Fusion energy technology developer Tokamak Energy is working on laser measurement technology crucial to controlling the extreme conditions inside future fusion power plants. The company is testing a laser-based dispersion interferometer system at its Oxford, England, headquarters and expects install the system on its ST40 fusion machine later this year. Tokamak Energy’s approach to fusion employs a tokamak, a device that uses a magnetic field to confine and control a plasma. The device features a spherical design, pioneered by company co-founder Alan Sykes in the 1980s, that is designed to improve efficiency, plasma stability, and cost-effectiveness. Tokamak Energy is testing a laser-based dispersion interferometer system to supplement existing diagnostic systems. The system will determine average density across the entire plasma. Courtesy of Tokamak Energy. “A laser beam fired through the plasma interacts with the electrons and tells us the density of the fuel, which is essential for sustained fusion conditions and delivering secure and reliable energy to the grid,” said Tokamak Energy plasma physicist Tadas Pyragius. “The extreme conditions created by the fusion process mean we need to perfect the laser-based diagnostics technology now to move forward on our mission of delivering clean, secure and affordable fusion energy in the 2030s.” Last year, Tokamak Energy successfully commissioned a Thomson scattering laser diagnostic on its ST40 spherical tokamak to provide detailed readings of plasma temperature and density at specific locations. To supplement this, the new dispersion interferometer system will determine average density across the entire plasma. Importantly, this system also shows promise in being suitably robust and reliable to operate in future power plant environments, the company said. According to Tokamak Energy, ST40 is the first privately-owned fusion machine to reach a plasma ion temperature of 100 million ºC, which is considered the threshold for commercial fusion. ST40 also achieved the highest triple product by a private company. Triple product is a measure of plasma density, temperature, and confinement, and collectively a key measure of progress on the path to realizing commercial fusion conditions. After breaking the records in 2022, ST40 has been through a series of hardware upgrades to improve its capabilities, including new power supplies and diagnostic systems. It will be back in operation later in 2024 following further upgrades and maintenance. Tokamak Energy said that it completed design work on its next advanced prototype fusion device, which it expects to be built by the late 2020s. The company expects a pilot plant by the 2030s, which it hopes will pave the way for globally deployable 500 MW commercial plants. Tokamak Energy has partnerships with Los Alamos National Laboratory, Princeton Physics Laboratory, Oak Ridge National Laboratory, Sandia National Laboratory, the University of Tokyo, Furukawa Electric, General Atomics, and the Sumitomo Corporation. The company is a 2009 spinoff from the UK Atomic Energy Authority.