IBIC2013 - List of Keywords (FIR)

Paper	Title	Other Keywords	Page
MOPC26	Optimization of Bunch-to-Bunch Isolation in Instability Feedback Systems	coupling, feedback, pick-up, kicker	116
	D. Teytelman Private Address, San Jose, USA
	Bunch-by-bunch feedback formalism is a powerful tool for combating coupled-bunch instabilities in circular accelerators. Imperfections in the analog front and back ends lead to coupling between neighboring bunches. Such coupling limits system performance in both feedback and diagnostic capacities. In this paper, techniques for optimizing bunch-to-bunch isolation within the system will be presented. A new method for improving the performance of the existing systems will be described. The novel approach uses a "shaper" filter in the digital signal processor to compensate for the imperfect response of the power amplifier and kicker combination. An objective optimization method to derive the optimal back end configuration will be presented and illustrated with measurements from several accelerators.
	Poster MOPC26 [0.851 MB]

MOPC28	The Hardware Implementation of the CERN SPS Ultrafast Feedback Processor Demonstrator	feedback, controls, SPS, CERN	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]

MOPC29	Realization of Transverse Feedback System for SIS18/100 using FPGA	feedback, BPM, transverse, controls	128
	T. Rueckelt Technische Universität Darmstadt (TU Darmstadt), Signal Processing Group, Darmstadt, Germany M. Alhumaidi, T. Rueckelt, A.M. Zoubir TU Darmstadt, Darmstadt, Germany
	Higher beam intensities in particle accelerator are usually prevented by beam instabilities. To cure these instabilities, additional active system must be used besides passive damping. For this purpose, we have developed a distributed low-latency Transverse Feedback System (TFS) using FPGAs. Data acquisition takes place on multiple BPMs with individual FPGAs and ADCs around the accelerator ring. Acquired data is compressed and sent over broadband fiber optic wires to a central unit. For synchronization, data is tagged using timestamps from a reference time, which is distributed by a specially constrained network time protocol to obtain cycle accuracy. The central unit provides an FIR filter for system bandwidth limitation, and an adaptive IIR filter for stable beam signal rejection. Feedback is given using a linear combination of the pre-processed BPM signals. The system provides substantial flexibility, due to the possibility to configure most parameters online. Filters, feedback sources and parameters, compression rate and more can be adapted via Ethernet interface, which also supplies analysis data. First results are shown.
	Poster MOPC29 [1.842 MB]

WEPC10	Capability Upgrade of the Diamond Transverse Multibunch Feedback	feedback, DIAMOND, controls, transverse	682
	M.G. Abbott, G. Rehm, I.S. Uzun Diamond, Oxfordshire, United Kingdom
	We describe an upgrade to the Transverse Multi-Bunch Feedback processor used at Diamond for control of multi-bunch instabilities and measurement of betatron tunes. The new system will improve both feedback and diagnostic capabilities. Bunch by bunch selectable control over feedback filters, gain and excitation will allow finer control over feedback, allowing for example the single bunch in a hybrid or camshaft fill pattern to be controlled independently from the bunch train. It will also be possible to excite all bunches at a single frequency while simultaneously sweeping the excitation for tune measurement of a few selected bunches. The single frequency excitation can be used for bunch cleaning or continuous measurement of the beta-function. A simple programmable event sequencer will provide support for up to 8 steps of programmable sweeps and changes to feedback and excitation, allowing a variety of complex and precisely timed beam characterisation experiments including grow-damp measurements in unstable conditions.
	Poster WEPC10 [0.427 MB]

WEPF29	The LHC Fast Beam Current Change Monitor	LHC, injection, CERN, beam-losses	887
	D. Belohrad, J.M. Belleman, L.K. Jensen, M. Krupa, A. Topaloudis CERN, Geneva, Switzerland
	The modularity of the Large Hadron Collider’s (LHC) machine protection system (MPS) allows for the integration of several beam diagnostic instruments. These instruments have not necessarily been designed to have protection functionality, but MPS can still use them to increase the redundancy and reliability of the machine. The LHC fast beam current change monitor (FBCCM) is an example. It is based on analogue signals from fast beam current transformers (FBCT) used nominally to measure the LHC bunch intensities. The FBCCM calculates the magnitude of the beam signal provided by the FBCT, looks for a change over specific time intervals, and triggers a beam dump interlock if losses exceed an energy-dependent threshold. The first prototype of the FBCCM was installed in the LHC during the 2012-2013 run. The aim of this article is to present the FBCCM system and the results obtained, analyse its current performance and provide an outlook for the final system which is expected to be operational after the long LHC shutdown.

Paper

Title

Other Keywords

Page

MOPC26

Optimization of Bunch-to-Bunch Isolation in Instability Feedback Systems

coupling, feedback, pick-up, kicker

116

D. Teytelman
Private Address, San Jose, USA

Bunch-by-bunch feedback formalism is a powerful tool for combating coupled-bunch instabilities in circular accelerators. Imperfections in the analog front and back ends lead to coupling between neighboring bunches. Such coupling limits system performance in both feedback and diagnostic capacities. In this paper, techniques for optimizing bunch-to-bunch isolation within the system will be presented. A new method for improving the performance of the existing systems will be described. The novel approach uses a "shaper" filter in the digital signal processor to compensate for the imperfect response of the power amplifier and kicker combination. An objective optimization method to derive the optimal back end configuration will be presented and illustrated with measurements from several accelerators.

Poster MOPC26 [0.851 MB]

MOPC28

The Hardware Implementation of the CERN SPS Ultrafast Feedback Processor Demonstrator

feedback, controls, SPS, CERN

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]

MOPC29

Realization of Transverse Feedback System for SIS18/100 using FPGA

feedback, BPM, transverse, controls

128

T. Rueckelt
Technische Universität Darmstadt (TU Darmstadt), Signal Processing Group, Darmstadt, Germany
M. Alhumaidi, T. Rueckelt, A.M. Zoubir
TU Darmstadt, Darmstadt, Germany

Higher beam intensities in particle accelerator are usually prevented by beam instabilities. To cure these instabilities, additional active system must be used besides passive damping. For this purpose, we have developed a distributed low-latency Transverse Feedback System (TFS) using FPGAs. Data acquisition takes place on multiple BPMs with individual FPGAs and ADCs around the accelerator ring. Acquired data is compressed and sent over broadband fiber optic wires to a central unit. For synchronization, data is tagged using timestamps from a reference time, which is distributed by a specially constrained network time protocol to obtain cycle accuracy. The central unit provides an FIR filter for system bandwidth limitation, and an adaptive IIR filter for stable beam signal rejection. Feedback is given using a linear combination of the pre-processed BPM signals. The system provides substantial flexibility, due to the possibility to configure most parameters online. Filters, feedback sources and parameters, compression rate and more can be adapted via Ethernet interface, which also supplies analysis data. First results are shown.

Poster MOPC29 [1.842 MB]

WEPC10

Capability Upgrade of the Diamond Transverse Multibunch Feedback

feedback, DIAMOND, controls, transverse

682

M.G. Abbott, G. Rehm, I.S. Uzun
Diamond, Oxfordshire, United Kingdom

We describe an upgrade to the Transverse Multi-Bunch Feedback processor used at Diamond for control of multi-bunch instabilities and measurement of betatron tunes. The new system will improve both feedback and diagnostic capabilities. Bunch by bunch selectable control over feedback filters, gain and excitation will allow finer control over feedback, allowing for example the single bunch in a hybrid or camshaft fill pattern to be controlled independently from the bunch train. It will also be possible to excite all bunches at a single frequency while simultaneously sweeping the excitation for tune measurement of a few selected bunches. The single frequency excitation can be used for bunch cleaning or continuous measurement of the beta-function. A simple programmable event sequencer will provide support for up to 8 steps of programmable sweeps and changes to feedback and excitation, allowing a variety of complex and precisely timed beam characterisation experiments including grow-damp measurements in unstable conditions.

Poster WEPC10 [0.427 MB]

WEPF29

The LHC Fast Beam Current Change Monitor

LHC, injection, CERN, beam-losses

887

D. Belohrad, J.M. Belleman, L.K. Jensen, M. Krupa, A. Topaloudis
CERN, Geneva, Switzerland

The modularity of the Large Hadron Collider’s (LHC) machine protection system (MPS) allows for the integration of several beam diagnostic instruments. These instruments have not necessarily been designed to have protection functionality, but MPS can still use them to increase the redundancy and reliability of the machine. The LHC fast beam current change monitor (FBCCM) is an example. It is based on analogue signals from fast beam current transformers (FBCT) used nominally to measure the LHC bunch intensities. The FBCCM calculates the magnitude of the beam signal provided by the FBCT, looks for a change over specific time intervals, and triggers a beam dump interlock if losses exceed an energy-dependent threshold. The first prototype of the FBCCM was installed in the LHC during the 2012-2013 run. The aim of this article is to present the FBCCM system and the results obtained, analyse its current performance and provide an outlook for the final system which is expected to be operational after the long LHC shutdown.