IPAC2013 - List of Authors (Kotzian, G.)

Paper	Title	Page
WEPME043	Performance of the LHC Transverse Damper with Bunch Trains	3022
	W. Höfle, F. Dubouchet, G. Kotzian, D. Valuch CERN, Geneva, Switzerland
	In 2012 the LHC has operated for Physics with bunch trains at 50 ns spacing. Tests have been performed with the nominal design bunch spacing of 25 ns. The transverse damper has been an essential element to provide beam stability for the multi-bunch beam with up to 1380 bunches used at 50 ns spacing. We report on the experience gained with 50 ns spacing and the improvements in the signal processing tested for the future 25 ns operation. The increase in bandwidth required for 25 ns spacing constituted a particular challenge. The response of the system was carefully measured and the results used to digitally pre-distort the drive signal to compensate for a drop in gain of the power system for higher frequencies. The bunch-by-bunch data collected from the feedback signal path provided valuable information during the 2012 Physics run that can be further explored for beam diagnostics purposes and instability analysis in the future. Performance estimates are given for the 7 TeV run planned for 2015, at 25 ns bunch spacing.

WEPME060	First Results and Analysis of the Performance of a 4 GS/s Intra-bunch Vertical Feedback System at the SPS	3070
	J.M. Cesaratto, J.E. Dusatko, J.D. Fox, J.J. Olsen, K.M. Pollock, C.H. Rivetta, O. Turgut SLAC, Menlo Park, California, USA H. Bartosik, W. Höfle, G. Kotzian, U. Wehrle CERN, Geneva, Switzerland
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research program ( LARP) We present experimental measurements taken from SPS machine development studies with an intra-bunch feedback channel. These studies use a digital signal processing system to implement general-purpose control algorithms on multiple samples across a single SPS bunch ( for ease of synchronization with the SPS RF frequency a sampling frequency of 3.2 GS/sec. is implemented). These initial studies concentrate on single-bunch motion, and study the vertical betatron motion as the feedback control is varied. The studies are focused on validating simulation models of the beam dynamics with feedback. Time and frequency domain results include excitation and damping of intra-bunch motion with positive and negative feedback. We present an overview of the challenges of intra-bunch feedback, and highlight methods to time-align the pickup and kicker signals within the closed-loop feedback channel.

Paper

Title

Page

Performance of the LHC Transverse Damper with Bunch Trains

3022

W. Höfle, F. Dubouchet, G. Kotzian, D. Valuch
CERN, Geneva, Switzerland

In 2012 the LHC has operated for Physics with bunch trains at 50 ns spacing. Tests have been performed with the nominal design bunch spacing of 25 ns. The transverse damper has been an essential element to provide beam stability for the multi-bunch beam with up to 1380 bunches used at 50 ns spacing. We report on the experience gained with 50 ns spacing and the improvements in the signal processing tested for the future 25 ns operation. The increase in bandwidth required for 25 ns spacing constituted a particular challenge. The response of the system was carefully measured and the results used to digitally pre-distort the drive signal to compensate for a drop in gain of the power system for higher frequencies. The bunch-by-bunch data collected from the feedback signal path provided valuable information during the 2012 Physics run that can be further explored for beam diagnostics purposes and instability analysis in the future. Performance estimates are given for the 7 TeV run planned for 2015, at 25 ns bunch spacing.

WEPME060

First Results and Analysis of the Performance of a 4 GS/s Intra-bunch Vertical Feedback System at the SPS

3070

J.M. Cesaratto, J.E. Dusatko, J.D. Fox, J.J. Olsen, K.M. Pollock, C.H. Rivetta, O. Turgut
SLAC, Menlo Park, California, USA
H. Bartosik, W. Höfle, G. Kotzian, U. Wehrle
CERN, Geneva, Switzerland

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research program ( LARP)
We present experimental measurements taken from SPS machine development studies with an intra-bunch feedback channel. These studies use a digital signal processing system to implement general-purpose control algorithms on multiple samples across a single SPS bunch ( for ease of synchronization with the SPS RF frequency a sampling frequency of 3.2 GS/sec. is implemented). These initial studies concentrate on single-bunch motion, and study the vertical betatron motion as the feedback control is varied. The studies are focused on validating simulation models of the beam dynamics with feedback. Time and frequency domain results include excitation and damping of intra-bunch motion with positive and negative feedback. We present an overview of the challenges of intra-bunch feedback, and highlight methods to time-align the pickup and kicker signals within the closed-loop feedback channel.