Fusion

A conversation with Rachel Bielajew, Head of Research at Rutherford Energy Ventures, and Riley Moeykens, Associate Technical Analyst there — Rutherford is a fusion-focused consulting firm, apparently the first of its kind — is where this one actually came from. Most of the conversation was about capital: their pitch is that financing structure, not physics, is one of the biggest levers determining which fusion bets actually make it to a commercial plant, and they specifically suggested this comparison — how differently the US, UK, and EU handle that lever. (The UK left Euratom as part of Brexit, so its fusion program is legally separate from the EU’s — not just geographically confusing to lump in.) The short version: these three aren’t just racing toward fusion at different speeds, they’re running the race through three genuinely different institutional playbooks for who supplies the capital, and on what terms. ...

Dennis Whyte (MIT’s plasma physics center director) and Andrew Lo (an MIT finance professor) just got a paper accepted to the Journal of Fusion Energy. Their pitch: the Lawson criterion tells you when a plasma produces net energy, independent of whatever specific reactor you’ve built it in. Nobody had built the economic equivalent, a single framework that tells you when a plant produces net profit, independent of whether it’s a tokamak, a stellarator, or a laser target chamber. So they built one, and called the output Q_econ: economic gain over economic cost. Above 1, viable. Below 1, not. ...

I recently spoke with Lennart Bock at Proxima Fusion, and he got me thinking about stellarators. I’d just finished writing about laser fusion — one bet on how to hold a plasma together. Stellarators and tokamaks are a different fork: both use magnetic fields, and disagree about how to shape them. What I actually wanted to know was which one wins. Turns out that’s the wrong question: the two designs aren’t competing to be better at the same thing. A tokamak buys compactness by driving a current through the plasma, which does most of the confinement work for free. A stellarator refuses that current and shapes the field entirely with a far more complex coil set. Every difference below traces back to that one decision. ...

Everyone who covers fusion eventually gets asked the same question: what would the electricity actually cost? Almost nobody answers it, because almost nobody can. There’s no operating laser fusion power plant, so there’s no bill to point to. What exists instead is a handful of assumptions about lasers, targets, and plants that don’t exist yet, wired together into a spreadsheet. So I built the spreadsheet. Then I turned it into something you can play with. ...

A few weeks ago the Fusion Industry Association put out its 2026 supply chain report, launched at the first-ever fusion supply chain trade show in New Mexico. The headline numbers: fusion companies spent $538 million with suppliers in 2025, up 24%, and project $681 million this year. Three quarters of surveyed suppliers invested in expanding fusion capacity in 2025, anywhere from $30k tooling upgrades to $65 million facilities. That’s real money moving through a supply chain most people don’t know exists. So I tried to map it. ...