# Measuring national capability over big sciences multidisciplinarity: A case study of nuclear fusion research

## TL;DR

This study maps and analyzes the evolving research capabilities of countries in nuclear fusion, emphasizing the role of large facilities like tokamaks in shaping scientific collaboration and national strengths.

## Contribution

It introduces a novel approach using normalized revealed comparative advantage and dynamic topic modeling to assess national capabilities in big science fields.

## Key findings

- China, India, and Korea show growth in fusion research.
- Canada, Japan, Sweden, and the Netherlands decline in research capability.
- Large facilities influence national research trajectories and collaboration patterns.

## Abstract

In the era of big science, countries allocate big research and development budgets to large scientific facilities that boost collaboration and research capability. A nuclear fusion device called the "tokamak" is a source of great interest for many countries because it ideally generates sustainable energy expected to solve the energy crisis in the future. Here, to explore the scientific effects of tokamaks, we map a country's research capability in nuclear fusion research with normalized revealed comparative advantage on five topical clusters -- material, plasma, device, diagnostics, and simulation -- detected through a dynamic topic model. Our approach captures not only the growth of China, India, and the Republic of Korea but also the decline of Canada, Japan, Sweden, and the Netherlands. Time points of their rise and fall are related to tokamak operation, highlighting the importance of large facilities in big science. The gravity model points out that two countries collaborate less in device, diagnostics, and plasma research if they have comparative advantages in different topics. This relation is a unique feature of nuclear fusion compared to other science fields. Our results can be used and extended when building national policies for big science.