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Instruments / Technical Area	Publication Details	Published
Accelerator Physics	Development of a pulsed injection stripline for Diamond-II R. Fielder , A. Lueangaramwong , A. Morgan FLS2023 DOI: 10.18429/JACoW-FLS2023-MO4B3 Open Access Show Abstract ▼ Abstract: Diamond-II will use a single bunch aperture sharing injection scheme. This applies a strong kick to both the injected and the targeted stored bunch with a very short duration (ideally <3 ns, if disturbance to the adjacent bunches is to be avoided). We have developed a design for the stripline kickers that can meet these requirements while minimising internal reflections and beam impedance. We show an analysis of the electric and magnetic fields produced by the stripline and simulations of the effects on injected and stored beam, and analysis of the wakefields and impedance of the structure.	Feb 2024
Accelerator Physics	Investigations into operating Pulse Picking by Resonant Excitation (PPRE) in the vertical plane S. Wilkes , A. Morgan , G. Karras , I. Martin , M. Warren 14th International Particle Accelerator Conference DOI: 10.18429/JACoW-IPAC2023-MOPM037 Open Access Show Abstract ▼ Abstract: As preparation for the upcoming Diamond-II upgrade, provisions for timing-users (those who predominantly care about the timing characteristics of the synchrotron radiation) are being investigated. Although ‘Hybrid bunch’ modes are currently employed at Diamond, such operation presents challenges for Diamond-II that merit investigating alternative approaches. PPRE, one such approach, involves resonantly exciting a targeted electron bunch using a Transverse Multi Bunch Feedback system (TMBF). We report on the efficacy of the TMBF for driving one (or few) bunches, focusing on studying the charge-dependent effects and the achieved vertical emittance, and also by considering the effect of long range impedance between bunches. Furthermore, to test experimentally the use of PPRE, we present our first results from a representative beamline. The work is also discussed in context of the proposed operational requirements for Diamond-II.	Sep 2023
Accelerator Physics	Study of aperture sharing injection scheme for Diamond-II H. Ghasem , A. Lueangaramwong , A. F. D. Morgan , I.p.s. Martin 14th International Particle Accelerator Conference DOI: 10.18429/JACoW-IPAC2023-MOPM073 Open Access Show Abstract ▼ Abstract: The Diamond-II storage ring has been designed to increase photon brightness by up to two orders of magnitude compared to the existing Diamond facility. A single-bunch aperture sharing injection scheme using short stripline kickers applied with high-voltage nano-second pulsers was proposed to provide both high injection efficiency and high photon beam stability in top-up mode. The quasi-transparent injection process has been optimised and studied using Accelerator Toolbox. The results of these study will be presented.	Sep 2023
Electrical Engineering	Study of single bunch instabilities with transverse feedback at diamond E. Koukovini-Platia , A. F. D. Morgan , G. Rehm , R. Bartolini IPAC2017 Show Abstract ▼ Abstract: Single bunch instability studies have been carried out at Diamond with and without the transverse multi-bunch feedback (TMBF) system. Single bunch instability thresholds were measured for zero, positive and negative chromaticity values by increasing the current till the instability onset. The bunch-by-bunch feedback system was then used to suppress the motion of the bunch centroid and the new thresholds were measured in all chromaticity regimes. The feedback loop phase of the TMBF was changed from resistive to reactive as well as intermediate to find the optimal feedback settings that maximize the single bunch instability thresholds.	Jun 2017
RF	First experiences with the longitudinal feedback system at Diamond Light Source A. F. D. Morgan , M. G. Abbott , G. Rehm IPAC2017 DOI: 10.18429/JACoW-IPAC2017-TUPIK114 Open Access Show Abstract ▼ Abstract: In order to avoid longitudinal multibunch instabilities potentially caused by the addition of normal conducting RF cavities into the Diamond storage ring, a longitudinal feedback was installed. The main components are newly developed feedback electronics, in-house built modulator and amplifier, and a low Q kicker cavity. This paper describes the performance of the cavity as well as the full longitudinal feedback system as it is installed on the machine and tested before the installation of the normal conducting RF cavities.	May 2017
Mechanical Engineering	Performance evaluation of molybdenum blades in an X-ray pinhole camera L. M. Bobb , A. F. D. Morgan , G. Rehm IBIC2016 DOI: 10.18429/JACoW-IBIC2016-WEPG63 Show Abstract ▼ Abstract: At Diamond Light Source transverse profile measure- ments of the 3 GeV electron beam are provided by x-ray pinhole cameras. From these beam size measurements and given knowledge of the lattice parameters the emittance, coupling and energy spread are calculated. Traditionally, tungsten blades are used to form the pinhole aperture due to the opacity of tungsten to x-rays in the keV spectral range. The physical properties of tungsten also make it difficult to work. To achieve the 25 μm × 25 μm aperture size required for high resolution measurements it is necessary to mount these tungsten blades in an assembly whereby the pinhole aperture size is defined by precisely machined shims. Here we propose to replace the tungsten blade and shim arrange- ment with machined molybdenum blades and evaluate the performance of the resulting imaging system.	Sep 2016
Mechanical Engineering	Design for the diamond longitudinal bunch-by-bunch A. F. D. Morgan , G. Rehm IBIC2016 DOI: 10.18429/JACoW-IBIC2016-TUPG12 Show Abstract ▼ Abstract: In 2017 it is planned to install some additional normal conducting cavities into the Diamond storage ring. In order to deal with the potential higher order modes in these, we are designing a longitudinal bunch-by-bunch feedback system. This paper will focus on the design of the overloaded cavity kicker, adapted to the Diamond beam pipe cross section. The design has evolved in order to reduce the strong 3rd harmonic resonance seen on the introduction of the racetrack beam pipe. Through a combination of geometry optimisation and the addition of integrated taper transitions this harmonic has been greatly reduced while also minimising sharp resonances below 15 GHz. The major features will be described, as well as the expected performance parameters.	Sep 2016
Controls	Operational status of the transverse multibunch feedback system at Diamond I. Uzun , M. Abbott , M. T. Heron , A. F. D. Morgan , G. Rehm ICALEPCS 2011 Show Abstract ▼ Abstract: A transverse multibunch feedback (TMBF) system is in operation at Diamond Light Source to damp coupled-bunch instabilities up to 250 MHz in both the vertical and horizontal planes. It comprises an in-house designed and built analogue front end combined with a Libera Bunch-by-Bunch feedback processor and output stripline kickers. FPGA-based feedback electronics is used to implement several diagnostic features in addition to the basic feedback functionality. This paper reports on the current operational status of the TMBF system along with its characteristics. Also discussed are operational diagnostic functionalities including continuous measurement of the betatron tune and chromaticity	Oct 2011
Controls Diagnostics	An FPGA-based Transverse Multibunch Feedback System for Diamond Light Source Isa Uzun , Mark Heron , Alun Morgan , Guenther Rehm 2010 International Conference on Field Programmable Logic and Applications Show Abstract ▼ Abstract: This paper describes the design and implementation of an FPGA-based transverse multibuch feedback system for Diamond Light Source. The system is designed to damp instabilities of the electron beam up to 250~MHz in both horizontal and vertical planes. The feedback algorithm and diagnostics features are implemented and verified using SystemVerilog HDL language on a Xilinx XCV2P30 FPGA.	Sep 2010
Accelerator Physics Diagnostics	Measurement of lattice parameters without visible disturbance to user beam at Diamond Light Source Guenther Rehm , Michael Abbott , Alun Morgan , James Rowland , Isa Uzun 2010 Beam Instrumentation Workshop (BIW10) Show Abstract ▼ Abstract: With refined lattice tuning it becomes increasingly important to monitor or feedback on many parameters to keep stable optimum operating conditions. To this end we present techniques to measure betatron tune, chromaticity, betafunction magnitude/phase, and orbit response matrices all in such a way that no disturbance to the stored beam can be observed by the users of the light source. Examples of measurements for the various categories are compared to established methods, and their use in feedback schemes is discussed.	May 2010

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