Feedback control systems for plasma operation at Wendelstein 7-X

Real-time feedback control is essential for meeting the physics and operational demands of Wendelstein 7-X (W7-X), particularly the need to respond effectively to transient events, maintain stationary high-performance phases and operate reliably across a wide range of magnetic configurations and plasma regimes. This work provides an overview of the feedback systems implemented and validated in recent campaigns, including the control of key plasma parameters such as density, radiation and heating power under varying conditions. These systems rely on the W7-X segment control architecture and its millisecond-scale real-time network, which enable precise and deterministic coordination of sensors and actuators. Representative experiments highlight robust performance, including long stationary discharges and integrated multi-parameter control. Additional boundary conditions such as core electron temperature limits ensure protection against radiative collapse and other failure modes. Looking forward, planned developments include advanced actuators, neural-network-assisted control strategies and long-term efforts toward full profile control of electron density and temperature. Overall, these developments establish real-time feedback control as an essential element of W7-X operation and a robust basis for advanced control concepts in future steady-state fusion devices.