bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy Saving Measures in the High-Power RF System of the European XFEL
Authors: Bousonville M , Choroba S , Göller S , Kröger V , Vogel V , Weinhausen T 
Published: January 2024

Abstract
The high-voltage modulators of the 26 klystrons in the XFEL represent the largest power consumer of the accelerator facility. The beam energy is usually 14 GeV, but a few weeks a year, lower and higher beam energies are also produced. For example, 11.5 and 16.3 GeV. Until mid-2022, the modulator voltages were set so that enough RF power for 16.3 GeV beam energy could be provided at all times. In order to save energy, the modulator voltages will now be lowered to a sufficient level for beam energies of ≤ 14 GeV. In this way, the previous power consumption of the modulators of 5 MW can be reduced up to 1 MW depending on the operation mode. Over the course of a year, this will save several GWh of energy. In the following, the relationship between the output voltage and the power consumption of the modulators is described. Afterwards, it is reported how the power consumption was reduced in various operating conditions in 2022.
Development of single mode cavity at 1.5 GHz for the third harmonic RF-system in PETRA IV
Authors: Karau S , Bousonville M , Hülsmann P , Choroba S 
Published: January 2024

Abstract
The PETRA IV storage ring currently under development at DESY will require a third harmonic 1.5 GHz RF-system to prevent negative effects on both, lifetime and emittance, caused by Touschek effect and Intrabeam scattering. These cavities lengthen the bunches and thereby reduce their charge density. For this 3rd harmonic system, a one-cell single-mode cavity with a simple mechanical and electrical structure is under design that should also reduce Higher Order Modes (HOMs) to a quality factor less than 100. Therefore, the well-known approach of the Choke Mode Cavity was chosen, that use a radial line damper to attenuate the HOMs and a radial choke that traps the acceleration mode. The general behaviour of the choke mode structure was simulated, discussed and optimized for the requirements of a one-cell cavity with high effective shunt impedance, high-quality factor and simple manufacturing.
Bayesian optimization of the dynamic aperture in UVSOR-IV design study
Authors: Salehi E. , Katoh M. 
Published: January 2024

Abstract
A lattice of a storage ring for the future plan of UVSOR synchrotron facility, UVSOR-IV, is designed at 1 GeV electron energy. The lattice of 12 compact double achromat cells conducts to an emittance of 4.2 nm at 1 GeV electron energy and 2.3 nm at 750 MeV electron energy in achromat condition, 82.5 m circumference, and six straight sections of 4 m long and six of 1.5 m long. The lattice requires strong sextupole magnets to compensate the natural chromaticity. To help deal with the challenge of dynamic aperture associated with the strong nonlinearities, we examined improving the dynamic aperture by optimizing the sextupole arrangement based on the Bayesian method. We have demonstrated optimizing the harmonic sextupole strength of four families with 100 iterations of running particle tracking simulation that is much faster than traditional methods such as complete parameter survey.
Beam Injection Using a Nonlinear Kicker for the HLS-II Storage Ring
Authors: Wang Zhe , Wang Guanliang , Chen Kemin , Yu Yongbo , Hosaka Masahito , Xu Wei 
Published: January 2024

Abstract
The single nonlinear kicker (NLK) injection has been adopted by several synchrotron radiation light source facilities or their upgrades. The injected beam receives a kick from an NLK and goes into the acceptance of the storage ring while the stored beam passes through the center of the NLK where the magnetic field is almost zero. Compared with the local-bump injection, NLK injection requires less space for kickers and causes less disturbance to the stored beam during injection. Currently, a conventional local bump injection including four pulsed dipole kicker magnets is adopted in the HLS-II storage ring. In this paper, we propose an NLK injection scheme by only replacing one kicker with a pulsed NLK for HLS-II. The simulation result is also presented.
Photon Diagnostics for the High-Gain THz FEL at PITZ
Authors: Boonpornprasert P , Aftab N , Amirkhanyan Z , Georgiev G , Gross M , Hoffmann A , Kongmon E , Krasilnikov M , Li X-K , Lueangaramwong A , Müller F , Niemczyk R , Richard C , Schneidmiller E , Stephan F , Vashchenko G , Weilbach T , Yurkov M 
Published: January 2024

Abstract
Research and development of an accelerator-based THz source prototype for pump-probe experiments at the European XFEL are ongoing at the Photo Injector Test Facility at DESY in Zeuthen (PITZ). Proof-of-principle experiments have been performed to generate a high-gain THz Free-electron Laser (FEL) based on the Self-Amplified Spontaneous Emission scheme. The FEL radiation pulses with a central wavelength of about 100 μm (3 THz) and single pulse energy of several tens μm can be generated. In this paper, we present and discuss the photon diagnostic setup for the THz FEL together with examples of diagnostic results, including pulse energy and an FEL gain curve. The upgraded photon diagnostic setup, capable of measuring pulse energy, transverse distribution, and spectral distribution, is expected to be operational in the spring of 2023.
3D Polarisation of a Structured Laser Beam and Prospects for its Application to Charged Particle Acceleration
Authors: Polak K. , Gayde J.-C. , Sulc M. 
Published: January 2024

Abstract
A Structured Laser Beam (SLB) is a type of optical beam with spatially inhomogeneous 3D polarisation structures. Generating SLBs from vector beams allows the creation of Hollow Structured Laser Beams (HSLB) with a dark central core. In this way, atypical electric and magnetic field vectors, which are purely longitudinally polarized in the dark zones of the beam, are obtained. The SLB spatial distribution can also include regions with both the electric and magnetic fields longitudinally polarized and oriented in the same or opposite directions. The SLB has a transverse distribution similar to that of a Bessel beam but can theoretically propagate to infinity, therefore giving the potential to generate strong, longitudinally oriented electric fields over long distances, which could possibly allow the acceleration of charged particles. The results of the study of this phenomenon, including simulations of the spatial distribution of the electromagnetic field components, are presented in this paper.
Study of the transfer and matching line for a PWFA-driven FEL
Authors: Iovine P , Bacci A , Biagioni A , Chiadroni E , Crincoli L , Del Dotto A , Ferrario M , Giribono A , Pompili R , Romeo S , Rossetti Conti M , Vaccarezza C 
Published: January 2024

Abstract
The development of compact accelerator facilities providing high-brightness beams is one of the most challenging tasks in the field of next-generation compact and cost affordable particle accelerators. Recent results obtained at SPARC_LAB show evidence of the FEL laser by a compact (3 cm) particle driven plasma-based accelerator. This work is carried out in the framework of the SPARC_LAB activities concerning the R&D on plasma wakefield accelerators for the realization of new compact plasma based facilities, i.e EuPRAXIA@SPARC_LAB. The work here presented is a theoretical study demonstrating a possible scheme concerning the implementation of an innovative array of discharge capillaries, operating as active-plasma lenses, and one collimator to build an unconventional transport line for bunches outgoing from plasma accelerating module. Taking advantage of the symmetric and linear focusing provided by an active-plasma lens, the witness is captured and transported along the array without affecting its quality at the exit of the plasma module. At the same time the driver, being over-focused in the same array, can be removed by means of a collimator.
Characterisation of a Cs–Implanted Cu Photocathode
Authors: Soomary L.A.J. , Welsch C.P. , Jones L.B. , Valizadeh R. , Noakes T.C.Q. 
Published: January 2024

Abstract
The generation of high-brightness electron beams is a crucial area of particle accelerator research and development. Photocathodes which offer high levels of quantum efficiency when illuminated at visible wavelengths are attractive as the drive laser technology is greatly simplified. The higher laser power levels available at longer wavelengths create headroom allowing use of manipulation techniques to optimise the longitudinal and transverse beam profiles, and so minimise electron beam emittance. Bi–alkali photocathodes which offer quantum efficiency ∼ 10 % under illumination at 532 nm are an example of this. Another solution is the use of modified photoemissive surfaces. Caesium has a low work function and readily photoemits when illuminated at green wavelengths (∼532nm). Caesium oxide has an even lower work function and emits at red wavelengths (∼635nm). We present data on our work to create a hybrid copper photocathode surface modified by implantation of caesium ions, measuring the surface roughness and probing its structure using MEIS. We measure the energy spread of photoemitted electrons, the QE as a function of illumination wavelength, and the practicality of this surface as a photocathode by assessing its lifetime on exposure to oxygen.
Longitudinal splitting of bunches with variable energies in synchrotron
Authors: Li Yan , Yao Hongjuan , Zheng Shuxin , Xing Qingzi , Wang Xuewu 
Published: January 2024

Abstract
The ever-enriching beam application has put for-ward more demands on accelerators. If multiple bunches of different energies can be extracted for FLASH point scanning in a short time (< 500 ms), the spatial dose distribution advantage of proton Bragg peak can be combined with the temporal effect ad-vantage of FLASH. This paper provides three methods for generating short bunches in synchrotron. By adjusting the pulse parameters of the barrier voltages in the induction synchrotron, the short bunches can be easily generated. The short bunches can be kicked out of the beam reference orbit by kickers. When the pro-cess is repeated for many times, and the energy-changing process is added to the time interval during which the short bunches are continuously generated, the short bunches of multiple energies can be extracted in one working cycle. By finely controlling the changes of rectangular pulses, the number of particles in the short bunches can be better controlled, making an important contribution to further enriching the application of synchrotron.
Design of synchrotron for proton FLASH radiotherapy
Authors: Li Yan , Yao Hongjuan , Zheng Shuxin , Xiong Yang , Wang Zejiang , Liu Xiaoyu , Xing Qingzi , Wang Xuewu 
Published: January 2024

Abstract
Proton FLASH, which combines the advantages of a better spatial dose distribution of protons with the unique temporal effect of FLASH radiotherapy, is currently a hot topic of international research. In this study, a series of innovative methods are proposed to manipulate the beam with the longitudinal dynamics and to extract particles from the synchrotron, thus meeting the dose rate requirements for proton FLASH point scanning radiotherapy in a 1L volume in the target area.
Beam based alignment of focusing solenoids at ARES
Authors: Yamin S. , Assmann R. , Burkart F. , Dinter H. , Jaster-Merz S. , Kellermeier M. , Kuropka W. , Mayet F. , Vinatier T. 
Published: January 2024

Abstract
ARES is an electron linear accelerator at the SINBAD facility at DESY. It aims to deliver reliable high-brightness beams with an energy in the range of 50 MeV to 150 MeV with fs to sub-fs bunch lengths. This is ideal for injection into novel high-gradient acceleration devices, such as dielectric laser accelerators (DLA), accelerator components R&D and medical applications. The ARES linac has been recently commissioned. Here we report the results of beam based alignment of focusing solenoids of ARES. The alignment is an important part of commissioning and is crucial for the beam quality.
Simulation study on the slow extraction for the improvement of the beam shill structure at J-PARC Main Ring
Authors: Muto R , Kimura T , Murasugi S , Okamura K , Shirakabe Y , Tomizawa M , Yanaoka E , Numai K , Matsumura A 
Published: January 2024

Abstract
J-PARC Main Ring (MR) delivers a slow extracted 30 GeV proton beam to the Hadron Experimental Facility using third-order resonance. One of the critical properties required for the proton beam is the flatness of the time structure of the extracted beam (spill structure). We performed a simple beam simulation of the MR slow beam extraction to investigate the effect of the current ripples of the main magnet power supplies on the beam spill structure. In addition, we investigated in the simulation the effects of the feedback control system on the betatron tune using fast Q magnets and the transverse RF system to improve the spill structure. The simulation qualitatively reproduced the measured spill structures. Now the attempts to optimize their parameters for better spill structure are ongoing.
Nonlinear optics from hybrid dispersive orbits
Authors: Li Yongjun , Xu Derong , Smaluk Victor , Rainer Robert 
Published: January 2024

AbstractIn this paper we present an expansion of the technique of characterizing nonlinear optics from off-energy orbits (NOECO) [1] to cover harmonic sextupoles in storage rings. The existing NOECO technique has been successfully used to correct the chromatic sextupole errors on the MAX-IV machine, however, it doesn’t account for harmonic sextupoles, which are widely used on many other machines. Through generating vertical dispersion with chromatic skew quadrupoles, a measurable dependence of nonlinear optics on harmonic sextupoles can be observed from hybrid horizontal and vertical dispersive orbits. Proof of concept of our expanded technique was accomplished by simulations and beam measurements on the National Synchrotron Light Source II (NSLS-II) storage ring.
Impact of two-dimensional decoherence on the measurement of resonance driving terms
Authors: Hofer M. , Tomás R. 
Published: January 2024

Abstract
In the presence of a tune spread induced by chromaticity or amplitude detuning, decoherence will lead to the damping of the beam centroid motion after a single transverse excitation. This in turn has implications for the analysis of turn-by-turn based optics measurements, as it affects the precision of the spectral analysis. In the past, it has been shown how the effect of decoherence on spectral lines in a single plane can be accounted for. In this paper, this work will be extended to include the effect from both transverse planes.
Studies of FCC-ee Single Bunch Instabilities with an Updated Impedance Model
Authors: Migliorati M. , Behtouei M. , Carideo E. , Rajabi A. , Zhang Y. , Zobov M. 
Published: January 2024

Abstract
The design of the FCC-ee collider is ongoing with the goal of optimizing beam parameters and developing various accelerator systems. As a result, the modelling of coupling impedance is continuously evolving to take into account the design of the collider vacuum chamber and hardware components. Concurrently, estimates of collective effects and instabilities are being continually updated and refined. This paper presents the current FCC-ee impedance model and reports the findings of the single-bunch instability studies. Additionally, some potential mitigation techniques for these instabilities are discussed.
Simulation of shot noise effects in the EIC strong hadron cooling accelerator using real number of electrons
Authors: Qiang Ji , Wang Erdong 
Published: January 2024

Abstract
In the electron ion collider design, in order to achieve the peak luminosity 1034/cm
2/s with a reasonable lifetime, an efficient coherent electron cooling scheme was proposed to reduce the hadron beam emittance growth. Such a cooling scheme requires a good electron beam quality with a small energy spread. However, the shot noise in the electron beam through the accelerator might be amplified due to the microbunching instability and degrades the electron beam quality in the modulator section of the strong hadron cooling channel and correspondingly cooling rate. In this study, we report on self-consistent simulations of these effects using a real number of electrons to capture the details of shot noise and analysis of the shot noise growth through the accelerator.
The SPES target ion source automated storage system
Authors: Lilli G , Andrighetto A , Centofante L , Manzolaro M , Monetti A , Oboe R 
Published: January 2024

Abstract
At the SPES (Selective Production of Exotic Species) facility, intense Radioactive Ion Beams (RIBs) are produced by the interaction of a 40 MeV proton beam with a multi-foil uranium carbide target employing the Isotope Separation On-Line (ISOL) technique. The Target Ion Source (TIS) unit constitutes the core of the isotope production process. TIS units are replaced on a periodic basis during operation to maintain high performance. An automated storage system has been designed to accept highly radioactive TIS units and house them during a cooling period prior to decommissioning. The system is conceived to meet strict functional and safety requirements. Its peculiar design allows for improved reliability and availability during critical operations, as well as minimization of staff exposure to ionizing radiation during maintenance tasks. This contribution describes the design and control architecture of the Temporary Storage System (TSS). The equipment is part of a structured framework of remote manipulation, consisting of various machines interlocked with the Access Control System (ACS) and the Machine Protection System (MPS).
Numerical calculation of the Lorentz force detuning and the pressure sensitivity for the HL-LHC crab cavity
Authors: Guillén-Hernández T , Artoos K , Calaga R , Cano-Pleite E , Capatina O , Carra F , Dassa L , Turaj K , Valverde-Alonso N 
Published: January 2024

Abstract
Crab cavities are fundamental components of the HL-LHC upgrade project. These Radio Frequency cavities, operated at the appropriate frequency, ‘tilt’ the proton bunches to increase the luminosity at the collision points IP1 (ATLAS) and IP5 (CMS). Two different superconducting crab cavities were developed: RF Dipole (RFD) for horizontal deflection and Double Quarter Wave (DQW) for vertical deflection. During operation, the cavity walls are deformed due to the loading conditions. This deformation changes the electro-magnetic field inside the cavity and consequently its RF frequency. In the present study, the numerical evaluation of the Lorentz Force Detuning (LFD) and the Pressure Sensitivity (PS) of the DQW cavity, using COMSOL Multiphysics, is presented. The LFD is the fundamental frequency change of the cavity due to the electro-magnetic forces acting on its walls, while the PS is the frequency shift when the cavity is subjected to pressure fluctuations of the helium bath. Finally, a comparison with the results measured during the cold test of the manufactured cavities, and with the previous simulations results obtained for the RFD cavity is done.
Finite element simulation of fast corrector magnets for PETRA IV
Authors: Christmann J , De Gersem H , von Tresckow M , Aloev A , Mirza S H , Pfeiffer S , Schlarb H 
Published: January 2024

Abstract
The new synchrotron light source PETRA IV at DESY will use a fast orbit feedback system with hundreds of fast corrector magnets to meet stringent orbit stability requirements. These magnets are operated at high frequencies, creating strong eddy currents that result in Joule losses and a time delay between applied voltage and aperture field. User experiments impose challenging requirements on beam operation to preserve the point of the radiation source. To meet the demanding feedback requirements, finite element simulations are needed to understand the characteristics of the corrector magnet. However, due to the small skin depths at high frequencies and the laminated structure of the yoke, these simulations need a very fine mesh and are thus very costly. Therefore, we homogenize the laminated yoke which reduces the computational effort but captures the eddy current effects accurately. The reduction of simulation times from several hours to a few minutes allows us to conduct extensive studies of the eddy current losses and the field quality of the magnets.
Magnets for a Muon Collider
Authors: Fabbri S. , Bottura L. , Quettier L. , Statera M. , Boattini F. , Mariotto S. , Caiffi B. 
Published: January 2024

Abstract
The renewed interest for a muon collider has motivated a thorough analysis of the accelerator technology required for this collider option at the energy frontier. Magnets, both normal and superconducting, are among the crucial technologies throughout the accelerator complex, from production, through acceleration and collision. In this paper we initiate a catalog of magnet specifications for a muon collider at 10TeV center-of-mass. We take the wealth of work performed within the scope of the US-DOE Muon Accelerator Program as a starting point, update it with present demands for the increased energy reach, and focus on the magnet types and variants with the most demanding performance. These represent well the envelope of issues and challenges to be addressed by future design and development. We finally give a first and indicative selection of suitable magnet technology, taking into account both established practices as well as the perspective evolution in the field of accelerator magnets.
Analysis of the bi-bridge topology and power device circuit of the TPS booster dipole power supply
Authors: Liu C Y , Wang B S , Wong Y S , Huang J C , Liu K B 
Published: January 2024

Abstract
This study primarily discusses a unique topology for constructing a double full bridge circuit. The study establishes a push-pull inverter model and analyses the balance circuit in its architecture. This allows the power supply to initiate the balance circuit and ensures the TPS (Taiwan Photon Source) booster magnet power supply operates smoothly in a safe and balanced voltage region when magnet energy is recovered. We employ the approach of adding Y circuits to mitigate the impact of common mode (CM) noise. Adding a Y circuit effectively suppresses the common-mode noise generation, improving the quality of the output current of the TPS dipole magnet power supply at low currents state and ramping the beam current energy from 150 MeV to 3 GeV. Furthermore, the reproducibility and stability of the injection point can enhance the injection efficiency of the TPS booster magnet power supply. This study presents the results obtained from these efforts.