The aim of fusion research is not only to understand high-temperature plasma but ultimately to develop practical systems for producing energy. Today, research spans a wide range of approaches, from large publicly funded international facilities to increasingly ambitious private-sector programmes. These efforts explore different confinement concepts, fuel cycles, magnet technologies and routes towards economically viable fusion power.

ITER

The largest international fusion project is ITER, an experimental tokamak under construction at Cadarache in southern France by seven Members: China, the European Union, India, Japan, Korea, Russia and the United States. Its plasma volume will be about 840 m³. ITER is designed to produce around 500 MW of fusion power from 50 MW of external plasma-heating power, corresponding to a plasma gain of Q ≥ 10. Under the current baseline, Start of Research Operation is planned for 2034 and deuterium–tritium operation for 2039.

Artist’s impression of a General Fusion magnetized target fusion reactor.

DEMO

The next major step beyond ITER is generally referred to as DEMO: a demonstration fusion power plant intended to produce electricity and test technologies required for commercial operation. Several ITER Members are developing their own DEMO concepts and schedules rather than a single common design. Europe is aiming for a demonstration plant around mid-century, while Japan, Korea, China and other programmes are following their own development pathways.

Present Tokamaks

Several dozen tokamaks are operating worldwide, ranging from small university experiments to large superconducting machines. Important facilities include EAST in China, KSTAR in Korea, WEST in France and JT-60SA in Japan. JT-60SA produced its first plasma in October 2023 and, with a plasma volume of about 160 m³, is currently the world’s largest operating tokamak. JET in the United Kingdom ended its experimental programme in 2023 after four decades of operation. Current tokamak research focuses increasingly on long-pulse operation, superconducting magnets, plasma control, divertor performance and materials able to withstand reactor-relevant heat and neutron loads. Smaller tokamaks remain essential for testing new concepts and diagnostics that can later be transferred to larger machines.

Stellarator Research

Stellarator research is led by Wendelstein 7-X in Germany, the world’s largest operating stellarator. Following major upgrades for actively cooled plasma-facing components, it has demonstrated increasingly long high-performance discharges. In 2025, Wendelstein 7-X sustained 1.8 GJ of energy turnover over 360 seconds and achieved a record long-duration stellarator triple product. Japan’s Large Helical Device (LHD) also made major contributions to stellarator research during more than 27 years of operation, but its experimental programme concluded in December 2025.

Laser-driven Fusion

In inertial confinement fusion, the National Ignition Facility (NIF) in the United States has achieved the most significant recent milestones. On 5 December 2022, NIF produced 3.15 MJ of fusion energy from 2.05 MJ of laser energy delivered to the target, achieving ignition for the first time. The result has since been repeated many times. On 7 April 2025, NIF produced a record 8.6 MJ from 2.08 MJ of laser energy, corresponding to a target gain of 4.13, and by June 2026 ignition had been achieved eleven times. Turning this scientific achievement into a practical power plant would still require major advances in laser efficiency, repetition rate, target production and injection, chamber materials and heat removal.

Aneutronic Fusion

TAE Technologies is developing a beam-driven field-reversed configuration (FRC) with the long-term goal of using aneutronic proton–boron fusion. Its current Norm device uses neutral beam injection both to form and sustain the plasma and is being upgraded towards temperatures of about 100 million K. In 2025, TAE shortened its development roadmap and began moving directly towards its planned Da Vinci prototype power plant.

Magnetized Fusion

Canada-based General Fusion is developing Magnetized Target Fusion, in which a magnetised plasma is mechanically compressed by a collapsing lithium liner. Its current Lawson Machine 26 (LM26) began operating in 2025. In October 2026, General Fusion and the UK Atomic Energy Authority reported electron temperatures above 1 keV, or more than 12 million °C, produced by compressional heating. The programme is now targeting substantially higher temperatures and ultimately the Lawson criterion.

Magneto-inertial Fusion

Helion Energy uses a pulsed field-reversed-configuration approach in which magnetised plasmas are accelerated, merged and compressed. Its seventh prototype, Polaris, is designed to demonstrate direct recovery of electrical energy from the expanding plasma. In February 2026, Helion reported measurable deuterium–tritium fusion in Polaris and plasma temperatures of about 150 million °C. The company ultimately aims to use deuterium–helium-3 fuel, which produces much less neutron energy than deuterium–tritium fusion, and to convert part of the fusion energy directly into electricity rather than through a conventional steam cycle.

Spherical Tokamaks

Tokamak Energy’s compact spherical tokamak ST40 reached an ion temperature of about 100 million K in 2022 and continues to serve as a platform for high-field spherical-tokamak research. The company is also developing high-temperature-superconducting magnet technology separately for future fusion systems. In the United States, Commonwealth Fusion Systems is assembling the SPARC high-field tokamak using REBCO high-temperature-superconducting magnets. SPARC is intended to demonstrate Q > 1 and provide the physics and engineering basis for the company’s planned ARC fusion power plant.

The United Kingdom is developing STEP (Spherical Tokamak for Energy Production), a prototype fusion power plant planned for the West Burton site in Nottinghamshire. The current programme aims to begin major construction around 2030 and bring the plant into operation around 2040 as a prototype fusion power plant designed to demonstrate fusion energy and electricity production.