Stars on Earth

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. ...

Amit Singh, CEO of NearStar Fusion, recently took the time to walk me through the world of inertial fusion versus magnetic fusion. At one point I told him that the last person I’d told about wanting to work in fusion had laughed at me. He didn’t laugh. Instead, he talked about working for a purpose, not a salary. That’s stuck with me since, and it’s got me thinking back on how I actually landed here in the first place. ...