bunching
MOZD2
A novel Vlasov approach for modeling electron cloud instabilities
8
This presentation discusses the generalization of the two-dimensional impedance model in the presence of an electron cloud. It will be discussed the implementation of a linear model of the e-cloud forces including both dipolar and quadrupolar forces to improve the modeling of the electron cloud instabilities. The linear model is included in the Vlasov equation, which allows for finding unstable modes. Benchmarking with conventional macro-particle tracking codes by also implementing the same linear model is discussed for negative, low, as well as large chromaticity. It is found that the instability modes by Vlasov agree well with those of the macro-particle simulations, using the same linear model for negative and low chromaticity. For large-chromaticity, the mode visible in the macro-particle simulations is among the unstable Vlasov modes. The present status of the checks with impedance-driven instabilities is being discussed also including recent benchmarking against tracking simulations and measurements.
Paper: MOZD2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOZD2
About: Received: 11 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOCD2
Multi-mode cavity design and characterization
18
We present the design and initial characterization of a multi-mode cavity, a novel electromagnetic structure with potential benefits such as compactness, efficiency, and cost reduction. The 2nd Harmonic mode was chosen to linearize the fundamental mode for use as an accelerating and bunching cavity. The reduction in the number of cavities required to bunch and accelerate promises cost and space savings over conventional approaches. Superfish and COMSOL simulations were used to optimize the cavity's geometry with the goal of balancing various design parameters, such as quality factor (Q-factor), harmonic modes, and mode coupling. A 3D-printed copper-plated cavity was used to validate code predictions. The cavity's multi-mode nature positions it for use with other harmonic modes with small deviations in design. For example, a 3rd Harmonic can be used to decrease energy spread by widening the peak of the fundamental. This research lays the foundation for further exploration of the cavity's applications and optimization for specific use cases, with potential implications for a wide range of accelerator fields.
Paper: MOCD2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOCD2
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOCN1
Performance of a longitudinal bunch by bunch feedback in a system with a passive harmonic cavity
21
While designed to be inherently stable, the accelerator upgrade SLS 2.0 will have a longitudinal multi-bunch feedback system, to be used as a diagnostics device and as a fallback against unexpected problems. Modelling the performance of the system is complicated by the presence of a passive harmonic cavity introduced for longer bunch lengths and correspondingly higher stability thresholds, which has the following effects: the voltage of the harmonic cavity varies with the beam current leading to a variation of the synchronous frequency, specially pronounced in the initial injection at very low currents. Even at full current, the presence of the ion clearing gap provokes transients in the main and harmonic system leading to a transient variation of the synchronous frequency over the bunch train. Another effect of the RF transients is a variation in the synchronous phase over the bunch train, which leads to cross talk effects, the open loop gain starts to vary with the order of the coupled bunch oscillation. The feedback filter needs to take account of all these effects for a satisfactory performance.
Paper: MOCN1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOCN1
About: Received: 13 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPC02
ZDC effective cross section for Gold-Gold Collisions During RHIC'S Run 16
32
The 2016 Relativistic Heavy Ion Collider (RHIC) Au-Au run took place from January 25 to June 27, 2016. Four so-called vernier scans were performed at 100 GeV per beam, with γ=107.396 at flattop at one of the interaction points, IP6. During this type of procedure, one beam is swept across the other, first horizontally and then vertically, recording the interaction rate as a function of the beam to beam separation. From that data, the effective cross section of the Zero Degree Calorimeter (ZDC) can be derived. This paper discusses the results of the scans, as well as the systematic uncertainties of the derived effective cross section.
Paper: MOPC02
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC02
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPC03
Crossing angle implementation for luminosity maximization in a narrow vertex region in RHIC operation
36
The Relativistic Heavy Ion Collider (RHIC) was designed for head-on collisions in the Interaction Regions. However, RHIC operation in recent years necessitated crossing angles to limit collisions to a narrow longitudinal vertex region, which created operating conditions with a large Piwinski angle (LPA). The angles were implemented by adjusting the shunt currents of four dipoles, the D0 and DX magnets, near the IP. The longitudinal bunch profile often deviates from Gaussian due to the utilization of high-order RF cavities, adding complexity to calculating luminosity reduction with crossing angle. This paper introduces two methods for implementing crossing angles, discusses resultant aperture concerns, conducts numerical calculations of luminosity reduction, and compares these findings with experimental observations.
Paper: MOPC03
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC03
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPC06
Luminosity maximization in a small vertex region at RHIC
44
For the 2024 100 GeV proton run at RHIC, the new sPHENIX detector will require a maximum amount of collisions within ±10 cm of its central Interaction Point (IP), and preferably few or no collisions outside this range. To maximize the collisions within the vertex, a large crossing angle of up to 2 mrad will be used, operating the Large Piwinski Angle (LPA) scheme. To compensate for the reduction in luminosity from the large Piwinski angle, a β=50 cm lattice has been designed and supported with dynamic aperture simulations. To further compensate the luminosity reduction, injector studies have been performed to support up to a 45% increase in the injected intensity relative to the previous 100 GeV run in 2015.1
Paper: MOPC06
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC06
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPC08
Expanding the CERN ion injector chain capabilities: new beam dynamics simulation tools for future ion species
51
The present ion physics program in the CERN accelerator complex is mainly based on lead (Pb82+) ion beams. Lighter ions have been considered both by the ALICE3 detector upgrade proposal at the Large Hadron Collider (LHC) --- as a potential way to achieve higher integrated nucleon-nucleon luminosity compared to the present Pb beams --- and also by the Super Proton Synchrotron (SPS) fixed-target experiment NA61/SHINE. However, there is little or no operational experience at CERN with ions species lighter than Pb. This calls for beam-brightness and intensity limitations studies to assess the performance capabilities of the CERN ion injector chain, which consists of LINAC3, the Low-Energy Ion Ring (LEIR), the Proton Synchrotron (PS) and the SPS. This paper presents tracking simulation resu lts for the SPS, compared against recent Pb beam emittance and beam loss measurements at the long injection plateau. The simulation models include limiting beam dynamics effects such as space charge and intra-beam scattering (IBS), whose impact on the future ion injector chain performance is discussed. Beam dynamics simulation results for the planned O8+ pilot physics run are also presented.
Paper: MOPC08
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC08
About: Received: 08 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPC11
Correlating start-of-ramp losses with beam observables at blat-bottom in the LHC
63
Power limitations are expected at injection energy for the main Radio Frequency (RF) system due to the doubled bunch intensity in the High Luminosity (HL-) Large Hadron Collider (LHC) era. One way to overcome these power limitations is to reduce the capture voltage. The smaller RF bucket, however, leads to increased beam losses at the start of the ramp. In practice, these beam losses, which contain both capture and flat-bottom losses, can trigger beam dumps if any of the Beam Loss Monitor (BLM) thresholds are reached. In this contribution, the correlation between start-of-ramp beam loss and beam observables before the ramp is investigated by analysing Beam Current Transformer (BCT) measurements from physics fills. Estimates of how the maximum ratio to BLM dump threshold scales with longitudinal losses are also made. The aim is to make predictions for operation at higher bunch intensities on the basis of these correlations in view of the intensity ramp up for the HL-LHC era.
Paper: MOPC11
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC11
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPC16
Evolution of special LHC optics configurations Run 3 update
83
The Large Hadron Collider (LHC) employs special optics and configurations, alongside low-beta* collision optics, to address specific experimental requirements. These include calibrating luminosity monitors (vdM) and facilitating forward physics measurements in TOTEM and ALFA experiments (high-beta). The special optics have been in use since Run 1, and for Run 3, they have been updated for compatibility with standard low-beta collision optics to ensure streamlined commissioning and reduced setup time. For vdM optics in Run 3, beam de-squeezing yields beta* values of 19 to 24 m, while in the high-beta optics, beams are de-squeezed to round beams with beta* of 120 m, followed by a second step to asymmetric optics with beta* of 3 km and 6 km in the horizontal and vertical planes. The 2023 high-beta optics run with the km beta* optics, incorporates tight collimation settings and the use of crystals at top energy for the first time, aiming to substantially reduce backgrounds in the experiments. This publication introduces and discusses the updated optics for Run 3, covering their validation, optics measurement results, and operational insights.
Paper: MOPC16
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC16
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPC17
Operation of the LHC during the 2023 proton run
87
In 2023 the LHC restarted after the yearly winter shutdown with a new machine configuration optimized for intensities of up to 1.8e+11 protons per bunch. In the first two months of the 2023 run the bunch intensities were pushed up to 1.6e+11 protons per bunch until a severe vacuum degradation, caused by a damaged RF bridge, occurred close to the ATLAS experiment. Following repair, the decision was taken to stop the intensity increase. After a period of smooth operation, a leak developed between the cold mass and insulation vacuum of a low-beta quadrupole, leading to an abrupt stop of the LHC. Thanks to a rapid intervention, the leak could be repaired without warning up large parts of the machine, and the LHC was ready for beam again early September. Special runs at very large beta* were completed in the remaining time before switching to Lead ion operation. The performance achievements and limitations as well as the issues that were encountered over the year will be discussed in this paper.
Paper: MOPC17
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC17
About: Received: 12 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPC18
Simulated impact of the HL-LHC beam on a graphite target
91
In the High Luminosity Large Hadron Collider (HL-LHC) era, the intensity of the circulating bunches will increase to 2.2e+11 protons per bunch, almost twice the nominal LHC value. Besides detailed studies of known and new failure cases for HL-LHC, it is also required to investigate failures beyond nominal design. A consequence of such failures can be the impact of a large number of high-energy particles in one location, resulting in a significantly increased dam- age range due to an effect called hydrodynamic tunnelling. This phenomenon is studied by coupling FLUKA, an energy deposition code, and Autodyn, a hydrodynamic code. This paper presents the simulated evolution of the deposited energy, density, temperature and pressure for the impact of the HL-LHC beam on a graphite target. It then computes the resulting tunnelling range and finally compares the outcome with previous studies using LHC intensities.
Paper: MOPC18
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC18
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPC23
Generating Super-Gaussian distribution and uniform sliced energy spread bunch for EIC strong hadron cooling
110
Strong Hadron Cooling (SHC), utilizing the coherent electron cooling scheme, has been extensively investigated for the Electron Ion Collider (EIC). Throughout our cooling optimization studies, we realized that a Super-Gaussian electron bunch offers enhanced performance in comparison to a Gaussian bunch. Our approach involves initiating the electron beam distribution in a double peak form, transitioning them into a Super-Gaussian distribution due to the longitudinal space charge. Subsequently, a chicane within the linac section compresses the bunch to meet the required bunch length. We tuned a third harmonic cavity amplitude to reduce the nonlinear term of the chicane. Moreover, given the low initial current leading to a small but non-uniform slice energy spread, we evaluated utilizing laser heating techniques to achieve a uniformly distributed slice energy spread. In this report, we discuss the concepts and simulation results.
Paper: MOPC23
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC23
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPC24
The design progress of a high charge low energy spread polarized pre injector for Electron Ion Collider
114
The polarized pre-injector for the Electron-Ion Collider is intended to produce four bunches every second, each containing 7 nC, with 85% polarization along the longitudinal axis, for injection into the Rapid Cycling Synchrotron. The pre-injector consists of a polarized electron source, bunching section, longitudinal phase space manipulation, and SLC-Type LINAC. To reduce energy spread and increase bunch length, a compact zig-zag chicane and dechirp cavity rotate the bunch in longitudinal phase space. In this paper, we will discuss the progress of recent pre-injection design and RF frequency selection. Additionally, we will examine the effects of wakefield, as well as coherent and incoherent synchrotron radiation on beam quality.
Paper: MOPC24
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC24
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPC28
Status of the commissioning of the X-band injector prototype for AWAKE Run 2c
121
The status of commissioning of the electron injector intended for the next phase of the proton driven wakefield experiment (AWAKE) is presented, showing first experimental results from operating the brazing-free electron gun. To provide a high-quality electron beam, the UV laser was centered on the copper cathode, and a novel simplex and beam-based alignment of the focusing solenoid was performed. Measurements of the beam parameters and working points are addressed. The electron gun is shown to provide a high quality, stable and reproducible beam.
Paper: MOPC28
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC28
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPC35
Design and test of a S band TW buncher for the injector linac of HEPS
140
The bunching system of injector Linac in High Energy Photon Source (HEPS) includes two sub-harmonic bunchers, a pre-buncher and a traveling wave S band buncher. The buncher is a 6-cell constant impedance traveling wave structure operating in 2π/3 mode at 2998.8 MHz. In this paper, the design and test of the traveling wave buncher are presented. First, the characteristic parameters are optimized in CST. Then the buncher is precisely tuned and cold tested with a vector network analyzer after fabrication. Finally, the high power test was finished before installation in Linac. The buncher can operate stably with input power of 10 MW after a week of conditioning. So far the buncher has been applied successfully in Linac of HEPS.
Paper: MOPC35
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC35
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPC38
Electromagnetic and beam dynamics modeling of LANSCE front-end elements with CST studio
146
The front end of the 800-MeV proton linac at the Los Alamos Neutron Science Center (LANSCE) is still based on Cockcroft-Walton voltage generators that bring proton and H- beams of various flavors to 750 keV. We have developed 3D CST models of the LANSCE front-end elements including low-frequency and main bunchers. The fields in these elements are calculated with MicroWave and ElectroMagnetic Studio. Beam dynamics is modeled with Particle Studio for beams with realistic charge distributions using the CST calculated fields. The modeling results provide insight into linac operations and a guidance for designing a modern, RFQ-based front end for the LANSCE linac.
Paper: MOPC38
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC38
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPC41
Magnetic focusing architecture for a compact electron buncher
153
We present a beam-focusing architecture using electro- and permanent magnets for a novel compact electron beam buncher under development for space-borne electron accelerators. Developing compact and efficient accelerator components has become desirable with renewed interest in using space-borne electron beams for ionospheric aurora research and very low frequency wave generation for particle removal from the magnetosphere. An electron gun injects a direct current electron beam, and the buncher modulates the DC beam into periodic bunches at a frequency of 5.7 GHz. A 5.7 GHz linear accelerator in the downstream will capture the bunched beam with minimal acceptance mismatch. The beam modulation is done by three radiofrequency pillbox cavities. The buncher uses the electrostatic potential depression (EPD) method to shorten the structure length remarkably. The electron gun and a tunable solenoid provide the initial focusing of the beam. We then use a series of permanent magnets surrounding the buncher cavities clamped together by ferromagnetic steel plates to focus the beam through the buncher. Permanent magnets do not consume any power and weigh less than solenoid magnets, which provide equivalent focusing, making them ideal for use on a satellite or sounding rocket. We use the three-dimensional (3D) particle tracking solver from CST Studio Suite to simulate the beam-focusing.
Paper: MOPC41
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC41
About: Received: 15 May 2024 — Revised: 16 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPC72
Advancing electron injection dynamics and mitigation approaches in the Electron-Ion Collider’s swap-out injection scheme
230
The Electron-Ion Collider (EIC) will use swap-out injection scheme for the Electron Storage Ring (ESR) to overcome limitations in polarization lifetime. However, the pursuit of highest luminosity with the required $28~\mathrm{nC}$ electron bunches encounters stability challenges in the Rapid Cycling Synchrotron (RCS). One method is to inject multiple RCS bunches into a same ESR bucket. In this paper we perform simulation studies investigating proton emittance growth and electron emittance blowup in this injection scheme. Mitigation strategies are explored. These findings promise enhanced EIC stability and performance, shaping potential future operational improvements.
Paper: MOPC72
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC72
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPC83
Polarization preservation methods for the Electron Storage Ring of the EIC
270
The Electron Storage Ring (ESR) of the Electron-Ion Collider (EIC) to be built at Brookhaven National Laboratory will provide spin-polarized electron beams at 5, 10, and 18 GeV for collisions with polarized hadrons. Electron bunches with polarizations parallel and anti-parallel to the arc dipole fields will co-circulate in the ring at the same time, and each bunch must be replaced once it is sufficiently depolarized by synchrotron radiation. In this work, we detail the unique challenges posed by designing such a collider ring to operate at different energies, and their solutions. This includes satisfying spin matching conditions, calculating optimal energies for polarization, determining best figures-of-merit, maintaining high polarization without a traditional longitudinal spin match, restoring the spin match with random closed orbit distortions, and implementing global coupling compensation and vertical emittance creation schemes that preserve high polarization. Nonlinear tracking results are presented showing polarization requirements are exceeded.
Paper: MOPC83
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC83
About: Received: 13 May 2024 — Revised: 03 Jun 2024 — Accepted: 03 Jun 2024 — Issue date: 01 Jul 2024
MOPG09
A faster algorithm to compute lowest order longitudinal and transverse resistive wall wake for non-ultrarelativistic case
312
With the development of the steady state micro bunching (SSMB) storage ring, its parameters reveal that the ultra relativistic assumption which is wildly used is not valid for the electron beam bunch train, which has length in the 100 nm range, spacing of 1 μm and energy in hundreds MeV range. The strength of the interaction between such bunches and the potential instability may need careful evaluation. At the same time, the effect of the space charge inside a single bunch due to space charge effect also needs to be considered. In this article, we reorganized the lowest-order longitudinal wakefield under non-ultra relativistic conditions, and the lowest-order transverse wakefield. We present the modified theoretical results and analysis. Then based on the result we have derived, we give a algorithm which is thousands time faster than direct calculation. It lays foundation in future research.
Paper: MOPG09
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG09
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG16
FLASH status – FEL user facility between two upgrade shutdowns
335
FLASH, the XUV and soft X-ray free-electron laser user facility at DESY, is in the transitional period between two substantial upgrade shutdowns within the FLASH2020+ upgrade project. FLASH consists of a common part FLASH0 (injector & superconducting linac), two FEL beamlines (FLASH1/2) and an experimental beamline FLASH3, accommodating the plasma wakefield experiment FLASHForward. The first (2021/22) shutdown was aimed at upgrading FLASH0 and install an APPLE-III undulator in the otherwise unchanged beamline FLASH2, enhancing the third harmonic at flexible output polarization. The next (2024/25) shutdown will focus on the complete exchange of the FLASH1 beamline to allow for externally seeded operation in the range from 60 nm down to 4 nm at 1 MHz bunch repetition rate (600 μs trains at 10 Hz train repetition rate). We report on the operation between the two shutdowns which was, to a large extend, dedicated to FEL operation for users and on the commissioning of the new features implemented in the last shutdown.
Paper: MOPG16
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG16
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG17
First commissioning of the corrector quadrupoles in the 2nd bunch compression chicane at FLASH
339
FLASH, the superconducting XUV and soft X-ray FEL is undergoing a substantial upgrade (FLASH2020+) with two long shutdowns 2021/22 and 2024/25. In the 1st shutdown, FLASH's 2nd bunch compression chicane (BC2) has been completely redesigned for the FLASH2020+ upgrade project. The redesign allowed the installation of two quad/skew-quad packs in each of the arms of the 4-dipole (C-type) chicane. With these corrector quadrupoles it should be possible to partially compensate linear correlations between the transverse centroids and the longitudinal position inside the bunch, so called bunch-tilts. During the limited commissioning/development shifts in a year of operation devoted to maximizing user hours we started measuring the impact of the quads on the bunch tilts and the unavoidable effects on dispersion closure and beam optics. In this contribution we report first results.
Paper: MOPG17
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG17
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPG24
High level software for operating an EEHG FEL
354
Reliable operation of a seeded Free Electron Laser requires the simultaneous control of several electron-beam, laser and accelerator parameters. With EEHG the complexity increases due to the second seed laser and the strong dependence of EEHG bunching to seeding parameters. With the recent upgrade of the FEL-1 line, FERMI is the first FEL facility to be operated in EEHG mode for users. This required a major work for developing software tools that could be used to easily set the FEL at the desired wavelength. We report here on the recent software developments at FERMI for the operations of the new FEL-1. An important prerequisite for EEHG is to determine both the electron beam energy spread and seed laser induced energy modulation. This is done by using HGHG time dependent bunching equations to match experimental parameters scans. With these data, optimal EEHG settings of the machine parameters are then calculated to reach the desired FEL wavelength. The requested parameters are then sent to interface tools that accurately control laser, undulator, chicane and electron beam.
Paper: MOPG24
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG24
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPG37
Simulation study for nanometer-scale modulation transfer in emittance exchange beamline
376
Generating nanometer-scale density modulation has been pursued due to its potential for compact X-ray source applications. Realization of this nanometer modulation involves two key challenges: development of sub-micron-scale momentum modulation method and conversion method to density modulation without quality degradation. Addressing the first challenge, emittance exchange (EEX) beamline is a promising candidate. Its unique capability of transverse-to-longitudinal phase space exchange makes it compatible with various modulators imparting either transverse or longitudinal modulations. This versatility allows us to find optimal radiators, addressing the second challenge. Study on degradation sources and their effects on the beam are underway to realize nanometer-scale modulation using EEX beamline. We present most recent results from our simulation study.
Paper: MOPG37
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG37
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPG38
Generation of sawtooth correlation for bunching factor enhancement
380
Bunch trains have been considered as a promising means of generating intense, coherent radiation in compact accelerator facilities. However, conventional methods, which impart a sinusoidal modulation on the beam’s longitudinal phase space, are inefficient for generating a high bunching factor density modulation. Only a small fraction of a sinusoidal modulation, which has linearity, primarily forms density spikes while other particles under nonlinear correlation have limited contribution to these spikes. One way to improve such bunching efficiency is imparting a saw-tooth correlation, which has piecewise-linearities. This correlation maximizes the peaks of density spikes as more than 90% of particles will contribute to the spikes. While such correlation can be generated by a series of transverse wigglers, a single transverse wiggler with shaped poles to introduce higher harmonics can generate saw-tooth or saw-tooth-like correlations. We present a recent study on this new approach, employing a shaped-pole transverse wiggler.
Paper: MOPG38
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG38
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG47
Characterization of low-emittance electron beams generated by a new photocathode drive laser system NEPAL at the European XFEL
388
An ultrafast laser system for driving the photocathode RF gun at the European XFEL has been recently put into operation. The new laser system, NExt generation PhotocAthode Laser (NEPAL) is capable of providing drive laser pulses of variable pulse lengths and shapes, supporting the facility to extend its capabilities to operate in multiple user-desirable FEL modes. In this paper, we present a preliminary characterization of the low-emittance electron beams produced by NEPAL in the photoinjector. Both experimental and numerical results will be presented and discussed.
Paper: MOPG47
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG47
About: Received: 06 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG53
Extreme pulse compression for impulsive ionization of valence wavepackets
396
We show how a chicane with anomalous dispersion can be used to compress an electron beam into a narrow, high-current, spike by exploiting the intrinsic chirp created by collective effects. We explore the limits of compression in a linearized model and then apply these beams to impulsively pump valence electrons. In the limit of an ultrashort electron beam, the valence electron wave-packet is accelerated so rapidly that the excited state forms an image of the bound state, allowing for unique insight into the structure of the electronic states of a molecule.
Paper: MOPG53
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG53
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPG65
Towards short-pulse generation at FLASH via laser-assisted electron bunch manipulation
404
The FLARE project aims to investigate special operation modes of the laser heater at the free-electron laser FLASH in Hamburg that enable the generation of few- or possibly sub-femtosecond soft X-ray pulses. To this end, laser pulses of the laser heater are split and then recombined after one pulse has been delayed. By controlling the interference of both pulses via their temporal overlap, a longitudinally non-uniform heating of the electron bunches can be achieved. Utilizing this, two short-pulse generation schemes are to be implemented as part of the FLARE project. In the first scheme, the energy spread of the bunch is increased to a degree that inhibits lasing, leaving only a small unheated region which emits a short FEL pulse. The second scheme works by imprinting an energy modulation with a linearly increasing amplitude onto the longitudinal phase-space distribution of the bunch. In subsequent magnetic chicanes, this phase-space structure results in a localized compression of the bunch, creating an extremely short current spike, which might be used to produce an X-ray pulse on the same time scale. The FLARE setup as well as first experimental results are presented.
Paper: MOPG65
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG65
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPG69
Simulations of dielectric-lined waveguide seeding option for THz FEL at PITZ
420
The first operational high peak and average power THz self-amplified spontaneous emission (SASE) free electron laser (FEL) at the Photo Injector Test facility at DESY in Zeuthen (PITZ) has demonstrated up to 100 uj single pulse energy at a center frequency of 3 THz from electron bunches of 2-3 nC. The measured shot-to-shot radiation pulse energy has a fluctuation of 10%. Shot-to-shot stability and temporal coherence in FELs can be greatly enhanced by the seeding method. In this paper, we propose the use of dielectric-lined waveguides (DLW) to enhance the initial seeding signal. Simulations of using electromagnetic wakefield in DLW to introduce energy modulation to the beam, controlling the conversion between energy modulation and density modulation, and space charge dominated beam matching in the chicane bunch compressor and the undulator will be presented.
Paper: MOPG69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG69
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPG71
Beam dynamics study for a high-repetition-rate infrared terahertz FEL facility
428
The paper introduces design and optimization of a high-repetition-rate infrared terahertz free-electron laser (IR-THz FEL) facility, which leverages optical resonator-based FEL technology to achieve a higher mean power output by increasing pulse frequency. Electron beam of the facility will be generated from a photocathode RF gun injector and further accelerated with a superconducting linear accelerator. Taking into account the collective effects, such as space charge, coherent synchrotron radiation (CSR), and longitudinal cavity wake field impacts, beam dynamics simulation for the injector, the accelerator, as well as the bunch compressor, has been done with codes of ASTRA and CSRTrack. With optimized microwave parameters of the linac, current profile with good symmetry has been obtained and the peak current can reach 100 A.
Paper: MOPG71
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG71
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPG74
Development progress of a tunable terahertz free electron laser based on a pre-bunched linear accelerator
438
To explore and detect novel effects and mechanisms inherent in materials, a tenable wavelength terahertz free electron laser (THz-FEL) is integrated into the terahertz near-field high-throughput material property testing system (NFTHZ). Employing a compact linear accelerator capable of adjusting electron energy within the range of 10 to 18 MeV as the injector, pre-bunching of electron bunches is implemented to create longitudinal spacing structures by manipulating the driving laser. By appropriately correlating the forming factor of electron bunches, electron beam energy at the undulator entrance, and the undulator K value, a terahertz free electron laser with peak power in the megawatt range and a central wavelength spanning from 0.5 to 5 THz can be achieved. This article provides an overview of the development progress of THz-FEL within the NFTHZ framework.
Paper: MOPG74
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG74
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPG76
A compact water window X-ray source based on inverse Compton scattering
441
X-rays in the water window (2.33 nm to 4.40 nm wavelength) can be used to provide high quality images of wet biological samples. Given the limited availability of current generation light sources in this energy range, table-top water window X-ray sources have been proposed as alternatives. We present start-to-end simulations in RF-Track of a water window X-ray source based on inverse Compton scattering. A brazing-free electron gun with a maximum beam energy of 7 MeV is considered, providing photon energies covering the full water window range. Performance estimates for the gun operating with copper and cesium telluride cathodes are presented. The cesium telluride cathode, combined with a burst mode Fabry-Perot cavity, allows for an increase in flux by orders of magnitude compared to single bunch copper cathode operation. A beamline of 1 m was determined to be sufficient to produce a high photon flux.
Paper: MOPG76
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG76
About: Received: 14 May 2024 — Revised: 28 May 2024 — Accepted: 28 May 2024 — Issue date: 01 Jul 2024
MOPR04
Extraction of Coulomb crystals with limited emittance growth
460
Laser Doppler cooled ion traps can produce stationary bunches of ions with extremely low velocity spread (0.6 m/s RMS) and emittance (10e-13 m normalized). This corresponds to temperatures of a few milli-Kelvin and allows the ions to settle into a fixed lattice analogous to a solid crystal, but with the Coulomb repulsion balanced by the trapping force, rather than a chemical bond. Extraction of such a bunch into a beamline could provide a new regime of ultra-low emittance beams if the emittance is preserved through the extraction operation. This paper shows that extraction from the ion trap and initial acceleration does not cause drastic growth, thus preserving the ultra-low emittance nature of the bunch. Techniques for compensating coherent 'emittance growth' effects such as nonlinear bunch distortion are also investigated.
Paper: MOPR04
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR04
About: Received: 02 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPR10
Quadrupole field instability in cylindrical dielectric wakefield accelerators
478
Dielectric Wakefield Acceleration is a technology under active research, providing the potential to accelerate charged particle bunches with gradients much greater than conventional RF-based metallic cavities. The stability of driving bunches needs to be solved before practical applications are seen. Strong transverse fields are known to be excited in DWAs, with previous research focusing on mitigating single-beam breakup instability (BBU) induced when a beam propagates off-center due to orbit-jitter or misalignment. It is also known that quadrupole-like fields are excited in planar/slab DWA structures and research has been conducted on mitigating this effect. We present simulation results that demonstrate quadrupole-like fields are also excited in circular DLWs, induced by beam astigmatism. We have shown that this in an extra source of instability within circular DWA structures and calculate the size of the fields excited as a function of beam astigmatism.
Paper: MOPR10
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR10
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPR22
Microbunching instability test for emittance exchange-based photoinjector
500
Previous start-to-end simulations of an emittance exchange (EEX)-based photoinjector have demonstrated highly attractive beam properties. The EEX-based photoinjector can provide another interesting opportunity that potentially eliminate the microbunching instability issue. The space-charge and/or CSR-induced amplification occurs during density-to-energy and energy-to-density modulation conversion process. This amplification becomes particularly pronounced when multiple compressors are implemented. In contrast, the proposed EEX-based photoinjector doesn’t require additional compression process. Moreover, the initial longitudinal phase space becomes the transverse phase space, resulting in a significant reduction of space-charge and CSR’s longitudinal interaction. We present preliminary simulation results of microbunching instability in EEX-based photoinjector.
Paper: MOPR22
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR22
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPR23
Start-to-end simulation of high-gradient, high-transformer ratio structure wakefield acceleration with TDC-based shaping
504
In collinear wakefield acceleration, two figures of merits, gradient and transformer ratio, play pivotal roles. A high-gradient acceleration requires a high-charge beam. However, shaping current profile of such high-charge beam is challenging, due to the degradation by CSR. Recently proposed method, utilizing transverse deflecting cavities (TDC) for shaping, has shown promising simulation results for accurate shaping of high-charge beams. This is attributed to its dispersion-less feature. We plan to experimentally demonstrate high-gradient (>100 MV/m) and high-transformer ratio (>5) collinear structure wakefield acceleration. The experiment is planned at Argonne Wakefield Accelerator Facility. We present results from start-to-end simulations for the experiment.
Paper: MOPR23
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR23
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPR24
Progress on high-power generation using sub-THz corrugated waveguide
507
Previously we had developed a new method to fabricate corrugated waveguides (CW) operating in sub-THz frequency regime. As the next step, collaborative effort is underway to demonstrate GW-level high-power sub-THz pulse generation using a CW. We plan to fabricate a CW operating at around 400 GHz. This waveguide will be driven by a bunch train including 16 bunches with nanocoulomb-level charges per bunch. We present an overview of project’s current status.
Paper: MOPR24
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR24
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPR25
Design, fabrication, and testing of a W-band corrugated waveguide for Wakefield acceleration
511
In the field of structure wakefield acceleration there is considerable interest in radiofrequency (RF) structures capable of producing high gradients. Structures in the sub-terahertz (sub-THz) regime are of note due to their high gradient and high efficiency, allowing for a low physical footprint. In the pursuit of this goal we have designed a metallic corrugated W-band structure using the CST Studio Suite. After optimizing for the maximum achievable gradient from a nominal Argonne Wakefield Accelerator (AWA) electron bunch at 65 MeV with a Gaussian distribution we attempted to achieve a higher transformer ratio using a shaped bunch. Shaped bunches such as these are achievable at the AWA emittance exchange (EEX) beamline. Preliminary results from the structure testing at AWA using shaped electron bunches will be presented. Further tests are planned, involving a comprehensive optimization of the beamline at AWA.
Paper: MOPR25
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR25
About: Received: 24 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPR40
Progress towards high-quality, high-repetition-rate plasma acceleration at FLASHForward
541
Plasma-wakefield acceleration represents an exciting route towards reducing the footprint of future high-energy electron accelerators by accelerating bunches in fields exceeding 1 GV/m. One such technique employs a double-bunch structure where the trailing bunch is accelerated in the field of a high-amplitude plasma-density wake driven by the leading bunch. A future particle collider or photon science facility incorporating plasma accelerators will be required to accelerate up to millions of bunches per second with high energy efficiency while preserving the brightness of the accelerating bunch. This contribution presents the latest progress towards these goals at FLASHForward (DESY).
Paper: MOPR40
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR40
About: Received: 14 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR41
Results and plans for run 2 of the advanced proton driven plasma wakefield acceleration experiment AWAKE
545
This talk summarizes the plans, challenges and key components of the four phases in the AWAKE roadmap. In addition, an overview of the rich measurement program of the second phase, AWAKE Run 2b, during 2023 and 2024 is given. Results from a unique 3-week measurement opportunity with a 10m discharge plasma source prototype are shown, including the effects of different gases, plasma densities, bunch charges and plasma lengths on the proton bunch self-modulation, ion-motion, current filamentation instabilities and plasma light. A new 10 m long rubidium vapor source was installed in the summer of 2023 with the possibility to generate a density step (0-10%) every 50 cm along the first 4 m. First measurement results with this plasma cell are also presented, showing the positive effect of the density step on the plasma light as well as an increased energy gain for externally injected electrons.
Paper: MOPR41
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR41
About: Received: 10 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPR43
Experimental characterization of the timing-jitter effects on a beam-driven plasma wakefield accelerator
553
Plasma wakefield acceleration is nowadays very attractive in terms of accelerating gradient, able to overcome conventional accelerators by orders of magnitude. However, this poses very demanding requirements on the accelerator stability to avoid large instabilities on the final beam energy. In this study we analyze the correlation between the driver-witness distance jitter (due to the RF timing jitter) and the witness energy gain in a plasma wakefield accelerator stage. Experimental measurements are reported by using an electro-optical sampling diagnostics with which we correlate the distance between the driver and witness beams prior to the plasma accelerator stage. The results show a clear correlation due to such a distance jitter highlighting the contribution coming from the RF compression.
Paper: MOPR43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR43
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR92
Evaluation of ultrafast THz near-fields for electron streaking
675
THz-frequency accelerating structures could provide the accelerating gradients needed for compact next generation particle accelerators. One of the most promising THz generation techniques for accelerator applications is optical rectification in lithium niobate using the tilted pulse front method. However, accelerator applications are limited by losses during transport and coupling of THz radiation to the acceleration structure. Applying the near-field of the lithium niobate source directly to the electron bunch removes losses due to transport and coupling, yielding a simplified and efficient system. Using electro-optic sampling we have reconstructed the full temporal 3D THz near-field close to the lithium niobate emission face and shown that it can be controlled by manipulating the generation setup. Analysis of the results of this measurement shows an estimated peak field strength of 86 MV/m. A future THz near-field electron streaking experiment is currently planned as a first test of manipulating an electron bunch with the THz near field. Analysis for this planned experiment has yielded an estimated THz near-field kick strength of 23 keV.
Paper: MOPR92
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR92
About: Received: 15 May 2024 — Revised: 28 May 2024 — Accepted: 28 May 2024 — Issue date: 01 Jul 2024
MOPS06
Simulations and experiments for dynamic aperture studies in the LHC ion operation
698
Dynamic Aperture (DA) studies, based on single-particle tracking simulations including important non-linear fields such as beam-beam effects, have played a crucial role in guiding the operation of the Large Hadron Collider (LHC) in proton-proton collisions. The correspondence between DA computed through simulations and the actual beam lifetime during operation has been established for proton beams through dedicated experiments at the LHC. However, such an approach has not yet been applied to the Pb ion operation of the accelerator, as the simulation tools have not been rigorously benchmarked against experimental data yet. The present paper presents the simulation studies and experimental tests performed to establish the correlation between DA and beam lifetime for ions. The main focus lies on exploring the beam-beam limit when the crossing angle is significantly reduced in all LHC experiments as compared to the nominal configuration. This approach opens the possibility to operate with reduced crossing angles or reduced $\beta^*$ within the beam-beam limit, potentially leading to an enhanced performance of the accelerator with ions.
Paper: MOPS06
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS06
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS19
Tracking study of the bimodal RF cavity for storage ring light source
748
Beam lengthening is an effective and commonly used method to improving the beamlife of storage rings. Based on the previously proposed design of a room temperature conducting bimodal RF cavity, we conducted relevant dynamic simulations. Tracking study on a simulated storage ring lattice with the beam energy of 2 GeV and the synchronous radiation energy of 357 KeV, the results show that, the bimodal RF cavity which contains an accelerating field and a third harmonic field can effectively lengthen beam length, the beam lengthening effect similar to the double RF system which consists of main RF cavity and third harmonic cavity.
Paper: MOPS19
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS19
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPS20
Analysis of nonlinear deviation in a generalized longitudinal strong focusing unit
751
In a generalized longitudinal strong focusing (GLSF) approach employed in steady-state microbunching (SSMB) storage rings, the objective is to achieve complete cancellation of modulations by ensuring that a particle's longitudinal position remains unchanged after passing through both modulators. This requires effective control over the deviation in longitudinal position, which arises from lattice nonlinearities. This paper derives analytical formulations for the mean and standard deviation of the particle position deviation, expressed in terms of the beam and lattice-dependent parameters. The aim is to provide valuable insights into the system's behavior and enable optimization of the GLSF unit's performance.
Paper: MOPS20
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS20
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPS21
Update on the beam-induced heating and thermal analysis for the EIC vacuum chamber components
755
One of the challenges of designing the Electron-Ion Collider (EIC) is to mitigate beam-induced heating due to the intense electron and hadron beams. Heating of the Electron Storage Ring (ESR) vacuum chamber components is mainly due to beam-induced resistive wall loss and synchrotron radiation. For the Hadron Storage Ring (HSR) components, heating is mainly due to resistive wall loss because of the large radial offset, electron cloud formation, and heat conduction from room temperature to cryo-components. In this paper, we provide an update on the beam-induced heating and thermal analysis for some EIC vacuum chamber components including the RF-fingers module of HSR cryogenic interconnect assembly. In addition, we provide simulation update for the HSR snake BPM, and abort kicker along with the change in ESR vacuum chamber profile. Similar analysis for other HSR and ESR components are available in Ref.~\cite{sangroulalocalized_NAPAC22, sangroula2023beam}. Our approach for thermal analysis involves calculating resistive wall losses using CST, evaluating heat loss due to synchrotron radiation and electron cloud formation and incorporating these losses into ANSYS for finding the temperature distribution.
Paper: MOPS21
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS21
About: Received: 16 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS22
Resistive wall heating and thermal analysis of the EIC HSR beam screen
759
The Electron-Ion Collider (EIC) utilizes the existing Relativistic Heavy Ion Collider (RHIC) rings as a Hadron Storage Ring (HSR) with some modifications. However, this presents significant challenges, primarily due to beam-induced Resistive Wall (RW) heating resulting from a larger radial offset and shorter EIC bunches (up to 10 times shorter than RHIC). Additionally, the formation of an electron cloud further complicates matters. To address these issues and operate the HSR effectively, this paper focuses on the RW heating and thermal analysis of the EIC HSR beam screen. Our approach involves the insertion of a copper-coated stainless steel beam screen with cooling channels and longitudinal slots. We conducted a detailed thermal analysis, assessing piecewise RW losses around the beam screen's profile due to an offset beam, employing the 3D commercial code CST. These losses, along with realistic boundary conditions, were then integrated into another code, ANSYS, to determine the thermal distribution.
Paper: MOPS22
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS22
About: Received: 18 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPS26
Macro-particle simulations of longitudinal peak-detected Schottky signals
767
The peak-detected Schottky system is a powerful diagnostic tool for observing the longitudinal beam parameters. According to the theoretical model, the peak value of the signal from a wide-band pick-up contains information on particle distribution as a function of the synchrotron frequency. Due to intrinsic assumptions needed for modelling the acquisition set-up and uncertainties in beam parameters, a one-to-one comparison of predictions and measurements remains a challenge. We obtained, for the first time, the peak-detected Schottky spectra in macro-particle simulations for a simplified experimental set-up. Following refinement of the theoretical model, a direct comparison was performed under controlled conditions. Agreement with the numerical results was improved by introducing an additional form factor describing the probability of a particle being present in the observation window. Modifications due to collective effects are briefly discussed as well.
Paper: MOPS26
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS26
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS32
Slow longitudinal mode 1 instability in electron storage rings with harmonic cavities
782
Recent studies have investigated a longitudinal instability that may develop in electron storage rings featuring higher-harmonic cavities. The instability, also referred to as periodic transient beam loading (PTBL), manifests as a slow oscillation of bunch longitudinal profiles following a coupled-bunch mode 1 pattern. In this contribution, we applied a well-established theory of longitudinal mode-coupling to assess the thresholds for this instability. Results obtained through this semi-analytical approach, considering different storage ring and harmonic cavity parameters, were validated using macroparticle tracking and compared against other methods proposed in previous investigations.
Paper: MOPS32
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS32
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS33
Single-bunch instabilities and their mitigation in Diamond-II
786
Diamond-II is a future 4-th generation synchrotron light source with a significantly narrower vacuum chamber compared to the existing Diamond storage ring. The strength of wake fields will increase, and, consequently, the risk of single-bunch instabilities also rises. We consider chromaticity adjustment and a passive harmonic cavity as mitigation measures, including for cases with impedance strength larger than the design value. This work presents single-bunch thresholds obtained in particle tracking simulations for the latest lattice and impedance database, including the case of non-equal bunch lengthening in realistic filling patterns due to beam loading in the RF cavities. The impedance database includes accurate computations of asymmetric vessels causing non-zero monopole and quadrupole components of the wake. Resulting emittance dilution due to impedance is found to be tolerable.
Paper: MOPS33
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS33
About: Received: 15 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
MOPS34
Incoherent and coherent tune shifts in Elettra 2.0
790
Elettra 2.0, will be a 4th generation synchrotron radiation source that will replace Elettra, the 3rd generation light source that has been in operation since 1993 at Trieste. In this paper, the effects of the quadrupolar wake fields are investigated, and the transverse mode coupling threshold is presented. Also, the incoherent tune shift for multi-bunch operation is examined considering the rhomboidal vacuum chamber of Elettra 2.0.
Paper: MOPS34
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS34
About: Received: 13 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPS35
Comparison between self-consistent and non self-consistent space charge analysis for the evolution of the coherent direct space charge modes
794
The question of the mitigation of the Transverse Mode Coupling Instability (TMCI) by space charge has been discussed for more than two decades. Since few years, it has become clear that the ABS model, which has been often used in the past and which assumes an air-bag bunch in a square well, is not sufficient to properly describe the complexity of the interaction between impedance and space charge. Considering a more realistic longitudinal Gaussian distribution, a fully self-consistent treatment of space charge was performed few years ago using the circulant matrix model, which revealed the usual TMCI mechanism but with oscillation modes shifted both by impedance and space charge. In this paper, a non self-consistent treatment of space charge is analyzed, still using a Gaussian distribution, to look at the evolution of the coherent direct space charge modes. It is shown in particular that it leads to exactly the same result as the self-consistent treatment for space charge parameters below 1 and that it is a much better approximation than the ABS model for space charge parameters above 1, as it reveals clearly how the positive modes lead to negative tune shifts.
Paper: MOPS35
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS35
About: Received: 02 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
MOPS36
Intrabunch motion in the presence of mode coupling
798
The intrabunch motion for independent longitudinal or transverse beam oscillation modes has been explained analytically for impedance driven bunched-beam coherent instabilities already several decades ago by Laclare and they have been observed in many measurements and simulations. These oscillation patterns do not depend on the bunch intensity, they are head/tail symmetric and they exhibit a number of nodes equal to the radial mode number. However, in many measurements and simulations of transverse beam instabilities (due to impedance only, impedance and beam-beam, impedance and space charge, or electron cloud), asymmetric patterns are observed depending on the bunch intensity. The latter can be described theoretically considering the interaction between several modes, i.e. mode coupling, which explains why and how different kinds of asymmetric intrabunch signals can be observed. In this paper, the intrabunch motion in the presence of mode coupling is explained first without maths and then with maths, considering the case of a bunch interacting with a transverse impedance, using the GALACTIC Vlasov solver.
Paper: MOPS36
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS36
About: Received: 02 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
MOPS39
Formulas of coherent synchrotron radiation induced microbunching instability in an arbitrary four-dipole chicane bunch compressor
806
Almost all linac-based free-electron laser (FEL) facilities have employed a symmetric three- or four-dipole chicane to compress the electron beam in order to achieve a kA-level bunch current. The achromatic C-type chicane has been widely used in present linac-FEL facilities. Coherent synchrotron radiation (CSR) induced microbunching instability (MBI) can be an issue in the chicane design. Recently a novel design of non-symmetric four-dipole chicane has been proposed to effectively mitigate the CSR-induced emittance growth. In this work we derive an analytical formula of the CSR-induced microbunching gain in a generic four-dipole chicane based on the iterative approach. The formulas have been benchmarked against semi-analytical Vlasov calculation, applied for a quick estimate of CSR-induced MBI for a generic four-dipole achromatic chicane beamline, and can be used to verify the effectiveness of suppressing MBI in a non-symmetric S-type four-dipole bunch compressor chicane.
Paper: MOPS39
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS39
About: Received: 03 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPS40
Microbunching threshold manipulation by a corrugated structure impedance at KARA
810
Two parallel corrugated plates can be used to manipulate the impedance of an electron storage ring such as the KIT storage ring KARA (KArlsruhe Research Accelerator). This impedance manipulation structure opens up the possibility to eventually control the electron beam dynamics and the emitted coherent synchrotron radiation (CSR). In this contribution, we present the impedance that is most effective to manipulate the threshold of the microbunching instability for different machine settings. Furthermore, it will be shown, how the resonance frequency of this impedance is related to the spectrum of the substructures in the electron bunches.
Paper: MOPS40
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS40
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS41
A novel coherent synchrotron radiation simulation method using cavity Green's functions
814
The mitigation of collective beam effects, in particular Coherent Synchrotron Radiation (CSR), is crucial for the development of particle accelerators with higher beam brightness. Among the strategies proposed in the literature, the use of appropriate shielding walls to curb CSR is an attractive strategy with many associated open problems. In particular, simulation methods that account for shielding effects usually employ image charges and assume free space potentials, making them only applicable for simple wall layouts. In this work, we will outline a novel simulation technique that makes use of cavity Green's functions to capture the field modes admitted by the shielding walls. In addition to better resolving the radiated fields, the proposed method will be robust to singularities that are typically encountered in the image charge approach. We will discuss the computational implications of using cavity Green's functions and discuss strategies to scale the method to complex geometries and large particle counts. The method will eventually be validated using results from a planned shielding study at the Argonne Wakefield Accelerator using a dipole chamber with variable gap size.
Paper: MOPS41
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS41
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPS42
Start-to-end simulations of microbunching instability based on optimized velocity bunching in linac-driven FELs
817
The microbunching instability (MBI) driven by beam collective effects can cause significant electron beam quality degradation in advanced X-ray free electron lasers. Typically, multiple stage magnetic bunch compressors used to generate high peak current electron beam will dramatically amplify the microbunching instability. In this paper, by redesigning the solenoid elaborately and adopting a dual-mode buncher cavity with the third harmonic mode used to correct the RF curvature, in combination with the evolutionary many-objective beam dynamics optimization, it is potential for the electron beam to be further compressed in velocity bunching (VB) process. Therefore, a VB plus one bunch compressor could be a promising alternative scheme to achieve moderate peak current beam for X-ray FELs. Start-to-end simulations based on the Shanghai high-repetition-rate XFEL and extreme light facility proves the feasibility of the scheme in suppressing the additional MBI gain due to multi-stage magnetic bunch compressors.
Paper: MOPS42
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS42
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPS45
Transverse instabilities in SOLEIL II storage ring in the presence of a harmonic cavity
821
SOLEIL II is an upgrade project of the existing Synchrotron SOLEIL facility. It aims to reach fourth-generation light source parameters. This includes reductions of the transverse beam emittance, vacuum chamber dimensions and momentum compaction factor. A new impedance model of the SOLEIL II storage ring was developed. This paper demonstrates the evaluation of transverse single- and coupled-bunch instabilities with an up-to-date impedance model. Storage ring operation with a harmonic cavity is an essential component of the project. A harmonic cavity provides bunch lengthening and perturbs synchrotron motion. Its effects on transverse instabilities in SOLEIL II are reported in this contribution.
Paper: MOPS45
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS45
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPS49
High gradient C-band photoinjector performance utilizing sacrificial charge to enhance brightness
828
We report simulation results showing the use of sacrificial bunch charge to achieve high brightness in photoinjector beamlines designed for Ultrafast Electron Diffraction (UED) and Inverse Compton Scattering (ICS). The beam undergoes nonlaminar focusing during which the tails dynamically linearize the core’s transverse phase space. An aperture then removes the resulting diffuse tails, leaving a beam with high brightness. We employ this scheme in C-band photoinjector guns, whose high gradients are attractive for both low (UED) and high charge (ICS) applications. In our simulations we use a 1.6 cell gun with a peak field at the cathode of 240 MV/m. We start with negligible intrinsic emittance and use a multi-objective genetic algorithm to obtain a Pareto front minimizing bunch length and emittance. For ICS applications, we obtain an extremely small minimum emittance of 80 nm at a final charge of 250 pC per bunch and 1.44 ps rms bunch length. For a final bunch charge of 1e+5 electrons, typical for UED experiments, we obtain an emittance of 1.2 nm at an rms bunch length of 50 fs. Both results far exceed the brightness state of the art for these applications.
Paper: MOPS49
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS49
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPS55
Multi-objective genetic optimization of high charge TopGun photoinjector
840
The TopGun photoinjector is a 1.6-cell C-band gun developed by the University of California, Los Angeles team. Originally optimized for 100 pC operation, its low emittance design has been our starting point. However, the Los Alamos National Laboratory (LANL) needs to operate with a 250 pC bunch charge while maintaining an emittance below 100 nm. The initial optimization of the high charge TopGun-like photoinjector design, intended for construction at LANL, has been previously reported. That design had a single objective: achieving the lowest possible emittance, which was attained at significantly longer bunch length, thereby limiting improvements in beam brightness. Here, we present a multi-objective genetic optimization of the high charge TopGun-like photoinjector design to obtain a Pareto front minimizing bunch length and emittance. We have successfully reduced the bunch length from 8.18 ps to 5.67 ps while maintaining similar emittance values.
Paper: MOPS55
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS55
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPS57
Proposal for a proton-bunch compression experiment at IOTA in the strong space-charge regime
848
The longitudinal compression of intense proton bunches with strong space-charge force is an essential component of a proton-based muon source for a muon collider. This paper discusses a proton-bunch compression experiment at the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab to explore optimal radio frequency (RF) cavity and lattice configurations. IOTA is a compact fixed-energy storage ring that can circulate a 2.5-MeV proton beam with varying beam parameters and lattice configurations. The study will aim to demonstrate a bunch-compression factor of at least 2 in the IOTA ring while examining the impact of intense space-charge effects on the compression process.
Paper: MOPS57
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS57
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS58
First-principle simulations of a laser-assisted bunch compression scheme
852
High brightness electron beams with high peak current are critical to reducing the size of XFEL. A promising approach consists in combining low emittance beam generated high-frequency photoinjector with a laser-assisted bunch compression scheme. Such a compression consists in using an infrared laser to modulate the electron beam energy in a planar undulator and a low R56 chicane to compress these modulations and produced a micro-bunched beam. We present first-principle simulations of this compression process including the impact of coherent synchrotron radiation (CSR) on the beam dynamics. These simulations were performed using the large-scale self-consistent LW3D code for two compression configurations under study for compact XFEL designs.
Paper: MOPS58
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS58
About: Received: 24 May 2024 — Revised: 25 May 2024 — Accepted: 28 May 2024 — Issue date: 01 Jul 2024
MOPS62
Generation of attosecond electron bunches through terahertz regulation
863
Obtaining ultrashort electron bunches is the key to the studies of ultrafast science, yet second and higher order nonlinearities limits the bunch length to a few femtoseconds after compression. Traditional regulation methods using rf higher order harmonics have already optimized the bunch length to sub-fs scale, yet the energy loss and rf jitter are not negligible. In this paper we demonstrate the second order regulation with THz pulses through a dielectric-loaded wave-guide. Simulations suggest that with higher order correction, the MeV electron bunches with tens of fC charges can be compressed to a 679 attoseconds rms and the second order distortion can be compensated. The transverse beam size is also optimized to 16.8 um rms. This scheme is feasible for a wide range of electron charges. The relatively short bunch length is expected to find a better time resolution in UED, UEM and other ultrafast, time-resolved studies.
Paper: MOPS62
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS62
About: Received: 11 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPS73
Utilizing neural networks to speed up coherent synchrotron radiation computations
901
Coherent synchrotron radiation has a significant impact on electron storage rings and bunch compressors, inducing energy spread and emittance growth in a bunch. While the physics of the phenomenon is well-understood, numerical calculations are computationally expensive, severally limiting their usage. Here, we explore utilizing neural networks (NNs) to model the 3D wakefields of electrons in circular orbit in the steady state condition. We demonstrate that NNs can achieve a significant speed-up, while also accurately reproducing the 3D wakefields. NN models were developed for both Gaussian and general bunch distributions. These models can potentially aid in the design and optimization of accelerator apparatuses by enabling rapid searches through parameter space.
Paper: MOPS73
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS73
About: Received: 13 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS79
Modeling and optimization of the FACET-II injector with machine learning algorithms
913
Linear particle accelerators are elaborate machines that demand a thorough comprehension of their beam physics interactions to enhance performance. Traditionally, physics simulations model the physics interactions inside a machine but they are computationally intensive. A novel solution to the long runtimes of physics simulations is replacing the intensive computations with a machine learning model that predicts the results instead of simulating them. Simple neural networks take milliseconds to compute the results. The ability to make physics predictions in almost real time opens a world of online models that can predict diagnostics which typically are destructive to the beam when measured. This research entailed the incorporation of an innovative simulation infrastructure for the SLAC FACET-II group, aimed at optimizing existing physics simulations through advanced algorithms. The new infrastructure saves the simulation data at each step in optimization and then improves the input parameters to achieve a more desired result. The data generated by the simulation was then used to create a machine learning model to predict the parameters generated in the simulation. The machine learning model was a simple feedforward neural network and showed success in accurately predicting parameters such as beam emittance and bunch length from varied inputs.
Paper: MOPS79
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS79
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUAN2
Measurement and modeling of beam transport in the FODO line of the Spallation Neutron Source Beam Test Facility
943
Ongoing studies at the Spallation Neutron Source (SNS) Beam Test Facility (BTF) seek to understand and model bunch dynamics in a high-power LINAC front-end. The BTF has recently been upgraded with a reconfiguration from a U-shaped line to a Straight line. We report the current state of model benchmarking, with a focus on RMS beam sizes within the FODO line. The beam measurement is obtained via three camera/screen pairs in the FODO line. This presentation discusses the methodology and results of this measurement.
Paper: TUAN2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUAN2
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
TUAN3
Understanding of the LHC warm vacuum module heating
947
During the third run of the Large Hadron Collider in 2023, which had the highest intensity bunch population compared to previous runs, increased losses attributed to pressure spikes within a warm vacuum sector triggered a beam dump. Subsequent inspections revealed localised annealing and plasticisation of the tension spring in the sliding contact radio-frequency finger module, alongside traces of vapour deposition on the various module components with the stainless-steel spring material. A comprehensive analysis involving vacuum and beam impedance studies was conducted to investigate the triggering mechanisms behind the radio-frequency finger module failure. The findings indicate localised beam-induced heating, which could lead to the annealing of the spring with a consequent cascade of effects. Additionally, investigations of potential mitigation measures were performed.
Paper: TUAN3
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUAN3
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
TUBD1
From RHIC to EIC hadron storage ring - overview of the engineering challenges
951
The Electron Ion Collider (EIC) Hadron Storage Ring (HSR) will reuse most of the existing hardware from the RHIC rings. However, extensive modifications will have to be performed in preparation for the new accelerator parameters and performance required by EIC. The beam vacuum chamber will have to be upgraded and new beam position monitors (BPM) implemented to account for the higher beam intensity and shorter EIC hadron bunches. The RF system will also need to be upgraded and include new cavities to drive the new bunch parameters. In some straight sections, existing superconducting magnets will have to be reshuffled and their cold powering scheme modified to accommodate the new accelerator lattice. The hadron injection scheme will also be modified to accommodate three time more bunches and the machine protection system will need to include new collimators. This paper aims to give an overview of the engineering modifications required to turn RHIC into the EIC HSR.
Paper: TUBD1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUBD1
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
TUBD2
Analysis of the performance in the 2023 LHC Pb-Pb run
955
In 2023, the Pb-Pb run in the Large Hadron Collider (LHC) took place during the last five weeks of operation at a record beam energy of 6.8 Z TeV. It marked the first heavy-ion run of Run 3, following a two-day test that took place in 2022 to verify some key machine and beam upgrades. The 2023 run profited for the first time of higher beam intensities than the previous runs and of machine upgrades that enable higher peak luminosities in the ion-dedicated ALICE experiment. This paper addresses two important performance aspects: firstly, it compares the achieved operational efficiency for the different filling schemes employed during the run, and secondly, it quantifies the main factors contributing to performance loss.
Paper: TUBD2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUBD2
About: Received: 07 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUBD3
Analyzing sudden beam loss in the SuperKEKB/Belle-II experiment with RFSoC technology
959
In the SuperKEKB/Belle-II experiment, a multitude of elementary particle reactions is initiated through the collision of 4 GeV positrons with 7 GeV electrons, paving the way for the exploration of new physics. The experiment includes plans for the substantial enhancement of luminosity in the future, aiming to achieve an integrated luminosity approximately 100 times the current level. However, the realization of this goal is impeded by a recurrent occurrence of a phenomenon known as "Sudden Beam Loss," which entails the abrupt disappearance of the beam within tens of microseconds. The cause and location of these occurrences have not yet been identified. To provide the tools to diagnose and debug these sudden beam loss events, a new Bunch Oscillation Recorder (BOR) has been developed to analyze this phenomenon, utilizing the Radio Frequency System on Chip (RFSoC) from AMD/Xilinx. The beam position of each individual bunch is measured and recorded by the BOR just prior to the onset of sudden beam loss. We will present how the signal from the button beam position monitor of the beam pipe is processed by RFSoC, along with the results obtained from observing the actual SuperKEKB beam using RFSoC.
Paper: TUBD3
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUBD3
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
TUZN1
Shanghai hard X-ray FEL facility progress status
967
SHINE (Shanghai Hard X-ray FEL Facility) is a high repetition rate X-FEL facility under construction in Shanghai, China. The facility is based on an 8 GeV CW superconducting linac and plans to have 3 undulator lines and 10 experimental stations in phase-I, covering the photon energy range of 0.4 – 25 keV. Mass production of the components and installation of the machine are in course. User experiments are expected to start in 2025. This presentation summarizes the proposed configuration and the status of R&D and production for the critical components and systems, discussing the key technologies. The current status of the project and the plans leading to the completion will be presented, outlining the major scientific goals of the facility.
Paper: TUZN1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUZN1
About: Received: 21 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC03
Multi-bunch beam dynamics studies for the C3 main linac
992
The Cool Copper Collider (C3) is a novel accelerator concept for a linear collider utilizing a cryogenically-cooled copper linear accelerator (linac) with a distributed coupling architecture. The C3 main linac is designed to accelerate electron/positron from 10 GeV to 125 GeV while preserving the beam emittance. Here we present the analysis of the multi-bunch beam dynamics for the C3 main linac. We show the beam dynamics simulation results of the C3 main linac to identify the frequency bands that cause emittance growth and the amount of frequency detuning required to suppress it. Results presented will be used to guide the future design of the accelerating structure.
Paper: TUPC03
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC03
About: Received: 13 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC04
ATF2-3 hardware upgrade and new experimental results to maximize luminosity potential of linear colliders
996
The ATF2-3 beamline is the only facility in the world for testing the Final Focus Beamline of linear colliders and is essential for the ILC and the CLIC projects. A vertical electron beam size of 41 nm (within 10% of the target), a closed-loop intra-bunch feedback of latency 133 ns, and direct stabilization of the beam position at the Interaction Point to 41 nm (limited by IP BPM resolution) have all been achieved at ATF2. These results fulfilled the two main ATF2 design goals, but were obtained with reduced aberration optics and a bunch population of approximately 10% of the nominal value of 10^10 electrons. Recent studies indicate that the beam degradation with the beam intensity is due to the effects of wakefields. To overcome this intensity limitation, hardware upgrades including new vacuum chambers, magnets, IP-Beam Size Monitor laser, cavity BPMs, wakefield mitigation station, as well as a comprehensive R&D program to maximize the luminosity potential are being pursued in the framework of the ILC Technology Network. This new R&D program focuses on the study of wakefield mitigation techniques, correction of higher-order aberrations, tuning strategies, including AI techniques, as well as beam instrumentation issues, such as the BPMs, advanced Cherenkov Diffractive Radiation monitors, and fast feedback systems, among others. This paper summarizes the hardware upgrades, the R&D program and the results of the Fall 2023-Winter 2024 experimental campaign performed in ATF2-3.
Paper: TUPC04
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC04
About: Received: 15 May 2024 — Revised: 29 May 2024 — Accepted: 29 May 2024 — Issue date: 01 Jul 2024
TUPC06
Dynamic aperture of the RCS during bunch merges
1003
The Rapid Cycling Synchrotron (RCS) of the Electron Ion Collider (EIC) will be used to accelerate polarized electrons from 400 MeV to a top energy of 5, 10, or 18 GeV before injecting into the Electron Storage Ring. At 1 GeV, the RCS will perform a merge of two bunches into one, adding longitudinal dynamics that effects the dynamic aperture, depending on the merge parameters. In this paper, results for different merge models will be compared, as well as finding the relationship between the merge parameters of the RCS and its dynamic aperture.
Paper: TUPC06
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC06
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC07
Measurements of beam correlations induced via coupled resonance crossing in the CERN PSB
1006
Beam profile measurements in the LHC and its injector complex show heavy tails in both transverse planes. From standard profile measurements, it is not possible to determine if the underlying phase space distribution is statistically independent. A measurement campaign in the CERN PSB was carried out to introduce cross-plane dependence in bunched beams in controlled conditions, in view of characterizing the LHC operational beam distributions. The results of the measurement campaign demonstrate how heavy tails can be created via coupled resonance excitation of the lattice in the presence of space charge, in accordance with predictions from the fixed line theory. The coupled resonance introduces dependence between the different planes, which persists after the resonance excitation is removed.
Paper: TUPC07
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC07
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC08
A review of the 2023 antiproton physics run in the CERN antimatter factory
1010
Despite a shorter-than-scheduled physics run due to a hardware problem, the AD/ELENA antiproton complex delivered record beam intensities to the experiments during the 2023 run. This paper reviews the performance of both the CERN Antiproton Decelerator (AD) and the Extra Low ENergy Antiproton (ELENA) decelerator and their associated transfer lines. It presents the main improvements that allowed these record beam intensities to be delivered to the experiments. Emphasis is put on the optimization of the injection line, progress made on the stochastic and electron cooling performance, increased deceleration efficiency and stability, and the software tools used. Remaining issues and potential future improvements for the coming run will also be presented.
Paper: TUPC08
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC08
About: Received: 07 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPC10
RF system upgrade for 1.3 MW operation of J-PARC main ring
1017
The J-PARC Main Ring accelerates proton beam from 3 GeV to 30 GeV and delivers it to T2K neutrino experiment with fast extraction and hadron experiments with slow extraction. In the last two years the beam power to the neutrino experiment was increased from 500 kW to 750 kW. The T2K detector is scheduled to be replaced by the new Hyper-K detector; the latter will be able to accept a 1.3 MW proton beam by 2028. To achieve 1.3 MW beam power, J-PARC plans to upgrade the Main Ring by increasing intensity and repetition rate. The Main Ring uses low frequency, high bandwidth RF cavities with Magnetic Alloy cores, powered by two 600 kW tetrode tubes. Under the upgrade plan, the number of RF cavities will be increased to secure the RF voltage and longitudinal acceptance. The anode power supply will be upgraded to provide enough current for both gap voltage and beam loading compensation. The upgraded LLRF system will be optimized to control fundamental and 2nd harmonic RF voltages, suppress coupled bunch instabilities and compensate beam loading effects. Current operational status as well as details of the upgrade plan and related simulation results will be discussed in this paper.
Paper: TUPC10
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC10
About: Received: 20 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
TUPC14
Application and comparative analysis of the APES_CBI module in BEPC-II experimental results
1033
In this paper, we delve into the application and comparative analysis of the Accelerator Physics Emulation System Cavity-Beam Interaction (APES_CBI) module within the BEPC-II (Beijing Electron-Positron Collider) experiments. We developed the APES_CBI module as an advanced time-domain solver, specifically designed to analyze RLC circuits driven by beam and generator currents and to simulate the dynamic responses and synchrotron oscillations of charged particles within the cavity. We begin by discussing our method for solving RLC parallel circuits, followed by an explanation of the logical architecture of our program. In the second part, we detailed our simulation results, starting with the BEPC-II electron ring. By comparing these results with experimental data, we validate the reliability of our simulations, showcasing our module's ability. Additionally, we extend our simulations to the CEPC Higgs mode on-axis injection conditions and studied the transient phase response to the sudden change of beam pattern.
Paper: TUPC14
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC14
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC16
Estimates of the recombination rate for the strong hadron cooling system in the EIC
1040
The strong hadron cooling system (SHC) for the electron-ion collider (EIC) consists of the modulator, the microbunching amplifier and the kicker section. In the modulator and the kicker section, the electrons are co-moving with the protons. If the relative velocity of an electron with respect to a proton is small enough, it can be captured by the proton and the resulting neutral particle, i.e. a hydrogen atom, will deviate from the designed trajectory and get lost around the cooling section. Since the probability of a proton capturing an electron depends on the relative velocity between them, one can align the energy of the two beams based on the number of hydrogen atoms detected by a recombination monitor. In this work, we estimate the rate at which the hydrogen atoms produced by the recombination process for the SHC in EIC.
Paper: TUPC16
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC16
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPC36
Initial operational experience of an LHC injection kicker magnet upgraded for HL-LHC
1080
The intensity of the HL-LHC beam will be twice that of LHC. Hence, an upgrade of the LHC injection kickers (MKIs) is necessary for HL-LHC to avoid excessive beam induced heating of the MKIs. In addition, any newly installed MKI magnet would limit HL-LHC operation for a few hundred hours due to dynamic vacuum activity. Extensive studies have been carried out to identify solutions to address these problems and they have been implemented in an upgraded LHC injection kicker magnet (MKI Cool): the MKI Cool was installed in the LHC during the 2022-23 Year End Technical Stop. Magnet heating has been reduced by redistributing a significant portion of the beam induced power deposition from the ferrite yoke to a ferrite loaded RF Damper, which is not at pulsed high voltage, and by water cooling of the damper. Furthermore, a surface coating, to mitigate dynamic vacuum activity, has been applied. This paper discusses the upgrades, presents results from the initial operational experience, and compares the predicted and ‘measured’ beam induced power deposition.
Paper: TUPC36
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC36
About: Received: 12 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPC41
Adaptation of the Fermilab proton source to support new muon facilities
1100
The PIP-II proton accelerator will provide the intensity sufficient to power a new generation of high energy facilities at Fermilab. Extension of that linac to higher energy with following acceleration and bunching rings could provide the intensity needed to feed a muon production target for a high-energy μ+-μ- collider. Scenarios using a rapid-cycling synchrotron or an ~8 GeV Linac are presented and discussed. Use of the existing Fermilab accelerators is also discussed. Support for other high-intensity experiments such as muon-ion collisions, neutrino sources and lepton flavor conservation is also considered.
Paper: TUPC41
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC41
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC44
Single bunch tracking on the ten-pass ER@CEBAF energy recovery beamline
1108
The proposed ten-pass energy recovery linac (ERL) demonstration (five accelerating, five decelerating) at the CEBAF accelerator, ER@CEBAF, involves a multi-GeV energy range of a continuous electron beam. New CEBAF transverse optics were designed for this ERL demonstration. This redesign incorporates additional components in Arc A, including a path length chicane and new quadrupoles to ensure proper dispersion localization. The new five energy recovery passes with a shared arc transport scheme challenge the overall beamline optics design, including large beta functions in the CEBAF spreaders and recombiners. Here we discuss results of bunch tracking performed using the elegant tracking code for the full ER@CEBAF beamline.
Paper: TUPC44
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC44
About: Received: 06 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
TUPG03
Summary of the commissioning of the active harmonic EU cavity
1224
A collaboration agreement between the ALBA, DESY and HZB institutions was signed on 2021 in order to commission the 3rd harmonic normal conducting, HOM damped, active cavity designed and prototyped by ALBA. The cavity prototype arrived to ALBA in December 2021, and successfully passed the low power RF and vacuum tests. Afterwards, in January 2022 it was sent to HZB and mounted in the SUPRALAB@HZB, in the HoBiCat bunker for bead-pull measurements and high-power conditioning. Finally, in May 2022 the cavity was installed in the BESSY-II ring for test with beam. In this contribution we summarize and highlight the major results after two years of commissioning with beam including the lengthening capability of the cavity for single bunch and homogeneous filling pattern, lifetime increase measurements, HOM damping capability and transient beam loading effects due to the presence of a gap in the filling pattern.
Paper: TUPG03
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG03
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
TUPG06
Particle accumulator ring restart and readiness for Advanced Photon Source upgrade commissioning
1228
At the Argonne (ANL) Advanced Photon Source (APS), a 425-MeV Particle Accumulator Ring (PAR) is used to stack 1-nC electron pulses from the linac and inject a single bunch into the booster at a 1-Hz repetition rate. All the APS injectors, including PAR, were shut down in April 2023 at the start of the APS Upgrade Dark Time. In this paper, we report on PAR re-start activities starting in Oct. 2023. The PAR vacuum pressure was unexpectedly high when first powering the fundamental and harmonic radiofrequency (rf) systems, as well as when first injecting the beam, which initially limited both the beam charge and rf gap voltage. These limits were overcome through many weeks of systematic rf and vacuum conditioning. Additional restart activities include commissioning two new kicker chambers with a special low-impedance, eddy-current-suppressing coating, commissioning of the digital low level rf system, and tests with the Injection Extraction Timing and Synchronization (IETS) system. We demonstrated initial APS-U commissioning performance goals: a stable, 5-nC injected bunch charge with a bunch length short enough for injection into the booster.
Paper: TUPG06
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG06
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPG07
APS upgrade booster commissioning
1232
After a long shutdown, the Advanced Photon Source (APS) booster synchrotron was recently re-commissioned for the APS Upgrade (APS-U) project. The APS-U requirements for the booster are more demanding than the old APS: much higher bunch charge, reduced beam emittance, and improved charge stability of better than 5% shot to shot. The booster accelerates electron bunches of 1-12 nC from 425 MeV to 6 GeV at a 1 Hz rep rate. While the booster ring hardware was largely kept the same, it is now run on a separate RF source, which allows for frequency manipulation during the booster ramp. Photon diagnostics have recently been upgraded for reduced thermal drift. This paper will report on the booster re-commissioning process, including checkout of various systems, tests of the new RF source, and tuning for improved performance. It will also detail plans for further improvements, in particular for achieving even higher bunch charge.
Paper: TUPG07
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG07
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
TUPG18
Studies for single bunch and multi-bunch beam instabilities in the Diamond-II booster
1246
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).
Paper: TUPG18
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG18
About: Received: 10 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
TUPG23
Radio frequency design and analysis of quasi-waveguide multicell deflecting cavities for the production of picosecond x-ray pulses for Elettra 2.0
1266
Picosecond-long x-ray pulses of moderate intensity and high repetition rate are highly sought after by the light source community, especially for time-resolved fine spectroscope analysis of matter in the linear response regime. As part of the upgrade of the Elettra 2.0, two radio frequency deflecting cavities will be installed to produce time-dependent orbit deflection to a few dedicated electron bunches with no effect on the regular bunches. This paper reports the radio frequency design of super-conducting deflecting crab cavities operating at 3.0 and 3.25 GHz. The design is based on a Quasi-waveguide Multicell Resonator (QMiR), firstly developed for Advanced Photon Source, which uses a trapped dipole mode for the crabbing of the bunches. QMiR has heavily loaded Higher Order Modes (HOMs) resulting in a sparse HOMs spectrum thus eliminating the need for HOMs couplers simplifying the cavity mechanical design. The detailed EM analysis, including HOM damping, particle tracking through the field, thermal & mechanical simulations are presented. This article reports both static and dynamic thermal loads and the conceptual design for "0 boil off" cavity cool down at 4.2 K or lower.
Paper: TUPG23
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG23
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPG25
Operation and developments at the ESRF-EBS light source
1270
The European Synchrotron Radiation Facility - Extremely Brilliant Source (ESRF-EBS) is a facility upgrade allowing its scientific users to take advantage of the first high-energy 4th generation storage ring light source. In December 2018, after 30 years of operation, the beam stopped for a 12-month shutdown to dismantle the old storage ring and to install the new X-ray source. On 25th August 2020, the user program restarted with beam parameters very close to nominal values. Since then beam is back for the users at full operation performance and with an excellent reliability. This paper reports on the present operation performance of the source, highlighting the ongoing and planned developments and the sustainability efforts.
Paper: TUPG25
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG25
About: Received: 10 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPG31
Progress of physics studies and beam commissioning of the High Energy Photon Source
1290
The High Energy Photon Source (HEPS) is a 34-pm, 1360-m storage ring light source being built in the suburb of Beijing, China. The HEPS construction started in 2019, with the main civil construction finished at the end of 2021. In the past year, the beam commissioning of the HEPS injector (both Linac and booster) was started and had been finished, and the equipment installation was underway for the storage ring simultaneously. In this paper, we will briefly introduce system conditioning and commissioning of the HEPS Linac and booster, and also simulation studies and high-level applications’ development for the commissioning of the storage ring.
Paper: TUPG31
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG31
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPG34
Networking activities of the I.FAST project in the high brightness accelerator for light sources
1298
The Innovation Fostering in Accelerator Science and Technology (I.FAST) project aims to enhance innovation in the particle accelerator community, mapping out and facilitating the development of breakthrough technologies common to multiple accelerator platforms. Task 7.2 of the I.FAST project, Enabling Technologies for Ultra Low Emittance Rings, focuses on networking in the area of low emittance rings dominated by the recent X-ray storage ring upgrades and exploiting synergies with existing and future e+/e- colliders. Strengthening networking activities in essential technologies ranging from magnet design, RF systems, vacuum, injection systems to feedback systems and beam instrumentation leads to a state where technological difficulties are shared, so that the R&D path is strongly linked to other facilities and scientific fields. Such a state also stimulates joint organizations to collaborate on projects with organic links worldwide. To facilitate networking, Task 7.2 has so far organized several thematic workshops, and is planning further workshops to prepare opportunities to strengthen networking. In this contribution we present our activities in the past and for the future.
Paper: TUPG34
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG34
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPG37
Status of the Advanced Light Source
1309
The LBNL Advanced Light Source, a pioneering third-generation soft x-ray synchrotron radiation source operating at 1.89 GeV with a 2~nm beam emittance, stands as one of the earliest facilities in its class, continually evolving to maintain its status at the forefront of soft x-ray sources. This paper reviews the most significant advancements in the accelerator's hardware and software infrastructures and presents the machine operational statistics over the last 15 years.
Paper: TUPG37
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG37
About: Received: 12 May 2024 — Revised: 19 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
TUPG44
Chromaticity and Landau damping effects in the SLS 2.0 transverse coupled bunch instability threshold
1334
Bunches excited by a transverse kick out of the closed orbit develop betatron oscillations, whose dynamics is affected by the chromaticity used in the accelerator or storage ring. Specifically, decoherence and recoherence effects caused by chromaticity can be modified by introducing Landau damping in the synchrotron phase space, when using a harmonic cavity to stretch the bunch length in order to improve the beam stability. Chromaticity will convert any oscillation in the longitudinal phase space into a frequency modulation of the betatron tune, changing the pattern of the echos of the kick in the beam offset. Focusing on the SLS 2.0 storage ring, we present a study about the damping of single bunch transverse oscillations with non zero chromaticity, including the harmonic cavity and the broadband impedance. These damping times are used to predict the threshold of the transverse coupled bunch instability in SLS 2.0.
Paper: TUPG44
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG44
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
TUPG45
Intra-beam scattering and Touschek scattering optimizations for the upgraded SSRF
1338
In this study, we present the design of a candidate lattice for the Shanghai Synchrotron Radiation Facility Upgrade (SSRF-U) storage ring, targeting the soft X-ray diffraction limit. Due to its ultra-low emittance, intra-beam and Touschek scattering are significant and require attention. We conducted simulations to examine the emittance growth and beam lifetime of different machine configurations in the SSRF-U storage ring. Equilibrium beam emittance variations due to beam coupling and bunch lengthening were identified through simulations. Additionally, Touschek scattering and beam lifetime were calculated.
Paper: TUPG45
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG45
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPG52
Design of a single mode 3rd harmonic cavity for PETRA IV
1361
The upgrade of PETRA III to PETRA IV at DESY is currently in its design phase. To achieve the desired beam parameters a 3rd harmonic cavity is necessary for the accelerating system. An investigation of three types of cavity structures thus is conducted to find the most cost effective and environmentally sustainable option. A high focus in this investigation is placed on the damping of higher order modes. Therefore, two of the investigated structures are so called single mode structures. Such structures have its cavity directly coupled to an RF-absorber, allowing for damping of all resonant modes but the desired ground mode. The design considered in this paper is from a conceptual test of Helmut Herminghaus (MAMI, Mainz, DE). Taking the requirements of PETRA IV into account, the design is adapted, numerically simulated and optimized.
Paper: TUPG52
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG52
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
TUPG67
Coherent radiation of a microbunched beam in a short undulator
1406
We calculate the coherent radiation of a modulated beam in a short resonantly tuned undulator taking into account the finite transverse size and the angular spread of the beam. The result allows to optimize the radiation by controlling the Twiss parameters in the undulator.
Paper: TUPG67
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG67
About: Received: 03 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
TUPG69
Tunable laser pulses enable the generation of femtosecond electron beams with controllable lengths
1409
In ultrafast electron diffraction experiments, the electron beam's length is crucial as it determines the timescale for observing ultrafast dynamic changes. Therefore, achieving continuous control over the length of these beams within a specific range is paramount for broadening the research scope in ultrafast science. This regulation ensures the accuracy of diffraction images from diverse samples, precise electron beam length measurement, and effective generation of terahertz radiation. Currently, typical methods employ radio frequency (RF) cavity compression to manage electron beam length. Nonetheless, this approach introduces time jitter and encounters challenges in continuously adjusting the electron beam length due to constraints of the RF cavity structure. This paper focuses on compressing femtosecond laser pulse methods to obtain laser pulses with continuously adjustable pulse widths. Subsequently, further controlling the distribution of photoemission electron beams can enhance the temporal resolution of ultrafast electron diffraction.
Paper: TUPG69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG69
About: Received: 14 May 2024 — Revised: 07 Jun 2024 — Accepted: 07 Jun 2024 — Issue date: 01 Jul 2024
TUPR06
Preliminary design of the normal conducting RF cavities for Electron-Ion Collider Hadron Storage Ring
1428
The Normal-Conducting Radio-Frequency (NCRF) systems for the Electron-Ion Collider Hadron Storage Ring (EIC HSR) consist of 4 unique cavity resonators. The HSR NCRF systems are composed of a 24.6 MHz capture and acceleration system, a combined 49.2 MHz and 98.4 MHz bunch splitting system, and a 197 MHz storage system for collider operations. This paper presents the preliminary design of the HSR NCRF systems. We describe the unique approach taken to optimize HSR performance while limiting the total number NCRF systems, reducing the NCRF systems contributions to the total HSR impedance while reducing operating complexity.
Paper: TUPR06
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR06
About: Received: 13 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPR78
LHC abort gap monitor electronics upgrade
1600
The LHC Abort Gap Monitor (AGM) is part of the LHC machine protection system (MPS) and is designed to measure the particle population in a 3us wide region known as the "abort gap." This region needs to be kept empty to ensure safe beam dumps. The AGM captures the synchrotron light generated in the visible part of the spectra and converts it into an electric signal. This signal is then processed by an acquisition system and can trigger the ‘abort gap cleaning’ process. The current AGM, which has been in operation since 2010, uses an analogue integrator ASIC and a 40 MHz analogue-to-digital (ADC) converter to provide the particle population information. However, this solution is now considered obsolete and is being replaced by a digital signal processing approach. Working directly in the digital domain not only offers more scalability but also better determinism and reliability. This work presents the new technical solution for the acquisition chain, compares the characteristics of both implementations, and showcases recent measurements conducted on the LHC ion beams.
Paper: TUPR78
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR78
About: Received: 11 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPS01
Study of longitudinal effects during transition crossing of the EIC hadron storage ring
1622
The Electron Ion Collider (EIC) Hadron Storage Ring (HSR) will accelerate all species except protons through transition to the desired storage energy. The effects at transition may cause unwanted emittance blowup beam loss due to bunch area mismatch and negative mass instability. In this paper, we will show the longitudinal dynamics of transition crossing in the HSR with current parameters using the accelerator code Beam Longitudinal Dynamics (BLonD).
Paper: TUPS01
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS01
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPS16
An overview of the proton storage ring upgrade at LANSCE
1669
The Los Alamos Neutron Science Center (LANSCE) is one of the oldest operating high-average-power accelerators in the United States, having recently celebrated its 50th anniversary of operation. LANSCE is comprised of an 800-MeV linac capable of concurrently accelerating both H+ and H- ions, and can presently provide beam to six separate user stations. The Proton Storage Ring (PSR) at LANSCE acts as a pulse-stacker, providing intense bunches of protons to the Lujan neutron scattering center target. Critical subsystems have become increasingly difficult to maintain due to spare parts availability; more generally, the PSR contributes significantly to our annual maintenance duration due to beam spill and component activation. The proposed LAMP project would extend the operating lifetime and improve the operational characteristics of the PSR via increasing the physical aperture by 50%; modernizing and improving the performance of the RF buncher system, extraction kickers and impedance inserts; and updating the injection line and stripper foil system for reduced injection losses and improved maintainability. This paper provides an overview of the PSR portion of LAMP.
Paper: TUPS16
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS16
About: Received: 08 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPS17
Longitudinal phase space measurements at MedAustron
1673
MedAustron is an ion therapy facility located in Wiener Neustadt, Austria, which uses third order resonant slow extraction to deliver protons and carbon ions for clinical irradiation. The foreseen upgrade of the new low level RF (LLRF) system facilitates advanced longitudinal beam manipulation schemes involving multiple RF harmonics, which will be exploited to improve the slow extraction process and the consequent spill characteristics. To support these studies and provide a new diagnostic tool longitudinal tomography is being implemented. This proceeding presents the employed measurement set-ups and compares the first obtained tomographic reconstructions with BLonD simulations.
Paper: TUPS17
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS17
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPS20
Final cooling with thick wedges for a muon collider
1684
In the final cooling stages for a muon collider, the transverse emittances are reduced while the longitudinal emittance is allowed to increase. In previous studies, Final 4-D cooling used absorbers within very high field solenoids to cool low-momentum muons. Simulations of the systems did not reach the desired cooling design goals. In this study, we develop and optimize a different conceptual design for the final 4D cooling channel, which is based on using dense wedge absorbers. We used G4Beamline to simulate the channel and Python to generate and analyze particle distributions. We optimized the design parameters of the cooling channel and produced conceptual designs (corresponding to possible starting points for the input beam) which achieve transverse cooling in both x and y by a factor of ~3.5. These channels achieve a lower transverse and longitudinal emittance than the best design previously published.
Paper: TUPS20
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS20
About: Received: 13 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPS26
Future directions for RF buncher at LANSCE proton storage ring
1687
Los Alamos Neutron Science Center (LANSCE) is designing a Proton Storage Ring (PSR) refurbishment as part of the proposed LAMP project. An important component of this is the ring RF bunching system at h=1 for one circulating bunch. It has operated with high availability since an upgrade was installed in 1999 to raise the gap voltage*. A second RF system at h=2 is planned to improve the bunching factor, reducing the peak beam current at the center of the bunch resulting from space charge forces, helping mitigate effects of electron cloud and leaving an avenue for circulating two bunches in the future. The unique low output impedance RF system for h=1 is based on a cathode follower configuration using push-pull triode vacuum tubes. This feature provides automatic beam loading compensation without active feedback or feedforward systems. The triodes are no longer produced, and suitable replacements are unavailable. The ferrite rings of the h=1 system are also obsolete. Our goals include determining a suitable replacement amplifier configuration that can work on either frequency, and developing a replacement resonator for each harmonic that uses current production ferrite material.
Paper: TUPS26
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS26
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPS32
Intensity reach of the barrier-bucket multi-turn transfer for fixed-target proton beam from PS to SPS
1710
Fixed target beams are extracted in five turns from the Proton Synchrotron (PS) at CERN to fill almost half the circumference of the Super Proton Synchrotron (SPS) with each transfer. To avoid beam loss during the risetime of the extraction kickers a longitudinal gap is generated with an RF barrier-bucket scheme. However, the synchronization of the gap with the PS extraction and SPS injection kickers requires the RF system to operate without any beam feedback during the transverse splitting process at the flat-top. Low RF voltage is moreover required during the process to keep a small momentum spread. Both conditions are unfavorable for longitudinal stability and a campaign of beam measurements has been performed to explore potential intensity limitations. Up to 3.3e+13 protons have been accelerated and remained longitudinally stable at high energy. Longitudinal coupled-bunch instabilities occurring at the intermediate plateau below transition energy are moreover cured by a dipole-mode feedback system initially developed for LHC-type beams. The contribution summarizes the results of the beam tests, probing the limits of the fixed-target proton beam production.
Paper: TUPS32
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS32
About: Received: 01 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
TUPS53
Optimization of AGS bunch merging with reinforcement learning
1782
The RHIC heavy ion program relies on a series of RF bunch merge gymnastics to combine individual source pulses into bunches of suitable intensity. Intensity and emittance preservation during these gymnastics require careful setup of the voltages and phases of RF cavities operating at several different harmonic numbers. The optimum setting tends to drift over time, degrading performance and requiring operator attention to correct. We describe a reinforcement learning approach to learning and maintaining an optimum configuration, accounting for the relevant RF parameters and external perturbations (e.g., a changing main dipole field) using a physics-based simulator at Brookhaven Alternating Gradient Synchrotron (AGS).
Paper: TUPS53
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS53
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
TUPS56
Machine learning-based extraction of longitudinal beam parameters in the LHC
1794
Accurate knowledge of beam parameters is essential for optimizing the performance of particle accelerators like the Large Hadron Collider (LHC). An initial machine-learning (ML) model for the reconstruction of the longitudinal distribution has been extended to extract the main parameters of multiple bunches at LHC injection. The extended model utilizes an encoder-decoder architecture to analyze sets of longitudinal profile measurements. Its development was partially driven by the need of a real-time beam energy error estimate, which was not directly available in the past. The derived beam parameters moreover include injection phase error, bunch length and intensity in the LHC, as well as the RF voltages at extraction from the Super Proton Synchrotron (SPS) and at capture in the LHC. In this paper, we compare the results of the ML model with conventional measurements of bunch length and energy error, from the beam quality monitor (BQM) and the orbit acquisition system, respectively. These benchmarks demonstrate the potential of applying the ML model for operational exploitation in LHC.
Paper: TUPS56
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS56
About: Received: 10 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
TUPS61
Preliminary results on the reinforcement learning-based control of the microbunching instability
1808
Reinforcement Learning (RL) has demonstrated its effectiveness in solving control problems in particle accelerators. A challenging application is the control of the microbunching instability (MBI) in synchrotron light sources. Here the interaction of an electron bunch with its emitted coherent synchrotron radiation leads to complex non-linear dynamics and pronounced fluctuations. Addressing the control of intricate dynamics necessitates meeting stringent microsecond-level real-time constraints. To achieve this, RL algorithms must be deployed on a high-performance electronics platform. The KINGFISHER system, utilizing the AMD-Xilinx Versal family of heterogeneous computing devices, has been specifically designed at KIT to tackle these demanding conditions. The system implements an experience accumulator architecture to perform online learning purely through interaction with the accelerator while still satisfying strong real-time constraints. The preliminary results of this innovative control paradigm at the Karlsruhe Research Accelerator (KARA) will be presented. Notably, this represents the first experimental attempt to control the MBI with RL using online training only.
Paper: TUPS61
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS61
About: Received: 14 May 2024 — Revised: 29 May 2024 — Accepted: 29 May 2024 — Issue date: 01 Jul 2024
TUPS84
PIP-II laser beam profile monitor laser system
1869
Fermilab is currently engaged in the development of an 800 MeV superconducting RF linac, aiming to replace its existing 400 MeV normal conducting linac. PIP-II is a warm front-end producing 2 mA of 2.1 MeV H-, followed by a sequence of superconducting RF cryomodules leading to 800 MeV. To mitigate potential damage to the superconducting RF cavities, PIP-II uses laser-based monitors for beam profiling via photoionization. This abstract provides an update on the project’s beam profiling, focusing on advancements made since the initial prototype. The prototype profile monitor featured a high-repetition-rate, low-power fiber laser and fiber optic transport that was tested with a 2.1 MeV H- beam at the PIP-II Injector Test (PIP2IT) accelerator. Since then, the fiber laser and fiber transport have been upgraded to a diode laser based system and free-space optical transport. This highlights a significant evolution in the laser system, enhancing its efficiency and adaptability. This paper will focus on an alternative laser system for the transverse beam measurements. The new system will use a variable pulse-width drive laser system via gain-switching, and the newly implemented free-space propagated optical beam
Paper: TUPS84
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS84
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEBD3
Technologies and concepts for the next generation of heavy ion synchrotrons
1919
New technical approaches are under investigation to further push the intensity frontier of the next generation heavy ion synchrotrons. Residual gas dynamics and corresponding charge exchange processes are key issues which need to be overcome by means of advanced UHV system technologies, but also by a focused design of the synchrotron as a whole. Cryogenics and superconductivity enable high field operation but in synergy also enable technologies for stabilizing the dynamic vacuum. Beam loss usually implicated as driver for activation and damages is as well an important initiator for residual gas pressure dynamics. Advanced superconducting cables promise lower energy consumption, fast ramping and higher average beam intensities. The cryo-pumping properties of specially developed cryogenic inserts, can also be used to upgrade existing synchrotrons and enable operation with lower charge states and higher intensities. The advancement of laser technologies may be applied as new devices in heavy ion synchrotrons for advanced manipulations, e.g. non-liouville injection or laser cooling. With FAIR, GSI has expanded its competence for the design of novel high intensity heavy ion synchrotrons.
Paper: WEBD3
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEBD3
About: Received: 04 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEZD1
Status of SuperKEKB and experience with nonlinear collimation
1923
An update on SuperKEKB status will be presented including an overview of performance limitations and experience with nonlinear collimation.
Paper: WEZD1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEZD1
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEZD2
The electron cloud and its impact on LHC and future colliders
1928
The secondary emission of electrons and their interaction with the electromagnetic fields of charged particle beams can lead to the build-up of electron clouds in accelerator beam chambers. The interaction of the electrons with both the beam and the chamber walls leads to detrimental effects, such as transverse instabilities and emittance growth, beam loss, pressure rise and heat load. Such effects are systematically observed in the Large Hadron Collider (LHC) during operation with proton beams with the nominal bunch spacing of 25 ns. Furthermore, the severity of electron cloud effects has increased after each long shutdown period of the machine, due to a degradation of the beam screen surfaces with air-exposure. Consequently, electron cloud is already limiting the total intensity in the collider and is one of the main concerns for the performance of the HL-LHC upgrade. In this contribution, the present understanding of electron cloud in hadron accelerators is reviewed. Measurements and observations at the LHC are presented, the impact on performance is evaluated and mitigation measures are discussed along with lessons for future machines.
Paper: WEZD2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEZD2
About: Received: 15 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
WEPC03
Bubble-beam accelerators: breaking the paradigm
1957
Most particle accelerators utilize beams with a charge density concentrated in the center of the bunch in real 3-dimensional space and the 6-dimensional phase space. In this work, by enhancing the space-charge forces in the photo-cathode injector of the Compact Linear Electron Accelerator for Research (CLEAR) at CERN, we produce electron bunches with a “bubble-like” shape, with a charge density mostly concentrated on the outside shell. We demonstrate that the dynamics of such beams can be tailored to achieve stable uniformity in the coordinate and momentum transverse planes simultaneously. This would allow reaching a uniform dose distribution without a severe loss of particles which is of the great interest in the irradiation community. Additionally, we investigate the potential benefits of bubble-beams across several accelerator pillars: for driving light sources, for advanced acceleration technologies, and for particle colliders.
Paper: WEPC03
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC03
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPC04
Beam dynamics modelling of the SLS linear accelerator
1961
The storage ring from the SLS is currently in the process of a significant upgrade to a new multi-bend achromat that aims to improve the performance of the machine by allowing it to deliver even brighter beams to the beamlines. The linear accelerator of the SLS is an ageing piece of infrastructure that needs to continue to run for the few decades to continue to feed SLS 2.0 reliably. In this work, we investigate potential upgrades to the linac with the aim of reducing the overall complexity of the system.
Paper: WEPC04
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC04
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC06
Characterisation and optimisation of a C-band photo-injector for compact light sources
1968
We performed an optimisation study of a C-band photoinjector for high-charge electron beams. Such a device is capable of producing high brightness electron beams, with low energy spread and small transverse emittance, which are properties required by Inverse Compton Scattering radiation sources and compact light sources in general. This work aimed to carry out, via numerical simulations, optimisation and benchmark results of the beam generated by such photoinjector, in the pursuit of its real application in the context of current projects, namely EuPRAXIA@SPARC_LAB, and proposals such as BoCXS at the University of Bologna.
Paper: WEPC06
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC06
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC12
Low-emittance beam generation at Argonne Wakefield Accelerator’s upgraded drive-beam photoinjector
1975
The Argonne Wakefield Accelerator (AWA) facility’s main beamline -- the drive-beam linac -- can produce electron bunches over a wide range of charges (100 pC up to 100 nC). A planned upgrade of the beamline includes the installation of a symmetrized RF gun and linac cavities with the ultimate goal of improving beam brightness. Simulations were done to explore the performance of the upgraded photoinjector to produce very low-emittance beams in conjunction with low mean-transverse-energy photocathodes. Additionally, selective collimation is also explored to further increase the beam brightness. An experiment to validate the devised operational modes will be discussed along with preliminary results on diagnostics tests.
Paper: WEPC12
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC12
About: Received: 25 May 2024 — Revised: 27 May 2024 — Accepted: 28 May 2024 — Issue date: 01 Jul 2024
WEPC14
A new rf design of the two-mode transverse deflecting structure
1983
SSRF (Shanghai Synchrotron Radiation Facili-ty)/SXFEL (Shanghai Soft X-ray FEL) Facility has de-veloped an advanced variable polarization transverse deflecting structure TTDS (two-mode transverse deflect-ing structure) to perform variable polarization based on the design of a dual-mode RF structure. The 15-cell prototype of the TTDS was fabricated at SSRF/SXFEL. Because the two modes operate in the same structure, any geometric change will affect both modes. A new RF design of the regular cell is proposed to improve rf per-formance. The two modes are coupled independently in two pairs of side coupling holes. The work presented in this paper is focused on the new design and the rf param-eters compared with the initial design.
Paper: WEPC14
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC14
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPC18
Commissioning an S-band hybrid photocathode gun in Mithra laboratory at UCLA
1996
In Mithra Laboratory at UCLA, we are commissioning an S-band Hybrid gun which has a photocathode RF gun and a traveling-wave velocity buncher section contained in one integrated structure. To analyze its performance, we have measured the beam energy at various launch phases and the cavity temperatures. The beam charge was observed up to 200 pC, and emittance and bunch length measurements are now underway. We will report the detailed results of this experimental campaign, and plans for the near future.
Paper: WEPC18
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC18
About: Received: 18 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPC22
Recent studies on high current operation at the compact ERL
2010
The compact ERL (cERL) is operated at mid-energy region around 17 MeV for beam studies on industrial applications since 2017. Toward the future high power FEL source for EUV lithography, high current beam operation was demonstrated at low bunch charge after install of undulators as a first step. It is critical to reduce beam loss not to exceed 20 uSv/h outside the shield wall of the cERL acceleration room, however, it can increase especially at the arc sections, the undulators, and superconducting cavities for decelerating. Therefore, 16 high-speed loss monitors are located along the whole beam line as the machine protection system. Recently, machine learning is applied for beam tuning to reduce all loss monitor signal. In addition, we tried the energy recovery operation while undulator light is amplified at a high bunch charge around 60 pC.
Paper: WEPC22
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC22
About: Received: 13 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC24
Optimization of bunch charge distribution for space charge emittance growth compensation in the PERLE injector
2018
Low energy electron bunches experience emittance growth due to space charge. This effect can lead to large emittances which are unacceptable for a facility like PERLE at IJCLab. PERLE will be an ERL test facility circulating a high current electron beam. The traditional method to reduce emittance due to this effect is already planned for the PERLE injector, this has a limit of how small the emittance can be reduced to. This limit is defined by the quality of the bunch as it is upon production at the cathode. The transverse and longitudinal properties of the laser pulse incident on the cathode defines some characteristics of the bunch, to which the space charge effect is related. In addition, the complex evolution of the bunch along the injector could result in optimal laser parameters which are different from the simple flattop distribution currently simulated. Presented here are simulation-based studies of the bunch charge distribution at the cathode and its subsequent evolution along the injector. An optimization of the laser parameters which create the bunch is also performed. We find that there is an optimal bunch charge shape which corresponds to minimal emittance growth.
Paper: WEPC24
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC24
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPC25
Optimisation of the PERLE injector using a multi-objective genetic algorithm
2022
The PERLE (Powerful Energy Recovery Linac for Experiments) project requires an injector capable of delivering a beam current of 20 mA at a total beam energy of 7 MeV with 500 pC bunches. These requirements present challenges for achieving the high quality beam required for the main ERL loop. At low energy and high bunch charge, the electron bunches will predominantly experience emittance growth due to the space charge effects. The compensation of this emittance growth will be performed with the traditional method of two solenoids a single bunching cavity and a linac to reach the intended injection energy. Additionally, the control of longitudinal and transverse bunch size must be performed to meet the requirements at the end of the injector. For stable operation of PERLE a rms bunch length of < 3 mm is required, with transverse emittances < 6 mm·mrad and acceptable transverse size. Presented here is the re-optimization of the injector settings used during commissioning for two alternative DC photoguns. It is found that the former cathode does not perform to the standard of previous optimizations. However, a newly procured cathode when optimized can meet the requirements for PERLE.
Paper: WEPC25
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC25
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPC49
Simulation of electron beams from the ELBE superconducting RF gun for ultrafast electron diffraction experiments
2072
Moving towards beam energies around 2-6 MeV in ultrafast electron diffraction (UED) experiments allows achievement of larger coherence length for better *k*-space resolution, while the temporal resolution is improved when shorter electron bunches are generated and the velocity mismatch between the optical pump and UED probe is reduced. At Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a series of superconducting cw RF (SRF) guns has been designed, build, and tested, with the latest version currently in routine operation as one of the electron sources for the ELBE Center for High Power Radiation. This SRF photoinjector produces bunches with a few-MeV energies at up to MHz repetition rates, making it a suitable electron source also for MeV-UED experiments. The high repetition rate provides a significant advantage for the characterization of samples with low scattering cross-sections such as liquids and gases. In this paper, we outline the conceptual MeV-UED instrument program under development at HZDR. We also showcase the beam quality achieved in first simulations of the ELBE SRF gun operating at low bunch charge as an electron source for diffraction experiments.
Paper: WEPC49
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC49
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPC68
Application of a reduced phase velocity high brightness photogun for MeV ultrafast electron diffraction
2129
MeV ultrafast electron diffraction has become a new frontier for the study of molecular dynamics. With the temporal resolution of MeV-UED being limited by the electron bunch length at the target, electron sources used for this technique are becoming ever more intricate in the the push for shorter bunches length. However, moving to these complex setups makes them less feasible in a small-scale setting, such as universities, where keV-UED setups have become common place. In this paper, we use a novel travelling-wave RF photogun without any additional bunch compressor to generate ultra-short electron pulses whose lengths rival that of the most intricate magnetic or ballistic compression schemes. The broadband nature of the TW device allows for unique operation schemes that combines significant acceleration and compression all within the TW photogun. Such a device, when combined with state-of-the-art synchronization systems and lasers will be demonstrated to cross the so-called ‘50-fs time-resolution barrier’ and push towards the femtosecond regime.
Paper: WEPC68
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC68
About: Received: 03 Jun 2024 — Revised: 03 Jun 2024 — Accepted: 03 Jun 2024 — Issue date: 01 Jul 2024
WEPC74
Dark current studies for a SW C-band electron gun with a deflector
2144
To generate the very high brightness beams in light sources, injectors based on radiofrequency photo-guns with very high peak electric fields on the cathode are used. However, this very high surface electric field on the surface of a radio frequency cavity leads to the generation of dark current due to the field emission effect which can damage the instrumentation and radio-activate components. Consequently, it is important to reduce the emission of these electrons and evaluate the subsequent transportation. In this paper, the deflector has been innovatively positioned at the exit of the photo-gun so as to reduce the dark current as much as possible. The dark current emission and spectrum of the dark current of the C-band electron gun have been evaluated by Particle-In-Cell simulations. The dark current before the accelerating sections has been captured and observed both with and without the deflector.
Paper: WEPC74
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC74
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG01
Beam position monitoring system and beam commissioning at APS-U storage ring
2170
Advanced Photon Source Upgrade (APS-U) storage ring, currently in installation and testing, is set for beam commissioning in early 2024. In the APS-U storage ring, there are 560 Beam Position Monitor (BPM) pickups, each equipped with high resolution electronics. This paper presents outcomes from pre-beam testing and beam commissioning of the APS-U BPM system. We discuss tailored features for advanced beam measurements, testing methodologies, challenges, and successful integration into the storage ring. Our findings demonstrate the robustness of the BPM system, emphasizing its crucial role in achieving the first beam and optimizing the APS-U storage ring's performance.
Paper: WEPG01
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG01
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPG08
NSLS-II bunch by bunch BPM development and beam operation
2191
The Radio Frequency System-on-Chip (RFSoC) FPGA-based high-performance bunch-by-bunch beam position monitor (BxB BPM) was developed and commissioned at NSLS-II. The new BxB BPM features a 14-bit 5 Gsps ADC, directly sampling 2 ns four-button signals, and digital signal processing with a synchronized 500 MHz RF reference clock. The BxB BPM provides 32 K points of ADC raw data, 5 K turns for up to 1320 bunch amplitude and position data, 2.6 million turn-by-turn (TxT) data points, 10 K turns of circular buffer, and 10 Hz streaming data. The potential applications include, but are not limited to measuring injection transient, efficiency, ion instability detection, and single/multi-bunch motion analysis. A ~15 μm single-bunch resolution was confirmed with the beam test. This paper will present the beam test results, hardware FPGA firmware architecture, and control system interface for operation.
Paper: WEPG08
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG08
About: Received: 17 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPG10
Design of the cryogenic BPM pick-up for the EIC hadron storage ring
2199
Designing the cryogenic BPM pick-up for the Hadron Storage Ring (HSR) of the Electron-Ion Collider (EIC) is a challenging task as it needs to provide reliable beam position measurements over a variety of beam species and operating modes with various energies. The existing RHIC BPM stripline pick-up are not compatible with the planned HSR beam parameters as the HSR beam, compared to RHIC, will have a factor of 10 shorter bunch length (to 6 cm rms), a factor of 3 more currents (0.69 Amps, with 290 bunches), and will have a large radial offset (±20 mm) to adjust the path length for different beam energies. The BPM pick-up design takes into consideration the potential elevated heating concerns caused by resistive wall loss due to radial beam offset and heat conduction through cryogenic BPM signal cables. The geometric impedance associated with the button configuration and housing transition to the adjacent HSR beam screen must also be minimized. This paper focuses on the design of the HSR cryogenic BPM pick-up and describes simulation results of the position-related voltage signals, and beam-induced losses on the metallic BPM buttons due to the radial offsets.
Paper: WEPG10
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG10
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG14
Detailed simulation study of wakefield induced beam dynamics in the dielectric dechirper at CLARA
2210
Minimising the energy spread within the electron bunch is essential for optimal performance of free electron lasers. Wakefields from corrugated and dielectric structures have been demonstrated to be effective in bunch dechirping. However, the repercussions in beam quality are not yet well understood. Here, a dielectric wakefield structure, manufactured to be included at the CLARA facility, has been studied with simulations. It consists of two planar and orthogonally oriented dielectric waveguides with an adjustable dielectric gap. This structure allows the longitudinal wakefield to compensate the energy spread whilst controlling the undesirable effect of the transverse wakefields on the beam quality. Simulations have been performed at different bunch lengths, bunch energy spreads and dielectric gaps to allow a better understanding of longitudinal and transverse wakefields beam effects within the dechirper.
Paper: WEPG14
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG14
About: Received: 10 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPG15
Passive longitudinal bunch diagnostics with a dielectric Wakefield streaker at CLARA
2214
Passive streaking devices have been proposed and developed at several facilities worldwide, providing a flexible and cost-effective longitudinal bunch profile diagnostic. A passive streaker, using wakefields excited in dielectric lined waveguides, is planned to be installed in the FEBE experimental chamber at CLARA Phase-2. We present experimental tests of bunch reconstruction performed during dielectric wakefield acceleration experiments at Phase-1 of CLARA, with 100 pC, 35 MeV electron beams. These profiles have been compared to simulated beam profiles, produced using S2E simulation codes Elegant and ASTRA. Conclusions have been drawn on the operation of passive streakers, applicable to the design and operation of the future streaker at CLARA.
Paper: WEPG15
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG15
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG17
Design of a non-invasive bunch length monitor using coherent synchrotron radiation simulations
2222
Synchrotron radiation (SR) is a phenomena found in most accelerator facilities. Whilst many look to reduce the amount of SR produced to minimize beam losses, its existence allows for several types of novel non-invasive beam instrumentation. The aim of this study is to use SR in the development of a non-invasive, high resolution, longitudinal bunch length monitor. The monitor will be capable of sub 100 fs bunch measurements, which are becoming more common in novel acceleration and free electron laser facilities. This contribution details the simulation work carried out in Synchrotron Radiation Workshop (SRW), which allows for complex studies into the production and features of coherent synchrotron radiation (CSR). The design of the monitor has also been discussed, alongside simulations of the planned optical setup performed in Zemax OpticStudio (ZOS).
Paper: WEPG17
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG17
About: Received: 08 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPG23
High-resolution bunch profile measurements for enhanced longitudinal beam diagnostics
2244
Efficient operation of the Large Hadron Collider (LHC) relies on accurate longitudinal beam measurements to diagnose beam instabilities and verify the correctness of bunch-shaping techniques. To achieve this goal, a diagnostic system was developed to perform high-resolution measurements of longitudinal bunch profiles. High-performance oscilloscopes, synchronized to precise accelerator events, are employed to carry out the measurements, acquiring data from wideband wall-current monitors installed in the machine. This paper provides details on the implementation of the system, highlighting its current and future applications that will play a key role in increasing beam intensity in the LHC.
Paper: WEPG23
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG23
About: Received: 02 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPG26
Overview of beam intensity issues and mitigations in the CERN-SPS fast wire scanners
2248
A new design of fast wire scanner was installed in the CERN injector complex as part of the upgrades linked to the High-Luminosity LHC Project. Initial operations with these beams were good, but during the planned intensity ramp-up one early 2023, all four SPS scanners failed at the same time. An urgent program was put in place to understand and address this failure with experts from across the accelerator fields. Many measurements and simulations were performed and solutions implemented. This paper gives an overview of the issues seen, understanding and mitigations put in place to allow the instrument to perform at the maximum planned operational intensities.
Paper: WEPG26
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG26
About: Received: 13 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG27
Real-time processing of longitudinal Schottky signals in CERN’s antiproton chain
2252
A low-latency, real-time diagnostic system for the analysis of longitudinal Schottky signals in CERN’s antiproton chain has been developed. The system, installed in CERN’s Antiproton Decelerator (AD), processes the combined output of two low-noise, wideband AC beam transformers. It uses a GPU and the NVIDIA CUDA Toolkit, exploiting the directly sampled data and hardware features provided by the low-level radio-frequency (LLRF) VMEBus Switched Serial (VXS) system and its companion ObsBox server, to implement the FFT-based multi-harmonic spectral analysis needed to set up and monitor the stochastic and electron cooling processes. Longitudinal beam properties, such as mean momentum and momentum spread, are also derived to evaluate and log the machine performance. This paper describes the implementation of the system and its integration within the CERN control system, achieved using the Front-End Software Architecture (FESA) framework and a graphics co-processor directly installed in the Front-End computer (FEC), running a real-time operating system environment. Preliminary results of its usage in the Extra Low ENergy Antiproton (ELENA) ring and next steps to process bunched beam spectra are also presented.
Paper: WEPG27
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG27
About: Received: 02 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPG28
Emittance and luminosity monitoring and modelling for LHC Run 3
2256
A comprehensive model accurately depicts and tracks emittance and luminosity evolution in the Large Hadron Collider (LHC), considering known effects like IBS, synchrotron radiation damping, coupling and incorporating data-driven factors on emittance growth and intensity losses. Used extensively in LHC Run 2, the model is updated for compatibility with new optics and operational schemes in Run 3, featuring luminosity leveling. This paper discusses the analysis of 2022 and 2023 LHC data, exploring emittance evolution and identifying extra blow-up at injection and collision energies compared to model predictions. Examining the model's agreement with collision data provides insights into the impact of degradation mechanisms, configuration options, filling schemes, and beam types on delivered luminosity. These studies offer valuable insights into potential gains in integrated luminosity for subsequent Run 3 years.
Paper: WEPG28
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG28
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG29
Impedance and thermal studies of the CERN SPS wire scanners and mitigation of wire heating
2260
All wires of the four CERN SPS rotational wirescanners broke when increasing the beam intensity towards the target for the LHC Injector Upgrade in 2023. Impedance and thermal studies were immediately launched, with simulations and measurements indicating that beam induced heating from resonant modes on the thin wire could be sufficient to cause these breakages. Mitigation measures to displace electromagnetic losses away from the wire were proposed and implemented. This allowed a much higher beam intensity to be reached, close to the LIU target. Simulations now predict that the modified wirescanners can sustain the LIU beam parameters.
Paper: WEPG29
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG29
About: Received: 13 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG30
Impact of second-order chromaticity on the Schottky spectra of bunched beam
2264
Observation of Schottky signals provides information on important beam and machine parameters, such as transverse emittance, betatron tune, and first-order chromaticity. However, the so-far developed theory of Schottky spectra does not include the impact of the higher-order chromaticity, known to be non-negligible in the case of the Large Hadron Collider (LHC). In this contribution, we expand the theory of Schottky spectra to also take into account second-order chromaticity. Analytical results are compared with macro-particle simulations and the errors resulting from neglecting second-order chromaticity are assessed for the case of the LHC.
Paper: WEPG30
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG30
About: Received: 10 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPG31
Experimental and simulated LHC Schottky spectra
2268
Schottky monitors are valuable non-invasive tools used for beam diagnostics, providing insights into crucial bunch characteristics such as tune, chromaticity, bunch profile, or synchrotron frequency distribution. This study investigates Schottky spectra at the Large Hadron Collider (LHC) through a combination of simulations and measurements. Experimental data from lead ion bunches are compared with simulated spectra derived from time-domain, macro-particle simulations. In particular, amplitude detuning due to the octupole magnets, known to influence the Schottky spectra, is incorporated into the simulations. These simulations are performed for various octupoles currents with the goal of better understanding the interplay between octupoles and the Schottky spectrum. Finally, measured spectra are compared to simulations performed using the best available knowledge of the parameters impacting the spectra.
Paper: WEPG31
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG31
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPG32
Impact of octupoles on the Schottky spectra of bunched beams
2272
Schottky monitors serve as non-invasive tools for beam diagnostics, providing insights into crucial bunch characteristics such as tune, chromaticity, bunch profile, or synchrotron frequency distribution. However, octupole magnets commonly used in circular storage rings to mitigate instabilities through the Landau damping mechanism, can significantly affect the Schottky spectrum. Due to the amplitude-dependent incoherent tune shift of individual particles, the satellites of the Schottky spectrum are smeared out as the octupolar field increases. This study investigates the impact of octupoles and their incorporation into theory, with the goal of improving beam and machine parameter evaluation from measured spectra. Theoretical findings are validated through macro-particle simulations conducted across a range of octupole strengths, encompassing typical operational conditions at the Large Hadron Collider.
Paper: WEPG32
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG32
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPG34
Time-interleaved-sampling for high bandwidth BPM signals
2280
BPM signal processing uses digital or analog down-conversion to report phase and magnitude at a single frequency, however the digitized BPM signal may contain many more harmonics and a larger bandwidth of information which may be useful. An FPGA implementation is described which captures the full bandwidth BPM signal with minimal processing and resources. This approach can be scaled to captures as many beam harmonics as needed, limited only by the bandwidth of the ADC used. The periodic nature of the BPM signal is utilized to use time-interleaved sampling to effectively multiply the sampling rate of the ADC.
Paper: WEPG34
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG34
About: Received: 16 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG43
Design of a 3-cell rectangular deflecting cavity for a compact THz-FEL
2315
Bunch length is an important parameter for free-electron laser (FEL). The deflecting RF cavity was used in the beam length diagnostic instrument. In this paper, we present the design of a 3-cell rectangular deflecting RF cavity for a compact terahertz (THz) free-electron laser (FEL) facility. The 3-cell deflecting cavity has a residual orbit offset of zero as compared to single-cell deflecting cavity. Rectangular deflecting cavity does not need to lock the dipole polarisation direction as compared to cylindrical cavity. The time resolution of the measurement system can reach 500 fs. In this paper, the cavity design is carried out using CST and the results of cavity analysis are presented. Particle tracking is performed with the Astra code and the space charge effect is taken into account.
Paper: WEPG43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG43
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG49
Beam studies using a Cherenkov diffraction based beam position monitor for AWAKE
2327
A beam position monitor based on Cherenkov diffraction radiation (ChDR) is being investigated as a way to disentangle the signals generated by the electromagnetic fields of a short-pulse electron bunch from a long proton bunch co-propagating in the AWAKE plasma acceleration experiment at CERN. These ChDR BPMs have undergone renewed testing under a variety of beam conditions with proton and electron bunches in the AWAKE common beamline, at 3 different frequency ranges between 20-110 GHz to quantify the effectiveness of discriminating the electron beam position with and without proton bunches present. These results indicate an increased sensitivity to the electron beam position in the highest frequency bands. Furthermore, high frequency studies investigating the proton bunch spectrum show that a much higher frequency regime is needed to exclude the proton signal than previously expected.
Paper: WEPG49
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG49
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG51
Resonant spin depolarization at the test facility KARA: overview of recent efforts
2335
The Karlsruhe research accelerator KARA offers a setup to measure the beam energy with resonant spin depolarization. The depolarization is excited by the stripline kickers of the bunch-by-bunch feedback system and the resonant frequency is measured via change in Touschek lifetime. Energy measurements with resonant spin depolarization are implemented as a standard routine in the control system and are used regularly to measure both the beam energy and the momentum compaction factor for different energies and optics regimes. Long-time experience with the setup, short polarization time, and variation options of beam energy in combination with much available beam time qualify KARA as a test facility for systematic studies. Such studies are of particular interest for future colliders designed for precision studies like FCC-ee, as resonant spin depolarization is known for its high accuracy. This contribution presents the resonant spin depolarization setup at KARA and selected results of recent measurement campaigns.
Paper: WEPG51
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG51
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPG52
Commissioning and experiments with a compact transverse deflecting system at FLUTE
2339
A Compact Transverse Deflecting System (Compact-TDS) designed for longitudinal electron bunch diagnostics in the femtosecond regime is presently undergoing commissioning at the Karlsruhe Institute of Technology (KIT). This technique, based on THz streaking using a resonator structure, demands a high level of electron beam controllability and stability at the micrometer scale. To meet these requirements, the linear accelerator FLUTE (Ferninfrarot Linac- Und Test-Experiment) has undergone major upgrades in 2023, incorporating a new RF system equipped with a klystron, RF photoinjector and solenoid magnet. In this contribution, we present first experiments conducted with the Compact-TDS at FLUTE, utilizing the upgraded RF setup.
Paper: WEPG52
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG52
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG53
Resonator design optimization for a compact transverse-deflecting system
2343
Various design options have been studied and simulated using CST MICROWAVE STUDIO for a compact transverse-deflecting system proposed for diagnostics of extremely short electron bunches. The idea of the method is to use terahertz radiation, produced from optical rectification of the facility’s electron gun laser pulse. The proposed system is to be checked experimentally at the test facility FLUTE (Ferninfrarot Linac- und Test-Experiment) at Karlsruhe Institute of Technology (KIT). The present paper is focused on the simulations of the resonator providing interaction between the electron bunch and the terahertz pulse. Two types of resonators and their arrays have been studied for this purpose: inverse split-ring resonator and tilted slit resonator. Different types of terahertz pulse structure have been studied, including plane wave and transversely focused (Gaussian) beam. Useful analytical models have been proposed to systematize the results of the simulations.
Paper: WEPG53
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG53
About: Received: 13 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG54
Electro-optical spectral decoding of THz pulses at MHz repetition rates
2347
A far-field electro-optical (EO) setup based on a balanced detection scheme has been set up to measure the coherent synchrotron radiation (CSR) at the Karlsruhe Research Accelerator (KARA). To enable the readout with a spectrally decoded scheme (EOSD), a KALYPSO based line array camera sensitive to NIR operating at a readout rate of 2.7 MHz has been included in the set-up. In this contribution, measurement results with the KALYPSO based spectrometer in combination with a commercial THz emitter are presented.
Paper: WEPG54
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG54
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPG55
Longitudinal phase space density tomography constrained by the Vlasov-Fokker-Planck equation
2350
Understanding the evolution of complex systems with numerous interacting particles requires advanced analytical tools capable of capturing the intricate dynamics of the phase space. This study introduces a novel approach to longitudinal phase space density tomography in an electron storage ring, leveraging constraints imposed by the Vlasov-Fokker-Planck equation. The Vlasov-Fokker-Planck equation provides a comprehensive description of the evolution of density functions in phase space, accounting for both deterministic and stochastic processes. Measurements of the turn-by-turn bunch profile offer a time-dependent projection of the phase space. Observing the bunch profile evolution of charged particles in regimes characterized by a rich phase space dynamics presents a challenging inverse problem for reconstructing the phase space densities. In this work, we present a tomographic framework for reconstructing the longitudinal phase space density of an electron bunch at the Karlsruhe Research Accelerator (KARA). This framework utilizes simulated data and applies the Vlasov-Fokker-Planck equation to drive the reconstruction process.
Paper: WEPG55
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG55
About: Received: 13 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPG56
Simulations of an electro-optical in-vacuum bunch profile monitor and measurements at KARA for use in the FCC-ee
2354
The Karlsruhe Research Accelerator (KARA) is an electron storage ring for accelerator research and the synchrotron of the KIT light source at the Karlsruhe Institute of Technology (KIT). KARA features an electro-optical (EO) in-vacuum bunch profile monitor to measure the longitudinal bunch profile in single shot on a turn-by-turn basis using electro-optical spectral decoding (EOSD). A simulation procedure has been set up to evaluate its suitability as a beam instrumentation for the operation of the future electron-position collider FCC-ee. In order to assess the simulations, this contribution focuses on a comparison to EO sampling (EOS) measurements at KARA and a study on the heat load of the EO crystal due to the expected high bunch repetition rate envisioned for FCC-ee.
Paper: WEPG56
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG56
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPG59
Implementing bunch-by-bunch diagnostics at the KARA booster synchrotron
2361
In the upcoming compact STorage ring for Accelerator Research and Technology (cSTART), LPA-like electron bunches are only stored for about 100 ms, in which the equilibrium emittance will not be reached. Therefore, to measure parameters such as bunch profiles, arrival times and bunch current losses, bunch-resolved diagnostics are needed. The booster synchrotron of the KARA accelerator accepts pre-accelerated bunches from a racetrack microtron and accelerates them further over a 500 ms long energy ramp. As the KARA booster synchrotron has a similar circumference and injection energy as the cSTART storage ring, new bunch-by-bunch diagnostics developed there can be transferred to the cSTART project with minimal effort. Currently the diagnostic system of the booster is not designed for bunch-by-bunch diagnostics, thus after using the booster as a testbed for cSTART, such a system could be used permanently. At the booster synchrotron we use the picosecond sampling system KAPTURE-II to read-out a button beam position monitor and an avalanche photo diode at the synchrotron light port and compare the results with a commercial bunch-by-bunch system.
Paper: WEPG59
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG59
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPG64
The study of single bunch instability at the Taiwan Photon Source
2371
Single-bunch instability is studied at the Taiwan Photon Source both with and without bunch-by-bunch feedback (BBF). The instability thresholds are investigated at various chromaticities by increasing the bunch current until the instability occurs. BBF and chromaticity can increase the maximum stored bunch current and allow the tune to cross the unstable region. As the bunch current increase, the tune around the betatron frequency decreases and the tune around the synchrotron sideband increases. High radiation doses are detected by beam loss monitors when the bunch current exceeds 2 mA, near the unstable region, originating from synchrotron light scattered by the photon absorber. As the single bunch becomes unstable, electron beam loss occurs after the first band magnet of the straight section with the smallest vertical aperture.
Paper: WEPG64
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG64
About: Received: 13 May 2024 — Revised: 16 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPG68
Sub-femtosecond resolution electro-optical arrival-time measurement of relativistic electron bunches in a free-electron laser
2386
SwissFEL is a normal conducting linear accelerator driving two separate free-electron laser (FEL) lines – one for soft and one for hard x-rays. We report jitter and correlation measurements of two electro-optical Bunch Arrival-Time Monitors (BAMs), which use directly the pulses from a mode-locked laser oscillator. The arrival-time is encoded in the amplitude of one single reference laser pulse in a fiber coupled Mach-Zehnder modulator driven by a fast RF-transient from a button pick-up. Using the modulation slope and the laser amplitude jitter, we demonstrate <1 femtosecond resolution at 200 pC bunch charges for the BAM with a 16 mm pick-up beam pipe diameter and <10 fs at 10 pC for the BAM with 8 mm pick-up beam pipe diameter. We also report a jitter correlation measurement of two independent BAMs over 1 min at 100 Hz machine repetition rate as well as a similar correlation measurement of one single BAM station with 8 mm pick-up beam pipe diameter and having two identical high resolution channels. The measured correlations are as low as 1.3 fs rms resulting in sub-femtosecond resolution of the optical detection scheme.
Paper: WEPG68
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG68
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPG70
Beam diagnostics status for the Korea 4GSR project
2389
The Korean 4GSR project is currently under construction in Ochang, South Korea, with the aim of first beam commissioning in 2027. Designed to achieve an emittance approximately 100 times smaller than that of third-generation synchrotron radiation storage rings, the project requires the development of several high-precision beam diagnostic devices. In particular, the beam position monitor is designed to reduce longitudinal wake impedance, thereby suppressing heating and beam instability. The electronics component has also been developed using RFSOC to enable Turn by Turn data acquisition and Bunch by Bunch beam position monitoring. Additionally, a Beam Loss Monitor utilizing 100 Hz operating-rate scintillating optical fibers has been developed, and an enhanced beam profile monitor utilizing GAGG has also been created. Furthermore, the development progress of a multi-bunch energy measurement beam position monitor system for linear accelerator energy feedback will be introduced. This presentation aims to provide an overview of the current status of beam diagnostic devices developed for the 4GSR project, including details on the overall system configuration.
Paper: WEPG70
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG70
About: Received: 21 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG77
Charge measurement systems on CLARA at Daresbury laboratory
2400
CLARA is a 250 MeV electron facility at Daresbury Laboratory, which will provide short bunches between 1 and 250 pC for a variety of experiments, including novel acceleration experiments. As part of the Phase 2 upgrade new charge measurement systems have been installed. This paper presents the charge measurement systems that will be used on CLARA, as well as commissioning results without beam for some of those systems. CLARA will include a Wall Current Monitor (WCM), 3 Integrating Current Transformers (ICTs) and five Faraday cups. The ICTs are commercial systems by Bergoz, while a custom front-end has been designed for the WCM and Faraday cups, which includes calibration circuitry and switchable gain. Calibration results, including measurements of resolution, are presented for the in-house front-end design.
Paper: WEPG77
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG77
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPG78
A single shot THz spectrometer for the FEBE experimental facility
2403
After current upgrades are completed, the Compact Linear Accelerator for Research Applications (CLARA) at Daresbury Laboratory (UK) will be capable of producing femtosecond-scale electron bunches, which will be used in the full energy beam exploitation (FEBE) experimental area. CLARA will employ multiple techniques to manipulate the longitudinal beam profile, including a variable bunch compressor (VBC). Optimisation procedures for the CLARA modules must be devised, which will require longitudinal diagnostics. Previous longitudinal diagnostics used on CLARA were multi-shot, but for user experiments a single-shot diagnostic operating at the machine repetition rate of 100 Hz is needed. Here, we present a single-shot, four-channel spectrometer to measure THz coherent transition radiation (CTR) produced by electron bunches, which will be used to deduce information about the bunch profile. In the device, a set of frequency-selective elements designed at STFC RAL Space (UK) distribute specific bandwidths onto single-shot pyroelectric detectors based on earlier wideband THz diagnostics on CLARA. The frequency-selective elements have been characterised using both simulations and THz time-domain spectroscopy. A start-to-end computer model of the spectrometer was created, and simulations were performed showing that the spectrometer can be used for both sextupole tuning on the FEBE arc and optimisation of the compression of the CLARA VBC. The instrument is currently being assembled and tested, and commissioning with beam is planned for the summer of 2024.
Paper: WEPG78
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG78
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG82
Real-time measurements of the RF-path of an electro-optical bunch arrival-time monitor with integrated planar pickup structure with low-charge electron beams at ELBE
2407
Ultra-low-charge operation of free-electron lasers down to 1 pC or even lower, requires adequate diagnostics for both, the users and the operators. For the electro-optical bunch-arrival time monitor (BAM) a fundamental design update is necessary to yield single-digit fs precision with such low charges. In 2023 a vacuum sealed demonstrator for a novel pickup structure with integrated combination network on a printed circuit board (PCB) was built for operation at the free-electron laser ELBE at HZDR. Together with a new low-pi-voltage ultra-wideband traveling wave electro-optical modulator, this concept reaches an estimated theoretical jitter charge product of 9 fs pC. Proof-of-concept measurements with the pickup demonstrator were carried out at ELBE.
Paper: WEPG82
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG82
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG84
Status of the new bunch length measurement system downstream of the injector of the S-DALINAC
2415
Energy-recovery linacs provide high beam currents with lower RF power requirements compared to conventional machines while maintaining the high beam quality of a linac. The S-DALINAC is a thrice-recirculating accelerator operating at a frequency of 3 GHz that is capable of being operated as a multi-turn superconducting energy-recovery linac. Its efficiency is currently limited by the bunch length, which by now is measured using the RF zero-crossing method. In order to improve both accuracy and measurement time a new setup using a streak camera is developed. Optical transition radiation from electron bunches passing an aluminum-coated Kapton screen is used to produce light pulses that can be measured with the streak camera. An imaging system consisting of multiple mirrors is used to maintain a high temporal resolution for the measurement and to support in shielding the streak camera from harmful radiation. The device will be used at two different measurement setups downstream of the injector. The design and current status of the measurement setup will be presented.
Paper: WEPG84
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG84
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPG89
Simulations of simultaneous measurement of GHz bunches using a fast kicker
2430
First proof-of-principle steady-state microbunching (SSMB) experiment proved that SSMB has the potential to produce high average power short wavelength light. Tsinghua University has proposed a conceptual design for the future SSMB accelerator light source. A bunch train with an average current of 1 A is required in the electron injector for the future SSMB light source with a bunch spacing of 350 ps. It is essential for diagnosis to measure each bunch in the bunch train. A method of using a fast kicker to measure different bunches simultaneously is proposed in this paper. By using a fast-rising edge power supply, the kicker can give different electron bunches different kick angles, allowing different bunches to be detected on the screen simultaneously. This paper presents measurement methods for the transverse distribution, energy spread, longitudinal phase space, and emittance, along with corresponding simulation results.
Paper: WEPG89
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG89
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG94
Detailed characterization of coherent synchrotron radiation effects using generative phase space reconstruction
2442
Coherent synchrotron radiation (CSR) in linear accelerators (linacs) is detrimental to applications that require highly compressed beams, such as FELs and wakefield accelerators. However, traditional measurement techniques lack the precision to fully comprehend the intricate multi-dimensional aspects of CSR, particularly the varying rotation of transverse phase space slices along the longitudinal coordinate of the bunch. This study explores the effectiveness of our generative-model-based high-dimensional phase space reconstruction method in characterizing CSR effects at the Argonne Wakefield Accelerator Facility (AWA). We demonstrate that the reconstruction algorithm can successfully reconstruct beams that are affected by CSR.
Paper: WEPG94
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG94
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG95
Simulation of the C-band transverse deflection structure with variable polarization for super tau charm facility
2446
Transverse deflection structures (TDS) have been widely used as diagnostic devices to characterize longitudinal properties of electron bunches in a linear accelerator. However, the conventional TDS can only measure either the horizontal or the vertical slice envelopes of electron bunches. In order to give full control of the angles of the transverse streaking field inside of the TDS to characterize the projections of the beam distribution on different transverse axes, we numerically investigate an X-band TDS with variable polarization in this paper. Through variable streaking direction, the orientation of the streaking field of the TDS is adjusted to an arbitrary azimuthal angle. This helps facilitate the development of next-generation TDS for the characterization of electron bunches, such as slice emittance measurement on different planes.
Paper: WEPG95
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG95
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPR08
Electron cloud studies for DAΦNE collider and FCCee damping ring
2469
DAΦNE is a a medium energy electron-positron collider operating in the National Laboratory of INFN at Frascati, Italy. The accelerator complex consists of two rings with an approximate circumference of 97 m. High-intensity electron and positron beams circulate and collide with the center of mass energy of around 1.02 GeV. The FCCee is an ongoing lepton collider project and its current injector design includes a damping ring for emittance cooling of positron beams. The electron cloud is one the most important collective effects and can represent a bottleneck for the performances of accelerators storing particles with positive charge. Several undesired effects such as transverse instabilities, beam losses, emittance growth, energy deposition, vacuum degradation may arise due to interaction of the circulating beam with the e-cloud. The aim of this presentation is to provide e-cloud buildup simulations for the DAΦNE positron ring and the Damping Ring of FCCee. This study will also include experimental studies concerning the instabilities induced by the e-cloud exploiting the opportunity offered by the positron beam at DAΦNE.
Paper: WEPR08
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR08
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPR14
Selected advances in the accelerator design of the Future Circular Electron-Positron Collider (FCC-ee)
2493
In autumn 2023, the FCC Feasibility Study underwent a crucial “mid-term review”. We describe some accelerator performance risks for the proposed future circular electron- positron collider, FCC-ee, identified for, and during, the mid-term review. For the collider rings, these are the collective effects when running on the Z resonance – especially resistive wall, beam-beam, and electron cloud –, the beam lifetime, dynamic aperture, alignment tolerances, and beam-based alignment. For the booster, the primary concern is the vacuum system, with regard to impedance and effects of the residual gas. For the injector, the layout and the linac repetition rate are primary considerations. We discuss the various issues and report the planned mitigations.
Paper: WEPR14
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR14
About: Received: 11 May 2024 — Revised: 18 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPR16
Report on an international accelerator school - ISBA23
2500
The sixth International School on Beam dynamics and Accelerator technology (ISBA23) was held for 10 days from August 3rd to 12th, 2023 at Pohang in Korea. ISBA23 was jointly hosted by Korea Atomic Energy Reꠓsearch Institute (KAERI) and Korea Accelerator and Plasma Research Association (KAPRA). After screening 83 registrant’s resumes and letters of recommendation, 70 students from Korea, Japan, China, Taiwan, India, and Thailand were finally admitted to the school. For 10 days, 20 professional scientists from Korea, Japan, China, Taiwan, Thailand, Germany, and the USA gave 30 valuable lectures and 14 hands-on training sessions with ASTRA and ELEGANT accelerator codes. Thanks to the generous financial support from 14 sponsors, the school was successfully completed. This is the first time that ISBA has been held outside of Japan, and it is a big step toward becoming a truly international accelerator school. We report on ISBA23, which is the biggest international accelerator school in Asia.
Paper: WEPR16
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR16
About: Received: 24 May 2024 — Revised: 29 May 2024 — Accepted: 29 May 2024 — Issue date: 01 Jul 2024
WEPR17
DAFNE operation strategy for the observation of the kaonic deuterium
2504
DAFNE, the Frascati F-factory the collider where the Crab-Waist collision scheme has been implemented and successfully tested, is presently working for a physics program in the field of exotic atoms. The present scientific program foresees the study and the characterization of the never observed before kaonic deuterium. Providing a suitable data sample for such measurement requires the collider to provide the highest flux of k- meson and the lowest possible background shower on the detector. The operation strategy, and the collider setup in terms of collisions and beam dynamics are presented and discussed.
Paper: WEPR17
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR17
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPR18
The design and electromagnetic analyses of the new elements in the FCC-ee IR vacuum chamber
2508
High currents of bunched electron and positron beams plan to be used in the proposed FCC-ee collider to achieve a high luminosity. Naturally, the impedance of the interaction region of the FCC must be as small as possible. Previously, a very smooth beam pipe in the interaction region was designed, and now we add necessary elements important for the beam operation, reduced backgrounds, and assembly. Among these elements are BPMs, expansion bellows, extension of the common beam pipe, and an elliptical synchrotron radiation mask. These new elements will be analyzed to see if they increase the impedance and, then, followed by discussions how to mitigate any issue.
Paper: WEPR18
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR18
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPR19
Emittance and energy distribution reduction in the positron injector of FCC-e+e-
2512
The FCC-e+e- project foresees the realization of the most intense ever realized source of positrons providing a bunch charge of the order of 5 nC. This big number of positrons (≈3.12e+10) is produced by pair conversion following a 6 GeV electron beam bremsstrahlung on a target, and as a consequence has large divergence and energy spread. The actual design of the positron injector includes a damping ring and a bunch compressor to reduce the beam particle distributions in the longitudinal and transverse phase spaces to values appropriate for the injection in the common LINAC, which accelerates both electron and positron beams from 1.54 to 6 GeV. An energy compressor installed after the positron LINAC improves the positron acceptance in the damping ring. This contribution presents relevant aspects related to the damping of the positron beam including the evaluation of the damping ring transmission efficiency through the whole transfer line from the positron source to the common LINAC, the energy compressor, and the bunch compressor in the injection and extraction branches of the Damping Ring.
Paper: WEPR19
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR19
About: Received: 15 May 2024 — Revised: 28 May 2024 — Accepted: 28 May 2024 — Issue date: 01 Jul 2024
WEPR24
Initial design of a proton complex for the Muon Collider
2528
The proton complex is the first piece in the Muon Collider, it comprises a high power acceleration section, a compressor and a target delivery system. For the International Muon Collider Collaboration we are investigating the possibility of having a full energy 5-GeV linac followed by an accumulator and a compressor ring and finally a target delivery system. In this paper we present the initial studies for the complex and derived initial beam parameters at each interface.
Paper: WEPR24
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR24
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPR29
Update of the PLACET2 code for the low-energy acceleration stages of the muon collider
2548
This work describes improvements made to the tracking code PLACET2 to make it possible to simulate the acceleration from 250 MeV to 63 GeV in a future muon collider. This software was selected because of its unique ability to optimally simulate recirculating linacs, which are part of the proposed layout for this initial muon acceleration stage. PLACET2 has been updated to simulate non-relativistic particles and to consider particle beams of different species, charges and masses. The main changes were introduced in the longitudinal dynamics, synchrotron radiation and wakefield descriptions. In addition, the decay of particles has been added as a new feature. The changes were benchmarked in different tests against RF-Track, a code able to simulate low energy muon beams and their decay. Finally, the lattice of the 16.6 GeV arc in the initial acceleration stage of the muon collider was simulated with both PLACET2 and RF-Track, providing another test. All the results showed excellent agreement between both codes, verifying the implementation in PLACET2.
Paper: WEPR29
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR29
About: Received: 07 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPR40
Simulation of the effects of transverse feedback system on beam performance at BEPCII
2582
During the operation of BEPCII, it is found that the transverse feedback system plays an important role on the collision luminosity. In this paper, we try to simulate the effect of the transverse feedback system on beam performance and luminosity in BEPCII.
Paper: WEPR40
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR40
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPR42
Optimizing Touschek lifetime with overstretched bunch profiles in the MAX IV 1.5 GeV ring
2586
Synchrotron light sources often use higher-harmonic rf cavities for bunch lengthening to enhance Touschek lifetime. By adjusting the harmonic voltage, a flat-potential condition for the longitudinal voltage can be achieved, typically improving Touschek lifetime by 4 to 5 times. It is known that exceeding the flat-potential voltage results in double-peaked bunch profiles, referred to as overstretched conditions. Simulations suggest overstretched profiles can surpass flat-potential improvements on lifetime. In this paper we report on experimental results from the MAX IV 1.5 GeV storage ring, demonstrating a longer beam lifetime with a stable beam in overstretched conditions compared to the flat-potential case. Additionally, a remarkable agreement between measured bunch profiles using a streak camera and predictions from a semi-analytical equilibrium solver was obtained for all tested harmonic voltages.
Paper: WEPR42
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR42
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPR43
Experimental evidence of the effect of transverse Landau damping on the microbunching instability
2590
The mechanisms that drive short-range modulations in the longitudinal phase space of accelerated electron bunches, otherwise known as the microbunching instability, have undergone intensive study. The various collective interactions between charged particles within the bunch, and their environment, can degrade the quality of these bunches, eventually making them unsuitable to drive light sources such as free-electron lasers (FELs). Although the most common method for removing this instability at X-ray FELs – namely, the laser heater – has proven to be very useful in improving the performance of these facilities, alternative methods to achieve this goal are active areas of research. In this contribution, we present experimental evidence of the influence of transverse Landau damping on mitigating the microbunching instability.
Paper: WEPR43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR43
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPR45
Observation of a synchro-betatron instability in Fermilab booster
2598
In preparation for PIP2, there has been interest in running the Fermilab Booster at a higher current more indicative of the PIP2 era operation. In July 2023 an experiment was performed to study collective instabilities over the transition crossing at the Fermilab Booster. Over the transition crossing, the synchrotron tune becomes small and synchro-betatron instabilities become possible. During the experiment, an intensity threshold was observed, above which a dipole instability with losses concentrated in the tail of the bunch. These losses are consistent with the Convective Instability.
Paper: WEPR45
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR45
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPR46
Experimental designs of coherent synchrotron radiation in complex beams
2601
Coherent synchrotron radiation (CSR) is one critical beam collective effect in high-energy accelerators, which impedes the generation of high-brightness beams. The Argonne Wakefield Accelerator (AWA) facility is unique in the experimental investigation of CSR effects in complex beams, offering a large parameter space for the bunch charge and size, various bunch profiles (round and flat beams), and the capability of generating shaped bunches through both laser shaping and the emittance exchange approach. This presentation will outline planned experiments at AWA and their designs, including a CSR shielding study using a dipole chamber with a variable gap size, and the effect of CSR on the beam phase space in a laser-shaped short electron bunch. This work is part of a comprehensive study involving self-consistent CSR code development and experimental investigation. The experimental component aims to provide benchmarking with the advanced codes under development, explore the boundaries of 1/2/3D CSR effects on beam dynamics, evaluate CSR effects in complex beams, and eventually propose CSR mitigation strategies.
Paper: WEPR46
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR46
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPR49
Near-infrared noise in intense electron beams
2608
Requirements for the noise in electron beams (NEB) have recently approached the Shot-noise level in some new applications. The density fluctuations of intense beams in the near-infrared (NIR) region are being measured at the Fermilab Accelerator Science and Technology (FAST) facility. The main goal of the experiment is to accurately compare the Shot-noise model with the observations of optical transition radiation (OTR) generated by the gamma=63 electron beam transiting an Al metal surface. In addition, evidence for longitudinal-space-charge-induced microbunching for the chicane-compressed beam was obtained with coherent enhancements up to 100 in the various bandwidth-filtered NIR OTR photodiode signals. With micropulse charges up to 1 nC, the beam parameters are close to those proposed for a stage in an Electron-Ion Collider (EIC) with coherent electron cooling (CEC). In this paper we present the current progress of the NEB project and compare the low electron energy measurements with ImpactX simulations.
Paper: WEPR49
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR49
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPR55
Modelling intra-beam scattering in the LHC for longitudinal beam loss studies
2619
In the Large Hadron Collider (LHC), intra-beam scattering (IBS) is one of the main drivers of longitudinal emittance growth during the long injection plateau. With the halo of the longitudinal bunch distribution being close to the separatrix, IBS consequently drives beam losses by pushing particles outside the RF bucket at the flat-bottom. As IBS and beam losses impose a requirement on the minimum RF bucket size, this mechanism has an important impact on the RF power requirements for the High Luminosity (HL-) LHC. In this contribution, the effect of IBS is introduced in the Beam Longitudinal Dynamics (BLonD) tracking code. This numerical model is then benchmarked against analytical estimates, as well as against beam measurements performed in the LHC. The impact of IBS-driven losses on the RF power requirements is discussed through the correlation between the time spent at flat-bottom and the average bunch length, which translates into start-of-ramp losses.
Paper: WEPR55
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR55
About: Received: 02 May 2024 — Revised: 19 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPR57
Simulations of incoherent effects driven by electron clouds forming in the inner triplets of the Large Hadron Collider
2627
During Run 2 and Run 3 of the Large Hadron Collider (LHC), slow losses from electron cloud (e-cloud) effects have been systematically observed during the full duration of fills with closely-spaced proton bunches. In particular, these effects had been found to depend strongly on the crossing angle of the two beams and the value of the betatron functions in the interaction points. Due to this observation, the main cause of this effect was attributed to the non-linear forces induced by electron clouds forming in the vacuum chamber of the LHC Inner Triplet quadrupole magnets. In this contribution, electron cloud buildup simulations reveal that the induced forces depend strongly on the transverse coordinates of the beam particles, on time, as well as on the longitudinal coordinate within the Inner Triplet. Finally, non-linear maps are generated based on the buildup simulations, and the effect of these forces on the motion of the protons is simulated.
Paper: WEPR57
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR57
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPR61
Measurements of the time-structure of the current to a single injection kicker module and simulation of its effect on the transverse beam dynamics in SIS100
2642
Distortions in the SIS100 injection kicker’s pulse time-form gives rise to beam emittance increase in the horizontal plane. Particle tracking simulations of the primary beam were carried out to try to predict the emittance at the end of the injection process for the modes of operation for antiproton (p̅) and Radioactive Ion Beam (RIB) production. The RIB cycle’s beam grew to just beyond the acceptance of the slow extraction separatrix at 27 Tm. During p̅ mode with the longitudinal RF cavities set to bunch the beam at the 5th harmonic of the beam revolution frequency instead of the originally planned 10th harmonic, the beam emittance increase was considerably reduced, resulting in -at most- negligible beam loss at the halo collimator.
Paper: WEPR61
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR61
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPR62
3D beam tracking studies including intrabeam scattering
2645
Particle tracking serves as a computational technique for determining the mean field of dynamically tracked charged macroparticles of a particle beam within an accelerator. Conventional solver tend to neglect collisionality, resulting in loss of relevant information (particle and momentum redistribution). In this study, macro-particle collisions are incorporated into a 3D Poisson solver. In the previous studies, identifying close particles have been performed in a static condition (IPAC23-Macroparticle collisionality in PIC solver). The requirement to uphold energy momentum within a dynamic tracking is initiated in simple lattices and the results are presented. A comparison with analytic model of the Bjorken-Mtingwa or Conte-Martini is included to verify.
Paper: WEPR62
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR62
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPR65
ImpactX space charge modeling of high intensity linacs with mesh refinement
2656
The code ImpactX represents the next generation of the particle-in-cell code IMPACT-Z, featuring s-based symplectic tracking with 3D space charge, parallelism with GPU acceleration, adaptive mesh-refinement, modernized language features, and automated testing. While the code contains features that support the modeling of both linear and circular accelerators, we describe recent code development relevant to the modeling of high-intensity linacs (such as beam transport for the Fermilab PIP-II upgrade), with a focus on space charge benchmarking and the impact of novel code capabilities such as adaptive mesh refinement.
Paper: WEPR65
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR65
About: Received: 14 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPR71
Simulation of coupled space charge and wakefield effects for a prototype TW-gun at SwissFEL
2672
In the injector section of electron linacs, both internal space charge forces and wakefield effects influence the beam dynamics. So far, existing simulation approaches can not account for both effects simultaneously. To fill this gap, we have developed a computational method to account for both effects self-consistently*. It couples a space charge solver in the rest frame of the bunch with a wakefield solver by means of a scattered field formulation. The novelty of this approach is that it enables us to simulate the creation of wakefields throughout the emission and acceleration process. In our contribution, we present extensive studies of the coupled wakefield and space charge effects in a traveling wave electron gun under development at the Paul Scherrer Institute. Wakefields created by the multi-cell design and the transition to the beam pipe are accounted for. Hence, the respective influences of these causes for geometric wakefields on particle dynamics are compared, providing detailed insights into the coupling of wakefields on bunches at low energies. Specifically, uncorrelated energy spread and emittance are investigated which are of key interest for FEL operation.
Paper: WEPR71
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR71
About: Received: 08 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPR74
Electron cloud simulations in the Fermilab booster
2680
As part of Fermilab's Proton Improvement Plan-II (PIP-II), the Fermilab Booster synchrotron will operate at a higher intensity, increasing from 4.5×10^12 to 6.7×10^12 protons per pulse (ppp). A potential challenge for achieving high-intensity performance arises from rapid transverse instabilities induced by electron clouds (EC). This research presents electron cloud simulations using PyECLOUD, which is an advanced computational tool that incorporates measurements of the secondary electron yield (SEY) from the Booster's combined function magnet material. By systematically varying beam parameters in PyECLOUD, such as bunch structure, SEY, bunch length, and intensity, it becomes possible to forecast the impact of EC effects on the beam stability of the PIP-II era Booster.
Paper: WEPR74
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR74
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPS05
Summary of the LANL mini-workshop on source region options for LAMP
2702
The core components of the LANSCE accelerator complex – the beam source area, drift-tube and cavity-coupled linear accelerators – are more than 50 years old; a critical subsystem for beam delivery to the Lujan Center, the proton storage ring (PSR), is more than 20 years old. The proposed LAMP project is intended to begin a revitalization and update of the LANSCE accelerator complex, starting with the beam source region, drift-tube linac, and PSR. To help assure we have selected an optimal candidate design for the source region, an internal workshop was held in August 2023 to consider options for providing two beam species at the peak and average currents, and beam macropulse formats, required by the various LANSCE user stations. This document describes the workshop goals and processes, presents the various configurations considered, and lists the results of the downselect process and potential paths forward.
Paper: WEPS05
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS05
About: Received: 08 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPS10
Installation and commissioning of the APS-U bunch lengthening system
2713
A new bunch lengthening cryomodule based a sin-gle-cell superconducting (SC) cavity operating at the 4th harmonic (1408 MHz) of the main RF has been installed into Argonne’s Advanced Photon Source (APS) storage ring as part of the U.S. DOE APS Up-grade project. The beam-driven system will be used to improve the Touschek lifetime by increasing the bunch length by up to several times. The 2-meter-long cryomodule is installed into one half of an APS straight section. The cavity will run at 2.1 K and pro-vide up to 1.3 MV of potential for bunch lengthening in a storage ring mode with a beam current of 200 mA evenly distributed into 48 bunches. System features include a pneumatic slow mechanical tuner and a pair of adjustable RF power couplers to adjust both the frequency and the loaded quality factor, providing a means of stabilizing the beam over a range of beam currents and fill patterns. Beam induced higher-order modes (HOMs) will be extracted along the beam axis and damped using a pair of room temperature silicon carbide absorbers. Cryogenic cooling is being provid-ed by a new 4.3 K liquid helium refrigerator combined with vacuum pumping and J-T expansion inside the cryomodule. We summarize the system features and report some results of initial cool down, testing, and measurements with beam.
Paper: WEPS10
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS10
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPS12
HOM power in the EIC crab cavity system
2720
Two types of crab cavities, one at 197 MHz and the other at 394 MHz, are designed to compensate the loss of luminosity due to a 25 mrad crossing angle at the interaction point (IR) in the Electron Ion Collider (EIC). The Higher Order Mode (HOM) damper designs of the EIC differs from the LHC designs since in the EIC the impedance budget is tighter, especially longitudinally, and in the EIC the HOM power is much higher due to the short and high intensity electron and ion beam. In this paper, HOM power in these two cavities is evaluated and optimized.
Paper: WEPS12
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS12
About: Received: 13 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPS13
Prototype and high-power test of SiC HOM
2723
The Electron Ion Collider (EIC), to be built at BNL, is a unique high-energy, high-luminosity, polarized electron-proton/ion collider. High-Order-Mode (HOM) damping is a big challenge for EIC electron accelerators, especially for 17 single-cell 591 MHz SRF cavities in EIC Electron Storage Ring (ESR) because of its high electron beam current (up to 2.6 A). Room temperature SiC Beamline HOM absorbers (BLA) were chosen as the baseline of the HOM absorber, due to its broadband and high power capability. A SiC HOM absorber was prototyped to test a preparing process and high power handling capability. The high power test demonstrates 0.3 W/mm^2 of power handing capability by far, and we are going higher power to test its limit. This paper will present the preparing process (shrink fit, cleaning and outgassing test) and high power test results of the SIC HOM absorber prototype.
Paper: WEPS13
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS13
About: Received: 09 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPS60
Preliminary design of a new superconducting harmonic cavity for HALF storage ring
2833
A superconducting (SC) 1.5 GHz (3rd harmonic) cavity is being developed for lengthening bunch and improving beam lifetime in the Hefei Advanced Light Facility (HALF) storage ring. This SC cavity is excited by an electron beam with 350 mA current, 1 nC charge, and ~6.7 ps length. This contribution presents optimizations on such a SC harmonic cavity in detail. Through optimizations it has a low R/Q < 45 Ω, which has potential to achieve a good bunch lengthening. It utilizes a large-radius beam pipe which traps the fundamental (1.5 GHz, TM010) mode, but allows all other cavity monopole and dipole higher-order-modes (HOMs) to travel into a room-temperature RF absorber. All of harmful HOMs are strong-ly damped using a pair of silicon carbide (SiC) rings. In addition, preliminary thermal analysis on the SiC rings is also described in this contribution
Paper: WEPS60
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS60
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THBD2
Bunch lengthening induced by a combination of higher-harmonic cavities of different order in low-emittance rings
2952
The next generation of light sources aim to provide bunch beams with small transverse emittances. A common feature in the design of light sources with small emittance lattices is the small value of the momentum compaction, which implies a short nominal equilibrium bunch length. Combined with the small transverse emittances, a short bunch length can pose severe limitations on the beam lifetime caused by collective effects such as intra-beam and Touschek scattering. To improve the beam lifetime of the bunches, an efficient way is to use a Higher-Harmonic Cavity (HHC) system, which leads to an increase of the equilibrium bunch length without an increase of the energy spread. Besides the improvement of beam lifetime, the HHC system plays an important role to cure beam instabilities and mitigate possible beam induced heating issues of the storage ring vacuum components. Present HHC systems are based on HHCs of the same order. To increase the bunch lengthening factor induced by the HHC system, we investigate a novel scheme based on the combination of HHCs of different order. The feasibility and performance of the novel scheme will be studied with the beam dynamics codes SPACE and Elegant, with parameters of the NSLS-II upgrade.
Paper: THBD2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THBD2
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPC05
Experimental measurement of the second-order transit time factor in a single-cell RF cavity for relativistic electron beams
2971
In this paper, we present a concise measurement of the Second-Order Transit Time Factor(TTF) of the relativistic electron beams within the bunching cavity of the Coherent Electron Cooling (CeC) Pop Experiment. Our study outlines a specialized measurement methodology that tackles the unique challenges posed by the CeC accelerator environment. The results not only provide significant insights into controlling CeC beam dynamics but also critically validate the theoretical prediction of the Second-Order TTF for relativistic electron beams. This work advances our understanding of beam dynamics and enhances the efficiency and control of CeC-based systems.
Paper: THPC05
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC05
About: Received: 21 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPC27
Quasi-isochronous conditions and high order terms of momentum compaction factor at the compact storage ring
3039
The compact storage ring project for accelerator research and technology (cSTART) is realized at the Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology (KIT). Flexible lattice of a ring benefits variety of operation modes. Different physical experiments are planned at cSTART. In particular, deep variation of momentum compaction factor with simultaneous control of high order terms of alpha would demonstrate the capture and storage of ultra-short bunches of electrons in a circular accelerator. Computer studies of linear and non-linear beam dynamics were performed with an objective to estimate arrangement and performance of dedicated three pole chicane magnets to provide quasi-isochronous conditions for electrons. Additional families of so called “longitudinal” sextupoles and octupoles were added in a ring model to control slope and curvature of momentum compaction factor as function of energy offset of particles in a bunch.
Paper: THPC27
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC27
About: Received: 03 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPC29
Simulation of the LANSCE PSR injection and extraction beamlines
3046
The Los Alamos Neutron Science Center (LANSCE) accelerator delivers high intensity proton beams for fundamental science and national security experiments since 1972. The Proton Storage Ring (PSR) accumulates a full 625-us macro-pulse of proton beam and compresses it into a 290-ns long pulse, delivering an intense beam pulse to the Lujan Neutron Science target. The proposed LANSCE Modernization Project (LAMP) is evaluating necessary upgrades to the accelerator that will guarantee continuous beam operations in the next decades. Upgrades to the PSR and its high-energy injection and extraction beamlines are being considered to handle the higher beam intensity enabled by the LAMP upgrades in the front-end. For the PSR upgrades studies, we are building models of the PSR injection and extraction lines in codes which include space charge calculations like Elegant and Impact. These better illustrate the beam dispersion and the beam halo in the high-energy transport. This work describes the LANSCE PSR injection and extraction lines and the corresponding simulation models. The models are compared to available beam diagnostics data where available.
Paper: THPC29
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC29
About: Received: 16 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPC30
Start-to-end simulations of the LAMP accelerator front-end
3049
The Los Alamos Neutron Science Center (LANSCE) accelerator delivers high intensity proton beams for fundamental science and national security applications since 1972. LANSCE is capable of simultaneous H+ and H- beam operations to multiple experiments requiring different time structures. This is achieved upstream in the facility with a combination of two 750 kV Cockcroft-Walton (CW) generators, a chopper and radiofrequency cavities, before going into the 800-MeV linac. The proposed LANSCE Modernization Project (LAMP) is evaluating critical machine upgrades necessary to continuous beam operations in decades to come. A significant component of LAMP is replacing the two CW with a dual-species 3-MeV Radiofrequency Quadrupole (RFQ). This change requires a full re-design of the LAMP front-end accelerator to deliver the existing and expanded capabilities of the facility. This contribution will discuss the LAMP front-end accelerator layout based on the general beam requirements and on standard accelerator codes, showcasing the start-to-end propagation of H+ and H- beams from the source to the linac entrance.
Paper: THPC30
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC30
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPC33
Simulation of longitudinal phase space measurements for the RUEDI ultrafast electron diffraction beamline
3060
The RUEDI (Relativistic Ultrafast Electron Diffraction & Imaging) ultrafast electron diffraction (UED) beamline aims to provide electron bunches to diffraction samples with an at-sample temporal resolution of sub-10 fs. Electron bunches of such short duration prove non-trivial to measure at electron beam kinetic energies of 4 MeV. A diagnostic beamline design is presented to enable simultaneous longitudinal phase space measurements (bunch duration, momentum and momentum spread) with a streaker and spectrometer. Several methods of measuring sub-10 fs bunch durations using both RF transverse deflecting cavities and THz streakers are outlined here with their limitations. Measurements are replicated in simulation to demonstrate the diagnostic beamline is capable of the high-resolution required for the longitudinal phase space measurements within the RUEDI UED beamline.
Paper: THPC33
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC33
About: Received: 13 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPC35
Impact of insertion devices on SSRF‑U lattice
3068
The Shanghai Synchrotron Radiation Facility upgrade (SSRF-U) lattice is a 4th generation, 3 GeV, upgrade plan for SSRF. It aims to reach the diffraction limit while keeping the existing beam lines and spaces. The majority of insertion devices (IDs) in operation of current SSRF will be considered as the ID scheme in SSRF-U. The kick-map method has been used to build ID models, including the EPUs and SCW. Optical distortion caused by IDs was compensated using both local and global corrections. Then, frequency map analysis (FMA) method was used to identify potentially dangerous resonance lines. After considering high-order magnetic field errors, the dynamic aperture, energy acceptance, and Touschek lifetime were examined.
Paper: THPC35
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC35
About: Received: 13 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPC40
Development of an ERL for coherent electron cooling at the Electron-Ion Collider
3086
The Electron-Ion Collider (EIC) is currently under development to be built at Brookhaven National Lab and requires cooling during collisions in order to preserve the quality of the hadron beam despite degradation due to intra-beam scattering and beam-beam effect. An Energy Recovery Linac (ERL) is being designed to deliver the necessary electron beam for Coherent electron Cooling (CeC) of the hadron beam, with an electron bunch charge of 1 nC and an average current of 100 mA; two modes of operation are being developed for 150 and 55 MeV electrons, corresponding to 275 and 100 GeV protons. The injector of this Strong Hadron Cooler ERL (SHC-ERL) is shared with the Precooler ERL, which cools lower energy proton beams via bunched beam cooling, as used in the Low Energy RHIC electron Cooling (LEReC). This paper reviews the current state of the design.
Paper: THPC40
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC40
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
THPC44
Broadband impedance induced heating proxy for operation at higher total current at SIRIUS
3090
SIRIUS, a brazilian 4th generation synchrotron light source, currently operates in top-up mode at 100mA in uniform fill. The main limiting factor for reaching higher currents is the temporary RF system in use. It is comprised of one PETRA 7-Cell cavity and two solid state amplifier towers that combined provide at most 120kW of power. By mid 2024, two superconducting RF cavities will replace the current cavity and two amplifier towers will be added to the system, allowing operation at higher currents. The design current of SIRIUS storage ring is 350mA, which can only be achieved once a third harmonic cavity is installed to lengthen the bunches to avoid excessive wake-induced heating of sensitive components. However, the installation of such cavity is not foreseen in the near future, which raises the question of which is the maximum current in uniform fill SIRIUS can be operated. This work will present some theoretical and experimental studies carried out to answer this question.
Paper: THPC44
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC44
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
THPC45
EIC impedance and beam dynamics
3094
A new high-luminosity Electron-Ion Collider (EIC) is being developed at BNL. Beam collisions occur at IP-6, involving two rings: the Electron Storage Ring (ESR) and the Hadron Storage Ring (HSR). The vacuum system of both rings is newly developed and impedance optimization is progressing. Beam-induced heating and thermal analysis are performed for both rings to manage and control thermal distribution. The study explores collective effects across the Rapid Cycling Synchrotron (RCS), ESR, and HSR using simulated single bunch wakefields. Discussions encompass impedance analysis, collective effects and beam interactions, and the impact of ion and electron clouds on beam dynamics.
Paper: THPC45
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC45
About: Received: 13 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPC46
Comparison of simulation and measurement of an in-vacuum undulator coupling impedance at NSLS-II
3098
The impedance of in-vacuum undulators (IVU) is a significant part of the total broadband impedance determining collective effects of beam dynamics in synchrotrons. It is computationally difficult to simulate the full few-meter-long 3D structure, which includes bellows, flanges, and taper transitions with a variable gap. So, the impedance is usually calculated separately for a simplified geometry of every component and the resistive-wall impedance is calculated using analytical formulas. The ECHO3D code based on a low-dispersive numerical technique provides an opportunity to compute the wakefield induced by a very short bunch in the full 3D model of the NSLS-II IVU. Here, we discuss the numerical simulations in comparison with beam-based measurements.
Paper: THPC46
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC46
About: Received: 10 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
THPC48
Impedance calculation for the hadron storage ring in the Electron-Ion Collider with ECHO3D
3104
ECHO3D has been used for calculating the geometric impedance for several beamline vacuum components in the hadron storage ring (HSR) of the EIC (Electron-Ion Collider) in the past few years. In this paper, we present the geometric impedances calculated from ECHO3D for the beam screen with pump slots, the polarimeter and the bellow with pump ports in the HSR. We also discuss some findings while cross-checking these results with what calculated from GdfidL and CST.
Paper: THPC48
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC48
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPC49
Impedance database for the Diamond-II booster
3108
Boosters in synchrotron injector systems have traditionally had more relaxed designs than storage rings, and consequently impedance has not been considered an important factor in their designs. In 4th generation light sources like Diamond-II, it is desirable to increase the extracted charge per shot to reduce filling times and enable advanced injection schemes. As such, the vacuum chamber impedance becomes a significant design parameter. An impedance database has been created for the Diamond-II booster, using the same AT-style lattice concept as for the storage ring, to be used as input into particle tracking and other simulations. We present here an overview of the database, including details of significant components and current progress on engineering designs.
Paper: THPC49
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC49
About: Received: 13 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
THPC50
Updates to the impedance database for the Diamond-II storage ring
3112
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.
Paper: THPC50
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC50
About: Received: 13 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
THPC55
Beam-cavity interaction in the CERN PS 80 MHz RF systems
3132
The 40 MHz and 80 MHz Radio Frequency (RF) systems in the CERN Proton Synchrotron (PS) are required to perform non-adiabatic bunch shortening before beam ejection. This manipulation allows to fit the bunches into the short RF buckets of the 200 MHz Super Proton Synchrotron (SPS). Although the impedance of the cavities is strongly reduced by feedback, the detailed understanding of the beam-cavity interaction is essential to evaluate their impact on the beam. This contribution focuses on the impedance characterization of the 80 MHz RF systems to describe how the RF amplification chain behaves as a function of beam current changes. Complementary measurement techniques, both beam and RF-based, were adopted. The results of the different measurements show good agreement. The aim is to study and predict possible beam quality degradation at beam intensities required by the High Luminosity LHC (HL-LHC), as well as to propose future consolidation to the high-frequency RF systems in the PS.
Paper: THPC55
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC55
About: Received: 03 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPC56
Simulation of beam loading compensation with RF-Track
3136
The beam loading effect results in a gradient reduction of the accelerating structures due to the excitation of the fundamental mode when the beam travels through the cavity. A recent implementation of this process in the tracking code RF-Track allows the simulation of realistic scenarios, thus revealing the impact of this phenomenon in start-to-end accelerator designs. In this paper, we present the latest update of the beam loading module which allows the simulation of the compensation of this effect and we explore the potential of the developed tool in heavy-loaded scenarios.
Paper: THPC56
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC56
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPC57
Assessment of the real part of the impedance of the LHC collimators with instability growth rate measurements
3140
The impedance of the Large Hadron Collider (LHC) is a source of instabilities and has to be monitored closely. It is usually assessed by measuring the tune-shift vs intensity, in particular at top energy where it is the most critical, as the collimators are the closest to the beam. However, to get information on the real part of the impedance, growth rate measurements are required. These are difficult to perform at flat-top because triggering the instability in a sharp and fast manner remains a challenge. Moreover, the length of the full cycle, including an energy ramp, prevents the measurement repetition. Instead, measuring growth rates at injection is more natural and allows rapid cycling, with the downside that the impedance at injection is not dominated by collimators but rather by fixed-gap devices. Here, we present measurements at injection energy, placing the collimators in tighter positions than the nominal ones, in an attempt to obtain a similar configuration as the flat top situation. The measurements are performed at several negative chromaticities to study the evolution of the growth rate of the rigid bunch mode instability. Results are finally compared to simulations.
Paper: THPC57
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC57
About: Received: 08 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
THPC58
Narrowband impedance studies in the HEPS storage ring
3144
The High Energy Photon Source (HEPS) is a fourth-generation synchrotron radiation facility with design beam emittance of less than 60 pm. Impedance modelling is an important subject due to the adopted small beam pipe as well as the tight requirements from beam collective effects. Narrowband impedances can be generated by the discontinuity of the vacuum chamber or the finite conductivity of the beam pipe. The coupled bunch instabilities caused by the narrowband impedances could restrict the beam current or perturb the synchrotron radiations. In this paper, the narrowband impedances in the HEPS storage ring are investigated element by element.
Paper: THPC58
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC58
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPC59
Investigation of transverse narrow-band impedance by coupled-bunch instability measurement in circular accelerator
3148
The transverse narrow-band impedance makes a major contribution to the transverse coupled-bunch instability, which may deteriorate the beam quality in multi-bunch, high-intensity circular accelerators. Thus, strict restriction on the transverse narrow-band impedance are implemented during the initial accelerator design phase. However, slight component structure deviations during the construction of accelerators and component modifications during the subsequent operation may lead to impedance difference from the design value. It is therefore more meaningful to obtain the impedance parameters of circular accelerators by beam experimental measurement during the machine operation. In this paper, by mode distribution of coupled-bunch instability and its growth rate, a method was proposed to obtain the transverse narrow-band impedance which is represented with an LRC resonator. In order to verify the effectiveness of the method, the numerical calculation with three known LRC resonators was used to check their difference and the fitted LRC resonator parameters are in good agreement with the setting values.
Paper: THPC59
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC59
About: Received: 13 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
THPC60
Studies and mitigation of TMCI in FCC-ee
3151
Previous studies have identified turbulent mode coupling instability (TMCI) as one of the most severe single-bunch instabilities in the FCC-ee collider, potentially limiting its performance. Its threshold is influenced by both transverse and longitudinal wakefields arising from vacuum chamber resistive wall effects, discontinuities, and beam-beam interactions, the latter of which can be seen as a transverse cross-wake force. In this paper, we investigate the TMCI using the most recent collider parameters and an updated impedance model. We also explore various mitigation techniques aimed at increasing the instability threshold, including positive chromaticity and a feedback system.
Paper: THPC60
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC60
About: Received: 08 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPC61
Estimation of impedances and corresponding instabilities in Korea-4th generation storage ring
3155
Due to the small vacuum apertures, impedance serves as a significant cause of beam instabilities in the 4th generation storage ring. These instabilities are directly affected by the bunch charge, thereby placing a limit on the maximum achievable beam current within the storage ring. The Korea-4th generation storage ring (Korea-4GSR) is currently under construction with the aim of reaching a maximum beam current of 400 mA. To meet this goal, we've conducted estimations and optimizations of the current storage ring’s impedance. In this presentation, we show the impedance of Korea-4GSR and the corresponding instabilities.
Paper: THPC61
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC61
About: Received: 19 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPC63
Emittance growth studies due to Crab Cavity induced amplitude noise in the SPS
3163
In the context of the HL-LHC upgrade, RF Crab Cavities (CCs) are one of the key components. Due to the increased intensity, the collider will operate with a large crossing angle scheme and these CCs will be used to counteract the geometrical reduction factor coming from the crossing angle. Amplitude and phase noise injected from the Low-Level RF, are known to induce transverse bunch emittance growth. This contribution presents the latest measurements of emittance growth induced by amplitude noise. The measurement was performed thanks to the SPS Beam Synchrotron Radiation Telescope (BSRT), that has been used to characterize the evolution of the transverse distributions. The measured emittance growth was found to be dependent on the amplitude detuning induced by the SPS octupoles, although no dependence was predicted by the available theories and models. In this paper, the measurement results will be presented and discussed.
Paper: THPC63
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC63
About: Received: 06 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
THPC64
Impedance model for the Fermilab Recycler ring
3167
We present an impedance model of the Fermilab Recycler ring using PyHEADTAIL. The model is constructed by incorporating analytical expressions for the wakefields of beamline components that contribute significantly to impedance. The effects of indirect space charge are included as an inductive impedance. Benchmarking against measured coherent Betatron tune shifts, the impedance model is found to capture 73.4% of observed tune shifts. Our findings serve as a stepping stone for the development of a realistic impedance model crucial for studying impedance-driven instabilities at higher intensity.
Paper: THPC64
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC64
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPC67
Updated analysis of beam halo measurements in LHC Run 2 and Run 3
3175
Measurements of the transverse beam halo in the Large Hadron Collider (LHC) provide crucial input for the performance evaluation of the collimation configuration in the High-Luminosity LHC (HL-LHC) era. Such measurements are carried out in various phases of the LHC operational cycle by scraping the beam with movable collimators. Understanding the halo population and halo formation mechanisms is crucial for optimising accelerator performance. Analysis of collimator scan data allows the evaluation of future needs for active halo depletion mechanisms at the HL-LHC, or other ways of mitigating halo-related risks to machine availability and protection. This contribution analyses the LHC Run 2 (2015-2018) and Run 3 (started in 2022) measurements using measured bunch-by-bunch beam intensity data. Different beam parameters are explored by profiting from upgraded beam parameters in the LHC injector complex.
Paper: THPC67
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC67
About: Received: 13 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPC68
Proton beam dynamics in bare IOTA with intense space-charge
3179
We are commissioning a 2.5~MeV proton beam for the Integrable Optics Test Accelerator at Fermilab, allowing experiments in the strong space-charge regime with incoherent betatron tune shifts nearing 0.5. Accurate modelling of space-charge dynamics is vital for understanding planned experiments. We compare anticipated emittance growth and beam loss in the bare IOTA configuration using transverse space-charge models in Xsuite, PyORBIT, and MAD-X simulation codes. Our findings reveal agreement within a factor of 2 in core phase-space density predictions up to 100 synchrotron periods at moderate beam currents, while tail distributions and beam loss show significant differences.
Paper: THPC68
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC68
About: Received: 15 May 2024 — Revised: 16 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
THPC69
Full-cycle simulations of the Fermilab booster
3183
The PIP-II project currently under construction at FNAL will replace the existing 400 MeV normal conducting linac with a 800 MeV superconducting linac. The beam power in the downstream rapid-cycling Booster synchrotron will be doubled by raising the machine cycle frequency from 15 to 20 Hz and by increasing the injected beam intensity by a factor 1.5. This has to be accomplished without raising uncontrolled losses beyond the administrative limit of 1 W/m. In addition, slip-stacking efficiency in the Recycler — the next machine in the accelerator chain- sets an upper limit on the longitudinal emittance of the beam delivered by the Booster. As part of an effort to better understand potential losses and emittance blow-up in the Booster, we have been conducting full cycle 6D simulations using the code pyORBIT. The simulations include space charge, wall impedance effects and transition crossing. In this paper, we discuss our experience with the code and present representative results for possible operational scenarios.
Paper: THPC69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC69
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
THPC72
Advanced modeling and optimization of nuclear physics colliders
3194
High energy colliders provide a critical tool in nuclear physics study by probing the fundamental structure and dynamics of matter. Optimizing the collider’s machine parameters is both computationally and experimentally expensive. A fast and robust optimization framework that includes both beam-beam and the detailed machine lattice will be crucial to attaining the best performance of the collider. In this paper, we report on the development of an integrated framework that includes an advanced Bayesian optimization software GPTune, a self-consistent beam-beam simulation code BeamBeam3D, and the detailed lattice model from MAD-X. Some application results to the RHIC facility optimization will also be presented.
Paper: THPC72
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC72
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPC73
Combined wakefield and beam-beam effects in the EIC design
3198
Collective wakefield and beam-beam effects play an important role in accelerator design and operation. These effects can cause beam instability, emittance growth, and luminosity degradation, and warrant careful study during accelerator design. In this paper, we report on the development of a computational capability that combines both short and long range wakefield models and a strong-strong beam-beam simulation model. Applications to the EIC will be discussed.
Paper: THPC73
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC73
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
THPC74
Generation femtosecond proton beam for laser plasma acceleration
3202
Laser plasma accelerators have a great potential to accelerate a charged particle beam to high energy within a short distance due to their extraordinarily high accelerating gradient. However, in order to effectively use the laser plasma accelerator, the input beam has to be moving at relativistic velocities, with a duration 100 femtoseconds or less. In this study, we propose a scheme to generate a femtosecond proton beam for the laser plasma acceleration. The self-consistent simulation including the three-dimensional space-charge effects was used to verify this concept in a simplified version.
Paper: THPC74
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC74
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPC75
Status of the Spallation Neutron Source beam test facility and progress of beam dynamics studies
3206
The Spallation Neutron Source (SNS) Beam Test Facility (BTF) supports the study of beam dynamics in the front end of a high power LINAC. The BTF combines a replica of the SNS front end, including nearly-identical ion source, RFQ and MEBT, with extensive phase space diagnostics and a FODO transport line. Diagnostic capabilities include direct measurement of 6D phase space distribution and detection of halo distributions to a sensitivity of greater than one part-per-million. The goal of on-going BTF studies is to demonstrate accurate particle-in-cell modeling of halo growth and evolution by leveraging unprecedented accuracy in the description of the initial beam distribution. This work is motivated by operational experience at the SNS, which currently operates with beam loss that cannot be described by any model. This paper summarizes progress in the BTF beam study program as well as diagnostics development and recent upgrades to the beamline configuration.
Paper: THPC75
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC75
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
THPC76
Discussion of space charge effects of a beam train containing infinitely many bunches
3210
In an electron linear accelerator, the continuous beam emitted by an electron gun will become an equally spaced beam train after passing through the bunching section. If the current of the beam is large, its expansion may be more intense than the case where only a single bunch is considered, resulting from the space charge forces between different bunches. In this article, using an algorithm capable of calculating the space charge effects of a beam train containing infinitely many bunches with uniform spacing, we compare bunch trains with different parameters to find the pattern of their space charge effects.
Paper: THPC76
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC76
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPC77
Status of beam-beam studies for the high-luminosity LHC
3213
Optimizing the configuration of an operational cycle of a collider such as the LHC is a complex process, requiring various simulation studies. In particular, Dynamic Aperture (DA) simulations, based on particle tracking, serve as indispensable tools for achieving this goal. In the framework of the high-luminosity LHC (HL-LHC) studies, our primary focus lies in performing parametric beam-beam DA simulations for the critical phases of the collision process, which includes the collapse of the beam separation bump, as well as the start, and the end of the luminosity leveling. In this paper, we present the status of our ongoing studies for different optics and filling schemes, and we comment on how they could guide the orchestration of the operational settings along the luminosity leveling phase of the HL-LHC cycle.
Paper: THPC77
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC77
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPC80
Bunch-by-bunch simulations of beam-beam driven particle losses in the LHC
3225
Recent experimental measurements in the Large Hadron Collider (LHC) have shown a clear correlation between beam-beam resonance driving terms and beam losses, with a characteristic bunch-by-bunch signature. This observation creates interesting conditions to study diffusive processes. Over the past few decades, early chaos indicators, frequency map analysis and dynamic aperture studies have been commonly used to study particle stability in circular machines. However, the underlying mechanisms driving particles to large amplitudes in the presence of high order resonances is still an open question. Leveraging on years of development on particle tracking tools, this paper presents full-fledged 6-dimensional bunch-by-bunch beam loss simulations in the LHC. The computed loss rates are shown to be in agreement with experimental observations from LHC Run 3.
Paper: THPC80
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC80
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPG01
A Kick-and-Cancel injection scheme for Diamond-II
3240
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.
Paper: THPG01
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG01
About: Received: 09 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
THPG02
Performance optimization design of photocathode injector based on multi-objective genetic algorithm
3244
Generating beam with nC-level charge is of great significance for particle colliders. In order to achieve lower emittance and length of bunch, based on the photocathode injector, we designed a L-band gun and L-band accelerating tube. However, with many coupled parameters, it is difficult to optimize its performance to the limit when optimizing them separately. Therefore, we employed a multi-objective genetic algorithm for searching in the multi-dimensional parameter space and utilized a deep Gaussian process as a surrogate model to solve the high-dimensional parameter optimization problem. Through optimization, we successfully obtained the normalized transverse emittance of 3.4 π mm·mrad and the bunch length of 1.0 mm for a fixed charge of 5 nC. This indicates that our method can effectively improve the performance of the photocathode injector.
Paper: THPG02
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG02
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPG03
Temporal profile shaping for a dispersive section using a multi-objective genetic algorithm
3247
Our research focuses on the design of a beamline. Due to the numerous beamline components involved, without strict optimization of each component's parameters, the transmitted temporal profile of beam may distort, failing to meet the expected requirements. Additionally, different initial temporal profile of the beam will undergo longitudinal shaping during transmission through the beamline. Therefore, we aim to determine the combination of initial beam temporal profile at the cathode and the parameters of the beamline components based on the specific beam distribution at the exit. We propose the application of an improved multi-objective genetic algorithm to solve this problem. Through multiple optimization iterations for a given temporal profile, our algorithm consistently identifies multiple suitable combinations of initial beam temporal profile and beamline component parameters to produce the desired specific temporal profile of the beam.
Paper: THPG03
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG03
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPG06
Tune feedback system in the Taiwan photon source
3258
The paper outlines the successful implementation of a global tune feedback system at the Taiwan Photon Source (TPS) to compensate the tune variation resulting from adjustments in the gap and phase of the insertion devices. The global tune feedback system deployed in the TPS employs two families of quadrupole magnets to sustain betatron tunes at the desired working point. The adjustment currents (feedback quantities) are crucial for this process, which are calculated from a tune response matrix derived from the lattice model, with tune shift quantities provided by the bunch-by-bunch feedback system, and the algorithm of singular value decomposition (SVD).
Paper: THPG06
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG06
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPG28
Status of the transverse bunch-by-bunch feedback system at APS-U storage ring
3311
Transverse bunch-by-bunch (BxB) feedback system has been designed, fabricated, installed, and tested with beam at the Advanced Photon Source Upgrade (APS-U) storage ring. The transverse feedback system (TFB) is designed to suppress coupled bunch instabilities and single bunch instabilities. It adapted a stripline kicker design which has the same profile as the APS-U injection/extraction kickers. The system uses digital controllers which provide powerful diagnostics, in addition to its major functionality for feedback control. This paper presents the status of the TFB system including early beam commissioning results.
Paper: THPG28
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG28
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPG31
First studies on error mitigation by interaction point fast feedback systems for FCC-ee
3322
During operation, the Future Circular electron-positron Collider (FCC-ee) will be subject to vibrations from mechanical sources and ground motion, resulting in errors with respect to the closed orbit. To achieve physics performance, luminosity and beam lifetime must be kept to design specifications. To correct for errors at the IPs, a fast feedback system is required. In this paper, we present the tolerances for the allowable beam offsets at the interaction points (IPs) and propose a fast feedback system to address these errors, with the methods of detecting and correcting errors discussed.
Paper: THPG31
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG31
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPG33
Experimental results on longitudinal RF beam phase feedback in the heavy-ion synchrotron SIS18
3329
In the SIS18 heavy-ion synchrotron at GSI, RF beam phase feedback systems are developed and tested with beam for the damping of coherent longitudinal bunch oscillations. In particular, a beam phase control system is currently commissioned for the damping of longitudinal dipole oscillations. The feedback system has to cope with both, a large RF frequency span (400 kHz to 5.4 MHz) and synchrotron frequencies of up to 6 kHz. It has to be compatible with several beam manipulation schemes such as dual-harmonic, bunch merging, and bunch compression. The system relies on recent upgrades of the SIS18 LLRF topology including a newly developed multi-purpose DSP system that is used for the RF cavity synchronization as well as for RF beam feedback. This paper describes the LLRF concept of the RF beam phase feedback at SIS18 and presents results from machine experiments with beam where an adaptive feedback filter for damping longitudinal dipole oscillations during the whole SIS18 machine cycle was realized and successfully applied. Finally, an outlook will be given towards the full integration into the central control system and towards the SIS100 bunch-by-bunch longitudinal feedback system.
Paper: THPG33
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG33
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPG69
Improvements of longitudinal stability with LLRF optimization at SIRIUS
3435
SIRIUS is a 4th generation synchrotron light source built and operated by the Brazilian Synchrotron Light Laboratory (LNLS). Recently, investigations of noise sources and the storage ring RF plant identification enabled a fine-tuning of the Digital Low-Level Radio Frequency (DLLRF) parameters. This paper presents the main improvements implemented, which include the mitigation of 60Hz noise from the LLRF Front End and the optimization of the control system parameters. Optimizations in the machine were based on an adjusted model of the SIRIUS storage ring RF plant. Tests with the model's parameters showed that the system's stability was strongly dependent on phase shifts introduced by nonlinearities from the high power RF sources. The new parameters significantly improved the control performance, increasing the bandwidth of the system and reducing longitudinal oscillations. BPM (Beam Position Monitor) and BbB (Bunch-by-Bunch) systems were employed to quantify longitudinal beam stability improvements.
Paper: THPG69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG69
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPG81
HPSim simulation of the highly bunched WNR beam at LANSCE
3457
The linac at the Los Alamos Neutron Science Center (LANSCE) provides beam to five user facilities with various beam energy and timing patterns. While the other four facilities have the same 201.25-MHz micro-bunch structure created by a pre-buncher and main-buncher pair, the Weapon Neutron Research (WNR) requires significantly higher charge per micro-bunch. This is achieved via adding a low frequency buncher at 16.77 MHz to the Low Energy Beam Transport. Such highly bunched micro-bunches create several challenges in operation and remain a critical capability to maintain for the LANSCE Modernization Project. We will demonstrate the HPSim simulation of the WNR beam through the LANSCE linac as a tool to address these issues in the future.
Paper: THPG81
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG81
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPR12
Simultaneous acceleration of multiple beams in novel LANSCE front end
3505
We present the 100 MeV injector design for the LANSCE Accelerator Facility, which is designed to replace the existing 750-keV Cockcroft-Walton-columns-based injector. This new Front End includes two independent low-energy transports for H+ and H- beams merging at the entrance of a single RFQ, with the subsequent acceleration of particles in the new Drift Tube Linac. The challenge of this design is associated with the necessity of simultaneous acceleration of protons and H- ions with multiple beam flavors in a single RFQ and DTL. The LANSCE operation regime provides simultaneous delivery of beams to five experimental areas, with a forecasted increase in the number of targets in the future. Each beam is characterized by a unique time structure, pulse length, emittance, and charge per bunch. The paper presents the details of this design and injector parameters.
Paper: THPR12
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR12
About: Received: 11 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPR15
Simple estimate, detailed computer simulation and measurement of the transverse kick in the SLAC accelerating structure
3516
We discuss the result of calculation and measurement of the transverse kick in the SLAC accelerating section in a single bunch and multi-bunch regimes. We present a simple estimate, which can be used in practical situations.
Paper: THPR15
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR15
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
THPR31
Study of the performance and beam loss limitations during injection of high-intensity LHC proton beams
3564
The LHC Injectors Upgrade project at CERN optimized the injection accelerator chain to deliver proton intensities per bunch of 2.3e+11 ppb. Throughout 2023, the LHC was filled with up to 2464 bunches per beam using a hybrid injection scheme, involving up to 236 bunches per injection, with a maximum intensity per bunch of 1.6e+11 ppb. These beam parameters already revealed significant beam losses at the primary collimator in Point 7 during injection, with large fluctuations from fill to fill, limiting in several cases the machine performance. This contribution analyses the performance of the LHC during injection and discusses possible improvements.
Paper: THPR31
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR31
About: Received: 01 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPR48
FLASHlab@PITZ beamline upgrade towards full functionality – status and plans
3621
At the Photo Injector Test facility at DESY in Zeuthen (PITZ), an R&D platform for electron FLASH cancer radiation therapy and radiation biology is being prepared: FLASHlab@PITZ. The design of the full beamline with optimized beam properties was finished; the setup is currently being finalized and the mechanical design and manufacturing is underway. The beamline runs in parallel to the SASE THz beamline at PITZ and is connected to it with a dogleg. Beam dynamics simulations were conducted to assure excellent beam quality at the experimental area. A fast kicker system will be installed which is capable of distributing electron bunches from a single bunch train freely over an area of 25mm x 25mm within one microsecond. When the full FLASHlab@PITZ beamline is ready in 2024, the accelerator will deliver 22 MeV electrons to generate dose rates from 0.01 Gy/s up to 10e+14 Gy/s to an experimental area, which can accommodate a variety of setups for irradiation studies. The flexible arrangement of the experimental area will make it possible for external users to collaborate with PITZ and conduct experiments with existing or newly designed irradiation setups.
Paper: THPR48
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR48
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
THPR57
Design study of a compact IH-DTL-based injector for proton therapy facilities
3647
A new proton injector based on the 425-MHz radio frequency quadrupole (RFQ) and interdigital H-mode drift tube linac (IH-DTL) has been designed. The injector is ~7 m long and comprises an electron-cyclotron-resonance (ECR) ion source, a low-energy beam transport, an RFQ, an IH-DTL, two triplets, a medium-energy beam transport, and a debuncher. The IH-DTL is specially designed with two tanks with different bunching phases, which can contribute to excellent transverse and longitudinal beam quality. The ion source produces an 18-mA proton beam with the energy of 30 keV. The output energy of the injector is 7 MeV with the transmission efficiency of 86.2%. A three-dimensional electromagnetic simulation was conducted, and the results agreed with the design. A systematic and mechanical design of the entire proton injector was also performed for the following research and development. The injector has great performance and is planned to be utilized in Shanghai APACTRON Proton Therapy facility (SAPT). In the future, it can also promote advanced proton accelerators for medical applications.
Paper: THPR57
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR57
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPS32
Ultrafast high-voltage kicker system hardware for ion clearing gaps
3809
Ionization scattering of electron beams with residual gas molecules causes ion trapping in electron rings, both in a collider and electron cooling system. These trapped ions may cause emittance growth, tune shift, halo formation, and coherent coupled bunch instabilities. In order to clear the ions and prevent them from accumulating turn after turn, the gaps in a temporal structure of the beam are typically used. Typically, the gap in the bunch train has a length of a few percent of the ring circumference. In those regions, the extraction electrodes with high pulsed voltages are introduced. In this paper, we present the design consideration and initial test results of the high-voltage pulsed kicker hardware that includes vacuum device and pulsed voltage driver, capable of achieving over 3 kV of deflecting voltage amplitude, rise and fall times of less than 10 ns, 100 ns flat-top duration at 1.4 MHz repetition rate.
Paper: THPS32
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS32
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPS60
Bead-pull measurement procedure for AREAL linear accelerator accelerating structure
3882
In this paper, the widely used RF measurement bead-pull technique for the S-band accelerating structure pre-tuning of the AREAL linear accelerator is presented. Bead-pull measurements were conducted before brazing with various group sets of accelerating cells to evaluate the effectiveness of “smart combinations” for AREAL accelerating structures. The “smart combination” technique represents the grouping of cells with corresponding lengths to achieve the same length sets (triplets for 2π/3 mode) as it is possible. Cell lengths were measured in advance based on TM resonance frequencies measurement. This procedure will significantly reduce the tuning routine required after brazing.
Paper: THPS60
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS60
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
FRYD1
High-efficiency klystrons from a dream to a reality
3933
During last year a comprehensive R&D program on high-efficiency klystrons has been carried out in collaboration with industry. The first prototypes are being tested and experimental results are promising. The talk will describe the main results of this R&D focusing in the experimental ones.
Paper: FRYD1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-FRYD1
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024