The State of Fusion Energy: Major Milestones in 2026 Reshape the Race to Commercial Power

The fusion energy industry is moving from scientific promise to engineering reality at a pace the field has never seen. In the first half of 2026 alone, a startup heated plasma to the temperature of the sun’s core inside a device the size of a soccer ball, the Western world’s most advanced private tokamak became three-quarters complete, and multi-government partnerships began funding next-generation reactor upgrades. These milestones sit on top of a record flow of private capital that has reshaped the competitive landscape.

Avalanche Energy: Desktop Fusion Reaches 11 Million °C

Seattle-based Avalanche Energy announced in June 2026 that its compact “Jyn” device achieved measured apparent ion temperatures above 1 keV — approximately 11 million °C — inside a reactor just 13 cm in diameter . This temperature is roughly equivalent to the core of the sun and surpasses the widely recognized 10-million-degree threshold considered necessary to sustain fusion reactions .

Only a handful of companies worldwide have crossed this mark. Avalanche said it spent less than $50 million in venture investment to get there, an unusually low capital requirement for a sector dominated by billion-dollar tokamak projects .

The temperature milestone builds on a sequence of high-voltage records the company set earlier. In 2025, Avalanche sustained 300,000 volts across 2.5 inches of space — an average electric field gradient of over 4.7 megavolts per meter . By June 2026, it had also achieved a record 200 kV electrostatic fusion milestone and closed a $40 million Series A funding round led by Lowercarbon Capital, with participation from Founders Fund and Toyota Ventures .

Avalanche’s approach relies on a magneto‑electrostatic confinement scheme called the Orbitron, which the company has detailed in three peer-reviewed papers . The technology targets compact reactors producing anywhere from 5 kilowatts to several hundred kilowatts, a fundamentally different scale from the stadium-sized machines pursued by most competitors . A new R&D facility, supported by a $10 million state grant from Washington, is expected to begin operations in 2027 .

Commonwealth Fusion Systems: SPARC at 75% Completion, Targeting Net Energy in 2027

Commonwealth Fusion Systems (CFS) is building SPARC, a tokamak in Devens, Massachusetts, designed to be the world’s first commercially relevant fusion machine to produce net energy (Q>1). As of April 2026, CFS reported that SPARC is about 75% complete, with the tokamak hall now a dense hive of assembly activity .

Key construction milestones over the past year include:

• Delivery and installation of the first 48-ton half of the vacuum vessel, the steel chamber that will contain plasma at 100 million °C .
• Installation of the first of 18 high-temperature superconducting toroidal field (TF) magnets, unveiled at CES 2026. Each 24‑ton D‑shaped magnet is strong enough, in theory, to lift an aircraft carrier .
• DOE validation of the full-scale TF magnet performance test in September 2025, conducted by an independent board of technical experts from U.S. national labs. CFS received $8 million from the DOE’s Milestone-Based Fusion Development Program following the validation .
• A new digital twin of SPARC being built in collaboration with NVIDIA and Siemens, using AI-powered industrial software to accelerate design iterations and operational planning .

CFS co-founder and chief science officer Brandon Sorbom said the company is “aiming for first plasma in 2027 and then getting a Q greater than one as fast as humanly possible” . The project previously targeted first plasma in 2025 and then 2026; the current timeline reflects the complexity of integrating an entirely new class of high-field superconducting magnets into a working tokamak .

CFS raised $863 million in its most recent funding round (Series B2), which the company described as the last raise before SPARC attempts to demonstrate net energy . Peer-reviewed papers published in the Journal of Plasma Physics predict SPARC will achieve Q>1 with a considerable margin . Once SPARC succeeds, CFS plans to build ARC, a fusion power plant designed to deliver electricity to the grid.

Tokamak Energy: $52M ST40 Upgrade and the ST80-HTS Path to a Pilot Plant

UK-based Tokamak Energy secured a $52 million joint funding project in May 2026 with the U.S. Department of Energy (DOE) and the U.K. Department of Energy Security and Net Zero (DESNZ) to upgrade its ST40 experimental spherical tokamak .

The upgrade, running from 2026 through 2028, aims to advance fusion conditions suitable for prolonged operation in a future pilot plant. Critical changes include replating the center column for higher performance, replacing graphite plasma-facing tiles with molybdenum-coated components, and applying a lithium coating to the inner walls of the ST40 vessel . Tokamak Energy calls the program LEAPS (Lithium Evaporations to Advance PFCs in ST40).

Before the upgrade, ST40 ended 2025 with a series of record-breaking results: its highest plasma current, highest stored energy, and highest fusion triple product — a composite metric measuring temperature, density, and confinement time .

Looking further ahead, Tokamak Energy is advancing plans for ST80-HTS, a high-field spherical tokamak using high-temperature superconducting magnets, to be built at the UK Atomic Energy Authority’s Culham Campus. The company previously targeted completion in 2026, but more recent plans point to a longer development timeline, with the machine intended to inform the design of a fusion pilot plant called ST-E1 that could deliver up to 200 MWe of electricity to the grid in the early 2030s .

The Broader Global Picture

The world’s largest operating tokamak, JT-60SA in Naka, Japan, restarted integrated commissioning in May 2026 after a major upgrade. European and Japanese teams installed new ring‑shaped coils roughly 26 feet in diameter, wound inside the vessel itself, to control plasma position at high speed . The machine is now preparing for a new round of experiments targeting hotter, longer, and more demanding plasma conditions.

China’s Experimental Advanced Superconducting Tokamak (EAST) maintained plasma stability at extreme densities previously considered impossible, and researchers have shown that deep reinforcement learning can help stabilize plasma in tokamaks — a capability now being extended to other machines .

The Market: €13 Billion and Counting, but No $73 Billion FT Figure Confirmed

The search did not retrieve a specific Financial Times article containing a $73 billion market figure. The FT did report on the Fusion Industry Association’s finding that fusion companies raised $2.6 billion in the 12 months to July 2025 , but no dedicated $73 billion market report was located in the available sources.

What is well documented is the surge in private capital:

• The Fusion for Energy (F4E) observatory reports that global private fusion investment reached €13 billion as of September 2025, a 30% increase in just three months and more than an eight‑fold rise since 2020. The U.S. and China account for over 85% of this total .
• The Fusion Industry Association tracked $2.64 billion in new funding during the 12 months to July 2025, the second‑highest yearly total on record and a 178% increase over the prior year .
• Market sizing varies dramatically depending on what analysts include. Research and Markets values the fusion energy market at $311 billion in 2026, growing to $420 billion by 2030 . Market Research Future projects a more narrowly defined market of $50.76 billion by 2035, up from $8.63 billion in 2025 . The wide spread — from $20 billion to $348 billion for 2025 alone — reflects fundamentally different scope choices: some reports count the entire nuclear fusion supply chain and adjacent industries, while others limit their analysis to reactor hardware.

What Wasn’t Confirmed

A dedicated DOE Fusion Science and Technology Roadmap was not found in the available sources. The DOE is visibly active in the fusion ecosystem — its independent validation of CFS’s TF magnet and its co‑funding of the Tokamak Energy ST40 upgrade are concrete examples — but no standalone, publicly released roadmap document surfaced in the search results.

2026 in Perspective

The fusion sector in 2026 has three defining features: diversification (desktop‑scale, spherical, and high‑field tokamak designs are all advancing in parallel), de‑risking (DOE‑validated magnets and multi‑government upgrade programs signal growing institutional confidence), and acceleration (€13 billion in private capital and real hardware filling tokamak halls). The remaining question is not whether fusion can reach net energy, but which design, at what scale, and on whose timeline will get there first.