This Week’s Fusion News: September 18, 2026

This week Inertia Enterprises reported that ignition-benchmarked simulations run with Lawrence Livermore National Laboratory show its commercial laser indirect drive target design achieves more than 25x gain, enough fusion energy to generate between 250 MWe and 1.3 GWe of grid electricity, with the paper posted to arXiv ahead of peer-reviewed submission. Commonwealth Fusion Systems ran the full cryogenic system for its SPARC tokamak at its 8 kelvin operating temperature, a commissioning milestone ahead of an integrated dry dress rehearsal of SPARC’s support systems and a preview of the equipment its ARC power plant will need. The United Kingdom Atomic Energy Authority and Princeton Plasma Physics Laboratory signed a Joint Declaration of Intent at the Global Fusion Policy Summit in London to explore federating UKAEA’s £45 million SUNRISE supercomputer with PPPL’s STELLAR-AI platform so both laboratories can train shared AI models on data from MAST Upgrade and NSTX-U. Israeli compact fusion company nT-Tao deployed a 50 MW pulsed-power subsystem built from 50 roughly 1 MW Power Electronic Generators with real-time nonlinear control, a five-fold scale-up meant to push its C3 prototype beyond 1.5 million degrees Celsius. Featured this week from The Fusion Report: Helion’s slide of full Orion output to 2029 or 2030 and what the FY2027 Department of Energy budget request means for fusion, plus the third article in the supporting technologies series on divertors and heat exhaust systems.