# Fusion reactors: Techniques

Doughnuts, twisted coils and 192 laser beams compared

Source page: https://www.materialinsights.org/energy/e_fusion/techniques/

What this tab covers The methods used to capture this energy: how each works, and how they compare on efficiency, cost, life-cycle emissions, maturity and scale.

Three machine families lead: tokamaks and stellarators, which hold hot plasma in magnetic fields, and laser inertial confinement, which crushes tiny fuel capsules. All are at the research stage and none supplies grid power.

#### Comparison

| Method | Efficiency | Cost | Life-cycle emissions | Maturity | Scale |
|---|---|---|---|---|---|
| **Tokamaks (ITER, JET, WEST, SPARC)**^[3](https://www.iter.org/sci/goals)^[4](https://iter.org/sites/default/files/media/2024-07/baseline_press_conference_summary_july-2024_b.pdf)^[5](https://media.nature.com/original/magazine-assets/d41586-022-00391-1/d41586-022-00391-1.pdf)^[6](https://www.gov.uk/government/news/jets-final-tritium-experiments-yield-new-fusion-energy-record)^[8](https://www.differ.nl/news/world-record-WEST)^[9](https://ideas.repec.org/a/eee/enepol/v177y2023ics0301421523000964.html)^[10](https://energy.mit.edu/wp-content/uploads/2024/08/2024.09.12-MITEI-The-Role-of-Fusion-in-a-Decarbonized-Electricity-System-Summary-of-Findings-webinar.pdf)^[11](https://ans.org/pubs/journals/fst/article-42694)^[17](https://physicsworld.com/a/iter-fusion-reactor-hit-by-massive-decade-long-delay-and-e5bn-price-hike/)^[21](https://techcrunch.com/2026/01/06/commonwealth-fusion-systems-installs-reactor-magnet-lands-deal-with-nvidia) | Q of 0.33 for 5 seconds at JET (2021); ITER's design target is Q=10 in 400-second pulses. WEST held a plasma for 1,337 seconds in 2025. | ITER's 2024 rebaseline adds about EUR 5 billion. Early commercial plants modelled above USD 150/MWh; about USD 80-100/MWh (2020 prices) needed to compete after 2040. MIT scenarios assume USD 5,600-8,000/kW in 2050 (2021 dollars). | About 9 g CO2e/kWh in a 2001 design study (15 for fission and wind in the same study); no newer quantitative life-cycle study was found. | research | No grid electricity. JET record 69 MJ in 5 seconds (2023). ITER deuterium-tritium operation planned from 2039. CFS installed the first of 18 SPARC magnets in January 2026 and aims to switch SPARC on in 2027. |
| **Stellarators (Wendelstein 7-X)**^[7](https://www.ipp.mpg.de/5532945/w7x) | No deuterium-tritium operation, so no Q. W7-X sustained a record triple product (the density-temperature-confinement measure of closeness to ignition) for 43 seconds in 2025. | No published plant cost. | No life-cycle study found. | research | Experimental devices only. |
| **Laser inertial confinement (NIF)**^[1](https://annual.llnl.gov/fy-2025/national-ignition-facility-2025)^[2](https://www.optica-opn.org/home/newsroom/2022/december/ignition_accomplished_nif_looks_to_the_future/)^[15](https://energy.unimelb.edu.au/__data/assets/pdf_file/0010/5512726/2025-Global-Fusion-Industry-Report.pdf)^[19](https://www.newswise.com/articles/slac-scientists-explain-what-is-inertial-fusion-energy) | Target gain 4.13 (April 2025); wall-plug about 3% (calculated) because the 1980s-era laser draws about 300 MJ per shot. | No published plant cost; pilot plants are concepts. | No life-cycle study found. | research | Single shots, a few per day; 11 of 53 surveyed private firms pursue inertial approaches. |

None of the routes has a cost or emissions record, because none has produced net electricity. Magnetic confinement has the larger industry (25 of 53 surveyed firms) and the clearest engineering path, though ITER's deuterium-tritium start has slipped four years to 2039. Lasers have achieved the only ignition but face the widest wall-plug gap.

#### How each method works
**Tokamaks (ITER, JET, WEST, SPARC)**

A doughnut-shaped vessel holds deuterium-tritium plasma above 100 million degrees C, kept off the walls by magnets and a current in the plasma. Fusion neutrons heat a surrounding blanket, which would drive a turbine.^[3](https://www.iter.org/sci/goals)^[4](https://iter.org/sites/default/files/media/2024-07/baseline_press_conference_summary_july-2024_b.pdf)^[5](https://media.nature.com/original/magazine-assets/d41586-022-00391-1/d41586-022-00391-1.pdf)^[6](https://www.gov.uk/government/news/jets-final-tritium-experiments-yield-new-fusion-energy-record)^[8](https://www.differ.nl/news/world-record-WEST)^[9](https://ideas.repec.org/a/eee/enepol/v177y2023ics0301421523000964.html)^[10](https://energy.mit.edu/wp-content/uploads/2024/08/2024.09.12-MITEI-The-Role-of-Fusion-in-a-Decarbonized-Electricity-System-Summary-of-Findings-webinar.pdf)^[11](https://ans.org/pubs/journals/fst/article-42694)^[17](https://physicsworld.com/a/iter-fusion-reactor-hit-by-massive-decade-long-delay-and-e5bn-price-hike/)^[21](https://techcrunch.com/2026/01/06/commonwealth-fusion-systems-installs-reactor-magnet-lands-deal-with-nvidia)
**Stellarators (Wendelstein 7-X)**

Twisted external coils, rather than a plasma current, create the confining field. This avoids sudden current disruptions and suits steady operation, at the price of complex coils.^[7](https://www.ipp.mpg.de/5532945/w7x)
**Laser inertial confinement (NIF)**

192 laser beams heat a small gold cylinder, whose X-rays implode a pea-sized capsule of frozen deuterium-tritium for billionths of a second. A plant would need about 10 shots a second with mass-produced targets.^[1](https://annual.llnl.gov/fy-2025/national-ignition-facility-2025)^[2](https://www.optica-opn.org/home/newsroom/2022/december/ignition_accomplished_nif_looks_to_the_future/)^[15](https://energy.unimelb.edu.au/__data/assets/pdf_file/0010/5512726/2025-Global-Fusion-Industry-Report.pdf)^[19](https://www.newswise.com/articles/slac-scientists-explain-what-is-inertial-fusion-energy)

#### Sources

1. [National Ignition Facility (FY2025 annual report)](https://annual.llnl.gov/fy-2025/national-ignition-facility-2025) Lawrence Livermore National Laboratory, 2025
2. [Ignition Accomplished: NIF Looks to the Future](https://www.optica-opn.org/home/newsroom/2022/december/ignition_accomplished_nif_looks_to_the_future/) Optica, Optics & Photonics News, 2022
3. [What will ITER do?](https://www.iter.org/sci/goals) ITER Organization, 2025
4. [Baseline press conference summary, July 2024](https://iter.org/sites/default/files/media/2024-07/baseline_press_conference_summary_july-2024_b.pdf) ITER Organization, 2024
5. [Nuclear-fusion reactor smashes energy record](https://media.nature.com/original/magazine-assets/d41586-022-00391-1/d41586-022-00391-1.pdf) Nature, 2022
6. [JET's final tritium experiments yield new fusion energy record](https://www.gov.uk/government/news/jets-final-tritium-experiments-yield-new-fusion-energy-record) UK Government (DESNZ / UKAEA), 2024
7. [Wendelstein 7-X sets new performance records in fusion research](https://www.ipp.mpg.de/5532945/w7x) Max Planck Institute for Plasma Physics, 2025
8. [World record for WEST](https://www.differ.nl/news/world-record-WEST) DIFFER, 2025
9. [Can fusion energy be cost-competitive and commercially viable? An analysis of magnetically confined reactors (Lindley et al., Energy Policy 177)](https://ideas.repec.org/a/eee/enepol/v177y2023ics0301421523000964.html) Elsevier, 2023
10. [The Role of Fusion in a Decarbonized Electricity System: Summary of Findings](https://energy.mit.edu/wp-content/uploads/2024/08/2024.09.12-MITEI-The-Role-of-Fusion-in-a-Decarbonized-Electricity-System-Summary-of-Findings-webinar.pdf) MIT Energy Initiative, 2024
11. [The Potential for Fusion Power to Mitigate U.S. Greenhouse Gas Emissions (Meier and Kulcinski, Fusion Science and Technology 39)](https://ans.org/pubs/journals/fst/article-42694) American Nuclear Society, 2001
12. [The global fusion industry in 2025](https://energy.unimelb.edu.au/__data/assets/pdf_file/0010/5512726/2025-Global-Fusion-Industry-Report.pdf) Fusion Industry Association, 2025
13. [ITER fusion reactor hit by massive decade-long delay and EUR 5bn price hike](https://physicsworld.com/a/iter-fusion-reactor-hit-by-massive-decade-long-delay-and-e5bn-price-hike/) Physics World, 2024
14. [SLAC scientists explain what is inertial fusion energy](https://www.newswise.com/articles/slac-scientists-explain-what-is-inertial-fusion-energy) SLAC National Accelerator Laboratory via Newswise, 2023
15. [Commonwealth Fusion Systems installs reactor magnet, lands deal with Nvidia](https://techcrunch.com/2026/01/06/commonwealth-fusion-systems-installs-reactor-magnet-lands-deal-with-nvidia) TechCrunch, 2026

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_fusion/index.md)
- [Overview](https://www.materialinsights.org/energy/e_fusion/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_fusion/correlation/index.md)
- [Efficiency](https://www.materialinsights.org/energy/e_fusion/efficiency/index.md)
- [Resources and labour](https://www.materialinsights.org/energy/e_fusion/resources/index.md)
- [Impact on the biosphere](https://www.materialinsights.org/energy/e_fusion/biosphere/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_fusion/links/index.md)