Automatic phase calibration for RF cavities using beam-loading signals
Precise calibration of the cavity phase signals is necessary for the operation of any particle accelerator. For many systems this requires human in the loop adjustments based on measurements of the beam parameters downstream. Some recent work has developed a scheme for the calibration of the cavity phase using beam measurements and beam-loading however this scheme is still a multi-step process that requires heavy automation or human in the loop. In this paper we analyze a new scheme that uses only RF signals reacting to beam-loading to calculate the phase of the beam relative to the cavity. This technique could be used in slow control loops to provide real-time adjustment of the cavity phase calibration without human intervention thereby increasing the stability and reliability of the accelerator.
Transient Beam Loading Based Calibration for Cavity Phase and Amplitude Setting
Traditional phase scan method for cavity phase and amplitude setting is offline and hard to track the variations of environment and operation points. An alternative beam loading based calibration method is investigated in this paper, which might become useful online/real time calibration method.
RECENT DEVELOPMENTS OF THE EUROPEAN XFEL LLRF SYSTEM
The European X-ray free electron laser (XFEL) [1] comprised more than 800 TESLA-type super-conducting accelerator cavities which are driven by 25 high-power multibeam klystrons. For reliable, reproducible and maintainable operation of the linear accelerator (linac), the lowlevel radio frequency (LLRF) system will process more than 3000 RF channels. Furthermore, stable FEL operation demands field stability better than 0.01 deg. in phase and 0.01 % in amplitude. To cope with these challenges, the LLRF system is developed on a MTCA.4 [2] platform. In this paper, we give an update on the latest electronics developments, improvements of the feedback controller algorithm and measurement results at FLASH.