Fundamentals of Fusion

Welcome. This is the very first entry point for learning about fusion on Fusionnica. Fusion is a reaction in which light atomic nuclei collide and merge into a heavier nucleus. In this process, a tiny fraction of the mass is converted into energy, and it is thanks to this reaction that the Sun keeps shining. In this section, you will learn how it works and why humanity is trying to achieve fusion here on Earth, building up step by step starting from high school physics.

This page is a study roadmap. It briefly introduces the content of each page and shows a recommended reading order. If you read from top to bottom, the pages are arranged so that even without prior knowledge you can naturally reach the most cutting-edge challenges.

What you will learn in this section

• The basic principle of what fusion fundamentally is
• What reactions exist and what is used as fuel
• Why fusion is expected to be the trump card for solving the energy problem
• The physical conditions that must be overcome to make fusion work
• How it compares with fission and renewable energy
• The history of how research has been built up over time

Recommended reading order

If you are reading for the first time, we recommend grasping the big picture with the following three pages.

• What Is Fusion: Carefully explains, using an analogy, how nuclei fuse and produce energy. Please start here.
• Fusion Reactions: Compares representative reactions and fuels, such as the D-T reaction that uses deuterium and tritium. You will understand the “ingredients” of fusion.
• The Energy Problem: Why fusion, and why now? It organizes the expectations placed on fusion in the context of fossil fuels and climate change.

Next, we dig into the “difficulty of achieving” fusion.

• The Lawson Criterion: Learn the conditions of temperature, density, and confinement time required for fusion to produce net energy. This is the most physics-heavy content in this section.
• Comparison with Fission: Even though both are “energy from atomic nuclei,” how does fusion differ from fission? It contrasts them from the standpoints of safety and waste.

Finally, we take a bird’s-eye view of the progress of research.

• The History of Fusion Research: From the dawn of the 1950s, through the appearance of the tokamak, JET and ITER, to the ignition achieved at NIF in 2022, it traces the challenges that have continued.

Sections to read next

Once you have finished the basics, it is time to dive deep into “plasma,” the star of fusion. To cause fusion, matter must be heated to nearly 100 million degrees into a state called plasma, and the central research challenge is how to confine this plasma and keep it hot and dense.

• Plasma Physics: A section for learning in earnest what plasma is and how it is confined by magnetic fields. It is the ideal next step after finishing the basics section.

This section is intended to be read first by high school students. If you find it difficult, it is fine to just skim the first section of each page, “Start with Intuition.” If you can simply come to like the phenomenon of fusion first, that is the very best first step.