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46 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5 [Next/Last]

Instruments / Technical Area	Publication Details	Published
Accelerator Physics	Kick-and-cancel injection scheme for the Diamond-II storage ring A. Lueangaramwong , R. T. Fielder , A. Morgan , J. Kallestrup , I. P. S. Martin , J. D. Hares , A. K. L. Dymoke-Bradshaw , P. A. Kellett Physical Review Accelerators And Beams 28 DOI: 10.1103/PhysRevAccelBeams.28.060701 Show Abstract ▼ Abstract: The Diamond-II storage ring upgrade will provide users with 1–2 orders of magnitude increase in brightness over the existing Diamond facility, as well as double the number of straight sections to allow for the installation of additional beamlines. A key performance requirement for the upgrade will be to provide a quasitransparent top-up injection scheme. The ring was originally designed to use a single-bunch aperture sharing injection scheme, in which short stripline kickers are used to kick the injected bunch into the storage ring’s dynamic aperture, while the kick remains weak enough to avoid displacing the existing stored bunch outside the acceptance. This scheme has been modified to implement a kick-and-cancel method to place the stored bunch back on axis and leave only the injected bunch to oscillate. The kicker power supplies are thus required to provide a double pulse with a few-microsecond pulse spacing. This new method is expected to significantly improve the transparency of the injection process and reduce the recovery time for the targeted bunch, along with minimizing the transverse wakefield effects and any interactions with the transverse multibunch feedback and harmonic cavity.	May 2025
Accelerator Physics Vacuum	Microwave instability driven by terahertz-scale resistive-wall impedance in electron synchrotrons Dmitrii Rabusov , Ian P. S. Martin , Siwei Wang , Richard T. Fielder Nuclear Instruments And Methods In Physics Research Section A: Accelerators, Spectrometers, Detectors And Associated Equipment 1072 DOI: 10.1016/j.nima.2024.170147 Open Access Show Abstract ▼ Abstract: Vacuum vessels of many existing and planned synchrotron light sources feature metallic coatings. In some combinations, they might cause a resonator-like peak in the longitudinal impedance. In this simulation study, we demonstrate how different parameters of non-evaporable getter (NEG) can increase momentum-spread growth and, hence, reduce microwave-instability thresholds. The first key insight of this study: The spread of the coating-layer thickness amongst vacuum vessels results in significantly reduced momentum-spread growth. Therefore, we recommend including randomised coating when designing vacuum components and modelling the impedance for a synchrotron light source. The second key insight of this study: Insertion devices featuring rectangular geometry and NEG coating might cause a multi-peak structure of the longitudinal impedance which can drive additional momentum-spread growth.	Dec 2024
Accelerator Physics	The design of a 2m long copper light extraction vessel at Diamond Light Source for the Diamond-II upgrade V. Danielyan , M. P. Cox , R. T. Fielder , S. L. Hodbod , T. Lockwood MEDSI2023 DOI: 10.18429/JACoW-MEDSI2023-WEPPP051 Open Access Show Abstract ▼ Abstract: Challenges associated with the design are, firstly, the heat loads of I05 beamline upgrade involving the installation of a powerful and highly divergent APPLE-II Knot Insertion Device. Secondly, it is not easy to produce the required homogeneous NEG (non-evaporable getter) coating on the complex internal geometry of the vessel. Synchrotron light raytracing and thermal analysis has shown that an aluminium vessel with discrete copper absorbers was not capable of handling the high heat loads and it was decided to change to a copper vessel with large integrated absorbing surfaces. FEA analysis of the copper vessel shows the peak temperature is reduced from 446°C to 95°C for the copper vessel as compared to the aluminium vessel. NEG coating trials are currently in progress and will be followed by a full prototype. The minimum vertical aperture is 6 mm and the trials will show whether it can be reduced to 5 mm. The change from an aluminium vessel to a copper vessel will not only reduce the peak temperature of the vessel thereby making it a workable solution, but has the added benefits of improved vacuum performance, reduced beam impedance and reduced capital and operating cost.	Jun 2024
Accelerator Physics	Updates to the impedance database for the Diamond-II storage ring R. Fielder , D. Rabusov , S. Wang IPAC24 Show Abstract ▼ Abstract: Impedance is a significant concern in modern storage rings like Diamond-II, due to instabilities limiting maximum bunch charge and other potential effects such as emittance dilution. Significant changes have been made to the Diamond-II impedance database, partly driven by progress in engineering design work, and partly by the requirements of particle tracking simulations and increase in available computing resources. We present an overview of the current state of the Diamond-II impedance database, focusing on the most significant updates and additions.	May 2024
Accelerator Physics	A Kick-and-Cancel injection scheme for Diamond-II A. Lueangaramwong , I. Martin , R. Fielder , J. Hares IPAC'24 DOI: 10.18429/JACoW-IPAC2024-THPG01 Open Access Show Abstract ▼ Abstract: The Diamond-II storage ring upgrade will provide users with 1-2 orders of magnitude brightness increase over the existing Diamond facility, for which a quasi-transparent top-up injection scheme will be a key performance requirement [1]. The ring was originally designed to use a single-bunch aperture sharing injection scheme [2], in which short stripline kickers are used to kick the injected bunch into the storage ring's dynamic aperture but remaining weak enough to avoid kicking the stored bunch outside the acceptance. A modification to this scheme which implements a kick-and-cancel method [3] shows promise for the stored bunch. The kicker power supplies are thus required to provide a double-pulse with few-microsecond pulse spacing. This new method is expected to significantly improve the transparency and reduce the recovery time for the targeted bunch, along with minimizing transverse wakefield effects and any interactions with the transverse multibunch feedback.	May 2024
Accelerator Physics	Studies for single bunch and multi-bunch beam instabilities in the Diamond-II booster R. Husain , R. Fielder , I. Martin , S. Wang , P. Burrows IPAC'24 DOI: 10.18429/JACoW-IPAC2024-TUPG18 Open Access Show Abstract ▼ Abstract: To reduce filling times and enable advanced injection schemes, it is desirable for the Diamond-II booster to provide high charge in both single and multi-bunch modes. The single bunch charge will be limited by short range wakefields in the booster, and long-range wakefields limit the charge for the multi-bunch trains. Due to the relatively low 100 MeV injection energy into the booster, the injected beam is susceptible to instabilities due to the very weak synchrotron radiation damping. In this paper, we present the simulation results carried out to estimate the single and multi-bunch charge thresholds in the Diamond-II booster including short and long range wakefields, RF cavity HOMs, and with physical apertures applied. Simulations results will also be presented that demonstrate the extracted multi-bunch charge could be increased by installing a transverse multi-bunch feedback (TMBF).	May 2024
Accelerator Physics	Evolution of equilibrium parameters ramp including collective effects in the Diamond-II booster R. Husain , P. N. Burrows , R. T. Fielder , I. P. S. Martin FLS2023 DOI: 10.18429/JACoW-FLS2023-TU4P19 Open Access Show Abstract ▼ Abstract: Efficient top-up injection into the Diamond-II storage ring will require upgrading the booster lattice for a beam emittance of <20 nm rad and a bunch length of <40 ps, including when operating with high single-bunch charge. The small vacuum chamber dimensions will drive the resistive wall instability and may adversely affect equilibrium parameters along the beam energy ramp. In addition, various diagnostic and vacuum chamber components will generate geometric impedances which may further disrupt the equilibrium parameters. Based on the detailed engineering designs, impedance models of the major components have been simulated using CST Studio and included in ELEGANT tracking simulations of the booster. In addition, the effects of synchrotron radiation emission and intra-beam scattering on the equilibrium parameters during the ramp are studied.	Feb 2024
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 Magnets	Development of fast BBA for Diamond Light Source J. M. Appleby , M. G. Abbott , R. T. Fielder , M. J. Gaughran 14th International Particle Accelerator Conference DOI: 10.1088/1742-6596/2687/3/032002 Open Access Show Abstract ▼ Abstract: Beam-based alignment (BBA) is a standard tool at accelerators for aligning particle beams to the centre of quadrupole magnets. Traditional BBA measurements have been slow, potentially taking many hours for a whole machine. We have developed a tool, based on results previously reported at the ALBA synchrotron, that uses fast excitation of magnets to speed up measurements. We show the results of different measurement and analysis techniques in comparison to the currently used slow method.	Jan 2024
Accelerator Physics	RF feedback simulation for Diamond-II using ELEGANT S. Wang , C. Christou , R. Fielder , P. Gu , I. Martin 14th International Particle Accelerator Conference DOI: 10.18429/JACoW-IPAC2023-MOPM047 Open Access Show Abstract ▼ Abstract: The Diamond-II storage ring will utilise normal conducting main cavities and a passive superconducting harmonic cavity in its RF system. To evaluate the effects of bunch lengthening and lifetime gain from the harmonic cavity for different filling patterns, transient beam loading effects need to be studied. When simulating these effects with ELEGANT, RF feedback for the main cavities must be defined using sets of infinite impulse response (IIR) filters. This paper describes the method used to convert proportional-integral (PI) feedback parameters representative of the RF feedback implemented at Diamond into equivalent ELEGANT settings and presents simulation results demonstrating the effectiveness of the RF feedback. Transient beam loading effects for the standard and hybrid filling pattern are also studied.	Sep 2023

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