Philip Burrows

Abstract:

The CLIC recombination scheme is a concept of multiplication of the drive beamfrequency in order to generate a 12 GHz RF wave for the main beam acceleration. CLIC isdesigned to be operated at nominal energy and in low energy modes. The low energy operationmodes require the train length to be increased by different factors in order to maintainthe same level of luminosity. Also the number of initial trains that are merged to formeach final train is changed. The combination scheme must be able to accommodate andrecombine both long and short trains for nominal and low energy CLIC operation modes. Therecombination hence becomes a non-trivial process and makes the correction of the errors inthe drive beam more challenging. The present paper describes in detail the recombinationprocess and its consequences. Copyright © 2012 by IEEE.

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). The system utilises a stripline beam position monitor (BPM) and single-stage down-mixing BPM processor. The system is designed to record the horizontal and/or vertical positions of up to three bunches in the DR with c. 150ns bunch spacing, or the head bunch of up to three trains in a multi-bunch mode with a bunch spacing of 5.6 ns. The FPGA firmware and data acquisition software allow the recording of turnby- turn data. An overview of the system and performance results will be presented. Copyright © 2012 by IEEE.

Abstract:

The CLIC drive beam provides RF power for acceleration of the main beam, and hence thedrive beam's longitudinal phase tolerances are very tight. A feedforward chicane consistingof four electromagnetic kickers is proposed as a correction system for the phase errors,which should allow loosening of the tolerances. A prototype of such a chicane systemdeveloped by CERN, INFN and the University of Oxford, is planned to be installed at CTF3 in2012. The present paper summarizes the parameters of the planned phase correction systemand presents simulations, which are used to make predictions of the performance of such afeedforward system at CTF3. Copyright © 2012 by IEEE.

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.