Plasma Ignited in Experimental Trial at Giant Japanese Power Plant

Japan has recently renovated a facility that provides scientific support to a larger fusion power plant test reactor being built in Europe.

Fusion power is advancing at a slow pace, but it holds the potential to significantly change the world’s energy production.

A significant step forward was made when the world’s largest fusion power plant to date was officially launched in Japan at the start of December.

The Naka experimental power plant, located in the north, stands over fifteen meters tall. It houses a ring-shaped vacuum space where the extremely hot fusion plasma is contained by superconducting magnets.

The new reactor has already produced plasma, albeit for ten seconds. The objective is to eventually maintain the plasma for approximately a hundred seconds. A notable achievement is that the Japanese reactor now holds more plasma than before.

The JT-60SA power station is a renovated reactor that has been operational since the 1980s. It’s an experimental plant as fusion reactors are still a distance away from electricity production. The aim of experimental power plants is not to generate electricity but to function in a controlled manner.

A significant challenge in fusion power is controlling the plasma, which is hotter than the Sun’s core. The plasma temperature in a fusion reactor can easily exceed a hundred million degrees, even reaching 200–300 million degrees.

Such high heat is necessary for hydrogen isotopes to fuse into helium and generate energy. On the Sun, fusion commences at lower temperatures due to the immense pressure within the star. On Earth, a substantial burst of energy is initially needed to trigger fusion.

In fusion, particles of the atom’s nucleus, known as neutrons, are released. These neutrons are present in different quantities in the isotopes.

The released neutrons heat the reactor’s mantle, generating steam that spins turbines and, in turn, powers generators – assuming we’re discussing a reactor that eventually produces electricity.

A fusion power plant, similar to a traditional nuclear power plant that operates on uranium fission, also produces steam.

It is a challenge to keep the extremely hot plasma under control using magnets to prevent it from touching the chamber walls, as no material could endure such conditions.

The newly commissioned reactor uses two isotopes of hydrogen, i.e., ordinary hydrogen and deuterium, as noted by the Bulletin of the Max Planck Research Institute. Ordinary hydrogen lacks neutrons, while deuterium has one.

Theoretically, the most efficient fusion would involve deuterium and tritium, which has two neutrons, making it easier to obtain energetic neutrons. However, tritium is the rarest isotope in nature and would need to be produced for future reactors.

The operational reactor is a collaborative project between Japan and the European Union, providing scientific support for a larger plant being built in Southern France. This broad joint project is commonly known as Iter.

Although the European power plant was initially expected to begin operation in 2025, the schedule has been uncertain due to years of delays and significantly increased estimated costs from the initial phase.

Iter already holds the reputation of being the most costly scientific project, even exceeding the expense of the 27-kilometer-long Cern particle accelerator in Geneva.

Iter is expected to be operational by the mid-next decade. Electricity-generating fusion power plants might become a reality once Iter demonstrates the feasibility of the technology. The test facility aims to produce ten times the energy needed to initiate fusion.

Published in Tiede magazine 1/2024.

Correction January 15 at 11:15: The word ‘fusion plasma’ has been removed from the title. This is a test power plant.

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