- By:
- Grulke, O.; Baylor, Larry R; Biewer, Theodore M; Ford, Oliver; Fujii, Keisuke ; Harris, Jeffrey H; Hinson, Edward T; Kajita, Shin; Klepper, Conrad ; Lomanowski, Bartosz A; Lore, Jeremy D; Parks, Kermit H; Meitner, Steven J; De Pascuale, Sebastian ; Tamura, Naoki; Villalobos granados, Edgardo
- Journal Name:
- Nuclear Fusion
- Page Number:
- 116003
- Volume:
- 66
- Issue Number:
- 11
- Publication Date:
- July 6, 2026
- View DOI Listing:
- https://doi.org/10.1088/1741-4326/ae5f32
Abstract
The Wendelstein 7-X (W7-X) stellarator has completed two consecutive experimental campaigns OP 2.2 (Sep.-Dec. 2024) and OP 2.3 (Feb.-May 2025) under a new operational strategy enabling more than one year of uninterrupted device availability. This approach, supported by exceptionally high subsystem reliability, allowed sustained high-efficiency plasma operations with up to 80–100 discharges per day across a broad range of magnetic configurations. Several key technical upgrades-most notably the first operation of a 1.5 MW class steady-state gyrotron, a new steady-state pellet injector, and advanced real-time feedback control systems significantly enhanced heating, fueling, and plasma control capabilities. Together, these improvements enabled major advances in long-pulse performance, high-β operation, and confinement optimization. Long-pulse discharges achieved 1.8 GJ of injected energy under fully detached divertor conditions, while reduced-field scenarios facilitated record volume-averaged β values approaching 3%. High-performance plasmas with centrally peaked density profiles, created via neutral beam injection (NBI) or sustained pellet fueling, demonstrated strongly reduced turbulent transport and stellarator-record fusion triple products. Complementary studies of power exhaust and divertor heat loads revealed the role of scrape-off-layer drift physics in shaping strike-line patterns under attached conditions. Together, the results from OP 2.2 and OP 2.3 significantly expand the operational space of W7-X and strengthen its role as a leading platform for steady-state stellarator research and reactor-relevant plasma scenarios.
