General Fusion's LM26 reaches 1.1 keV by crushing plasma with a metal wall

On Monday a utility planner opens a forwarded link with one line from upstairs asking whether fusion just got cheaper. The planner has to answer by Friday, and the answer has to hold up through the next budget cycle.

The announcement covers two things: an experiment that has run and a plant that has not been built. LM26 is the experiment. It injects magnetically confined plasma into a chamber and squeezes it with a collapsing metal wall ^[4]. It got electrons above 12 million degrees Celsius ^[2]. According to Interesting Engineering, passing 1 keV is an internationally recognized milestone that only a handful of experimental reactors have reached ^[3]. Taking the reading at all was hard. The plasma sits inside a collapsing liner, and the probe could not disturb it ^[9].

The plant is still a proposal. According to the article, mechanical compression avoids rare, delicate materials. Commercial plants would run a circulating liquid-metal layer to absorb neutron radiation and heat, so engineers could build reactors from conventional industrial metals ^[13]. A temperature reading does not test the cost claim. The account does not include a cost estimate for a plant or for the electricity it would sell.

The next physics step is large. The 10 keV target is about nine times the temperature LM26 has reached ^[11]. Temperature is also only one input: the Lawson criterion General Fusion is working toward is a balance of heat, density and confinement time ^[8]. Chief executive Greg Twinney described LM26 as one step on a longer road. "We built LM26 to achieve important technical milestones that will help get us to a first-of-a-kind plant in the next decade, and step-by-step we are advancing on this path," he said ^[15]. The Vancouver company is backed by Canada's Strategic Response Fund and advised by General Atomics ^[10].

I would file LM26 as a physics result and keep it out of any cost model until General Fusion publishes a plant estimate. That has a cost of its own. A team that waits for the estimate starts its own diligence later than one that follows the refit now, and the refit is where the next hard data will come from ^[7].

To sort this headline and the next fusion one, use a 2x2. One axis is who measured the number: an outside lab or reviewer, or the company alone. The other is what the number describes: plasma physics, or plant cost and schedule. The 1.1 keV reading goes in outside-measured physics, with a UK national lab on the diagnostic and a journal review still pending ^[5][6]. General Fusion's 10 keV goal and its path to Lawson go in company-stated physics ^[7][8]. Its industrial-metals design and pilot plant date belong in company-stated cost and schedule ^[13][14]. Only the first box goes into a planning model as fact. Everything else goes in as a scenario labelled with General Fusion's name.