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Laser-based plasma accelerators (LPA) have successfully demonstrated their capability to generate high-energy electron beams with intrinsically short bunch lengths and high peak currents at a setup with a small footprint. These properties make them attractive drivers for a broad range of different applications including injectors for rf-driven, ring-based light sources. In close collaboration the Deutsches Elektronen-Synchrotron (DESY), the Karlsruhe Institute of Technology (KIT) and the Helmholtz Institute Jena aim to develop a 50 MeV plasma injector and demonstrate the injection into a compact storage ring. This storage ring will be built within the project cSTART at KIT. As part of the ATHENA (Accelerator Technology HElmholtz iNfrAstructure) project, DESY will design, setup and operate a 50 MeV plasma injector prototype for this endeavor. This contribution gives a status update of the 50 MeV LPA-based injector and presents a first layout of the prototype design at DESY in Hamburg., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil The 12th International Particle Accelerator Conference, IPAC 2021, Campinas, Brazil, 24 May 2021 - 28 May 2021; JACoW Publishing, Geneva, Switzerland 4 pp. (2021). doi:10.18429/JACOW-IPAC2021-TUPAB163, The laser-driven generation of relativistic electron beams in plasma and their acceleration to high energies with GV/m-gradients has been successfully demonstrated. Now, it is time to focus on the application of laser-plasma accelerated (LPA) beams. The 'Accelerator Technology HElmholtz iNfrAstructure' (ATHENA) of the Helmholtz Association fosters innovative particle accelerators and high-power laser technology. As part of the ATHENAe pillar several different applications driven by LPAs are to be developed, such as a compact FEL, medical imaging and the first realization of LPA-beam injection into a storage ring. The latter endeavor is conducted in close collaboration between Deutsche Elektronen-Synchrotron (DESY), Karlsruhe Institute of Technology (KIT) and Helmholtz Institute Jena. In the cSTART project at KIT, a compact storage ring optimized for short bunches and suitable to accept LPA-based electron bunches is in preparation. In this conference contribution we will introduce the 50 MeV LPA-based injector and give an overview about the project goals. The key parameters of the plasma injector will be presented. Finally, the current status of the project will be summarized., Published by JACoW Publishing, Geneva, Switzerland

Over the last years, the generation and acceleration of ultra-short, high quality electron beams has attracted more and more interest in accelerator science. Electron bunches with these properties are necessary to operate and test novel diagnostics and advanced high gradient accelerating schemes such as plasma accelerators or dielectric laser accelerators. Furthermore, several medical and industrial applications require high-brightness electron beams. The dedicated R&D facility ARES at DESY will provide such probe beams in the upcoming years. After the setup of the normal-conducting RF photoinjector and linear accelerating structures, ARES successfully started the beam commissioning of the RF gun. This paper gives an overview of the ARES photoinjector setup and summarizes the results of the gun commissioning process. The quality of the first generated electron beams is characterized in terms of charge, momentum, momentum spread and beam size. Additionally, the dependencies of the beam parameters on RF settings are investigated. All measurement results of the characterized beams fulfill the requirements to operate the ARES linac with this RF photoinjector.

Zukünftige Beschleunigerprojekte und Nutzerexperimente erfordern für ihren Betrieb einen hochbrillanten Elektronenstrahl mit hohem mittlerem Strom. Eine Elektronenquelle mit dem Potential die Anforderungen erfüllen, ist ein supraleitender Hochfrequenz (SHF) Photoinjektor im Dauerstrichbetrieb. Die Strahldynamik eines solchen Photoinjektor Systems bestimmt die maximal zu erreichende Strahlbrillanz und wird ihrerseits von den Design und Betriebsparametern des Photoinjektors beeinflusst. Ziel ist immer die entscheidenden Design- und Betriebsparameter der Elektronenquelle hinsichtlich einer maximalen Strahlbrillanz zu wählen. Diese Aufgabe verlangt ein detailliertes Verständnis der Strahldynamik-Prozesse. Ferner ist es notwendig, eine Optimierung des Photoinjektors als Ganzes, mit dem Ziel einer maximalen Strahlqualität bei hohem mittlerem Strom, vorzunehmen. Dieses ermöglicht auch, die physikalischen Grenzen eines gegebenen Designs zu ermitteln und im Betrieb vollständig auszunutzen. Diese Doktorarbeit befasst sich mit der Strahldynamik in einem SHF Photoinjektor, unter Berücksichtigung interner Raumladungseffekte. Die Erkenntnisse zur Strahldynamik werden für die Entwicklung eines Optimierungsprogramms verwendet, um die Leistung des Injektors hinsichtlich der Strahlbrillanz zu verbessern. Die entwickelte Methode basiert auf Pareto-Optimierung mehrerer Zielfunktionen, unter Verwendung eines generischen Algorithmus. Das zentrale Ergebnis dieser Arbeit umfasst ein universelles Optimierungsprogramm, das für Photoinjektoren unabhängig von ihrem Design und Anwendungsgebiet genutzt werden kann. Für den Betrieb mit hoher Strahlbrillanz ist es möglich aus den erhaltenen Pareto-optimalen Lösungen einen stabilen Satz an Einstellwerten für den Photoinjektor zu extrahieren. Durch die allgemeine Optimierungsstrategie lässt sich das entwickelte Programm auch für andere Beschleunigerabschnitte, oder die Optimierung einer ganzen Anlage mit erweiterter Zielsetzung anpassen. An increasing number of future accelerator projects, light sources and user experiments require high brightness, high average current electron beams for operation. Superconducting radio-frequency (SRF) photoinjectors running in continuous-wave (cw) mode hold the potential to serve as an electron source that generates electron beams of high brightness. Different operation and design parameters of the SRF photoinjector impact the beam dynamics and, thus, the beam brightness. Therefore, an in-depth understanding of the beam dynamics processes in an SRF photoinjector and the dependency of the beam dynamics on the photoinjector set parameters is crucial. A high brightness beam operation requires a global optimization of the SRF photoinjector that allows to find suitable photoinjector settings and to figure out and extend the physical performance limits of the investigated injector design. The dissertation at hand offers a detailed analysis of the beam dynamics in an SRF photoinjector regarding internal space charge effects. Furthermore, the impact of the photoinjector elements on the electron beam is discussed. The lessons learned from this theoretical view are implemented in the development of an optimization tool to achieve a high brightness performance. A universal multi-objective optimization program based on a generic algorithm was developed to extract stable, optimum gun parameter from Pareto-optimum solutions. This universal tool is able to optimize and find the physical performance limit of any (S)RF photoinjector independent from the individual application of the electron source (energy recovery linac, free electron laser, ultra-fast electron diffraction). This thesis thereby verifies and complements existing theoretical considerations regarding photoinjector-beam interactions. The global optimization strategy can be introduced to variable optimization objectives as well as it can be extended to an optimization of further parts of the accelerator facility.

10th International Particle Accelerator Conference, IPAC'19, Melbourne, Australia, 19 May 2019 - 24 May 2019; JACoW Publishing, Geneva, Switzerland 143-146 (2019). doi:10.18429/JACOW-IPAC2019-MOPGW027, SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility aims to produce ultrashort bunches (sub-fs) at ~100 MeV, suitable for injection into novel accelerators e.g. dielectric Laser acceleration (DLA) and Laser Driven Wakefield acceleration (LWFA). The LWFA experiment demands β functions to be of the order of 1 mm to reduce energy spreads and emittance growth from nonlinearities. Matching such a space charge dominated beam to such constraints with conventional electromagnets is challenging. A Permanent Magnetic Quadrupole (PMQ) triplet is one promising focusing strategy. In this paper, we investigate the performance of a PMQ triplet to fit the requirements of the electron beam properties in a plasma cell and discuss the realizable phase spaces for the LWFA experiment planned at SINBAD., Published by JACoW Publishing, Geneva, Switzerland

The ARES (Accelerator Research Experiment at SINBAD) linac at the accelerator R facility SINBAD (Short innovative bunches and accelerators at DESY) will drive multiple independent experiments including the acceleration of ultrashort electron bunches. In addition the linac will host an experimental area, open for transnational access, to study advanced high gradient, laser driven, acceleration concepts, like the ones studied within the ACHIP (accelerator on a chip) project. The area will be operational mid-2019. This paper will report on the current status of the experimental area, including hardware parameters, beam optics, achievable beam parameters, design of the experimental chamber and commissioning plans. The modification plans for a micro-bunching experiment in the frame of the ACHIP experiment and future upgrade plans will be shown and discussed in detail., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a demonstration facility for the science and technology of ERLs for future light source applications. BERLinPro is designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the last year's progress, including the comissioning of the gun module as the first SRF component to be installed in BERLinPro., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

Helmholtz-Zentrum Berlin (HZB) is currently constructing a high average current superconducting (SC) ERL as a prototype to demonstrate low normalized beam emittance of 1 mm-mrad at 100 mA and short pulses of about 2 ps. To attain the required beam properties, an SRF based photo-injector system was developed and during the past year underwent RF commissioning and was setup within a dedicated diagnostics beamline called Gunlab to analyze beam dynamics of both, a copper cathode and a Cs2KSb cathode as well as their quantum efficiency at UV and green light respectively. The medium power prototype - a first stage towards the final high power 100 mA design - presented here features a 1.4 x λ/2 cell SRF cavity with a normal-conducting, high quantum efficiency CsK2Sb cathode, implementing a modified HZDR-style cathode insert. This injector potentially allows for 6 mA beam current and up to 3.5 MeV kinetic energy, limited by the modified twin TTF-III fundamental power couplers. In this contribution, the first RF commissioning results of the photo-injector module will be presented including dark current analysis as well as measured beam properties with an initially installed Copper cathode., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

Several future accelerator projects, light sources and user experiments require high brightness electron beams. SRF photoinjectors operating in continuous-wave (cw) mode hold the potential to serve as an electron source generating beams of high average brightness and short bunch lengths. Different operation and design parameters of the SRF photoinjector impact the beam dynamics and thus the beam brightness. A universal multi-objective optimization program based on a genetic algorithm was developed to extract optimum gun parameter settings from Pareto-optimum solutions. After getting the first optimum results, the photoinjector is supplemented with a booster section downstream. The new optimization results are presented. Further, the optimization program is applied to evaluate the impact of the field flatness of the gun cavity on the high brightness performance., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The Superconducting RF (SRF) photoinjector programme for the energy-recovery linac (ERL) test facility BERLinPro sets out to push the brightness and average current limits for ERL electron sources by tackling the main challenges related to beam dynamics of SRF photoinjectors, the incorporation of high quantum efficiency (QE) photocathodes, and suppression of unwanted beam generation. The paper details the experimental layout of the SRF photoinjector and the gun test facility GunLab at Helmholtz-Zentrum Berlin., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a demonstration facility for the science and technology of ERLs for future light source applications. BERLinPro is designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the project status. This includes the completion of the building and the installation of the first accelerator components as well as the assembly of the SRF gun and GunLab beam diagnostics, which are now ready for commissioning., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Superconducting RF photoinjectors, running in continuous-wave (cw) mode, are able to generate electron beams of high average brightness and ultra-short bunches. Therefore, they satisfy the requirements of future accelerator facilities, such as energy recovery linacs (ERL). Further, SRF guns are able to provide relativistic probe beams for ultrafast electron diffraction (UED). Choosing suitable values for the drive laser, cavity and solenoid settings poses a great challenge for the injector commissioning and operation. Using multi-objective optimization based on an evolutionary algorithm, optimum gun parameter settings are extracted from Pareto-optimum solutions. The development of a universal multi-objective optimization algorithm for SRF photoinjectors as well as first Pareto optimum results for an ERL and UED application of GunLab, the compact SRF gun test facility at Helmholtz-Zentrum Berlin, will be presented., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

RF photoelectron sources with superconducting cavities provide the potential to generate high quality, high brightness electron beams for future accelerator applications. At Helmholtz-Zentrum Dresden Rossendorf, such an electron source was operated for many years. The commissioning of an improved SRF Gun with a new high-performance gun cavity with low field emission and a superconducting solenoid inside the gun cryomodule (SRF Gun II) has started in June 2014. Simulations of the experimental set-up with ASTRA and ELEGANT were performed. First low current measurements as well as studies of unwanted beam transport using SRF Gun II with Cu photocathode and an acceleration gradient up to 9 MV/m will be presented. First beam characterization of the SRF Gun in combination with ELBE, a two-stage superconducting linear accelerator will be discussed., Proceedings of the 4th International Beam Instrumentation Conference, IBIC2015, Melbourne, Australia

The Helmholtz Zentrum Berlin is constructing the Energy Recovery Linac Project BERLinPro on its site in Berlin Adlershof. The project is intended to expand the required accelerator physics and technology knowledge mandatory for the design, construction and operation of future synchrotron light sources. The project goal is the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beamat 2~ps rms bunch duration or below. The planning phase of the project is completed and the design phase of most of the components is finished. Many of them have already been ordered. After some delay the construction of the building has started in February 2015. The status of the various subprojects as well as a summary of current and future activities will be given. Major project milestones and details of the project time line will be finally introduced., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The Berlin Energy Recovery Linac Prototype BERLinPro is to be constructed at the Helmholtz Zentrum site in Berlin. The aim of the project is to expand the required accelerator physics and technology knowledge mandatory for the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. Since the funding decision in October 2010 the project has entered a phase of detailed planning. Hardware specifications have been defined and various components have been ordered. Furthermore, extensive tests of principal superconducting accelerator components successfully demonstrated the envisaged hardware performance. A summary of the most recent activities together with the details of the project timeline for the coming years are given in this paper., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

In a SRF photoinjector the close relationship between the laser pulse and the generated electron bunch parameters requires continuous monitoring of some of the laser pulse parameters. A laser diagnostic system, called virtual cathode, is a key part of a system that controls the stability of the laser. One of the main challenges for the virtual cathode is to cover the large dynamic range of the photocathode laser between commissioning at 120 Hz and operation at 1.3 GHz repetition rate with constant laser pulse parameters. The design of the virtual cathode as well as first measurements with a photocathode drive laser for the SRF injector test facility GunLab of BERLinPro will be presented., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The Helmholtz Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro at the Berlin Adlershof site. The project is intended to expand the required accelerator physics and technology knowledge mandatory for the design, construction and operation of future synchrotron light sources. The project goal is the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the project progress: since spring 2015 the building is under construction, ready for occupancy in January 2017. The planning phase for the first project stage is completed for the warm machine parts, the SRF gun and partly for the SRF booster. Most of the components have been ordered and are in fabrication with some already delivered. An update of the status of the various subprojects as well as a summary of future activities will be given. Project milestones and details of the timeline will be reviewed., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea