Storage rings and free electron lasers use undulators to produce high-brilliant X-ray photon beams. In order to increase brilliance and photon energy tunability it is necessary to enhance the undulator magnetic peak field on axis by reducing its period without decreasing the electron beam stay clear. Undulator technologies aiming to reach this goal are presented.

As a part of the High Energy upgrade to the Linac Coherent Light Source II at SLAC, LBNL is responsible for the update of the undulators of the Soft X-Ray (SXR) line. In order to span the required photon energy range, the SXR undulators require longer magnetic period. This increased magnetic period leads to higher magnetic force, requiring updates to certain elements of the design. In contrast, many elements can safely remain unchanged. This presentation details the updates and analyses performed to support the adaptation to HE-SXR, as well as pre-production undulator results.

The aims of the CLARA experiment at the Fermilab Integrable Optics Test Accelerator (IOTA) were to directly measure the coherence length of undulator radiation emitted by a single electron and to test whether the radiation is in a pure classical Glauber coherent state or in a quantum mixture of coherent and Fock states. We used a Mach-Zehnder interferometer (MZI) to study visible radiation generated by 150-MeV electrons circulating in the ring. The relative delay between the two arms of the MZI was adjusted by varying the length of one of them with a resolution of 10 nm. The intensity of the circulating beam spanned several orders of magnitude, down to single electrons. A pair of single-photon avalanche diodes (SPADs) was placed at the output of the MZI arms to detect photocounts with high efficiency and timing resolution. We describe the observed interference patterns and photocount rates as a function of interferometer delay and discuss their implications.

The Fritz-Haber-Institut (FHI) der Max-Planck-Gesellschaft Free Electron Laser (FEL) achieved first light from its Mid-IR beamline at 18 microns on February 14, 2012. In the subsequent years, the 3 to 60 micron light has been supplied to users resulting in 96 refereed publications in Chemical Physics. In 2019, the FEL Group initiated an upgrade to add a Far-IR beamline to the system. On June 8, 2023, first light was achieved at 8 microns from this beamline which spans 4.5 to 165 microns in tunable radiation. A unique feature of this upgrade is the inclusion of a 500 MHz kicker cavity that can send the 1 GHz electron pulses alternatively into the MIR and FIR beamlines. On December 8, 2023, first light was obtained simultaneously at 18 and 55 microns respectively, thereby achieving the project goal of independently-tunable two-color lasing. We will discuss the physics and engineering design of the new FIR beamline and provide details of the radiation spectrum and parameters. We will also outline planned user experiments using this new radiation tool.

The CXFEL project at ASU will produce coherent soft x-ray radiation at a university-scale facility. Unlike conventional XFELs, the CXFEL will use an optical undulator in addition to nanobunching the electron beam instead of a static magnetic undulator. This reduces the undulator period from cm-scale to micron scale and lowers the requirements on the electron beam energy. CXFEL’s overtaking geometry design reduces the effective undulator period to 7.86 μm to produce 1 keV photons. This is accomplished by crossing the laser and electron beam at a 30 degree overtaking angle, and using a tilted laser pulse front to maintain temporal overlap between the electron beam and laser pulse. The inverse Compton scattering interaction between a microbunched electron beam and an optical undulator falls out of the range of most accelerator codes. We employ MITHRA, a FEL full-wave FDTD solver software package which includes inverse Compton scattering to simulate the FEL lasing process. We have adapted the code to the CXFEL instrument design to simulate the radiation/electron beam interactions and report results of studies including scaling of key parameters.

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.

In high-gain free-electron lasers (FELs) with planar undulators it is possible (in the linear regime) to independently amplify at the fundamental and at odd harmonics, a process referred to as Harmonic Lasing (HL). For the HL process preservation of the quality of the incoming high-brightness electron beam is essential. This requires suppression of the lasing at the fundamental, which can be achieved using several methods such as special phase shifter set points and attenuation of the fundamental radiation using intra-undulator optical high-pass filters. The European XFEL variable-gap undulator beamline SASE2 features two intra-undulator stations combining a magnetic chicane and the possibility to insert a thin diamond crystal onto the optical axis of the beamline. While installed for the operation in hard x-ray self seeding (HXRSS) mode, this hardware is well-suited for HL experiments at a low electron beam energy corresponding to a fundamental photon energy of about 2keV. In this contribution we present numerical simulations of third-harmonic lasing at this working point.

The SASE3 Variable Polarization project is intended to offer polarization control of the X-ray FEL pulses at the European XFEL. The project was completed in early 2022. During the winter shutdown 2021-2022, all four APPLE-X helical undulators were placed in the tunnel and first lasing was achieved in April 2022. Unfortunately, further use of the helical afterburner proved impossible, as the encoders used to position the magnetic structures of the undulator were damaged by radiation. To carry out repairs, all undulators were removed from the tunnel in the summer 2022, and investigations were carried out to determine the cause of the radiation damage. This article presents measures taken to minimize further radiation damage in order to ensure the continued operation of the helical afterburner.

Scientific opportunities with very hard XFEL radiation demands dedicated facility development towards FEL operation in the sub-ångström regime. Very hard X-rays provide capabilities of high Q-range coverage and high penetration, and also allow access to the K-edge spectroscopy of high-z materials. Production of such X-rays using FELs takes advantage of general FEL characteristics such as large coherence, short pulse option, variable pump-probe delay control and higher brightness compared to conventional storage ring sources. R$\&$D activities in the characterization and production of high energy photon beams beyond 25 keV has been launched since 2021 at the EuXFEL. Photon beams of 30 keV have been produced, characterized and delivered to experimental hutches. In this paper, we give an overview of the overall development. Obtained results will be discussed.

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.

This work presents the design of a compact high-efficiency terahertz source, a collaborative effort between UCLA and RadiaBeam Technologies. The system, driven by a thermionic RF gun, features prebunching elements including alpha-magnet and electromagnetic chicane to effectively compress the long beam generated from the gun. By sending such beam into tapering enhanced waveguide oscillator, we can achieve high efficiency energy extraction in different regimes. This work focuses on the beam dynamics in the beamline prior injection into the undulator. A brief mention of the simulation results for radiation generation is also presented.

A single-pass THz free-electron laser (FEL) at the Photo Injector Test facility at DESY in Zeuthen (PITZ) was designed and implemented for a proof-of-principle experiment on a tunable high-power THz source for pump-probe experiments at the European XFEL. THz pulses are generated at a radiation wavelength of 100 μm within a 3.5 m long, strongly focusing planar LCLS-I undulator. High gain is achieved by driving the FEL with high brightness beams from the PITZ photoinjector at 17 MeV and a bunch charge of up to several nC. In addition to the mechanisms of self-amplified spontaneous emission (SASE), seeding of the THz-FEL by electron bunch modulation at the photocathode is also being investigated. The experimental results, including the gain curves and spectral properties of the THz-FEL radiation, are presented in comparison with theoretical predictions and numerical simulations.

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.

Cavity-based XFEL, or CBXFEL, is a future photon source concept under intense development at SLAC. It is considered a path towards full 3D coherence at angstrom wavelength, delivering another 2-3 orders of magnitude leap in source brightness compared to current XFELs configurations. In a first phase of the project, one of the goals is to demonstrate the regenerative amplification by returning and amplifying the seed pulse from 7 LCLS Hard X-ray Undulators (HXUs) with a rectangular crystal cavity. In this paper, we report on the recent measurement of early stage XFEL lasing characteristics at 9.831 keV photon energy by using 7 LCLS HXUs under e-beam conditions close to those chosen for the first phase of CBXFEL gain demonstration.

Manipulation electron beam phase space technology by laser-electron interaction has been widely used in accelerator-based light sources. The energy of the electron beam can be modulated effectively under resonant conditions by using an intense external laser beam incident into the undulator together with the electron beam. Enhancing the modulation efficiency is crucial for the performance of high repetition rate seeded free electron lasers (FELs) and other related devices. In this paper, we propose a new scheme to augment the efficiency of laser-electron interaction by employing the interaction between a vortex beam and an electron beam within a helical undulator. Three-dimensional time-dependent simulation results indicate that the modulation repetition rate of laser-electron interaction using a vortex beam can be improved by one order of magnitude over the conventional Gaussian beam at the same input power.

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.

The vertical beam halo is the main limitation for very low gap operation of in-vacuum undulators at the ESRF EBS. The vertical halo is due to Touschek electrons with large energy deviation crossing some betatron resonances. The crossing of the resonances can transfer horizontal momentum to vertical momentum. The beam halo has been characterized and measured and different low halo optics have been studied and tested to allow the operation of the machine with lower in-vacuum undulator gaps.

As part of the Diamond-II upgrade project*, the Diamond storage ring will be replaced with a new modified hybrid 6 bend achromat (M-H6BA) lattice, in which each existing arc sections will be split in two to provide additional mid-straights and thereby increase the ring capacity. The majority of insertion devices currently in operation will be either retained or upgraded, and the new mid-straights allow the total number of ID beamlines to be increased from 28 to 36. Therefore, it is important to investigate how the IDs will affect the equilibrium emittance and energy spread, along with their impact on the linear and nonlinear beam dynamics. Methods to compensate for their effects have been established, including a re-optimization of the octupole settings and identification of alternative working points. A kickmap approach has been used to model all IDs, including the APPLE-II IDs and APPLE-II-Knot with active shim wires. In this paper, the outcome of these investigations will be presented and discussed.

Echo-enabled harmonic generation (EEHG) has been proposed as a seeding method for free-electron lasers but can also be employed to generate ultrashort radiation pulses at electron storage rings. With a twofold laser-electron interaction in two undulators, each followed by a magnetic chicane, an electron density pattern with a high harmonic content is produced, which gives rise to coherent emission of radiation at short wavelengths. The duration of the coherently emitted pulse is given by the laser pulse lengths. Thus, the EEHG pulse can be three orders of magnitude shorter and still more intense than conventional synchrotron radiation. At the 1.5-GeV synchrotron light source DELTA at TU Dortmund University, the worldwide first implementation of EEHG at a storage ring was achieved by reconfiguring an electromagnetic undulator. The paper reviews the experimental setup and describes the present status of the project.

A Force-Neutral Adjustable Phase Undulator (FNAPU) has been constructed at the Advanced Photon Source. The FNAPU is a 2.4-meter-long planar hybrid permanent magnet undulator with a 27-mm period length and a fixed gap of 8.5 mm. It consists of two magnetic assemblies with matching periods: one featuring an undulator magnetic structure and the other a simpler magnet structure to compensate the force of the undulator. The magnetic field measurement results of the undulator will be presented.

The Advanced Photon Source Upgrade (APS-U) project has developed and installed a multi-bend achromat (MBA) lattice operating at 6.0 GeV beam energy to replace the existing APS storage ring lattice that operated at 7.0 GeV. A major part of the project is to install 60 hybrid permanent magnet undulator (HPMU) insertion devices (IDs) that include 12 revolver undulators, each with two magnetic structures (for a total of 72 magnetic structures); and one electromagnetic undulator for intermediate energy x-rays (IEX). These IDs will outfit 35 sectors. We have developed new HPMU designs for five different period lengths used in 46 magnetic structures, and we will reuse 26 existing magnetic structures with four additional period lengths. Eight new superconducting undulators (SCUs) have been designed and built with two short period lengths and three different overall lengths [1-3]. The SCUs will be installed in both inline and canted configurations after beam commissioning is completed and the user runs start. Demanding field requirements for the undulators were expected to be challenging for the undulator tuning, especially given the tight schedule. All undulators underwent rigorous tuning and control system tests before they were installed in the new storage ring. We will provide a status and schedule update including presenting measurement results of the IDs.

The Advanced Photon Source Upgrade (APS-U) will deliver a new storage ring based on a Multi-Bend Achromat (MBA) lattice featuring swap-out on-axis injection, enabling the use of small diameter insertion device vacuum chambers. To leverage this advantage, we designed an X-undulator similar to the APPLE-X undulator but with a fixed gap and additional simpler magnet arrays for force compensation. The X-undulator is a pure permanent-magnet-based polarization variable undulator with a 30 mm period length and an 8.5 mm diameter bore in the beam center. The gaps between neighboring undulator magnetic arrays are 3 mm. Variation of the radiation wavelength and polarization is achieved using the longitudinal motion of the undulator magnetic arrays. This contribution covers the magnetic and mechanical design, as well as the optimization of this X-undulator.

Prior to assembly into the operational cryostat each superconducting undulator (SCU) at the Advanced Photon Source undergoes testing in a LHe bath cryostat where coil training and magnetic measurements are performed. If necessary, the baseline magnetic measurements are used for phase error tuning which is achieved by adjusting the magnetic gap of the SCU at prescribed locations. An optimization routine using a genetic algorithm is used to determine the magnitude of the gap change. Once complete, the SCUs are incorporated into the production cryostat and magnetic measurements of the final assembly are performed. Details of the process during phase error tuning and LHe bath testing of a 1.5 m-long SCU magnet are presented.

An Argonne-SLAC collaboration is working on the design of a superconducting undulator (SCU) demonstrator for a free-electron laser (FEL)*. A SCU magnetic structure consisting of a 1.5-m-long planar SCU magnet, and a superconducting phase shifter have been designed. A novel three-groove correction scheme has been implemented for the SCU magnet. A compact four-pole phase shifter with magnetic shields was also designed. This paper presents the calculations of the magnetic performance of the phase shifter and a planar SCU magnet, which include magnetic field and field integrals with end corrections.

New Hybrid Permanent Magnet Undulators (HPMUs) have been designed and manufactured using servo motors for precise and reliable gap motion control for the Advanced Photon Source Upgrade (APS-U) project. Meanwhile, existing HPMUs equipped with legacy stepper motors are systematically replaced with servo motors. In parallel with mechanical modifications of the undulators, a comprehensive upgrade has been implemented for the control of the devices. This upgrade includes integration of standardized industrial components for replacement of motor controllers and motor drives using the Kollmorgen Programmable Controller Multi-axis Master (PCMM) controllers and the AKD2G series servo drives. Soft Input Output Controllers (IOCs) are developed and deployed to replace the legacy VME-based IOCs for both single-period undulators and Revolver undulators. In this paper, we will present the architecture of the new insertion device control system, including control mechanisms, interlock protocols, and tools for diagnostics and troubleshooting.

Taiwan Photon Source (TPS) is a 3 GeV synchrotron light source at the National Synchrotron Radiation Research Center (NSRRC) in Taiwan. Several in-vacuum undulators are expected to be installed before the end of 2024. Before installation in the storage ring, an in-vacuum undulator's magnetic field has been measured at operational gaps. In order to assess the performance of the in-vacuum undulator, we integrated two measurement methods in the vacuum chamber: one is the SAFALI (Self Aligned Field Analyzer with Laser Instrumentation) system to measure the magnetic field, and the other is the stretched wire system to measure the magnetic field integral. In this work, we designed a stretched wire measurement system integrated with the SAFALI system inside the vacuum chamber. This measurement system was applied to the in-vacuum undulator with a period of 22mm and a magnetic length of 2 m.

RadiaBeam is developing and manufacturing a 15-mm period, 1.15 T high temperature superconductor undulator using Magnesium Diboride (MgB2) wire to operate in a temperature range of 10 K - 15 K. This temperature range can be achieved by a cryocooler, a simpler and less expensive cryogenic solution compared to a liquid helium approach. As the supported current density, and ultimately the quench behavior of MgB2 wire, is a combined problem of magnetic field, tensile stress, tensile strain and temperature, a multiphysics approach is required. We will present the details of this multiphysics design addressing the magnetic, mechanical and thermal engineering challenges, along with the devices anticipated performance characteristics.

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.

In the framework of the SABINA project (Source of Advanced Beam Imaging for Novel Applications), a new Free Electron Laser line will be realized at the Laboratori Nazionali di Frascati (LNF). It will be based in the SPARC_LAB laboratory with the purpose to supply radiation in the Thz/MIR range to external user. The line layout foresees two correctors between the three APPLE-X undulators devoted to providing angular and position offset correction to the beam aiming to maximize the efficiency of the FEL process. They will steer the electron beam both in the X and Y axis at the mrad level, and they will be integrated with Beam Position Monitors to perform the trajectory correction and the position monitoring at the same point. This paper presents the magnetic design of the two correctors performed by OPERA 3D software, the mechanical design, the manufacturing together with the magnetic measurement performed at the magnetic laboratory facility in LNF using a Hall probe system.

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.

The research is focused on finding new ways to generate high-intensity, monochromatic X and gamma-rays, surpassing the capabilities of existing methods. While Free-Electron Lasers (FEL) have limitations on photon energy, and Inverse Compton Scattering relies on powerful lasers, the search for alternatives continues. TECHNO-CLS, a PATHFINDER project funded by the European Innovation Council, is dedicated to crafting innovative gamma-ray Light Sources (LSs), utilizing linear, bent, or periodically bent crystals. Similar to magnetic undulators, crystals leverage a strong interplanar electrostatic field to prompt particle oscillation, resulting in electromagnetic radiation. By reducing the oscillation period to sub-mm dimensions, these undulators can produce tens of MeV in photon energy when exposed to GeV electron beams*. As a passive and sustainable element, CLSs show great promise. In the initial phase of the project, we identified techniques to realize CLSs, using alternated pattern deposition on silicon, using simulation to optimize the pattern and conducted experiments at CERN PS with Tungsten and Iridium crystals.

A novel soft X-ray BPM (sXBPM) for high-power white beams of synchrotron undulator radiation has been developed through a joint effort of BNL/NSLS-II and Stony Brook University. In our approach, custom-made multi-pixel GaAs detector arrays are placed into the outer portions of the X-ray beam, and the beam position is inferred from the pixel photocurrents. Our goal is to achieve micron-scale positional resolution without interfering with user experiments, especially the most sensitive ones exploiting coherent properties of the beam. An elaborate mechanical system, which provisions for possible intercepts of kW-level beam in abnormal conditions, has been designed, fabricated, and installed in the 23-ID canted undulator beamline first optical enclosure. Separately, GaAs detectors with specially tailored spectral response have been designed, fabricated, and tested in the soft and hard X-ray regions at two NSLS-II beamlines. The paper gives an overview of the sXBPM system, presents the first results from the high-power white X-ray beam, and explains why our approach can be beneficial for XBPMs in future light sources with highly coherent beams.

The large amount of energy required to operate large-scale facilities with particle accelerators within has been considered as one of the important research topics over the past years. This sheds light on the importance of the research field of energy management that entitles, with a view to long-term operations, the implementation of smart and sustainable technologies. One of the key technologies in accelerators are superconductor (SC)-based designs. The vanishing electrical resistance together with the ability to provide field values well above those from conventional conductors is the main motivation behind exploiting superconducting wires in building coils and magnets for large-scale accelerators. However, these superconductors can also quench under certain conditions, driving the wires into the normal state and potentially allowing for overheating and destruction of the conductor material and/or the whole design. This work will present the results of optimization-based analyses performed on accelerator SC-sample components aiming at goal designs that are more energy efficient at a reference operational field or current. A compromise between getting the best performance for excellent science from a design (with superconductivity preserved and safe operation maintained) and reducing its power consumption (and eventually its effective cost) will be addressed too.

The National Synchrotron Radiation Research Center (NSRRC) has conducted a study on the magnetic circuit design of a high-temperature superconducting undulator (HTSU). This study explores the potential use of second-generation high-temperature superconducting (2G-HTS) materials in undulator magnet, which offer advantages such as higher current density and operating temperature. To evaluate the feasibility of HTSU design, a preliminary magnetic circuit analysis has been conducted. The simulation of the HTSU involved the use of several commercial 2G-HTS tapes with different widths. Insulating and non-insulating HTS tapes were compared to evaluate their effects on current density and magnetic field. Additionally, the maximum field strength on the surface of the tape was determined to establish the optimal operating temperature and current density for the HTSU. These simulation results provide valuable insights for optimizing the design and performance of the HTSU, ultimately contributing to advancements in particle accelerator technologies.

The European Synchrotron Radiation Facility (ESRF) presently operates with the Hybrid Multi-Bend Achromat (HMBA) lattice that features 𝛽-functions of 6.9 m and 2.7 m in the horizontal and vertical planes at the center of the straight sections. New optics were designed to increase the brilliance of beam lines with a single undulator placed at the center of the straight section. The reduction of the in-vacuum undulator gap and of the beta-functions both contribute to this increase. This paper reports on the optics beam commissioning results and experimental observation with the reduced in-vacuum undulator gap.

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.

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.

An exact solution for the radiation field of a particle in a helical undulator, valid for an arbitrary point in space and an arbitrary particle energy, was obtained by the partial domain method, generalized for the case of spiral motion of a particle. The interface between the regions is a cylindrical surface containing the spiral trajectory of the particle. A comparison is made with the existing solution, which is valid in the far zone at high particle energies.

In 2016 the Australian Synchrotron embarked on the BRIGHT program to build four new insertion device beamlines: Biological Small Angle X-ray Scattering (BioSAX), High Performance Macromolecular Crystallography, Advanced Diffraction and Scattering and Nanoprobe beamlines. To maximize the flux for these very demanding beamlines, cryogenic and short period devices have been selected. In particular a 1.6 m long 16 mm period superconducting undulator, a 3 m long 18 mm period cryogenic undulator (CPMU), 3 m long 17 mm in-vacuum undulator and a 2 m long 48 mm period superconducting wiggler. This report will discuss some of the design considerations and overall parameters of the new insertion devices.

SIRIUS is the Brazilian 4th generation synchrotron light source. Currently, SIRIUS is in its Phase 1 stage of the project, with 14 beamlines proposed, some of which are already used by external users. Recently, the SABIÁ beamline underwent a transition where its commissioning insertion device (ID) was replaced by the beamline’s titular ID, an in-house developed DELTA undulator. This device offers versatility in generating various polarizations of light depending on the relative positions of the ID cassettes. However, each permissible configuration engenders distinct perturbations in beam dynamics, particularly affecting beam orbit, optics, and equilibrium parameters. This paper reports the impacts of the DELTA on beam dynamics and outlines the correction strategies implemented to mitigate these effects

We discuss the design and properties of a proposed planar cryogenic permanent magnet undulator with 20 mm period length called CPMU-20. The undulator is set to use (Pr,Nd)2Fe14B as permanent magnet material and Permendur poles and is set to be part of the planned SoTeXS beamline at the BESSY-II upgrade which will offer a unique working environment for research into energy-materials – especially energy-storage materials. The CPMU-20 is designed to produce high photon fluxes in the energy range of 0.5 to 5 keV with a maximum K-value of 2.2 which permits research into a wide range of materials used in state of the art batteries. The optimization process that led to the specific device properties like the period length, the width of the poles and the end-magnet configuration – which ensures an aligned electron beam through the device for the whole gap-range from 6 to 22 mm - will be presented in detail. This includes a discussion of the usage of the UNDUMAG and WAVE software written by Michael Scheer for the optimization and simulations.

The SABINA project will add a user facility to SPARC_LAB at INFN in Frascati (Rome). For the THz line, an electron beam is transported to the APPLE-X undulators to produce photon pulses in the ps range, with energy of tens of µJ, with linear or elliptical polarization. Each undulator has four magnetic arrays that can be moved radially simultaneously to set the operating gap. Two arrays can also move longitudinally for phase displacement. A structural analysis of this unique mechanical structure has been performed by the production company (KYMA S.p.a) to ensure good field quality and beam trajectory. To support those, a set of tests has been performed with FBG acting as strain sensors in Frascati. An FBG is a phase grating inscribed in the core of a single-mode fiber, whose Bragg-diffracted light propagates back along the fiber. Any deformation of the grating affects its pitch, which changes the diffracted Bragg wavelength thus giving information about the occurred deformation. Application of the technique at the state-of-the-art level allows to perform strain measurements with 1 µStrain resolution. Such analysis and results will be presented in this contribution.

Undulators are X-ray sources which are widely used in synchrotron storage rings or in future light sources such as free-electron lasers. Due to sustainability and energy efficiency the development envisages small-scale high-field and compact undulators with short period lengths (<10 mm) and narrow magnetic gaps (<4 mm). Therefore, high-temperature superconducting (HTS) tapes, which can provide both large critical current densities and high critical magnetic fields, are widely used and investigated at KIT. A new concept of superconducting undulators (SCUs) was introduced and further developed by laser-scribing a meander pattern into the superconducting layer to achieve quasi-sinusoidal current path through the tape. In this contribution, we present our results from the design study in respect of the cooling concept for a compact SCU. The foreseen cooling is based on the one hand on calculations of the different heat loads through synchrotron radiation, impedance, and current supplies and on the other hand on the design of the liner including the tapering.

Cryogenic permanent-magnet undulators (CPMUs) have become a point of interest in the development of short-period undulators. However, electron beam-induced heating presents a significant challenge to CPMU devel-opment. The CU15, using a conduction-cooled cooling mechanism, demonstrates exceptional spectral and opera-tional performance, even when operating at small gaps with a beam current of 500 mA. This CPMU has served as a reliable light source for a powder-diffraction beamline for over three years.

RadiaBeam is designing and manufacturing a 15-mm period, 1.15 T field superconducting undulator. Realizing these parameters require a small gap, on the order of 5 mm. This small gap imparts a thermal management challenge due to heating from resistive walls, wakefields, upstream dipoles, and particle losses which is challenging to overcome with NbTi or NbSn3 wires without the use of liquid helium. Further, to reduce operating costs and reliance on liquid helium infrastructure, this undulator is designed to run off cryocoolers. In order to provide sufficient thermal overhead for cryocooling capacities, we will utilize Magnesium Diboride (MgB2), a metallic superconductor with a transition temperature at around 39 K. Thermo-mechanical engineering design studies and production plans of our prototype will be presented.