From the secret laboratories that invented the tokamak to Russia's modern fusion ambitions, the Soviet program shaped the entire trajectory of magnetic confinement research worldwide.
No single national program has exerted more influence on the course of fusion energy research than the Soviet Union's. The tokamak concept—born in classified Soviet laboratories—became the dominant approach to magnetic confinement fusion and remains so today. The story of Soviet fusion is one of brilliant theoretical physics, Cold War secrecy, dramatic international revelations, and a legacy that continues to shape every major fusion device on Earth.
Soviet fusion research began in the early 1950s under conditions of extreme secrecy. In 1950, Andrei Sakharov and Igor Tamm proposed a toroidal magnetic confinement device they initially called a "magnetic thermonuclear reactor."¹ Their concept used a combination of toroidal and poloidal magnetic fields to confine a hot plasma in a doughnut-shaped chamber. The name tokamak—a Russian acronym for "toroidal chamber with magnetic coils"—was coined by Igor Golovin. Early experimental devices were built at the Kurchatov Institute in Moscow under the direction of Lev Artsimovich, who became the driving force behind the Soviet tokamak program.
At the 1958 Atoms for Peace conference in Geneva, the Soviet delegation disclosed the existence of their fusion program, though Western scientists remained skeptical of their results for years. Through the 1960s, Artsimovich's team at the Kurchatov Institute achieved steadily improving plasma temperatures and confinement times on a series of tokamak devices—T-1, T-2, and most importantly T-3. In 1968, the T-3 tokamak reported electron temperatures of roughly 10 million degrees Celsius, far exceeding what Western devices had achieved.² A British team from Culham Laboratory traveled to Moscow in 1969 and independently confirmed these results using Thomson scattering diagnostics. This confirmation triggered a worldwide pivot to the tokamak configuration.
Following the T-3 confirmation, virtually every major fusion laboratory in the world began building tokamaks. The Soviet program continued to lead with increasingly ambitious devices. T-7 (1978) was the world's first tokamak with superconducting magnets, demonstrating a technology that would become essential for future reactors.³ T-10, operational from 1975, explored electron cyclotron resonance heating and achieved plasma temperatures above 100 million degrees. T-15, which began operation in 1988, was the largest Soviet tokamak and featured superconducting niobium-tin magnets. Soviet physicists also made foundational contributions to plasma theory, including the understanding of neoclassical transport, magnetohydrodynamic instabilities, and plasma-wall interactions.
The dissolution of the Soviet Union in 1991 dealt a severe blow to Russian fusion research. Funding collapsed, many talented scientists emigrated, and facilities deteriorated. Despite these hardships, Russia remained a partner in the ITER project, contributing roughly 9% of construction costs and providing critical expertise. The Kurchatov Institute continued operating T-15, and an upgrade program—T-15MD—achieved first plasma in 2021.⁴ Russia has also maintained contributions to plasma theory and diagnostics. However, geopolitical tensions following 2022 have complicated Russia's participation in international collaborations, raising questions about the future of its role in ITER and the broader global fusion effort.⁵
The Soviet fusion program's legacy is immeasurable. The tokamak concept it pioneered is the basis for ITER, JET, EAST, KSTAR, and dozens of other devices worldwide. Soviet theoretical contributions underpin much of modern plasma physics. While Russia's current fusion program operates under significant constraints, the intellectual heritage of Sakharov, Tamm, Artsimovich, and their colleagues remains the foundation upon which the entire field builds.