Germany's Wendelstein 7-X (W7-X) stellarator has set a new device record for energy turnover, achieving 1.3 gigajoules in a single experiment. This result, an 18-fold increase over its previous 75 megajoule record, was sustained over an eight-minute plasma discharge. The milestone demonstrates the effectiveness of recent hardware upgrades, including a water-cooled divertor and enhanced plasma heating systems, which are critical for exploring the long-pulse, high-power operational scenarios required for a future fusion power plant. These results, published in a special issue of the journal *Nuclear Fusion*, confirm the stellarator's potential for continuous operation, a key design advantage over the inherently pulsed nature of many tokamak designs. Source: EUROfusion

The high-performance plasma discharges also yielded significant advances in core plasma parameters. Researchers at the Max Planck Institute for Plasma Physics (IPP) in Greifswald reported achieving a central ion temperature of nearly 40 million Kelvin (approximately 3.4 keV) and a plasma density of 2 x 10^20 particles per cubic meter. These conditions led to a fusion triple product (n·τ·T) of 6.4 x 10^26 Kelvin seconds per cubic meter, equivalent to 5.5 x 10^19 keV·s·m⁻³. This value brings the W7-X into a performance regime comparable to that of large-scale tokamaks, validating the complex, optimized magnetic field geometry of the stellarator design. The sustained performance was enabled by 10 megawatts of microwave heating power. Source: EUROfusion

The high-performance plasma discharges also yielded significant advances in core plasma parameters.

A central component of the recent experimental campaign was the commissioning and operation of the new water-cooled divertor. This system is designed to handle the immense heat and particle fluxes exhausted from the plasma edge during long-pulse operations. The successful management of these loads for eight minutes without significant degradation is a critical step in de-risking the technology for future steady-state devices. The divertor's performance, coupled with the stability of the plasma confinement, allowed for the unprecedented energy turnover. The next operational goal for the W7-X program is to extend high-power plasma discharges to 30 minutes, further testing the limits of the new cooling systems. Source: EUROfusion

These results from W7-X provide crucial data for the design of future stellarator-based power plants. Unlike tokamaks, which use a large plasma current for confinement, stellarators rely entirely on external magnetic coils to shape the plasma. This eliminates the risk of current-driven disruptions, a major challenge for tokamak operations, and allows for inherently steady-state operation. The recent achievements at W7-X, particularly in handling high heat loads and maintaining plasma stability over extended periods, bolster the case for the stellarator as a viable alternative path to commercial fusion energy. This progress is relevant to the broader fusion technology landscape and informs the design of next-generation machines. Source: EUROfusion