Nuclear fusion

Generating energy by fusing light atoms, as the sun does.

The United States leads nuclear fusion research, with 27.5% of the 10% most cited papers published 2021–2025; China is second with 14.8%.

FirstUnited States27.5%

SecondChina14.8%

1.9×lead, by share of the 10% most cited papers, 2021–2025

Highlight a country

Standings

1USUnited States27.5%2CNChina14.8%3DEGermany11.8%4GBUnited Kingdom10.1%5FRFrance5.3%6ITItaly5.0%7CHSwitzerland3.2%8–9JPJapan2.2%8–9ESSpain2.2%10KRSouth Korea1.6%

Share of the 10% most cited papers, 2021–2025; 901 papers. Source: OpenAlex, pulled 18 October 2026. Method

Year by year

Share of the 10% most cited papers published in each year. Source: OpenAlex, pulled 18 October 2026. Method

Inside the field

Always the top 10%Pilot

Each paper sorted into one sub-area by an AI model reading its title and abstract, then credited as usual. On 200 hand-labelled papers it chose the same sub-area, or a defensible second, 92% of the time.

Sub-area	Papers	First	Second	Third
Plasma-facing and structural materials (tungsten, irradiation)	130	CNChina46.6%	USUnited States14.7%	GBUnited Kingdom8.7%
Tokamak confinement, transport and turbulence	116	USUnited States23.5%	DEGermany18.4%	GBUnited Kingdom11.8%
Divertor, plasma-wall interaction and power exhaust	99	USUnited States21.0%	DEGermany16.2%	FRFrance15.5%
Reactor and device design, breeding blankets and economics	96	ITItaly18.7%	USUnited States18.1%	GBUnited Kingdom18.0%
Instabilities, energetic particles and disruptions	81	USUnited States26.6%	DEGermany14.5%	CNChina10.1%
Inertial confinement and laser fusion	78	USUnited States75.1%	CNChina6.8%	GBUnited Kingdom3.3%
Heating, current drive and diagnostics	76	USUnited States23.0%	GBUnited Kingdom11.5%	CNChina7.9%
Stellarators	65	USUnited States39.3%	DEGermany34.8%	ESSpain10.6%
Plasma control, data-driven and AI methods	64	USUnited States25.9%	GBUnited Kingdom17.2%	CNChina11.2%
Superconducting fusion magnets	44	CNChina26.5%	USUnited States25.9%	GBUnited Kingdom11.3%

Share of each sub-area's papers in the top 10%. Source: OpenAlex, pulled 18 October 2026. Method

Earlier and recent

The same top 10%, split into 2021–2023 and 2024–2025.

FallingRising2021–20232024–2025Change

USUnited States 28.4%26.4%−2.0 pts

CNChina 15.6%14.0%−1.6 pts

DEGermany 12.3%11.2%−1.1 pts

GBUnited Kingdom 8.7%11.7%+3.0 pts

FRFrance 5.8%4.7%−1.0 pts

ITItaly 5.1%4.9%−0.2 pts

CHSwitzerland 4.0%2.2%−1.7 pts

JPJapan 2.5%1.9%−0.6 pts

Share of the 10% most cited papers: 492 papers in 2021–2023, 409 in 2024–2025. Source: OpenAlex, pulled 18 October 2026. Method

2026 so far: a different count

Not the most cited papers: every 2026 paper matched so far (1,683), and a paper counts in full for each country on it. This year's papers are too new to rank by citations, so these shares cannot be compared with the ones above.

CNChina35.3%of 2026 papers have an author here
USUnited States26.5%of 2026 papers have an author here
DEGermany13.6%of 2026 papers have an author here
FRFrance10.4%of 2026 papers have an author here
GBUnited Kingdom10.0%of 2026 papers have an author here

Who cites the top papers

How much more often a country's top papers are cited from home than its size predicts. Expected is the country's share of all papers in the field; the bar is the excess, in percentage points. Home citers include authors citing their own earlier work.

HomeExpectedExcess

USUnited States 53.0%28.5%+24.5

CNChina 73.0%29.0%+44.0

DEGermany 43.8%14.7%+29.1

GBUnited Kingdom 32.1%10.6%+21.5

Based on up to 100 of each country's most cited single-country papers in the top 10%. Source: OpenAlex, pulled 18 October 2026. Method

Behind the share

Institutions with the most credit

1DEMax Planck Institute for Plasma PhysicsResearch facility6.9%
2USLawrence Livermore National LaboratoryResearch facility4.1%
3GBUnited Kingdom Atomic Energy AuthorityGovernment lab3.0%
4CHÉcole Polytechnique Fédérale de Lausanne3.0%
5USPrinceton Plasma Physics LaboratoryResearch facility2.7%
6USMassachusetts Institute of Technology2.6%
7DEMax Planck Institute for Plasma Physics - GreifswaldResearch facility2.5%
8USGeneral Atomics (United States)Company2.3%
9GBCulham Centre for Fusion EnergyResearch facility2.1%
10CNChinese Academy of SciencesGovernment lab2.0%

Share of the top 10%. Institutions across all 45 technologies

Who does the work

Sector	All	US	CN	DE
Research facilities	40.1%	41.7%	29.6%	88.0%
Universities	39.0%	41.2%	55.0%	10.6%
Government labs	11.8%	0.4%	14.0%	0.1%
Companies	6.8%	15.8%	1.4%	0.4%

Share of credit by type of institution, overall and for the three leading countries.

Across borders

53.4% of the top 10% have authors in more than one country.

DEUSGermany with United States133
GBUSUnited Kingdom with United States106
DEFRGermany with France101
DEGBGermany with United Kingdom95
FRUSFrance with United States88

Most frequent pairings, by number of shared papers.

The papers behind the numbers

The five most cited papers this definition catches. If one looks out of place, the definition needs work.

Magnetic control of tokamak plasmas through deep reinforcement learning
Nature, 2022CHGB
739citations
Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment
Physical Review Letters, 2022GBUS
532citations
Development and large volume production of extremely high current density YBa2Cu3O7 superconducting wires for fusion
Scientific Reports, 2021CHJPNZRUUS
280citations
The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas
Nuclear Fusion, 2021CACHCNCZDEES
215citations
Superconductors for fusion: a roadmap
Superconductor Science and Technology, 2021CHCNFRGBITJP
215citations

How this technology is defined

A paper counts if its title or abstract matches the search below. Articles in core journals and proceedings only; retracted papers are excluded.

"nuclear fusion" OR tokamak OR stellarator OR "inertial confinement fusion" OR "fusion reactor" OR "magnetic confinement" OR "fusion plasma"

and its main topic in OpenAlex is one of: Magnetic confinement fusion research; Fusion materials and technologies; Laser-Plasma Interactions and Diagnostics; Superconducting Materials and Applications; Plasma Diagnostics and Applications; Pulsed Power Technology Applications. The topic check removes papers that only mention the technology.

Papers matched, 2021–2025: 8,994
In the top 10%: 901
In the top 1%: 93
Countries with credit: 50
Credit with no known country: 7.5%

Every one of the 1,077 most cited papers was checked for relevance; 34 were left out as not about nuclear fusion

The most cited of those left out:

Superconducting materials: Challenges and opportunities for large-scale applications251 citations
Electronic density response of warm dense matter94 citations
Accurate temperature diagnostics for matter under extreme conditions83 citations
Recent progress of laboratory astrophysics with intense lasers80 citations
Progress of ultra-high-field superconducting magnets in China78 citations
Superconducting properties of commercial REBCO-coated conductors with artificial pinning centers63 citations
Proton stopping measurements at low velocity in warm dense carbon58 citations
Physics and instabilities of low-temperature E × B plasmas for spacecraft propulsion and other applications58 citations
Unraveling electronic correlations in warm dense quantum plasmas46 citations
Static Electronic Density Response of Warm Dense Hydrogen: Ab Initio Path Integral Monte Carlo Simulations45 citations
Micron-scale phenomena observed in a turbulent laser-produced plasma44 citations
Strengthening of copper with homogeneous dispersion of nanoscale tungsten particles fabricated by spark plasma sintering38 citations

Definition version 0.5, pilot. It is a plain text file: copy it, change it, rerun it.

Read the method