How tokamaks confine plasma, and why fusion power remains out of reach

The brief in 8 cards

1. Note1 / 8

   WHY IN NEWS?

   • China's EAST tokamak sustained high-confinement plasma for 1,066 seconds in January 2025, a world record.
   • Progress at ITER in France and the US National Ignition Facility (NIF) has renewed global interest in fusion as a clean energy source.
   • A Hindu explainer notes that, despite these advances, no tokamak has generated net energy for commercial power.
2. Note2 / 8

   KEY CONCEPTS

   1. What is a tokamak?

   It is a doughnut-shaped vacuum chamber that uses powerful magnetic fields to confine superhot plasma. Soviet physicists Igor Tamm and Andrei Sakharov developed it in the 1950s.

   2. How is fusion different from fission?

   Fission splits heavy atoms such as uranium. Fusion joins light atoms such as hydrogen isotopes, releasing energy as the Sun does.

   3. What does "Q" mean?

   Q is the ratio of fusion power produced to heating power supplied. Q above 1 means the plasma gives out more energy than it receives. ITER aims for Q = 10.

   4. How does a stellarator differ from a tokamak?

   A tokamak relies partly on electric current in the plasma to shape its field. A stellarator twists its magnetic field using external coils alone, as Germany's Wendelstein 7-X does.

3. Note3 / 8

   HOW A TOKAMAK WORKS

   The table walks through each stage. Notice how heat moves from plasma to turbines.

   Stage	What happens
   Plasma	Hydrogen isotopes are heated until they become ionised gas, or plasma; ITER will use deuterium and tritium (D-T)
   Confinement	External coils create a toroidal field and plasma current creates a poloidal field, together forming helical field lines
   Heating	Ohmic heating, neutral beams and radio waves raise plasma to about 100–150 million °C
   Fusion	Deuterium and tritium fuse into helium and a neutron, releasing 17.6 MeV
   Energy capture	Neutrons carry energy into a surrounding blanket; coolant turns it into steam for turbines
   Fuel breeding	Lithium in the blanket can produce new tritium when struck by neutrons

4. Note4 / 8

   GLOBAL DEVELOPMENTS

   Several projects have set new records. The table summarises them.

   Project	Milestone
   ITER, France	Seven members representing 35 countries aim for 500 MW from 50 MW of heating (Q = 10); D-T operations planned for 2039
   EAST, China	1,066 seconds of high-confinement plasma in January 2025
   NIF, US	Achieved scientific ignition in 2022; produced 8.6 MJ from 2.08 MJ of laser energy in April 2025
   Wendelstein 7-X, Germany	Demonstrates stellarator design
   JET, UK	Produced 69 MJ over about five seconds in its final D-T experiments in 2023

   The NIF uses lasers, not magnets, to compress fuel. Its "ignition" counts only laser energy reaching the target, not the facility's total power use.

5. Note5 / 8

   INDIA'S FUSION PROGRAMME

   • ADITYA / ADITYA-U: India's first indigenous tokamak, operating at the Institute for Plasma Research (IPR), Gandhinagar, since 1989.
   • SST-1: India's superconducting tokamak achieved first plasma in 2013.
   • ITER: India is one of seven members and provides about 9% of contributions in kind, including the cryostat and cooling systems.
   • PRAGYA: Pranos Fusion's privately built compact tokamak, unveiled in 2026, focuses on plasma control and magnetic confinement.
6. Note6 / 8

   PROMISE AND HURDLES

   Fusion offers major benefits, but serious obstacles remain. The table compares them.

   Promise	Hurdle
   One kilogram of D-T fuel can theoretically release about 3.4 × 10¹⁴ joules	Turbulence and disruptions threaten plasma confinement
   No direct carbon emissions, complementing renewables	High-energy neutrons damage reactor walls; ITER uses tungsten-faced components
   Deuterium is plentiful in seawater; tritium can be bred from lithium	Tritium is scarce, so breeding and recycling are essential, IAEA research notes
   Losing confinement cools the plasma, so no runaway chain reaction is possible	Plasma energy gain is not net electricity, since auxiliary systems use much power
   No conventional spent fuel	Neutron-activated materials remain radioactive
   –	ITER's cost overruns and delays, and gaps flagged by the US GAO, show commercial power is far off

7. Note7 / 8

   WAY FORWARD

   These are suggested measures, not approved policy.

   • Strengthen research at IPR and the IITs in superconductors, cryogenics and plasma physics.
   • Develop radiation-resistant, low-activation materials for reactor parts.
   • Speed up lithium-based tritium breeding and recycling.
   • Support fusion start-ups with research grants and testing facilities.
   • Use machine learning to monitor plasma in real time and predict disruptions.
   • Use ITER and IAEA collaboration to share technology and knowledge.
8. Note8 / 8

   

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