NSLS-II Bunch-by-bunch Feedback Commissioning
Bunch-by-bunch feedback systems at NSLS-II have been commissioned during the week of May 5-9, 2014. In commissioning period, feedback operation in vertical and horizontal planes has been demonstrated. During commissioning, diagnostic capabilities of iGp12 feedback signal processors have been used to characterize transverse tunes, instability modal patterns, beam transfer functions. Recently introduced feature of active single-bunch tune tracking has been tested as well, operating reliably down to very low excitation levels.
Vertical grow/damp measurement
Vertical grow/damp measurement shown here captures typical observed behavior, with rapidly saturating growth of low-frequency modes. This is normally a signature of ion-driven instabilities.
Single bunch transfer function
Single bunch transfer function measurement shows interesting features at roughly ±1 kHz separation from the betatron peak (much smaller than 2.7 kHz synchrotron frequency). Better understanding of these peculiarities requires further study.