this post was submitted on 19 Feb 2025
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I didn't see any mention of the output in the article. 22MW injected, but does anyone know if the reaction was actually generating a positive output?
No magnetic confinement fusion reactor in existence has ever generated a positive output. The current record belongs to JET, with a Q factor of 0.67. This record was set in 1997.
The biggest reason we haven't had a record break for a long time is money. The most favourable reaction for fusion is generally a D-T (Deuterium-Tritium) reaction. However, Tritium is incredibly expensive. So, most reactors run the much cheaper D-D reaction, which generates lower output. This is okay because current research reactors are mostly doing research on specific components of an eventual commercial reactor, and are not aiming for highest possible power output.
The main purpose of WEST is to do research on diverter components for ITER. ITER itself is expected to reach Q ≥ 10, but won't have any energy harvesting components. The goal is to add that to its successor, DEMO.
Inertial confinement fusion (using lasers) has produced higher records, but they generally exclude the energy used to produce the laser from the calculation. NIF has generated 3.15MJ of fusion output by delivering 2.05MJ of energy to it with a laser, nominally a Q = 1.54. however, creating the laser that delivered the power took about 300MJ.
https://www.theguardian.com/environment/2023/aug/06/us-scientists-achieve-net-energy-gain-second-time-fusion-reaction
I've seen a few mentions of positive output in the last few years.
OK, so we should be clear there are broadly two approaches to fusion: magnetic confinement and inertial drive.
In magnetic confinement a plasma is confined such that it can be driven to sufficient density, temperature and particle confinement time that the thermal collisions allow the fuel to fuse. This is what the OP article is talking about. This Tokamak is demonstrating technologies that if applied to a larger the experiment could probably reach a positive energy output magnetically confined plasma.
The article you referenced discusses inertial drive experiments, where a driver is directly pushing the fuel together, like gravity in the sun, a fission bomb shockwave in a hydrogen bomb, or converging laser beams in Livermore's case.
Livermore's result is exciting, but has no bearing on the various magnetic confinement approaches to fusion energy.