IBIC2013 - List of Authors (Höfle, W.)

Paper

Title

Page

The Hardware Implementation of the CERN SPS Ultrafast Feedback Processor Demonstrator

124

J.E. Dusatko, J.M. Cesaratto, J.D. Fox, J.J. Olsen, C.H. Rivetta
SLAC, Menlo Park, California, USA
W. Höfle
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)
An ultrafast 4GSa/s transverse feedback processor has been developed for proof-of-concept studies of feedback control of e-cloud driven and transverse mode coupled intra-bunch instabilities in the CERN SPS. This system consists of a high-speed ADC on the front end and equally fast DAC on the back end. All control and signal processing is implemented in FPGA logic. This system is capable of taking up to 16 sample slices across a single SPS bunch and processing each slice individually within a reconfigurable signal processor. This demonstrator system is a rapidly developed prototype, consisting of both commercial and custom-design components. It can stabilize the motion of a single particle bunch using closed loop feedback. The system can also run open loop as a high-speed arbitrary waveform generator and contains diagnostic features including a special ADC snapshot capture memory. This paper describes the overall system, the feedback processor and focuses on the hardware architecture, design and implementation.

Poster MOPC28 [1.684 MB]

TUBL2

A 4 GS/s Feedback Processing System for Control of Intra-Bunch Instabilities

323

J.D. Fox, J.M. Cesaratto, J.E. Dusatko, J.J. Olsen, K.M. Pollock, C.H. Rivetta, O. Turgut
SLAC, Menlo Park, California, USA
W. Höfle
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 the architecture and implementation overview of a digital signal processing system developed to study control of Electron-Cloud and Transverse Mode coupling instabilities in the CERN SPS. The system is based on a reconfigurable processing architecture which samples vertical bunch motion and applies correction signals at a 4 GS/s rate, allowing 16 samples across a single 5 ns SPS RF bucket. The system requires wideband beam pickups and a vertical kicker structure with GHz bandwidth. This demonstration system implements a general purpose 16 tap FIR control filter for each sample. We present results from SPS machine studies showing the impact of wideband feedback to excite/damp internal modes of vertical motion as well as stabilize an unstable beam. These results highlight the challenges of intra-bunch feedback and show proof of principle feasibility of the architecture.

Slides TUBL2 [12.154 MB]

TUPF29

Tune Measurement from Transverse Feedback Signals in LHC

579

F. Dubouchet, W. Höfle, G. Kotzian, T.E. Levens, D. Valuch
CERN, Geneva, Switzerland
P. Albuquerque
HES-SO//Geneva, Geneva, Switzerland

We show how bunch-by-bunch position data from the LHC transverse feedback system can be used to determine the transverse tunes. Results from machine development experiments are presented and compared with theoretical predictions. In the absence of external beam excitations the tune is visible in the spectra of the position data with the feedback loop as a dip, while with external excitation a peak is visible. Both options, observation with and without excitation, are demonstrated to be complementary. Periodic excitation and observation of the free oscillation can also be used to determine the damping time of the feedback in addition to the coherent tune. Plans are outlined for hardware upgrades of the LHC transverse feedback system that will enable fast online processing of bunch-by-bunch, turn-by-turn data using Graphical Processing Units (GPU). By using GPUs we gain the ability to compute and store the spectrum of all bunches in real-time and the possibility to reconfigure test and deploy algorithms. This data acquisition and analysis architecture also allows changes to be made without disturbing the operation.

Poster TUPF29 [1.052 MB]

WEPC12

Evaluation of Strip-line Pick-up System for the SPS Wideband Transverse Feedback System

690

G. Kotzian, W. Höfle, R.J. Steinhagen, D. Valuch, U. Wehrle
CERN, Geneva, Switzerland

The proposed SPS Wideband Transverse Feedback system requires a wide-band pick-up system to be able to detect intra-bunch motion within the SPS proton bunches, captured and accelerated in a 200 MHz bucket. We present the electro-magnetic design of transverse beam position pick-up options optimised for installation in the SPS and evaluate their performance reach with respect to direct time domain sampling of the intra-bunch motion. The analysis also discusses the achieved subsystem responses of the associated cabling with new low dispersion smooth wall cables, wide-band generation of intensity and position signals by means of 180 degree RF hybrids as well as passive techniques to electronically suppress the beam offset signal, needed to optimise the dynamic range and position resolution of the planned digital intra-bunch feedback system.

Paper	Title	Page
MOPC28	The Hardware Implementation of the CERN SPS Ultrafast Feedback Processor Demonstrator	124
	J.E. Dusatko, J.M. Cesaratto, J.D. Fox, J.J. Olsen, C.H. Rivetta SLAC, Menlo Park, California, USA W. Höfle 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) An ultrafast 4GSa/s transverse feedback processor has been developed for proof-of-concept studies of feedback control of e-cloud driven and transverse mode coupled intra-bunch instabilities in the CERN SPS. This system consists of a high-speed ADC on the front end and equally fast DAC on the back end. All control and signal processing is implemented in FPGA logic. This system is capable of taking up to 16 sample slices across a single SPS bunch and processing each slice individually within a reconfigurable signal processor. This demonstrator system is a rapidly developed prototype, consisting of both commercial and custom-design components. It can stabilize the motion of a single particle bunch using closed loop feedback. The system can also run open loop as a high-speed arbitrary waveform generator and contains diagnostic features including a special ADC snapshot capture memory. This paper describes the overall system, the feedback processor and focuses on the hardware architecture, design and implementation.
	Poster MOPC28 [1.684 MB]

TUBL2	A 4 GS/s Feedback Processing System for Control of Intra-Bunch Instabilities	323
	J.D. Fox, J.M. Cesaratto, J.E. Dusatko, J.J. Olsen, K.M. Pollock, C.H. Rivetta, O. Turgut SLAC, Menlo Park, California, USA W. Höfle 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 the architecture and implementation overview of a digital signal processing system developed to study control of Electron-Cloud and Transverse Mode coupling instabilities in the CERN SPS. The system is based on a reconfigurable processing architecture which samples vertical bunch motion and applies correction signals at a 4 GS/s rate, allowing 16 samples across a single 5 ns SPS RF bucket. The system requires wideband beam pickups and a vertical kicker structure with GHz bandwidth. This demonstration system implements a general purpose 16 tap FIR control filter for each sample. We present results from SPS machine studies showing the impact of wideband feedback to excite/damp internal modes of vertical motion as well as stabilize an unstable beam. These results highlight the challenges of intra-bunch feedback and show proof of principle feasibility of the architecture.
	Slides TUBL2 [12.154 MB]

TUPF29	Tune Measurement from Transverse Feedback Signals in LHC	579
	F. Dubouchet, W. Höfle, G. Kotzian, T.E. Levens, D. Valuch CERN, Geneva, Switzerland P. Albuquerque HES-SO//Geneva, Geneva, Switzerland
	We show how bunch-by-bunch position data from the LHC transverse feedback system can be used to determine the transverse tunes. Results from machine development experiments are presented and compared with theoretical predictions. In the absence of external beam excitations the tune is visible in the spectra of the position data with the feedback loop as a dip, while with external excitation a peak is visible. Both options, observation with and without excitation, are demonstrated to be complementary. Periodic excitation and observation of the free oscillation can also be used to determine the damping time of the feedback in addition to the coherent tune. Plans are outlined for hardware upgrades of the LHC transverse feedback system that will enable fast online processing of bunch-by-bunch, turn-by-turn data using Graphical Processing Units (GPU). By using GPUs we gain the ability to compute and store the spectrum of all bunches in real-time and the possibility to reconfigure test and deploy algorithms. This data acquisition and analysis architecture also allows changes to be made without disturbing the operation.
	Poster TUPF29 [1.052 MB]

WEPC12	Evaluation of Strip-line Pick-up System for the SPS Wideband Transverse Feedback System	690
	G. Kotzian, W. Höfle, R.J. Steinhagen, D. Valuch, U. Wehrle CERN, Geneva, Switzerland
	The proposed SPS Wideband Transverse Feedback system requires a wide-band pick-up system to be able to detect intra-bunch motion within the SPS proton bunches, captured and accelerated in a 200 MHz bucket. We present the electro-magnetic design of transverse beam position pick-up options optimised for installation in the SPS and evaluate their performance reach with respect to direct time domain sampling of the intra-bunch motion. The analysis also discusses the achieved subsystem responses of the associated cabling with new low dispersion smooth wall cables, wide-band generation of intensity and position signals by means of 180 degree RF hybrids as well as passive techniques to electronically suppress the beam offset signal, needed to optimise the dynamic range and position resolution of the planned digital intra-bunch feedback system.