Machine 4 was First Light Fusion's proposed projectile-driven inertial fusion ignition demonstrator, developed with UKAEA and Tractebel. In March 2025 First Light dropped plans to build a power plant, discontinued Machine 4, and pivoted to supplying amplifier/target technology to partners and non-fusion customers.
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Current state
| Status | Cancelled |
| Country | United Kingdom |
| Location | Oxford area |
| Developer | First Light Fusion |
| Developer type | Private |
| Concept | Other |
| Fuel | D-T |
| Purpose | Demonstration |
Notes
concept "Other" = projectile-driven (amplifier) inertial fusion. Included to document the pivot.
Timeline
- 2024-02 — First Light set a new attainable-pressure record on Sandia's Z Machine with its amplifier technology on its first shot. (source)
- 2025-03-03 — First Light Fusion announced it would stop developing a fusion power plant and discontinue its Machine 4 ignition demonstrator. (source)
The timeline is append-only: corrections are added as new entries. Stated targets appear in the current-state table, never as milestones.
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Sources
- First Light Fusion switches strategy, drops plans to develop power plant — World Nuclear News, checked 2026-10-11
- First Light Fusion announces strategic update — First Light Fusion (primary), checked 2026-10-11