Several laboratories and facilities recently started joined efforts towards the realization of a python accelerator middle layer (pyAML) for control, tuning and optimization. This software is intended as a successor to matlab middle layer (MML), inheriting its features but also expanding to new ones (e.g., nonlinear optics and machine learning tools). Presently, several codes are available that provide some of the desired features. These codes have been adapted and tested at several of the participating laboratories to give input to the design of the pyAML. The most relevant features and results have been analyzed and are presented here together with the implications for the pyAML design.

The ESRF booster has been built more than 30 years ago as injector of the first ESRF storage ring and it is still used to inject in the EBS. Several components of the booster have been updated in the years and it is now operated off-energy and with emittance exchange at extraction, however the lattice has not been modified since the '90s. A project to reduce the equilibrium emittance and bunch length of the booster by exchanging 18 quadrupole magnets has been proposed. In this paper we present the beam dynamics studies in presence of errors and the expected gain in injection efficiency.

A new lattice for the EBS is proposed as preliminary candidate for the next generation ESRF storage ring. This new optics would feature lower emittance, matched optics at all ID, transparency conditions for insertions and overall a net gain in brilliance coherence and flux. Due to the reduced dynamic aperture, on-axis injection with a low emittance beam would be a requirement in order to progress with these optics.

The presence of third order horizontal resonance island buckets at the ESRF EBS has been observed in simulations and in the machine. The islands appear at a few mm distance from the core with a specific horizontal tune and octupole setting. When the electrons are kicked with an injection kicker, a fraction of the beam can be captured in the island. The procedures to send the beam into the island and to measure the capture rate and the lifetime of the beam in the island are described. The dependency of the presence of stable islands with different horizontal and vertical tunes and different octupole settings are shown.

Synchrotron radiation light sources normally operate at a low coupling between the transverse planes in order to achieve flat beams and produce high peak brilliance. Instead, operating at a high coupling has other advantages such as smaller emittance degradation due to intra-beam scattering, improved Touschek lifetime, and lower sensitivity to vibrations of the photon beam. Moreover, it has been suggested that a high coupling may enable achieving higher bunch currents thanks to sharing of the beam-induced wakefields between the transverse planes. We were able to take advantage of this effect to substantially increase the TMCI threshold at zero chromaticity and nearly double the single bunch current limit at high chromaticity at ESRF-EBS.

The Future Circular Collider, FCC-ee, is a proposed next generation electron-positron collider aiming to provide large luminosities at beam energies from 45.6 up to 182.5 GeV. This collider faces a major challenge to deliver the design performance in the presence of realistic lattice errors. A commissioning strategy has been developed including dedicated optics designs, efficient beam-based alignment and optics corrections based on refined optics measurements. First specifications on main magnets, corrector circuits, and instrumentation have also been investigated. A summary of all these aspects is presented in this paper.

SOLEIL II is an ambitious upgrade project that aims to reduce the horizontal emittance of the SOLEIL facility from 4 nm to 84 pm (to be further reduced to 50 pm by running with round beams). The SOLEIL II lattice will utilise a combination of permanent magnets and electro-magnetic corrector magnets. In the case of beam losses, it is of critical importance to localise the losses to certain shielded areas or dedicated collimators in order to prevent the risk of demagnetisation of the permanent magnets. The study and development of different beam loss scenarios will be presented.

The LHC is approaching the end of its third operational run, with machine protection and performance having demanded an excellent control of the single-particle dynamics. Additionally, the requirement to rapidly commission multiple diverse sets of optics configurations within each year, and from year-to-year, placed clear demands on the measurement and correction methods employed. Tight tolerances on the linear optics have been consistently achieved, with the drive to ever-more pushed optics for the High Luminosity LHC era continuing to introduce new challenges. Routine control of linear coupling has been an operational necessity, while significant progress has also been made extending the understanding and control of the optics into the nonlinear regime. This paper presents the key methods used, the results obtained, and discusses the challenges to control of the beam-optics in the LHC.

Storage ring commissioning-like simulations are necessary to assess the feasibility of proposed future lattice designs. This paper proposes a python package for commissioning-like simulations based on python accelerator toolbox (pyAT). The software includes: 1) errors definition, 2) correction routines from open trajectory to optics and coupling correction and 3) the evaluation of the relevant parameters, such as dynamic aperture (DA), injection efficiency (IE) and Touschek lifetime (TL). The software is fully exploiting parallel resources (local or on a computing cluster) and is thought to be easily configured for any machine (examples are given for EBS DBA and HMBA, for PETRA IV and for FCC-ee). Whenever possible analytic formulas are made available to the user. Several examples are detailed in this paper and included in the code as demonstrations of use.

The European Synchrotron Radiation Facility Extremely Brilliant Source (ESRF-EBS) is the first fourth generation 6 GeV storage ring (SR) light source making use of the hybrid multibend achromat lattice, reaching a natural horizontal emittance of 140 pm rad. Further, reducing the horizontal emittance would provide a more brilliant and a higher quality photon source for the EBS users. One way of achieving this is to operate the SR off-energy. The first approach reduces the electron beam energy by −1%, which gives a 121 pm rad natural horizontal emittance. To fulfill operation requirements, the full ring had to be rematched, including both the quadrupoles and the sextupoles in the linear optics correction. The off-energy settings are then tested in the SR in terms of lifetime, injection efficiency, and operability. Published by the American Physical Society 2024

Following the measurements done at MAX-IV [1], we try to exploit for the ESRF-EBS Storage Ring (SR) off-energy response matrix measurement for the optimization of Touschek lifetime. The measurements performed with fast AC steerers on- and off-energy are analyzed and fitted producing an effective model including quadrupole and sextupole errors. Several alternatives to extrapolate sextupoles strengths for correction are compared in terms of lifetime. For the time being none of the corrections could produce better lifetime than the existing empirically optimized set of sextupoles.

The European Synchrotron Radiation Facility (ESRF) storage ring (SR) has been dismantled and replaced by the Extremely Brilliant Source (EBS) which has now been commissioned. This new fourth generation light source has much smaller vacuum chambers than its predecessor, which necessitates a careful optimization of the vacuum systems and an accurate impedance model to be able to deliver all beam modes at the design current and predict future machine performance in the presence of strong collective effects. This paper will report on the first beam based measurements with a single bunch in order to characterize the short range wakefield model of the EBS SR and to make a first comparison with predictions. The results from transverse instability thresholds and tune shift measurements will be presented, as well as bunch length and phase variation with the current. Microwave instability threshold measurements have shown some discrepancy with predictions, which could arise from welding defects in the machining of the chambers. These discrepancies and other possible causes will be discussed.

Several high-energy synchrotron facilities adopted the Hybrid Multi-Bend Achromat scheme (HMBA) developed for the ESRF-EBS [1]. The considered lattice has been developed for a generic 6 GeV storage ring (SR) of 1100 m circumference [2]. It includes a short bending (SB) magnet at the center of the cell, and achieves a ~70 pm rad equilibrium horizontal emittance. The optics of such SR are modified introducing reverse bending magnets [3, 4] to further reduce the natural horizontal emittance to 53 pm rad. The impact of such modification on dynamic aperture and lifetime is assessed and optimized.

The European Synchrotron Radiation Facility (ESRF) operates a 6 GeV fourth generation light source, the ESRF-Extremely Brilliant Source (EBS). This storage ring is the first to implement the hybrid multibend achromat lattice (HMBA) that provides a reduction of the horizontal emittance of approximately a factor 30 with respect to the former double bend achromat structure. By combining several innovative concepts, the HMBA lattice allows the achievement of ultralow emittance while maintaining excellent lifetime and dynamic aperture performance. In this paper, beam commissioning experience and results of the new ESRF storage ring will be presented with an emphasis on the specific challenges relating to the HMBA lattice. The issues, methods, and concepts developed during the commissioning period and first months of operation are discussed.

Top-up operation was recently introduced at the European Synchrotron Radiation Facility (ESRF) to provide constant beam current to the beam line users. This mode of operation involves frequent injections that can be the source of significant perturbations on the stored beam. Beam lines running experiments with a timescale longer than the injection period may be impacted by such perturbations. The ESRF storage ring injection systems and layout were not designed to allow for transparent injection, i.e., without visible perturbations on the stored beam. These perturbations are driven directly or indirectly by rapidly pulsing elements, the effect of which cannot be corrected by standard methods such as feedback loops. Major efforts were put into the development of mitigation measures at the ESRF. Depending on the source of perturbation different approaches were used. They all contribute to the achievement of transparent injections and unperturbed continuous data acquisition for the beam lines. After a review of the ESRF injection systems, these developments and the resulting reduction of the injection perturbations are described in this paper.

Work on the conceptual design of a dedicated fourth-generation fourth-generation Specialized Synchrotron Radiation Source (SSRS-4) is in progress at the Kurchatov Institute, Moscow. The project is being developed in collaboration with the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. In this paper, the initial results of our work on this project are reported, major directions of current research are presented, and possible areas of application of the SSRS-4 are outlined. The key element of the currently discussed design is a 6-GeV storage synchrotron with an orbit length of ~1300 m and the magnetic lattice that should provide a horizontal transverse emission of 70–100 pm rad. Further optimization may allow for reducing the emittance to 20–40 pm rad. Of the injection schemes under discussion, one features a full-scale booster synchrotron deployed in the same tunnel as the main storage ring, and the second is a topup linac. The latter can also be used as an electron-beam driver for a free-electron laser.