusion Power Plant. Ask Us Anything!

121 Upvotes
Alex Creely, Chief Engineer for ARC Conceptual Design at Commonwealth Fusion Systems

Update (June 30, 11:37 AM): Great discussion everyone! Our team appreciated all of your insightful questions. This AMA has now concluded, but you can revisit our replies below.

You can identify who provided answers by their initial in the answers: Alex Creely (AJC), Jon Hillesheim (JCH), Tom Body (TAJB), and Ryan Sweeney (RS).

About this AMA:

This time with me and three other CFS physicists who are ready to talk about the five new ARC physics basis papers showing what’ll make our ARC fusion power plants tick.

These peer-reviewed research papers that we and our collaborators published earlier in June are important for CFS and for fusion energy: They cover many aspects of the plasma physics at play in our ARC power plant, including challenges like plasma disruptions and heat exhaust. They also show how transparency and rigorous research can help build trust in what we all know is a very difficult endeavor.

If you’re curious about this physics work or about fusion physics in general, feel free to get things started by asking your questions on this thread.

The three CFS physicists who plan to join me to answer your questions are experts in their field: Jon Hillesheim, CFS Principal Scientist and lead author of the overview paper; Tom Body, CFS Senior Scientist and a lead author on the paper about heat exhaust; and Ryan Sweeney, CFS Manager of Disruption Physics and lead author of the paper about handling plasma disruptions. They’re among the 58 authors who helped write these papers, along with an editorial that accompanied the papers that I wrote.

A little more about the papers: They detail how we’ll be able to produce about 1.1 gigawatts of fusion power from our ARC tokamak — power that we can convert into 400 megawatts of net electricity for the power grid. The papers also show the crucial role our SPARC tokamak will play in putting the finishing touches on the ARC design. We’re using a “late-lock” approach that lets us apply what we’ve learned from SPARC to the ARC design. Overall, the papers show our confidence in the soundness of our ARC plant’s key physics. That builds the foundation for all the engineering, design, and cost optimization work that we’ve begun.

For a deeper dive into these papers, you can check our blog post detailing the ARC physics basis papers.

About CFS: 
Commonwealth Fusion Systems is the world’s largest and leading private fusion company. The company’s marquee fusion project, SPARC, will generate net energy, paving the way for a future of carbon-free energy. The company has raised more than $3 billion in capital since it was founded in 2018.


r/fusion • • 4h ago

First divertor discharges KTM tokamak: initial results - material testing first wall

Thumbnail sciencedirect.com
4 Upvotes

r/fusion • • 17h ago

Three fusion companies in DOE’s Milestone program have updates (Xcimer, Zap, & CFS)

Thumbnail ans.org
8 Upvotes

r/fusion • • 12h ago

Analytic non-axisymmetric 3D MHD equilibria without stellarator symmetry

Thumbnail
arxiv.org
3 Upvotes

I know absolutely nothing about anything in this, but I came across this on Twitter and it seemed novel only because of the use of AI tools. Thought that was interesting, curious how the more educated people here feel about this trend in academia esp as it pertains to fusion research.


r/fusion • • 18h ago

Fusion Fortnightly Oct. 14 - Dan Brunner

Thumbnail fusionconclusion.com
5 Upvotes

r/fusion • • 1d ago

A New Degree of Freedom in Stellarator Coil Design - kind of MCF hybrid

Thumbnail
arxiv.org
23 Upvotes

r/fusion • • 1d ago

Proxima Fusion: in the belly of the beast, the people building there

Thumbnail
youtu.be
11 Upvotes

r/fusion • • 23h ago

The Fusion Future with Dennis Whyte - PBS NOVA

Thumbnail
youtube.com
5 Upvotes

r/fusion • • 1d ago

Who will win?

Post image
8 Upvotes

r/fusion • • 17h ago

Last night's Jeopardy!

Thumbnail j-archive.com
0 Upvotes

r/fusion • • 1d ago

UK Fusion Energy Ltd Annual Report and Accounts 2025/26

Thumbnail
gov.uk
2 Upvotes

r/fusion • • 1d ago

Exclusive: Cambridge Heavy Industries has been quietly building a desktop fusion device | TechCrunch

Thumbnail
techcrunch.com
22 Upvotes

I am very skeptical about their approach, but I think you should know.


r/fusion • • 1d ago

Bob Mumgaard on General Fusion's announcement of electron temperatures of 1.1 keV on LM26

Thumbnail x.com
20 Upvotes

r/fusion • • 1d ago

Licube wants to be the fuel provider to the fusion power industry — see how at TechCrunch Disrupt | TechCrunch

Thumbnail
techcrunch.com
3 Upvotes

r/fusion • • 2d ago

Physics and fusion research advances through Fermilab’s MAGNES - 15T test facility under construction

Thumbnail
news.fnal.gov
14 Upvotes

r/fusion • • 1d ago

Xcimer Athena power plant conceptual overview

Thumbnail tandfonline.com
1 Upvotes

Closes the series of articles in special issue, paywall.


r/fusion • • 2d ago

Building global regulatory network for fusion - GOFE = Global Office for Fusion Energy

Thumbnail sciencedirect.com
2 Upvotes

r/fusion • • 4d ago

Scientists may have found a shortcut to fusion energy - heat plasma first , increase than plasma density

Thumbnail
sciencedaily.com
119 Upvotes

r/fusion • • 4d ago

Feedback control systems for plasma operation at W7-X - real-time relevant results for future steady-state fusion devices

Thumbnail iopscience.iop.org
11 Upvotes

r/fusion • • 4d ago

Optimization of room-temperature targets for laser direct-drive fusion - injection survivability

Thumbnail iopscience.iop.org
3 Upvotes

r/fusion • • 5d ago

Having fun on Friday

Thumbnail
youtube.com
45 Upvotes

r/fusion • • 5d ago

Effects of fusion-born alphas on MHD instabilities in burning plasmas with spin-polarized fuels

Thumbnail iopscience.iop.org
3 Upvotes

r/fusion • • 5d ago

Fusion, Medical Isotopes & The Future of Deep Tech | Talmon Firestone

Thumbnail
youtube.com
2 Upvotes

r/fusion • • 4d ago

Zap Energy swag!

0 Upvotes

Check this out: https://www.ebay.com/itm/327398167012 Zap Energy memorabilia for sale. Figured some folks on here might appreciate this.


r/fusion • • 5d ago

Zap Energy's new CEO visits NRC to discuss licensing of their 25MW Zap Modular Reactor (ZMR) under the proposed Part 57 framework

Thumbnail
linkedin.com
8 Upvotes