A sub-micron resolution, bunch-by-bunch beam trajectory feedback system and its application to reducing wakefield effects in single-pass beamlines

Abstract

A high-precision intra-bunch-train beam orbit feedback correction system has been developed and tested at the KEK Accelerator Test Facility, ATF2. The system uses the vertical position of the bunch measured at two beam position monitors to calculate a pair of kicks which are applied to the next bunch using two upstream kickers, thereby correcting both the vertical position and trajectory angle. Using trains of two electron bunches separated in time by 187.6 ns, the system was optimised so as to stabilize the beam offset at the feedback BPMs to better than 350 nm, yielding a local trajectory angle correction to within 250 nrad. The quality of the correction was verified using three downstream witness BPMs and the results were found to be in agreement with the predictions of a linear lattice model used to propagate the beam trajectory from the feedback region. This same model predicts a corrected beam jitter of c. 1 nm at the focal point of the accelerator. Measurements with a beam size monitor at this location demonstrate that reducing the trajectory jitter of the beam by a factor of 4 also reduces the increase in the measured beam size as a function of beam charge by a factor of c. 1.6.

Application of Video Feedback System to Technical Analysis and Diagnosis of Throwing Athletes

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A one-time sampling method for the real-time measurement of bunch-by-bunch three-dimensional positions in storage rings

“…Indeed, it is convenient for beam physical analysis, but incapable to provide real-time beam information to the light source and optimize machine states directly. Whereas the synchronous sampling method, composed of one high-speed signal digitizer and one digital processing unit, usually monitors one beam parameter in real time [9][10][11][12][13], which is capable to restrain multi-bunch instabilities and reduce wakefield effects [14][15][16][17]. However, the synchronous sampling method relies extensively on JESD204B protocol based high-speed acquisition boards, which are dominantly used in high-speed 2022 JINST 17 P11001 data converter applications [18,19].…”

A high-resolution, low-latency, bunch-by-bunch feedback system for nano-beam stabilization

“…A feedback system was deployed in the upstream section of the ATF2 extraction line, using high-resolution bunchposition measurements from stripline beam-position monitors (BPMs) [9], to demonstrate [10] the resolution, correction-range and latency requirements for the ILC IP beam collision feedback system [11]. An extended feedback system based on this hardware was recently used to stabilize the beam trajectory before its entrance to the final-focus region, and yielded a significant reduction in the impact of 'wakefields' on the beam-size growth [12].…”