The WEST tokamak, operated by France's Alternative Energies and Atomic Energy Commission (CEA), has achieved a plasma discharge lasting 1,337 seconds, or just over 22 minutes. During this record-setting pulse, the plasma temperature was maintained at approximately 50 million degrees Celsius. The experiment successfully injected and sustained 1.15 gigajoules of energy within the plasma. This result surpasses the previous long-pulse record and marks a significant operational achievement for a tokamak featuring a fully tungsten-clad interior, a design choice with direct implications for future fusion reactors. Source: DOE Fusion

The WEST (Tungsten Environment in Steady-state Tokamak) facility serves as a critical testbed for the international ITER project. Its primary mission is to investigate the performance of tungsten components, particularly the divertor, under reactor-relevant conditions. Tungsten was selected for the ITER divertor due to its high melting point and resistance to sputtering, which minimizes plasma contamination. Sustaining a stable, high-temperature plasma for extended durations in direct contact with tungsten surfaces is a key challenge in fusion science, as high-Z impurities can lead to significant radiative energy losses and plasma disruption. This 1,337-second shot provides crucial data on plasma-wall interactions and heat-load management in a steady-state tungsten environment. Source: DOE Fusion

The WEST (Tungsten Environment in Steady-state Tokamak) facility serves as a critical testbed for the international [ITER](/programs/iter) project.

This achievement eclipses the previous duration record of 1,056 seconds, set by China's EAST (Experimental Advanced Superconducting Tokamak). While other devices have reached higher ion temperatures, the WEST result is notable for its combination of duration and a fully metallic, high-Z plasma-facing wall. Managing impurity influx and core plasma dilution over such a long timescale without compromising performance is a major technical hurdle. The successful demonstration at WEST validates operational scenarios and control strategies that will be essential for maintaining stable, long-pulse H-mode plasmas in future devices like ITER and the DEMO-class reactors that will follow. Source: DOE Fusion

The data gathered from this long-pulse operation will inform the final design and operational planning for ITER's tungsten divertor, which will need to withstand heat fluxes far greater than those in any existing machine. Researchers will analyze the erosion and redeposition of tungsten, the retention of hydrogenic fuel in the plasma-facing components, and the overall impact of the sustained plasma exposure on the material's structural integrity. These findings are essential for predicting the component lifetime and maintenance requirements for ITER, directly impacting its operational availability and the economic viability of future fusion power plants. The results from WEST contribute directly to the public-sector fusion development timeline. Source: DOE Fusion