‘World’s largest’ tokamak’s stable Deuterium-Tritium plasmas to help reactor design

The need for limitless, clean energy has pushed scientists to explore efficient fusion reactor designs. Now, the world’s most advanced tokamak has achieved stable Deuterium-Tritium plasmas, which will help decide on an accurate fusion reactor design in the future.

Conducted by the Joint European Torus (JET), the new Deuterium-Tritium experiment provides unique characteristics expected in future fusion reactors. These include the presence of highly energetic ions in low plasma rotation conditions.

The experiment also found that some reactor-relevant plasma conditions may be very beneficial. The strong impact of zonal flows has been found to play a key role in the reduction of turbulent energy transport, according to the experiment.

Plasma provides an integrated solution for future tokamak reactors

The plasma achieved provides an integrated solution for future tokamak reactors . The results of the study also suggests improved energy confinement in future D-T plasma conditions.

The study aimed to provide solid evidence on the characteristics of Deuterium-Tritium plasmas .

“We show that very good properties are achieved in terms of energy confinement and stability. The type of confinement expected in baseline reactor plasmas is obtained because of the better energy confinement in Deuterium-Tritium with respect to the same conditions in Deuterium,” said researchers.

For electrons, energy losses by transport are low

In particular, for electrons, the energy losses by transport are low, which allows temperatures of about 110 million K. For ions, the core heat transport is significantly reduced in Deuterium-Tritium compared to Deuterium when instabilities generated by energetic ions are observed, according to the study published in Nature .

Researchers claimed that several plasma configurations and Deuterium-Tritium concentrations were explored in JET to cover a wide range of possible configurations in future tokamak reactors.

To minimize external torque and thus toroidal rotation, the plasmas in this study were primarily heated with ion cyclotron frequency (ICRF), ensuring that a low external torque is applied.

ICRF heating can accelerate ions to MeV (mega electron-volt) energies, and hence, it was used as a proxy for alpha particle-heated dominated plasmas.

Findings can lead to economical and simpler design of tokamaks

Researchers claimed that the findings open the way for a more economical and simpler design of tokamaks, confirming that nuclear fusion by means of magnetically confined Deuterium-Tritium plasmas is a promising source of clean energy.

“However, further studies, such as compatibility with power exhaust capabilities and exploration at higher density and power, are required to fully qualify these plasmas as a solid route toward tokamak reactors,” said researchers.

They maintained that exploring a broad range of plasma conditions in present-day tokamaks is essential to evaluate how Deuterium-Tritium plasmas might behave in the future.

This is because the physics mechanisms expected to play a role in ITER and future fusion reactors cannot be completely reproduced in an integrated way in existing tokamaks, and therefore specific studies must be performed, according to researchers .

JET was designed to study fusion in conditions approaching those needed for a power plant. It is claimed to be the only experiment that can operate with the deuterium-tritium fuel mix that will be used for commercial fusion power.

Operated by the Culham Centre for Fusion Energy, JET is the world’s largest and most advanced tokamak, where plasmas are hotter than anywhere in the solar system.