Watch Nuclear Fusion Happen in This 3D Tokamak Simulation

You can now see how nuclear fusion takes place in a doughnut-shaped receptacle called a tokamak, thanks to a new 3D visualization by the École Spéciale de Lausanne.

What is nuclear fusion, and why does it matter?

Nuclear fusion is the reaction that powers stars like our Sun. It occurs when two light atomic nuclei fuse, forming a single, heavier nucleus and releasing a huge amount of energy in the process.

If humans could catalyze fusion reactions that yield a net energy gain—including the energy it takes to power up the relevant devices—it could be the beginning of a reliable, zero-carbon energy source. You can read more about engineers’ quest for fusion energy here.

Nuclear fusion is done in different ways; some methods involve lasers while others rely on superheated plasma. The latter option occurs in tokamaks, doughnut-shaped vessels that contain plasma, which physicists can control using magnetic fields. The largest tokamak in the world is currently being constructed in the south of France.

What are these visualizations and what do they show?

In the nuclear fusion visualizations, EPFL’s Laboratory for Experimental Museology turned terabytes of data from tokamak simulations and plasma tests into a 3D visualization that shows how particles move through the toroidal chamber. The interior of the tokamak is an exact replica of EPFL’s variable-configuration tokamak (TCV), rendered from scans of the contraption’s interior.

“To produce just a single image, the system has to calculate the trajectories of thousands of moving particles at a speed of 60 times per second for each eye,” said Samy Mannane, a computer scientist at the laboratory, in an EPFL release. “We were even able to capture the wear and tear on the graphite tiles lining the reactor walls, which are subject to extremely high temperatures during test runs of the TCV.”

The graphite tiles in the tokamak have to handle temperatures exceeding 180 million degrees Fahrenheit (100 million Celsius) and are faithfully represented in the visualization. Electrons are represented in red, protons are green, and the tokamak’s magnetic field is in blue.

“The physics behind the visualization process is extremely complicated,” said Paolo Ricci, the new director of EPFL’s Swiss Plasma Center, in the same release. “Tokamaks have many different moving parts: particles with heterogenous behavior, magnetic fields, waves for heating the plasma, particles injected from the outside, gases, and more. Even physicists have a hard time sorting everything out.”

The future of fusion energy is bright—and made literally brighter by these illuminating images of the tokamak’s inner workings.