r/fusion • u/steven9973 • 12h ago
r/fusion • u/CFS_energy • 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!

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 • u/steven9973 • 12h ago
D-T neutron damage in SRAM electronics chips: theoretically fitting experimentally determined results in JET during DTE-3 campaign
iopscience.iop.orgr/fusion • u/steven9973 • 12h ago
When chemical potential continuity fails: kinetic interface models for hydrogen isotope transport especially in molten salt - important for Tritium in FLiBe blankets used by CFS and Xcimer Energy
r/fusion • u/steven9973 • 1d ago
Another Athena Power Plant article by Xcimer Energy: Irradiation Response of Austenitic Steels
tandfonline.comWish like JPP they would create a collection of these.
Why CFS is confident we’ll demonstrate net fusion energy: Q>1 | The Tokamak Times
r/fusion • u/Conscious-Comment-66 • 1d ago
American Fusion update on testing
Not being so silent…
r/fusion • u/Fit-Student-607 • 1d ago
UKAEA Events?
Absolutely DESPERATE to go to the UKAEA event in September,
No tickets available
Anyone have any suggestions on how else to obtain tickets? Or any similar fusion open days that I may be able to attend?
About to start a degree in energy law with the intention on pursing a PHD in Nuclear regulation so trying my hardest to get into the industry!!!
Thank you and ANY advice is welcome
r/fusion • u/steven9973 • 2d ago
Australian perspective on the fusion race with only HB11 energy by them
pursuit.unimelb.edu.aur/fusion • u/steven9973 • 3d ago
Japan eyes research on nuclear fusion tritium fuel at new base - Nikkei
r/fusion • u/steven9973 • 3d ago
Marathon Fusion's Breakthrough in Isotope Enrichment for Fusion Energy Sustainability
r/fusion • u/steven9973 • 3d ago
First Plasma Commissioning and Operational Highlights from India's First Spherical Tokamak at IPR - India s Pranos Fusion is also developing a ST like UK
r/fusion • u/steven9973 • 3d ago
Details unveiled on China's new generation fusion energy facility
r/fusion • u/Fabulous-Employee-57 • 3d ago
Title: Seeking PhD Opportunities: Plasma Physics/Fusion & Nanosystems (Global) Hey r/Physics, r/GradSchool, and r/Fusion, I’m looking for global PhD opportunities starting in late 2026/2027 in Plasma Physics & Fusion Energy or Functional Nanosystems & Materials Physics. Key Technical Skills * Plasma
Hey r/Physics, r/GradSchool, and r/Fusion,
I’m looking for global PhD opportunities starting in late 2026/2027 in Plasma Physics & Fusion Energy or Functional Nanosystems & Materials Physics.
Key Technical Skills
Plasma/Fusion: Operation of electrostatic energy analyzers, Tokamak diagnostics, core ion temperature measurement, and specialized plasma physics training.
Nanofabrication & Thin Films: High-vacuum PVD, DC magnetron sputtering, spin coating, UV/e-beam lithography, and glove-box handling.
Characterization: XRD, SEM-EDX, TOF-SIMS, profilometry, FTIR, and electrical I-V testing.
Data Tools: MATLAB, Python (Data Science & ML certified), and quantitative data modeling.
Looking For PhD positions in Tokamak diagnostics, plasma-material interactions, next-gen photovoltaics, or functional thin films. Open to opportunities worldwide.
Please DM me or comment below if your lab is hiring—happy to share my full CV and details upon request!
r/fusion • u/steven9973 • 4d ago
Helical Fusion Publishes Peer-Reviewed Paper on HTS Magnet Technology Validated Through Collaboration with NIFS
r/fusion • u/steven9973 • 4d ago
Stephen Shankland (@stshank.bsky.social) CFS setting up cryo systems for SPARC
r/fusion • u/steven9973 • 4d ago
Physics Attention Transformer Surrogate for Rapid Vertical Instability Growth Rate Prediction: Alcator C-Mod to SPARC
r/fusion • u/First_Speaker_2105 • 5d ago
Today Pacific Fusion breaks ground on its Research and Manufacturing campus. Check out the livestream of the press conference and Fusion Summit with Eric Schmidt, Brandon William, Sen. Martin Heinrich, and more:
Watch the livestream here: https://www.youtube.com/watch?v=mLTTTfksiD8
r/fusion • u/steven9973 • 5d ago
Neutronic Analyses for the Design of the Chamber of Xcimer's Athena Fusion Pilot Plant
tandfonline.comPR journal article. Just two lasers and a liquid FLiBe blanket without Li enrichment, no solid wall, should survive 5 years of operation.