Dr Douglas Bett

Abstract:

For future linear colliders the precise control and mitigation of pulse-to-pulse orbit jitter will be very important to achieve the required luminosity. Diagnostic techniques for the orbit jitter measurement and correction for multibunch operation are being addressed at the KEK Accelerator Test Facility 2 (ATF2). In this paper we present recent studies on the vertical jitter propagation through the ATF2 extraction line and final focus system. For these studies the vertical pulse-to-pulse position and angle jitter have been measured using the available stripline beam position monitors in the beamline. The cases with and without intra-train orbit feedback correction in the ATF2 extraction line are compared. Copyright © 2012 by IEEE.

Abstract:

The FONT5 upstream beam-based feedback system at ATF2 is designed to correct the position and angle jitter at the entrance to the ATF2 final-focus system, and also to demonstrate a prototype intra-train feedback system for the International Linear Collider interaction point. We discuss the hardware, from stripline BPMs to kickers, and RF and digital signal processing, as well as presenting results from the latest beam tests at ATF2.

Abstract:

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.

Abstract:

An FPGA-based monitoring system has been developed to study multi-bunch beam instabilities in the damping ring (DR) of the KEK Accelerator Test Facility (ATF), utilising a stripline beam position monitor (BPM) and existing BPM processor hardware. 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. An overview of the system and initial results will be presented. Copyright © 2011 by IPAC'11/EPS-AG.

Abstract:

A prototype Interaction Point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider, has been designed and tested on the extraction line of the KEK Accelerator Test Facility (ATF). The FONT5 intra-train feedback system aims to stabilise the beam orbit by correcting both the position and angle jitter in the vertical plane on bunch-to-bunch timescales, providing micron-level stability 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. A total systemlatency as low as approximately 140 ns has been demonstrated. Copyright © 2011 by IPAC'11/EPS-AG.