Innovation Winter 2024.25

FEATURE

Dr. Michel Laberge, founder of General Fusion, works in the company’s Richmond headquarters.

injection and liquid metal together in 2019 before making its primary compression prototype in 2022. The primary technical challenge of this integration was proving that the liquid lithium could be compressed smoothly into the plasma. “If the compression is pulling up little bits of liquid metal into the plasma, that would kill the plasma,” said Donaldson. “But the testbed matched up with our simulations, which proved that the simulation tools we were using could be relied on for larger-scale versions of the technology.” In 2017, General Fusion’s P13 plasma injector prototype reached a temperature of 3-million degrees Celsius on a near full-scale machine, which puts it on track for its 100-million-degree target temperature in accordance with scaling laws. Currently, they are working on a large-scale fusion demonstration machine, which aims to produce more energy than it consumes by 2026, called LM26. As of July 2024, the company has created a model at one-fifth the scale of the LM26 system.

“We've come a long way, and it's always been about compressing a plasma with liquid metal,” said Donaldson. “The key idea behind our technology hasn't changed since the day that I started here 15 years ago. What has changed is the smaller details of the method of compression, and what exactly your plasma is going to look like. So, you see that evolution.” While earlier prototypes mainly targetted a piston-based compression system, the LM26 prototype focuses on electromagnetic compression with theta-pinch coils to simplify the system. “What LM26 is all about is showing that the fusion aspect is going to work,” said Donaldson. “We’ve shown that we can make the cavity, and that it can collapse the way that we needed to. But there are other details in being able to put it together. We feel that the biggest risk is about the behaviour of plasma being compressed, so it’s where we want to focus our efforts.” The coils, set up in a circular configuration, apply magnetic force, driving the solid lithium liner inward, compressing the plasma. These simpler systems, with a two-metre

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Winter 2024/25

Innovation