DIPAC2011 - List of Authors (Christian, G.B.)

Paper	Title	Page
MOPD79	An FPGA-based Turn-by-Turn Beam Position Monitoring System for Studying Multiple Bunch Beams in the ATF Damping Ring	230
	G.B. Christian, D.R. Bett, B. Constance, M.R. Davis JAI, Oxford, United Kingdom R. Apsimon, P. Burrows, A. Gerbershagen, C. Perry Oxford University, Physics Department, Oxford, Oxon, United Kingdom J. Resta-López IFIC, Valencia, Spain
	Instabilities associated with beam-size blow-up have previously been observed with multi-bunch beam in the damping ring (DR) of the KEK Accelerator Test Facility (ATF). A system has been developed to monitor such instabilities, utilising an ATF stripline beam position monitor (BPM) in the DR, and BPM processor hardware designed for the FONT upstream feedback system in the ATF extraction line. The system is designed to record the horizontal and/or vertical positions of up to three bunches in the DR in single-bunch multi-train mode or the head bunch of up to three trains in multi-bunch mode, with a bunch spacing of 5.6 ns. The FPGA firmware and data acquisition software were modified to record turn-by-turn data for up to six channels and 1–3 bunches in the DR. The maximum memory configuration on the FPGA allows 131071 bunch-turn-channels of data to be recorded from a particular machine pulse, and the system has the capability to select only certain turns at a regular interval in which to record data, in order to zoom out and cover the entire period of the damping cycle at the ATF. An overview of the system and initial results will be presented.

MOPD80	An FPGA-based Bunch-by-Bunch Position and Angle Feedback System at ATF2	233
	G.B. Christian, R. Apsimon, D.R. Bett, B. Constance, M.R. Davis JAI, Oxford, United Kingdom P. Burrows, C. Perry Oxford University, Physics Department, Oxford, Oxon, United Kingdom A. Gerbershagen CERN, Geneva, Switzerland J. Resta-López IFIC, Valencia, Spain
	The FONT5 intra-train feedback system serves as a prototype for an interaction point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider. The system has been tested on the KEK Accelerator Test Facility (ATF) and is deployed to stabilise the beam orbit at the ATF2. The goal of this system is to correct both position and angle jitter in the vertical plane, providing stability of ~1 micron at the entrance to the ATF2 final-focus system. The system comprises three stripline beam position monitors (BPMs) and two stripline kickers, custom low-latency analogue front-end BPM processors, a custom FPGA-based digital processing board with fast ADCs, and custom kicker-drive amplifiers. An overview of the hardware, and the latest results from beam tests at ATF2, will be presented. The total latency of the system with coupled position and angle feedback loops operating simultaneously was measured to be approximately 140 ns. The greatest degree of correction observed was down to a jitter of 0.4 microns at one of the feedback BPMs, a factor of six compared to the uncorrected beam jitter, for a very high degree of bunch-to-bunch correlation.

Paper

Title

Page

An FPGA-based Turn-by-Turn Beam Position Monitoring System for Studying Multiple Bunch Beams in the ATF Damping Ring

230

G.B. Christian, D.R. Bett, B. Constance, M.R. Davis
JAI, Oxford, United Kingdom
R. Apsimon, P. Burrows, A. Gerbershagen, C. Perry
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
J. Resta-López
IFIC, Valencia, Spain

Instabilities associated with beam-size blow-up have previously been observed with multi-bunch beam in the damping ring (DR) of the KEK Accelerator Test Facility (ATF). A system has been developed to monitor such instabilities, utilising an ATF stripline beam position monitor (BPM) in the DR, and BPM processor hardware designed for the FONT upstream feedback system in the ATF extraction line. The system is designed to record the horizontal and/or vertical positions of up to three bunches in the DR in single-bunch multi-train mode or the head bunch of up to three trains in multi-bunch mode, with a bunch spacing of 5.6 ns. The FPGA firmware and data acquisition software were modified to record turn-by-turn data for up to six channels and 1–3 bunches in the DR. The maximum memory configuration on the FPGA allows 131071 bunch-turn-channels of data to be recorded from a particular machine pulse, and the system has the capability to select only certain turns at a regular interval in which to record data, in order to zoom out and cover the entire period of the damping cycle at the ATF. An overview of the system and initial results will be presented.

MOPD80

An FPGA-based Bunch-by-Bunch Position and Angle Feedback System at ATF2

233

G.B. Christian, R. Apsimon, D.R. Bett, B. Constance, M.R. Davis
JAI, Oxford, United Kingdom
P. Burrows, C. Perry
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
A. Gerbershagen
CERN, Geneva, Switzerland
J. Resta-López
IFIC, Valencia, Spain

The FONT5 intra-train feedback system serves as a prototype for an interaction point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider. The system has been tested on the KEK Accelerator Test Facility (ATF) and is deployed to stabilise the beam orbit at the ATF2. The goal of this system is to correct both position and angle jitter in the vertical plane, providing stability of ~1 micron at the entrance to the ATF2 final-focus system. The system comprises three stripline beam position monitors (BPMs) and two stripline kickers, custom low-latency analogue front-end BPM processors, a custom FPGA-based digital processing board with fast ADCs, and custom kicker-drive amplifiers. An overview of the hardware, and the latest results from beam tests at ATF2, will be presented. The total latency of the system with coupled position and angle feedback loops operating simultaneously was measured to be approximately 140 ns. The greatest degree of correction observed was down to a jitter of 0.4 microns at one of the feedback BPMs, a factor of six compared to the uncorrected beam jitter, for a very high degree of bunch-to-bunch correlation.