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A team of scientists has made a major breakthrough in fusion energy research that could bring us a step closer to limitless energy. The researchers, at the UK Atomic Energy Authority (UKAEA), have used magnetic coils to apply a 3D magnetic field to a spherical tokamak to stabilize plasma for the first time. The new method could allow the scientific community to overcome one of the key hurdles associated with fusion energy – maintaining plasma stability. Supressing fusion plasma instability Nuclear fusion is the reaction the sun and stars use to produce energy. When two atoms slam together, they form a heavier nucleus, releasing practically endless amounts of energy in the process. A tokamak utilizes powerful magnets to control and stabilze the burning plasma required for the reaction to take place. The largest spherical tokamak operating today is called MAST Upgrade. It was commissioned by UKAEA and the The European Atomic Energy Community (EURATOM) and began operating in 2020. The nuclear fusion experiment is located at the Culham Centre for Fusion Energy, Oxfordshire. To achieve fusion using MAST Upgrade, scientists confine fusion fuel within the tokamak at extremely high temperatures. At these temperatures, the fuel creates plasma, allowing for the fusion reaction to take place. However, if the pressure, density, or current is too high, the plasma can become unstable. This instability can lead to poor performance. In more extreme cases, it can cause damage to expensive tokamak components. In a UK government press statement, the UKAEA team outlined how they used Resonant Magnetic Perturbation (RMP) coils to completely supress ELMs within the MAST Upgrade machine. Edge Localised Modes (ELMs) are instabilities that occur at the edge of a plasma and can pose serious problems to the components of a nuclear fusion plant. The team’s RMP coils apply a small 3D magnetic field at the plasma edge. Acording to the researchers, this is the first time supression has been observed in a spherical tokamak. “Suppressing ELMs in a spherical tokamak is a landmark achievement,” James Harrison, Head of MAST Upgrade Science at UKAEA, explained in the press statement. “It is an important demonstration that advanced control techniques developed for conventional tokamaks can be successfully adapted to compact configurations to develop the scientific basis for future power plants like STEP, the Spherical Tokamak for Energy Production.” The UK’s £2.5 billion nuclear fusion investment The new experiment was performed during MAST Upgrade’s fourth scientific campaign, which focused primarily on plasma properties, as well as controlling plasma exhaust. The UKAEA team states that the new findings will help it overcome the issue of ELMs. Ultimately, this could help unlock nuclear fusion as a viable energy source. The finding will also directly inform the design of future ELM control systems for the UK’s Spherical Tokamak for Energy Production (STEP) Fusion program, which aims to produce net electricity from fusion by 2040. The STEP program is at the center of a £2.5 billion ($3.4bn) investment by the UK government aimed at making fusion energy a reality.
