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China’s EAST Reactor Advances Magnetic Fusion Technology.

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On January 20, 2025, Chinese scientists operating the Experimental Advanced Superconducting Tokamak (EAST) reactor achieved a milestone by sustaining plasma at 100 million degrees Celsius for 1,066 seconds—more than doubling the reactor’s previous record of 403 seconds set in 2023.

EAST, dubbed China’s “artificial sun,” is a testbed for the International Thermonuclear Experimental Reactor (ITER), a global fusion project delayed until 2033 due to cost overruns and technical challenges.

The Science of Nuclear Fusion

Fusion v/s Fission:

• Nuclear fusion occurs when light atomic nuclei (e.g., deuterium and tritium) merge to form heavier nuclei, releasing energy. Unlike nuclear fission (splitting heavy atoms like uranium), fusion produces minimal radioactive waste, making it a clean energy source.
• Scientists have pursued fusion for decades, but achieving sustained reactions requires overcoming immense technical hurdles.

The Tritium Problem:

Fusion reactions depend on deuterium (abundant in seawater) and tritium (rare and artificially produced in heavy-water reactors in Canada, India, and South Korea). Tritium’s scarcity poses a supply challenge for large-scale fusion.

Temperature and Confinement:

Fusion requires temperatures exceeding 100 million degrees Celsius to overcome proton repulsion. At these temperatures, matter becomes plasma, a state where charged particles are stripped from atoms.

Magnetic confinement (using tokamaks) or inertial confinement (using lasers) traps plasma to sustain reactions.

EAST’s Tokamak Technology

Magnetic Cage:

EAST uses a tokamak—a doughnut-shaped reactor with toroidal and poloidal magnetic fields generated by superconducting electromagnets. These fields confine plasma in a spiral path, preventing contact with reactor walls.

In 2025, EAST’s operators doubled the thermal power input, stabilizing plasma for 1,066 seconds—a critical step toward self-sustaining reactions.

Record Progression:

• 2007: ITER was launched 
• 2016: Sustained high-confinement plasma at 50 million°C for 60 seconds.
• 2017: Extended to 100 seconds.
• 2023: Achieved 403 seconds of steady-state plasma.
• 2025: Broke its own record with 1,066 seconds.

EAST’s Role in ITER

EAST’s advancements validate technologies for ITER, which aims to produce more energy than consumed. However, ITER’s €18 billion cost and delayed timeline (first plasma in 2033) have sparked criticism.

China contributes 9% to ITER’s construction and uses EAST’s data to refine ITER’s design.

Alternatives to Tokamaks

Stellarators:

• These reactors use twisted magnetic fields to avoid needing a poloidal field, but their complex design makes them harder to build.

Inertial Confinement Fusion (ICF):

• In the U.S. National Ignition Facility (NIF), lasers compress deuterium-tritium pellets, achieving a 3.15 MJ energy output in 2022—exceeding the input energy (2.05 MJ) for the first time.
• A similar project, LIFE, was canceled in 2013 after failing to reach ignition.

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EAST Nuclear Fusion Reactor

Source: 

THE HINDU