The PETRA-IV next-generation synchrotron radiation source at DESY is currently in preparation with a completely new accelerator and a new experimental hall, retaining as much of the existing PETRA-III buildings, tunnels and experimental beamlines as possible. We have set up a CAD integration model for the complete accelerator and photon science complex. The model hierar-chy has levels reflecting decisions on project organisation, project phases, design process, and overall product structure. Modularisation and designing in three levels of detail help to manage the complexity and keep the model performant. Placement of accelerator components is determined by the lattice through direct access to spreadsheet data, allowing fast design changes after a lattice update and ensuring consis-tency between mechanical and lattice design. The resulting model will support engineering processes over the complete facility lifecycle.

The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created. The first operation of the European X-ray free-electron laser facility accelerator based on superconducting technology is reported. The maximum electron energy is 17.5 GeV. A laser average power of 6 W is achieved at a photon energy of 9.3 keV.

A special feature of the European XFEL X-ray laser is the possibility to distribute the electron bunches of one beam pulse to different free-electron laser (FEL) beam-lines. This is achieved through a combination of kickers and a Lambertson DC septum. The integration of a beam abort dump allows a flexible selection of the bunch pattern at the FEL experiment, while the superconducting linear accelerator operates with constant beam loading. The driver linac of the FEL can deliver up to 600 µs long bunch trains with a repetition rate of 10 Hz and a maximum energy of 17.5 GeV. The FEL process poses very strict requirements on the stability of the beam position and hence on all upstream magnets. It was therefore decided to split the beam distribution system into two kicker systems, long pulse kickers with very stable amplitude (flat-top) and relatively slow pulses and fast stripline kickers with moderate stability but very fast pulses. This contribution gives a brief overview of the fast kicker system.

Bunch compressors are essential for the generation of short bunches with applications in e.g. colliders, free electron lasers, and advanced accelerator concepts. The up-andcoming ARES accelerator located at SINBAD, DESY will support the formation of ∼100 MeV, pC, sub-fs electron bunches for LWFA research and development. We give an overview on the ARES bunch compressor, providing start-toend simulations of the machine and an update on its technical design.

A collaboration between DESY, PSI and CERN has been established to develop and build an advanced modular Xband transverse deflection structure (TDS) system with the new feature of providing variable polarization of the deflecting force. The prototype of the novel X-band TDS, the Polarizable X-band (PolariX) TDS, was fabricated at PSI following the high-precision tuning-free production process developed for the C-band Linac of the SwissFEL project. Bead-pull RF measurements were also performed at PSI to verify, in particular, that the polarization of the dipole fields does not have any rotation along the structure. The highpower test was performed at CERN and now the TDS is at DESY and has been installed in FLASHForward, where the first streaking experience with beam will be accomplished. We summarize in this paper the status of the project, the results of the bead-pull measurements and the high power test. INTRODUCTION Several experiments at DESY (FLASH2, FLASHForward, SINBAD) and PSI (ATHOS at SwissFEL) are interested in the utilization of high gradient X-band TDS systems for high resolution longitudinal diagnostics [1]. In this context, a collaboration between DESY, PSI and CERN has been established to develop and build an advanced modular X-Band TDS system with the new feature of providing variable polarization of the deflecting force [2]. The prototype of the novel X-band TDS, the Polarizable X-band (PolariX) TDS, has been fabricated at PSI following the high-precision tuning-free production process developed for the C-band Linac of the SwissFEL project and already used for the fabrication of the tuning-free X-band structure prototypes for CLIC [3–5]. Bead-pull RF measurements has been performed at PSI between December 2018 and January 2019 in order to verify that the polarization of the dipole fields does not have any rotation along the structure. Figure 1 shows the detail of the input and output couplers (left), the whole TDS prototype (middle) and the basic disk geometry (right). The main RF parameters of the TDS and RF pulse ∗ paolo.craievich@psi.ch compressor are summarized in Table 1. High power test on the prototype has been performed at CERN between March and April 2019. In this paper we summarize the status of the collaboration focusing on the results of the bead-pull measurements and the high power tests. Figure 1: Left: detail of the input/output coupler. Middle: whole TDS prototype. Right: basic disk. BEAD-PULL MEASUREMENTS The dipole field flatness and polarization were measured with the bead-pull method. The structure was allocated in a vertical frame and a stepper motor was used to drive along the structure a 2 mm diameter dielectric sphere fixed to a dielectric wire with diameter of 0.16 mm. The bead pulling has been repeated for different offsets, both in the XZ and YZ planes, in ±2 mm range. The measurements were performed with a 4-port VNA and the reflection coefficient resulted to be less than −35 dB with an insertion loss of −5.5 dB. Figure 2 (upper plot) shows results of the bead-pull measurement with offset 0 mm both in X and Y and phase difference between ports of 0 deg. Cell-to-cell phase advance (lower plot) resulted to be 2π/3 with a dispersion of 0.8∘ rms at the working frequency of 11995.2 MHz with a temperature of 33.9∘C. It is worthwhile noting that same results for the phase ad-vance was obtained varying the relative phase between ports, namely for different polarizations. A spherical and dielectric bead perturbs only the electric field, but cannot distinguish between longitudinal and transverse components. However, since the longitudinal component has the largest 39th Free Electron Laser Conf. FEL2019, Hamburg, Germany JACoW Publishing ISBN: 978-3-95450-210-3 doi:10.18429/JACoW-FEL2019-WEP036

The PETRA IV project is to upgrade the current PETRA III light source to a 4th generation synchrotron radiation source reaching the diffraction limit of X-ray energies of about 10 KeV. Due to the small dynamic aperture of the PETRA IV storage ring, a horizontal on-axis injection is necessary. In this paper, the preliminary study of the injection scheme is described, including the details of the injection pattern and the technical requirements of kickers and septa. A beam abort scheme for the high intensity, low emittance beam is explained. To meet the requirements for the on-axis injection, upgrading the injector complex consisting of the Gun, the LINAC and the booster is planned. Several options are discussed in this paper.

Since 2016 DESY has been pursuing R&D towards upgrading its PETRA synchrotron light source to a fourth-generation machine, PETRA IV, which is expected to start operation in 2027. The conceptual design of a 6 GeV seven-bend-achromat-based lattice with an approx. 10pm emittance along with critically important technical systems has been completed. We will present the status of the project, the expected parameter space of the facility, and lattice design and beam dynamics issues for the main ring.

A collaboration between DESY, PSI and CERN has been established to develop and build an advanced modular Xband transverse deflection structure (TDS) system with the new feature of providing variable polarization of the deflecting force. This innovative CERN design requires very high manufacturing precision to guarantee highest azimuthal symmetry of the structure to avoid the deterioration of the polarization of the streaking field. Therefore, the high-precision tuning-free production process developed at PSI for the Cband and X-band accelerating structures will be used for the manufacturing. We summarize in this paper the status of the production of the prototype and the waveguide networks foreseen in the different facilities.

The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) is foreseen to host multiple ex-periments relating to the production of ultra-short electron bunches and novel high gradient acceleration techniques. The SINBAD-ARES linac will be a conventional S-band linear RF accelerator allowing the production of low charge (0.5 pC - tens pC) ultra-short electron bunches (FWHM length ≤ 1 fs - few fs) with 100 MeV energy. The installation of the linac will proceed in stages. In this paper we report on the status of the characterization of the ARES RF gun and the installations of the related infrastructure.

ARES (Accelerator Research Experiment at Sinbad) is a linear accelerator for the production of low charge (from few pC to sub-pC) electron bunches with 100 MeV energy, fs and sub-fs duration and excellent arrival time stability. This experiment is currently under construction at DESY Hamburg and it is foreseen to start operation by the begin-ning of 2018 with the commissioning of the RF-gun. After an initial beam characterization phase, ARES will provide high temporal resolution probes for testing novel acceleration techniques, such as Laser driven plasma Wake-Field Acceleration (LWFA), Dielectric Laser Acceleration (DLA) and THz driven acceleration. In this work we present an overview of the most up-to-date design of the linac with a special focus on 3D integration considerations and phases of the installation of the beamline.

For the Linac II, which supplies the accelerator chain at DESY with electrons and positrons, a new injection system is planned. It is supposed to ensure reliable operation and to avoid the beam loss of about 60% before the positron converter and the associated activation. The main components are a 6 A/100 kV triode gun, buncher and a dispersive section for energy collimation. The output energy is 5 MeV. The new buncher structure is a hybrid of a standing wave and traveling wave structure and allows a compact design and good electron capture. Its main part is a traveling wave structure in 2π/3 mode, to which one capture cell is coupled in π mode. The function of the injector components, the entire injection system and the acceleration in the linac sections were optimized in simulations. In addition, the design is analysed in a test rig before final installation. Test rig and subsequent injector are equipped with extensive diagnostics. Besides the design of the injection system results of simulations and measurements on the test rig will be presented.

For successful operation of X-ray Free Electron Lasers, one crucial parameter is the ultrashort electron bunch length yielding a high peak current and a short saturation length. In order to effectively compress the bunches during the acceleration process, a detailed understanding of the full longitudinal phase space distribution already in the injector is required. Transverse deflecting RF structures (TDS) can shear the bunch transversely, mapping the longitudinal coordinate to a transverse axis on an observation screen downstream. In addition to the bunch length, the slice emittance along the bunch as well as the full longitudinal phase space can be obtained. At the Photo Injector Test Facility at DESY, Zeuthen site (PITZ), an S-band traveling wave TDS is under commissioning since 2015. This cavity is a prototype for the TDS in the injector part of the European XFEL and has been designed and manufactured by the Institute for Nuclear Research (INR RAS, Moscow, Russia). In this paper, first commissioning results of the system at PITZ are presented and discussed.

The 3.9 GHz cryomodule and RF system for the XFEL Injector is being assembled and delivered to the underground building in summer 2015, for the injector commissioning in Fall 2015. This contribution outlines the status of the activity and reports the preparation stages of the technical commissioning of the system.

A new injection system is under development for the LINAC II at DESY to improve the reliability of the machine and mitigate the radiological problem due to electron losses at energy of hundreds of MeV. It consists of a 100 kV triode DC gun, a 2.998 GHz pre-buncher, a novel 2.998 GHz hybrid buncher, and the dedicated beam transport and diagnostic elements. As the key components, the pre-buncher and the hybrid buncher realize a two-stage velocity bunching process including the ballistic bunching and the phase space rotation. Therefore, they produce a certain number of wellbunched 5 MeV micro-bunches from the input 2 ns-50 ns electron pulse for the downstream LINAC II. The overall upgrade plan, developments of the critical components, as well as the latest beam test results will be reported.

ARES is a planned linear accelerator for R&D for production of ultra-short electron bunches. It will be hosted at the SINBAD facility, at DESY in Hamburg [1]. The goal of ARES is to produce low charge (0.2 - 50 pC), ultra-short (from few fs to sub-fs) bunches, with high arrival time stability (less than 10fs) for various applications, such as external injection for Laser Plasma Wake-Field acceleration [2]. The baseline layout of the accelerator foresees an S-band photo-injector which compresses low charge electron bunches via velocity bunching and accelerates them to 100 MeV energy. In the second stage, it is planned to install a third S-band accelerating cavity to reach 200 MeV as well as two X-band cavities: one for the linearization of the longitudinal phase space (subsequently allowing an improved bunch compression) and another one as a Transverse Deflecting Cavity (TDS) for longitudinal beam diagnostics. Moreover a magnetic bunch compressor is envisaged allowing to cut out the central slice of the beam [3] or hybrid bunch compression.