A model-based optimal control approach has been developed for the slow orbit feedback (SOFB) system to enhance orbit stability in the Siam Photon Source (SPS) storage ring. The control strategy utilizes a linear quadratic regulator (LQR) based on a multi-input, multi-output (MIMO) state-space model of the linear SPS storage ring, derived through system identification using MATLAB and SIMULINK. The necessary and sufficient conditions for controllability and boundedness of the dynamic system are established. Experimental simulations were conducted to assess the performance of the LQR controller in a practical SPS storage ring. The results demonstrate that the proposed control method effectively minimizes the quadratic cost function and error signals between setpoints and process variables for both horizontal and vertical orbit positions while ensuring system stability and robustness. The study also outlines the fundamental principles of optimal control theory, system identification, and future development directions.

The Synchrotron Light Research Institute (SLRI) operates the SPS-I facility located in Nakhon Ratchasima, Thailand, which provides synchrotron light for various scientific and industrial applications. The linac injector, serving as the primary injector, is responsible for electron beam bunching and acceleration to 40 MeV, after which the beam is transported to the booster ring via the Low-Energy Beam Transport line (LBT). To ensure optimal beam quality and efficient transport, various beam instrumentation devices are installed along the linac injector and LBT for diagnostics and monitoring. This contribution presents an overview of the beam instrumentation used to measure beam current, transverse profiles, and energy profiles, serving as a fundamental reference for future beam optimization and performance improvements of the SPS-I linac injector system.

The Siam Photon Source (SPS) is a 1.2-GeV synchrotron facility in Thailand, operated by the Synchrotron Light Research Institute (SLRI), providing synchrotron radiation for various applications to the user community. The SPS injector linac generates 40-MeV electron bunches, which are then transported to the booster synchrotron via the Low-Energy Beam Transport line (LBT). To ensure effective beam monitoring along the injector linac and LBT, key beam diagnostics—including beam current, transverse profile, and energy profile monitoring—have been installed in the injector linac. In order to maintain full diagnostic performance, the screen monitor system is planned to be upgraded to enhance transverse beam profile monitoring, improve radiation resistance, and support injector linac optimization for higher machine performance. This paper presents the current status of the screen monitor system for the SPS injector linac and discusses the design and implementation plan for its upgrade.

This paper presents the enhancement of photon beam position stability at the Siam Photon Source (SPS) synchrotron through a real-time feedback control system incorporating a fault-tolerant control (FTC) algorithm. The system utilizes Photon Beam Position Monitor (pBPM) measurements within a global orbit feedback loop to minimize beam position fluctuations. The FTC algorithm plays a critical role in ensuring system reliability by detecting and compensating for disturbances, sensor errors, and actuator faults, maintaining stable beam conditions under varying operational scenarios. Experimental results demonstrate that the FTC-based feedback system significantly reduces photon orbit deviations, improving synchrotron radiation quality. By enhancing robustness and adaptability, the control system ensures precise beam positioning, making the SPS more reliable for scientific and industrial applications requiring high beam stability.