Global Fusion Explorer
Why does a map of fusion machines tell a story about politics as well as about physics?
Prior knowledge
- The T-3 results of 1968 were confirmed by a British team in 1969chapter Science across the Iron Curtain
- ITER began with the 1985 Geneva summit and has seven memberschapter ITER: why, where and who
Think about it
In 1955 a fusion physicist in Princeton could not tell a colleague in Moscow what she was working on: both worked in secret, on opposite sides of the Iron Curtain. Today, physicists from China, India, Russia, the United States and Europe build one machine together in southern France and share their data by e-mail every day. Somewhere between these two pictures, the map of fusion research changed.
How did fusion research move from secret national projects to a worldwide network, and how can a map show it?
Review: science across the Iron Curtain
Sentence starters
- During the Cold War, fusion research was probably …
- Today I think research is done in …, because …
- A map could show … but not …
Think about it: a map of science
Discuss with a partner, then write two or three sentences.
Where do you think fusion research was done in the 1950s, and where is it done today? What can a map of fusion facilities show about history, and what can it not show?
Pair work: share your ideas aloud, then each of you writes.
Model answer
During the Cold War, fusion research was probably done in a few rich countries with nuclear weapons, such as the United States and the Soviet Union. Today I think research is done in many countries, including China, Japan and Europe, because the machines are very expensive and countries cooperate. A map could show where and when machines were built, but not what the scientists said to each other or how good their results were.
Assess your own answer
Tick the points your own answer already contains.
Review the theory summary.
Predict
Make your predictions before investigating 2 questions
Prediction 1: the early map
Prediction 2: the map today
Investigate
How to read the explorer
The Global Fusion Explorer shows 63 fusion research facilities: retired, operating, under construction and planned. Each marker is a site; a number on a marker means that several devices stand at the same place. Select a marker or a line in the list to open the facility's panel: its type, status, years, achievements, importance, sources and the date they were checked.
Use the filters to ask questions: search, country, device type, status and the year slider (operating in the year). The list under the map always shows exactly the facilities that the filters leave, so the explorer works without the map too.
Read the data critically:
- The list is a selection, not every fusion device ever built. A country without a marker may still have done fusion research.
- Country is today's country. For older machines the panel also names the state of that time, such as the Soviet Union or West Germany.
- Some years are unknown. A line such as Model A, 1953–? means that no source gives the machine's end year. The year filter then counts it only for ten years after its start, or up to the last year a source shows it running; the note at the end of the panel says which. This is a careful guess, not a fact.
- One machine can have two records. COMPASS ran first at Culham in the United Kingdom and later in Prague, so it has a record for each place.
- Results of private companies are usually company-reported, and every date of a planned machine is a plan.
The Global Fusion Explorer
The map loads its background from OpenStreetMap, so it needs an internet connection. The list and the panels work even without the map.
Missions: from competition to collaboration
Work in pairs and write your findings in a table with the columns year, facilities, countries and notes.
- The secret years. Untick any year and move the year slider to 1958. Which facilities and countries does the list show? Open ZETA and T-1.
- Unknown years. Move the slider slowly from 1958 to 1975. Model A and the Perhapsatron disappear after 1963: open Model A and read the note at the end of its panel. Why does the filter stop counting it there? Then tick any year and look at the start years: which countries had machines that started before 1970, and which countries followed in 1973?
- The age of big machines. Untick any year and set the year to 1985. Count the facilities and countries. Which machine is shared by several countries? Open its panel.
- Today's network. Set the year to 2026 and count the facilities and countries. Then tick any year and choose Under construction and Planned: who builds new machines?
- Machines that cross borders. Open the panels of ITER, JT-60SA and HL-2A, and search for COMPASS: why does one machine have two records? Note for each one which countries are involved.
- Back to the timeline. Open the unit Fusion history: an interactive timeline, find the events of 1958, 1969 and 1985, and follow a Show on the map link back to this explorer.
Word bank
site · facility · device · operating · retired · under construction · planned · to cluster · to spread · to share · a joint project · a network · secrecy · the Cold War
Sentence starters
- In 1958 the list shows … facilities in … countries.
- By 1985, … had joined, and … was shared by …
- In 2026, operating facilities stand in …
- The biggest change is that …
- One limitation of the data is …
Record and compare your findings
Discuss with your partner, then write four or five sentences from your table.
How many facilities and countries did you find in 1958, in 1985 and in 2026 (operating)? Which machines involve several countries? Name one limitation of the data that affected your counts.
Pair work: one of you operates the explorer, the other writes; swap roles after mission 3.
Model answer
In 1958 the list shows six facilities in three countries: the United States (Model A, Model B, the Perhapsatron and Scylla I), the United Kingdom (ZETA) and the Soviet Union (T-1). By 1985 it shows eight machines in six countries: the United States, the Soviet Union, the United Kingdom, France, West Germany and Japan, and JET in the UK was shared by European countries. In 2026, 24 facilities operate in 12 countries on three continents, from Canada to South Korea. ITER (seven members), JT-60SA (Japan and Europe), HL-2A (built from German ASDEX parts in China) and COMPASS (two records: first at Culham in the UK, then in Prague) cross borders. One limitation of the data is that no source gives the end year of some old machines, such as Model A, so the year filter only guesses: it counts them for ten years after their start.
Assess your own answer
Tick the points your own answer already contains.
Review the theory summary.
Theory summary
From competition to collaboration
In the early 1950s, fusion research was secret. The United States, the Soviet Union and the United Kingdom each hoped that controlled fusion would give them an advantage, and each worked alone. In September 1958, at the second United Nations conference on the peaceful uses of atomic energy in Geneva, the three countries declassified their fusion research. They found that all of them had the same unstable, leaky plasmas. In the explorer's data, the machines that started before 1970 stand in exactly these three countries (the selection leaves out, for example, West Germany's first Wendelstein stellarators of 1960); in 1958 the year filter shows six of them.
Openness made independent verification possible. In 1968 Soviet scientists reported that their T-3 tokamak reached about ten million degrees. In 1969 a British team from Culham took a laser to Moscow and confirmed the result, and laboratories all over the world started building tokamaks: in the explorer, France's TFR and West Germany's Pulsator both started in 1973. In 1978 European countries set up the JET Joint Undertaking to build one shared machine at Culham.
At the Geneva summit of November 1985, Mikhail Gorbachev proposed to Ronald Reagan that their countries build a fusion experiment together. This idea became ITER. In 2006 seven members signed the ITER Agreement: China, the European Union, India, Japan, Russia, South Korea and the United States. Machines also cross borders: Germany's ASDEX became China's HL-2A, the British COMPASS moved to Prague, and Japan and Europe built JT-60SA together. In the explorer's data, 24 facilities operating in 2026 stand in 12 countries on three continents, from Canada to South Korea, many of them linked to ITER, and private companies have added new sites since the 2010s.
Key idea
The geography of fusion research changed from a few rival nuclear powers working in secret to a worldwide network. Three things drove the change: declassification in 1958, the need for independent checks of surprising results, and machines so expensive that only many countries together can build them. Competition did not disappear: countries and companies still race for records. But today they share data, people and parts, and the largest project, ITER, is a joint one.
Words of the lesson
Back to your predictions
Compare your predictions with your own counts and with the story. In one or two sentences: what changed the geography of fusion research most?
Would you change your prediction?
Apply
Word bank
was built in · started operating in · was shut down in · is still running · is shared by · achieved · was the first to · matters because
Sentence starters
- … is a … in …, which started operating in …
- Its most important result was …
- It matters for the story of collaboration because …
Write a museum label
Imagine the explorer becomes an exhibition. Choose one facility (not ITER) and write its museum label of 60–90 words. Use the facts in its panel: name, place, type, years, one achievement with its date, and why it matters for the story from competition to collaboration. Write in your own words.
Model answer
JET, Culham, United Kingdom (1983–2023). The Joint European Torus was a tokamak built and run by European countries together, under a joint undertaking set up in 1978. For 40 years it was the largest tokamak in the world. In 1997 it produced $16\ \text{MW}$ of fusion power, and in 2023 it released $69\ \text{MJ}$ of fusion energy in a single pulse. JET matters because it showed that only countries working together can afford the biggest fusion machines: it was the model for ITER.
Assess your own answer
Tick the points your own answer already contains.
Review the theory summary.
Find the error
Common misconception
"No marker means no research." The explorer is a selection of important facilities. Many smaller machines, universities and theory groups are missing, so an empty region on the map is a gap in the data, not proof that nothing happened there.
"More markers mean a better programme." One large shared machine, such as JET or ITER, can matter more than many small ones. Count markers, but read the panels before you judge.
Check your understanding
1. History: the turning point
2. Data: reading the explorer
3. Collaboration: which machine?
Sentence starters
- Before 1970, fusion machines in the explorer stood only in …
- Today, the map shows …
- The change happened because …
- However, the data has limits: …
- Competition has not disappeared: …
4. Write: from competition to collaboration
Write a paragraph of 100–140 words. Compare the geography of fusion machines before 1970 with today's network. Use at least two pieces of evidence from the explorer (counts, facilities or panels) and one event from the timeline, explain why the change happened, and name one limit of the data.
Model answer
Before 1970, fusion machines in the explorer stood only in the United States, the United Kingdom and the Soviet Union, and until 1958 their large programmes were secret. Today, operating facilities stand in 12 countries on three continents, and the largest machine, ITER, is built by seven members. The change happened because the 1958 Geneva conference made the field open, because surprising results such as T-3's needed independent checks, and because machines became too expensive for one country: JET (1978) and ITER (agreement in 2006) were shared. Machines even crossed borders, like Germany's ASDEX, which became HL-2A in China. However, the data has limits: it is a selection, and for old machines with unknown end years, such as T-3, the year filter can only guess. Competition has not disappeared: countries and companies still race for records.
Assess your own answer
Tick the points your own answer already contains.
Review the theory summary.
Summary
- Until 1958 the large fusion programmes of the United States, the Soviet Union and the United Kingdom were secret; the 1958 Geneva conference made them open. Before 1970 the explorer shows machines only in these three countries.
- Independent verification (the British measurement of T-3 in 1969) and expensive machines pushed countries to work together: JET (1978), the Geneva summit (1985), the ITER Agreement (2006).
- In 2026 the explorer's operating facilities stand in 12 countries on three continents; private companies have added new sites.
- A data map is a selection: check unknown end years, today's and historical country names, and who reported a result.
Le coin français
The biggest marker on the map is in France. Listen, repeat, and show your partner ITER on the map while you say the last sentence. In the hints, capitals show the stressed syllable, and õ, ã, ẽ are nasal vowels: the air goes through the nose and no n is heard.