Speaker
Description
Stable top-up operation requires bunch-by-bunch fill-pattern control as well as total beam current regulation. In PLS-II, time-based top-up injection makes it difficult to promptly identify under-filled buckets, over-filled buckets, or abnormal injection shots, which can cause fill-pattern modulation and beamline micro-flux variations.
We developed a bunch-by-bunch current diagnostic IOC using the SUM signal of the Dimtel iGp12 feedback processor. The BPM SUM signal is down-converted to baseband, converted into per-bucket amplitudes, baseline-subtracted, and calibrated to the DCCT total current, providing a robust fill-pattern monitor without additional photodiode hardware.
An Injection Difference Viewer visualizes shot-by-shot current increments versus bucket number and injection step, enabling identification of missing shots, under-filling, over-filling, and abnormal injection sequences. A lifetime IOC also estimates train, camshaft-bunch, total-current, and DCCT-based lifetimes using stitched fitting under top-up operation.
This infrastructure supports the transition from time-based top-up injection to current/lifetime-aware bucket selection for flatter fill-pattern control and future AI-assisted top-up operation.
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