World's largest stellarator turns ten: How W7-X achieves steady plasma

The Wendelstein 7-X (W7-X), the world’s largest and most advanced stellarator, recently marked its tenth anniversary, demonstrating significant progress from an engineering prototype to a functional laboratory for fusion research. Unlike tokamaks, stellarators use complex, externally wound coils to create a three-dimensional magnetic field that confines plasma without relying on large internal plasma currents, potentially avoiding instabilities that limit continuous operation. Since its first plasma in 2015, W7-X has undergone extensive international collaboration and precision engineering, proving the feasibility of its coil and control systems. However, the critical question remained whether it could sustain high-performance plasmas for durations relevant to power plant operation. In 2025, W7-X achieved a breakthrough during the OP2.3 campaign by sustaining high-performance plasmas for 43 seconds and setting a world record for the triple product (density × temperature × confinement time) in long plasma discharges. This performance matched the best tokamak results for similar pulse lengths,