Uploaded April 2025 | Updated September 2026, 2 weeks ago
A plasma pulse from our 2025 ST40 plasma physics campaign, showing boron being introduced into the plasma via our new impurity powder dropper (IPD). Boron is used in the tokamak for wall conditioning, creating a protective layer on the first wall and preventing unwanted impurities like oxygen from entering the plasma. With the IPD, we can investigate the impact of light impurities on the plasma edge. Dropping boron will also reinforce the boron coating in areas where the plasma contacts with the walls. In the future, we plan to use the IPD with lithium to explore its effects on edge and pedestal properties, recycling, and core confinement.
Our main aim for this campaign is to maximise the fusion ‘triple product’, a key measure of plasma performance that includes temperature, density, and energy confinement time. ST40 has already achieved the highest triple product of any spherical tokamak (ST), placing ST plasma physics in the same region as larger conventional tokamaks, achieved in significantly less time and at a lower cost. It demonstrates the exciting potential of the ST pathway to clean, limitless, and secure fusion energy.
A plasma pulse from our 2025 ST40 plasma physics campaign, showing boron being introduced into the plasma via our new impurity powder dropper (IPD). Boron is used in the tokamak for wall conditioning, creating a protective layer on the first wall and preventing unwanted impurities like oxygen from entering the plasma. With the IPD, we can investigate the impact of light impurities on the plasma edge. Dropping boron will also reinforce the boron coating in areas where the plasma contacts with the walls. In the future, we plan to use the IPD with lithium to explore its effects on edge and pedestal properties, recycling, and core confinement.
Our main aim for this campaign is to maximise the fusion ‘triple product’, a key measure of plasma performance that includes temperature, density, and energy confinement time. ST40 has already achieved the highest triple product of any spherical tokamak (ST), placing ST plasma physics in the same region as larger conventional tokamaks, achieved in significantly less time and at a lower cost. It demonstrates the exciting potential of the ST pathway to clean, limitless, and secure fusion energy.
