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‘This is highly significant’, explains Prof. Ralf Kaiser, Head of Programmes at UNESCO’s Abdus Salam International Centre for Theoretical Physics (ICTP), ‘because it is experimental scientific proof that fusion energy can work. One could say that, until now fusion was basic science but from now on it is going to be technology.’

This means that it is no longer a question of if, but when the first fusion power plant will become a reality. ‘Up until now, fusion research has been chronically underfunded’, explains Prof. Kaiser. ‘This is changing, thanks to private investment. In fact, this news is timely because it will end up on the desks and screens of venture capitalists and hedge fund managers who may then invest in the more than 30 existing private fusion companies. If these investors pump enough money into the system, the first fusion power plant could see the light of day on shorter timescales than one would expect’.

The Fusion Industry Association groups more than 30 public companies in Europe and North America which are taking half a dozen different routes towards nuclear fusion. In 2022, global investment in these companies at about US$2.8 billion.

‘Once fusion energy has been realized’ Kaiser says, ‘there will still be a place for other renewables but no longer for fossil fuels. Compared to other renewables, fusion energy will use a lot less area, which is the main issue with other renewables. Fusion energy will not be without its problems – any large-scale technology has an impact on the environment – but it will have less of an environmental impact than the alternatives’.

Nuclear fusion also has a significant advantage over nuclear fission (splitting the atom), the technology powering today’s nuclear power reactors, in that nuclear fusion does not generate radioactive waste.

This breakthrough at the NIF offers a perfect illustration of the links between basic science and sustainable development, the theme of the International Year being piloted by UNESCO within the United Nations that winds up in June 2023.

For a fusion reaction to happen, the hydrogen nuclei have to come close enough together to fuse. In practice, this means keeping hydrogen at a high enough temperature and density for long enough. This is also referred to as ‘confinement’. In the Sun, it is gravity which provides the confinement. The enormous mass of the Sun creates a combination of temperature and density at the core that allows a fusion reaction to take place. ‘If we want to replicate this on Earth’ comments Kaiser, ‘we need to find a different way of doing the same’.

There are different approaches but the two main ones use magnetic fields (magnetic confinement) or very short timescales (inertial confinement). The experiment at the NIF used inertial confinement with extremely short and extremely powerful laser pulses that hit a small target of hydrogen from all sides to create a shockwave that leads to the fusion reaction.

Once completed, the International Thermonuclear Experimental Reactor (ITER) that is under construction in France will take a different approach. It will use large superconducting magnets to produce net energy through magnetic confinement. ‘Among scientists, there is little doubt that ITER will eventually achieve this’, remarks Kaiser.

The list of ITER members comprises China, members of the European Union via the European Atomic Energy Community (Euratom), India, Japan, the Republic of Korea, Russian Federation and USA.

ITER was launched at the end of the Cold War, at a time when the Europeans were world leaders in fusion research. Participating national laboratories are contributing to different aspects of the ITER research programme, such as through the Joint European Torus in in the UK, the D3D Nuclear Fusion Facility in the USA, China’s Experimental Advanced Superconducting Tokamak (pictured) or the Republic of Korea’s KSTAR magnetic fusion device.

When one considers how long it has taken to prove the feasibility of nuclear fusion, it is remarkable that the ICTP should have chosen plasma physics as the theme of one of its first big workshops as long ago as 1964. Moreover, this workshop covered both inertial and magnetic fusion. This course was introduced by the founder and first director of the ICTP, Nobel laureate Abdus Salam.

‘Abdus Salam was rather far-sighted’, observes Prof Swadesh Mahajan, organiser of the ICTP’s Plasma Physics College.[1]. ‘When he asked me to direct the Plasma Physics College’, says Mahajan, ‘we decided to impart extensive training in nuclear fusion. There are literally hundreds of people in both developing and developed countries who have been trained at our plasma college over the years who are now contributing to the grand enterprise’. The ICTP’s most recent Plasma Physics College took place from 7 to 18 November this year. Since 2007, about 350 young scientists from developing countries have been trained in this way, most of them from Asia and Africa.

About one-third of these young scientists have been women. Sehila Gonzalez de Vicente from the International Atomic Energy Agency (IAEA) notes with satisfaction that ‘the ICTP’s Plasma Physics College is paying particular attention to attracting women to this discipline, in order to contribute to creating a workforce pipeline in this area’. She is Chair of Women in Fusion, an advocacy group set up in the wake of the IAEA’s Fusion Energy Conference in 2021.

Fusion remains a niche field of research. Only 6% of scientific output is being produced in lower middle-income and low-income countries. International collaboration is common in nuclear fusion research, however, which is why the cumulative total of articles per income group adds up to more than 100% (see figure « nuclear fusion » under SDG7) .

Worldwide, there were just 25 026 scientific publications on nuclear fusion between 2012 and 2019, equivalent to 0.13% of total scientific output, according to an original study by UNESCO that may be consulted in the UNESCO Science Report (2021). If we compare output on nuclear fusion over 2012–2015 with that over 2016–2019, we find that publications increased by just 6%.

It is the USA which published most on nuclear fusion over 2016–2019 (3 266), closely followed by China (3 082) then by Germany (2 377), France (1 640), the Russian Federation (1 402), Italy (1 302), Japan (1 279) and the UK (1 205).

Among these leading countries, Germany, the Russian Federation and France specialize in nuclear fusion, since they publish twice the global average proportion of publications on this topic (see table). The output of China, the UK and USA, on the other hand, is only equivalent to the global average intensity on this topic.

Not surprisingly, publishing on nuclear fusion has grown among most ITER members over the dual four-year periods analysed by UNESCO, as in the case of China (2 379/3 082), India (517/564) and the Russian Federation (869/1042).

However, two ITER members showed a negative growth rate for publications on nuclear fusion over this period, namely France and Japan (see table). One contributing factor may be that France raised domestic research expenditure by 2.8% (in PPP$) between 2014 and 2018, even as the country’s researcher pool grew by 12.8%, causing the amount available to each full-time equivalent researcher to shrink by 8.9%. Overall, French scientific productivity remained stable between 2015 and 2019, according to the UNESCO Science Report (2021).

In Japan, meanwhile, government research expenditure stagnated as a consequence of the tight fiscal situation and university staff spent more time securing funding for their research proposals than previously, leaving them less time for research. Scientific productivity overall was lower in Japan in 2019 than in 2012.

The European Union specializes in nuclear fusion (Specialization Index of 1.41) but the bloc’s output has remained relatively stable (0.98 growth rate) since 2012. Some of the strongest growth in the European Union has been observed in countries which were once part of the Soviet bloc, such as Bulgaria (22/41), Hungary (97/118), Poland (256/297) and Romania (80/143). Slovenia even showed the fastest growth (45/87) of any country in the world producing at least 100 publications on nuclear fusion over 2012–2019.

In the developing world, it is Iraq (2/21) which showed the fastest growth in output on nuclear fusion among countries with at least 20 publications on this topic over 2012–2019. Kazakhstan almost doubled its own output, albeit from a low starting point (14/25). Kazakhstan is one of the partners of ITER, along with Australia and Canada, which both publish on nuclear fusion. In South and Southeast Asia, Malaysia (19/28), Pakistan (10/24) and Thailand (17/21) all showed strong growth in this field.

Notable growth was observed in Iran (106/142). Although Iran does not specialize in nuclear fusion (SI of 0.49), the Joint Comprehensive Plan of Action signed in 2015 and commonly referred to as the Iran Nuclear Deal included a special provision for nuclear fusion.

The great majority of countries publish little or nothing on nuclear fusion.. In sub-Saharan Africa, the only countries publishing more than three articles on this topic over 2012–2019 were Ethiopia (6/2) and South Africa (9/16). In the Arab world, Iraq was joined by Egypt (27/21), Saudi Arabia (15/18) and the United Arab Emirates (3/6).

Research on nuclear fusion declined somewhat in the leading countries for research in Latin America, namely Argentina (24/19), Brazil (80/69) and Mexico (40/24). In parallel, domestic research expenditure (in PPP$) dropped in all three countries over 2014–2018: by 5.8% in Argentina, 6.4% in Brazil and 20.6% in Mexico. In the region, Colombia (2/9) and Costa Rica (11/15) bucked the trend towards lower publishing levels on nuclear fusion. Costa Rica even published four times the global average intensity on this topic (see table).