Search

Third update of the XLS Data Management Plan and deliverable D1.2 of CompactLight, published on 31.12.2021, at the end of the project., On behalf of the CompactLight Collaboration

The report presents, as the main result of the CompactLight project, the conceptual design of the CompactLight hard X-ray FEL. It is devided in the following chapters: 1. Executive Summary 2. Introduction 3. Science Goals and Photon Output Requirements 4. Systems Design and Performance 5. Accelerator 6. Light Production 7. Civil Engineering 8. Strategy and Implementation 9. Examples of CompactLight Facilities 10. Alternative Technology Solutions A. Appendices, On behalf of the CompactLight Partnership - see list of all authors in the document.

CompactLight Deliverable D2.1: Science Requirements and Performance Specification for the CompactLight X-Ray Free-Electron Laser, On behalf of the CompactLight Collaboration

The aim of WP7 is to promote the use of the CompactLight technologies through activities that address and inform potential users and by generating instruments and documents that support them in developing and implementing their projects for the construction or upgrading of CompactLight-based facilities. D7.1 is the first version of the corresponding documentation, containing the state of the work and the results achieved by the end of 2019. It presents in particular the insights obtained so far from the dialogue with the scientific user community, preliminary results for the landscape analysis, an explanation of the methodologies and strategies used for market, SWOT and risk analyses, a description of the Project Breakdown Structure and the methodology for the cost analyses, as well as user-relevant information on the project’s data management and ’Open Data’., On behalf of The CompactLight Collaboration.

This report describes the salient conceptual features of the CompactLight photon source, describing the machine layout and its modus operandi. The main parameters of the facility, grouped into facility sub-systems, are summarized in tables, which identify the baseline facility configuration, the proposed upgrade phases, and the technological recommendations provided by the individual work packages for its implementation. As a result, this document anticipates the CompactLight design study, and paves the way to the production of a more detailed conceptual design report., On behalf of the CompactLight Collaboration

As part of the deign studies, the CompactLight project plans to use an injector in the C-band. Which constitutes a particular complication for the harmonic system in charge of linearising the beam’s phase space, since it means its operation frequency could be higher than the standard X-band RF technologies. In the present work, we investigated a 36 GHz (Ka-band) as the ideal frequency for the harmonic system. A set of structure designs are presented as candidates for the lineariser, based on different powering schemes and pulse compressor technologies. The comparison is made both in terms of beam dynamics and RF performance. Given the phase stability requirements for the MW class RF sources needed for this system, we performed careful studies of a Gyro-Klystron and a multi-beam klystron as potential RF sources, with both showing up to 3 MW available power using moderate modulator voltages. Alternatives for pulse compression at Ka-band are also discussed in this work., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The CompactLight project is currently developing the design of a next generation hard X-ray FEL facility, which is based on high-gradient X-band (12 GHz) structures. However, to carry out pump-and-probe experiments in the project, two-bunch operation with a spacing of 10 X-band rf cycles is proposed. A sub-harmonic transverse deflecting structure working at S-band is proposed to direct the two bunches into two separate FEL lines. The two FEL pulses will have independently tunable wavelengths and can be combined in a single experiment with a temporal delay between pulses of ± 100 fs. The rf design of the transverse deflector is presented in this paper., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The H₂020 CompactLight Project aims for the design of innovative, cost-effective, compact FEL facilities to generate higher peak brilliance radiation in the soft and hard X-ray. In this paper we assess via simulation studies the performance of a variably polarising APPLE-X afterburner positioned downstream of a helical Super Conducting Undulator (SCU). We discuss the optimum balance between the active SCU length and the afterburner length, considering the peak brilliance and pulse energy of the output. Our studies are complemented with analysis of the optical beam quality of the afterburner output to determine the design constraints of the photon beamline that delivers the FEL output to the experimental areas., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The CompactLight European consortium is designing a state-of-the-art X-ray free-electron laser driven by radiofrequency X-band technology. Rooted in experimental data on photo-injector performance in the recent literature, this study estimates analytically and numerically the performance of the CompactLight delivery system for bunch charges in the range 75–300 pC. Space-charge forces in the injector, linac transverse wakefield, and coherent synchrotron radiation in bunch compressors are all taken into account. The study confirms efficient lasing in the soft X-rays regime with pulse energies up to hundreds of microjoules at repetition rates as high as 1 kHz.

In the framework of the Compact Light XLS project, we have designed a higher harmonic RF accelerating structure in order to linearize the longitudinal space phase. The design of this compact Traveling Wave (TW) accelerating structure operating on the third harmonic with respect to the linac frequency (11.994 GHz) with a (100-125) MV/m accelerating gradient is presented, together with numerical electromagnetic simulations were carried out by using the numerical codes High Frequency Structure Simulator (HFSS) and CST Particle Studio.

The effect of multiple small-angle Coulomb scattering, or intrabeam scattering (IBS) is routinely observed in electron storage rings over the typical damping time scale of milliseconds. So far, IBS has not been observed in single pass electron accelerators because charge density orders of magnitude higher than in storage rings would be needed. We show that such density is now available at high brightness electron linacs for free-electron lasers (FELs). We report measurements of the beam energy spread in the FERMI linac in the presence of the microbunching instability, which are consistent with a revisited IBS model for single pass systems. We also show that neglecting the hereby demonstrated effect of IBS in the parameter range typical of seeded VUV and soft x-ray FELs, results in too conservative a facility design, or failure to realise the accessible potential performance. As an example, an optimization of the FERMI parameters driven by an experimentally benchmarked model, opens the door to the extension of stable single spectral line emission to the water window (2.3–4.4 nm), with far-reaching implications for experiments in a variety of disciplines, ranging from physics and chemistry to biology and material sciences, and including nonlinear x-ray optics based on the four-wave-mixing approach.

A backward computation method has been developed to accelerate modelling of the critical state magnetization current in a staggered-array bulk high-temperature superconducting (HTS) undulator. The key concept is as follows: i) a large magnetization current is first generated on the surface of the HTS bulks after rapid field-cooling (FC) magnetization; ii) the magnetization current then relaxes inwards step-by-step obeying the critical state model; iii) after tens of backward iterations the magnetization current reaches a steady state. The simulation results show excellent agreement with the H-formulation method for both the electromagnetic and electromagnetic-mechanical coupled analyses, but with significantly faster computation speed. Solving the FEA model with 1.8 million degrees of freedom (DOFs), the backward computation method takes less than 1.4 hours, an order of magnitude or higher faster than other state-of-the-art numerical methods. Finally, the models are used to investigate the influence of the mechanical stress on the distribution of the critical state magnetization current and the undulator field along the central axis., 12 pages, 7 figures

Accelerating structures operating in Ka-Band are foreseen to achieve gradients around 150 MV/m. Among possible applications of a Ka-Band accelerating structure we refer to the beam phase-space manipulation for the Compact Light XLS project as well as medical and industrial applications. In this paper, a Ka-Band Klystron amplifier is being investigated in order to feed Ka-Band accelerating structures. The initial design is presented including the high-power DC gun and the beam focusing channel., 4th European Advanced Accelerator Concepts Workshop (EAAC2019)

Second update of the XLS Data Management Plan and deliverable D1.2 of the project, to be further developed in the course ofthe project.

Second update of the XLS Data Management Plan and deliverable D1.2 of the project, to be further developed in the course of the project., On behalf of the CompactLight Collaboration

CompactLight (XLS) is an International Collaboration of 24 partners and 5 third parties, funded by the European Union through the Horizon 2020 Research and Innovation Programme. The main goal of the project, which started in January 2018 with a duration of 36 months, is the design of an hard X-ray FEL facility beyond today’s state of the art, using the latest concepts for bright electron photo-injectors, high-gradient accelerating structures, and innovative shortperiod undulators. The specifications of the facility and the parameters of the future FEL are driven by the demands of potential users and the associated science cases. In this paper we will give an overview on the ongoing activities and the major results achieved until now.

We studied the degree of polarisation of the FEL radiation from the diverted-beam scheme [1,2] using the layout of the CompactLight facility [3], which is in the process of being designed. To satisfy the polarisation requirements defined by the users [4] without compromising the aim of the facility to be compact, we studied a configuration comprising a helical Super Conductive Undulator (SCU) followed by a Delta afterburner (configured to generate linearly polarised light). The trade-offs between the SCU length, afterburner length, degree of polarisation and pulse energy are presented and discussed.

We present the design of a Free-Electron Laser (FEL) doubler suitable for the simultaneous operation of two FEL lines. The doubler relies on the physical selection of two longitudinal portions of an electron bunch at low energy, and on their spatial separation at high energy. Since the two electron beamlets are naturally synchronized, FEL pump- FEL probe experiments are enabled when the two photon pulses are sent to the same experimental station. The proposed solution offers improved flexibility of operation w.r.t. existing two-pulse, two-color FEL schemes, and allows for independent control of the color, timing, intensity and angle of incidence of the radiation pulses at the user end station. Detailed numerical simulations demonstrate its feasibility at the FERMI FEL facility.

In this deliverable we report an overview of the available tools to perform start to end simulations for the CompacLight facility, covering the beam transport from the cathode to the undulator exit, including space charge effects, coherent synchrotron radiation in magnetic compressors, wakefield effects in the X-band linac and FEL performance. The main objective of WP6 is to provide the key parameters and performance estimates of a facility which meets the user requirements. We need to develop consistent tools for modelling the machine, as the basis for the final integrated performance studies. To this end the tasks of WP6 can be split into three simulation sections, in parallel to facility sections Low energy injector (including gun, prelinac and first bunch compressor) High energy linac (including high energy BCs for both soft and hard X-Ray layout) FEL production (both soft and hard X-Ray FELs) Different simulation tools have been used by the collaborating institutions suitable for the problems mentioned above. All programs used by the team will be utilized during the course of CompactLight design in order to benefit the experience of partners. However, to perform an integrated simulation one of the existing tool for each section is going to be used. Many of the those tools have been evaluated properly on specific problem for each tool and capabilities has been summarized in this report. In addition, the requirement for the translator tool between each code has been discussed., On behalf of the CompactLight Collaboration.

A central element in designing CompactLight is a global optimization that takes into account the performances and costs of the different parts of the facility; injector, linac and photon production. Each of these different areas is individually highly complex, and there are many interconnections. This deliverable report describes the array key computer-based tools which have been assembled and developed for use in the optimization of the CompactLight linac This report describes the array of key computer tools which have been put into place in order to carry out the design, simulation and optimization of the CompactLight linac as well as some preliminary results., On behalf of the CompactLight Collaboration

This document describes with analytical and numerical methods, i.e., approximated mathematical expressions and particle tracking runs, the process of bunch length compression of relativistic electron beams in linear accelerators. In particular, it reviews state-of-the-art compression options, based on magnetic insertions and radio-frequency (RF) accelerators, for the increase of peak current and preservation of the six-dimensional beam brightness as requested by x-ray freeelectron lasers (FELs). After a theoretical introduction to the topic, guidelines for the determination of the compression scheme for the CompactLight FEL are provided, by considering for example RF compression in combination with four dipoles chicanes. The study considers single particle dynamics, tolerance budget and collective effects involved in the compression process. On the basis of FEL specifications, the main parameters of the electron beam and of the compressors in the CompactLight accelerator are illustrated. Finally, a preliminary RF design of X-band and Ka-band accelerating cavities to support magnetic compression is presented. As a result, this review of most advanced electron beam compression schemes provides a solid basis for the definition of the beam manipulation aimed to meet the requirements of CompactLight FEL., On behalf of the CompactLight Collaboration.

The present report is a comprehensive overview of undulator technologies, which are either already exploited at fully operating free-electron laser facilities or going to be available within the forthcoming 5 years. Main emphasis is given to devices based on permanent magnets and on superconducting technologies, scrutinised in terms of status and perspectives, but also novel concepts with a different readiness level are addressed. A technology comparison based on expected performance and a cost estimate of the undulator system are drawn., On behalf of the CompactLight Collaboration

We present the design of a free-electron laser (FEL) doubler suitable for the simultaneous operation of two FEL lines, in either self-amplified spontaneous emission or externally seeded configuration. The doubler relies on the physical selection of two longitudinal portions (beamlets) of a single electron bunch at a low energy and on their spatial separation at high energy. Since the two beamlets are naturally synchronized, FEL pump–FEL probe experiments are enabled when the two photon pulses are sent to the same experimental station. The proposed solution offers improved flexibility of operation compared with existing or designed two-pulse, two-color FEL schemes, as it allows independent control and continuous tunability of the color, timing, intensity, and angle of incidence of the radiation pulses at the user end station. Detailed numerical simulations and experimental results demonstrate its feasibility at the Free Electron laser Radiation for Multidisciplinary Investigations (FERMI) FEL facility.

News article in Accelerating News (Issue 29, CERN, Geneva, 12 July 2019) on the project's secondMidterm Review Meeting in Helsinki 2019.

The CompactLight project is currently developing the design of a next generation hard X-ray FEL facility, based on high-gradient X-band (12 GHz) structures, bright electron photo-injectors, and compact short period undulators. However, to improve the brightness limitations due to the non- linear energy spread of the electron bunches, a Kaband (36 GHz) linearizer is being considered to provide a harmonic compensation during the bunch compression. In this paper, we analyze the feasibility of such linearizer. &nbsp

First update of the XLS Data Management Plan and deliverable D1.2 of the project, to be further developed in the course ofthe project.

First version of the XLS Data Management Plan and deliverable D1.2 of the project, to be further developed in the course ofthe project.

The H2020 CompactLight Project aims at designing the next generation of compactX-rays Free-Electron Lasers, relying on very high gradient accelerating structures (X-band, 12 GHz), the most advanced concepts for high brightness electron photo injectors, and innovative compact short-period undulators. Compared to existing facilities, the proposed facility will benefit from a lower electron beam energy, due to the enhanced undulators performance, and will be significantly more compact, with a smaller footprint, as a consequence of the lower energy and the high-gradient X-band structures. In addition, the whole infrastructure will also have a lower electrical power demand as well as lower construction and running costs.

In this paper we report the start-to-end simulation results of one of the options under consideration for the Compact- Light Project (XLS). The XLS is a hard X-ray Free Electron Laser under design, using the latest concepts for bright electron photo injectors, very high-gradient X-band structures, and innovative short-period undulators. Presently there exist various tracking codes to conduct the design process. Therefore identifying the most convenient code is of notable importance. This paper compares the tracking codes, Placet and General Particle Tracer, using the XLS lattice based on a S and X-band Injector. The calculation results in terms of beam quality and tracking performance of a full 6-D simulation are presented.

The CompactLight project supported by European H₂020 is to design a hard X-ray FEL facility beyond today’s state of the art. The project integrates photo injector, X-band acceleration and innovative compact short-period undulators together to make the machine more compact. RF undulator has an extraordinary advantage of working at very short undulator period. A conceptual design for a RF undulator at 36 GHz using a corrugated cylindrical waveguide operating in the HE11 mode is presented in this paper. Based on beam dynamics simulation and photon beam radiation simulations, the possibility of RF undulator to be used in CompactLight project is evaluated., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

High gradient rf photo-injectors have been a key development to enable several applications of high quality electron beams. They allow the generation of beams with very high peak current and low transverse emittance, satisfying the tight demands for free-electron lasers, energy recovery linacs, Compton/Thomson sources and high-energy linear colliders. In the paper we present the design of a new full C-band RF photo-injector recently developed in the framework of the XLS-Compact Light design study and of the EuPRAXIA@SPARC_LAB proposal. It allows to reach extremely good beam performances in terms of beam emittance (at the level of few hundreds nm), energy spread and peak current. The photo-injector is based on a very high gradient (>200 MV/m) ultra-fast (RF pulses 200 ns) C-band RF gun, followed by two C band TW structures. Different types of couplers for the 1.6 cell RF gun have been considered and also a new compact low pulsed heating coupler working on the TM020 mode on the full cell has been proposed. In the paper we report the design criteria of the gun, the powering system, and the results of the beam dynamics simulations. We also discuss the case of 1 kHz repetition rate., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Microwave undulators have great potential to be used in short-wavelength free-electron lasers. In this paper, the properties of a corrugated waveguide and its performance as an undulator cavity for a UK X-ray free-electron laser were systematically studied. The equations presented in this paper allow a fast estimation of the dimensions of the corrugated waveguide. An undulator cavity operating at 36 GHz designed for the HE11and HE12modes was investigated and the performance of both modes compared.

Presentation of the CompactLight project at the FLS2018 Conference, which took place on 05-09 March 2018 in Shanghai (China), held by Andrea Latina (CERN) on behalf of the CompactLight Collaboration.

H2020 CompactLight Project aims at designing the next generation of compact hard X-Rays Free-Electron Lasers, relying on very high accelerating gradients and on novel undulator concepts. CompactLight intends to design a compact Hard X-ray FEL facility based on very high-gradient acceleration in the X band of frequencies, on a very bright photo injector, and on short-period/superconductive undulators to enable smaller electron beam energy. If compared to existing facilities, the proposed facility will benefit from a lower electron beam energy, due to the enhanced undulators performance, be significantly more compact, as a consequence both of the lower energy and of the high-gradient X-band structures, have lower electrical power demand and a smaller footprint. CompactLight is a consortium of 24 institutes (21 European + 3 extra Europeans), gathering the world-leading experts both in the domains of X-band acceleration and undulator design., Proceedings of the 60th ICFA Advanced Beam Dynamics Workshop on Future Light Sources, FLS2018, Shanghai, China

In this deliverable we report an overview of the possible injector options suitable to match the CompactLight X-band high brightness linac able to drive short wavelength FELs user facilities. Different schemes have been investigated including RF gun injectors at different operating frequency (S, C and X band) and a DC gun based design. The electromagnetic and RF designs for all cases are reported and discussed, including a preliminary evaluation of the laser/cathode system requirements. Matchings with the downstream linac are also investigated with beam dynamics simulations. State of the art S-band injectors look appropriate to achieve the required parameters at low repetition rate ( 100 Hz). On the other end a compact C-band (or X-band) RF gun design is expected to have even better performances at low repetition rates and moreover, due to the lower thermal load, could allow higher repetition rates operation, up to 1 kHz, with acceptable performances degradation. DC guns are also very promising solutions for kHz range operation.

CompactLight is a consortium funded by the European Union through the Horizon 2020 Research and Innovation Programme under Grant Agreement No. 777431. The 24 partner institutes are working collaboratively towards the conceptual design of a next-generation x-ray free-electron laser (FEL). CompactLight intends to design an x-ray FEL facility beyond today’s state of the art, using the latest concepts for bright electron photo-injectors, high-gradient X-band structures at 12 GHz, and innovative short-period undulators. All of these enhancements will make our design more affordable to build and operate when compared against the existing facilities. The CompactLight prime objective is to generate a compact and affordable FEL facility design. The specifications of this future FEL are driven by the demands of potential users and the associated science case. This report summarizes the findings of our interactions with potential users since the start of the design study through a number of different avenues, culminating in a dedicated CompactLight User Meeting that was held from the 27th to the 28th of November 2018 at CERN., On behalf of the CompactLight Collaboration.

The Horizon 2020-funded project, CompactLight, will soon begin to design the first hard X-ray Free Electron Laser based on 12 GHz X-band technology. A consortium of 21 leading European institutions, including industries, together with the Shanghai Institute Of Applied Physics, the Australian Synchrotron, and the University of Melbourne, are partnering up to achieve this goal within the 36-month duration of the recently-awarded grant. The ambition of the CompactLight collaboration goes even beyond compact acceleration, as the consortium aims at simultaneously investigating and developing the next generation of undulators.

Self consistent analytic and numeric design for a set of electron guns with a high beams quality to be used in high power Ka-band klystrons are presented in this paper. The set of electron guns can be used in the high power Ka-band klystrons in order to feed linear accelerating structures at 36 GHz with an estimated 20 MW input power by achieving an effective accelerating electric field in the (100-150) MV/m range. In the framework of the Compact Light XLS project, a short Ka-band linearizer by working at 36 GHz able for providing an integrated voltage of at least 15 MV is proposed for bunch- phase linearization. In order to optimize the Ka-band klystrons efficiency for achieving 20 MW RF output power, dierent electron guns and beam focusing channel designs are examined and discussed in this paper.

The Horizon 2020-funded project, CompactLight, will soon begin to design the first hard X-ray Free Electron Laser based on 12 GHz X-band technology. A consortium of 21 leading European institutions, including industries, together with the Shanghai Institute Of Applied Physics, the Australian Synchrotron, and the University of Melbourne, are partnering up to achieve this goal within the 36-month duration of the recently-awarded grant. The ambition of the CompactLight collaboration goes even beyond compact acceleration, as the consortium aims at simultaneously investigating and developing the next generation of undulators., On behalf of the CompactLight Collaboration

CompactLight is a consortium funded by the European Union through the Horizon 2020 Research and Innovation Programme under Grant Agreement No. 777431. The 24 partner institutes are working collaboratively towards the conceptual design of a next-generation x-ray free-electron laser (FEL). CompactLight intends to design an x-ray FEL facility beyond today’s state of the art, using the latest concepts for bright electron photo-injectors, high-gradient X-band structures at 12 GHz, and innovative short-period undulators.All of these enhancements will make our design more affordable to build and operate when compared against the existing facilities. The CompactLight prime objective is to generate a compact and affordable FEL facility design.The specifications of this future FEL are driven by the demands of potential users and the associated science case. This report summarizes the findings of our interactions with potential users since the start of the design study through a number of different avenues, culminating in a dedicated CompactLight User Meeting that was held from the 27th to the 28th of November 2018 at CERN.

In this deliverable we report an overview of the possible injector options suitable to match the CompactLight X-band high brightness linac able to drive short wavelength FELs user facilities. Different schemes have been investigated including RF gun injectors at different operating frequency (S, C and X band) and a DC gun based design. The electromagnetic and RF designs for all cases are reported and discussed, including a preliminary evaluation of the laser/cathode system requirements. Matchings with the downstream linac are also investigated with beam dynamics simulations. State of the art S-band injectors look appropriate to achieve the required parameters at low repetition rate ( 100 Hz). On the other end a compact C-band (or X-band) RF gun design is expected to have even better performances at low repetition rates and moreover, due to the lower thermal load, could allow higher repetition rates operation, up to 1 kHz, with acceptable performances degradation. DC guns are also very promising solutions for kHz range operation., On behalf of the CompactLight Collaboration

Self consistent analytic and numeric design for a set of electron guns with a high beams quality to be used in high power Ka-band klystrons are presented in this paper. The set of electron guns can be used in the high power Ka-band klystrons in order to feed linear accelerating structures at 36 GHz with an estimated 20 MW input power by achieving an effective accelerating electric field in the (100-150) MV/m range. In the framework of the Compact Light XLS project, a short Ka-band linearizer by working at 36 GHz able for providing an integrated voltage of at least 15 MV is proposed for bunch- phase linearization. In order to optimize the Ka-band klystrons efficiency for achieving 20 MW RF output power, dierent electron guns and beam focusing channel designs are examined and discussed in this paper.

The Insertion Device group of the Paul Scherrer Institute has started an R&D program on a high temperature superconducting undulator to reduce the period length and increase the undulator's magnetic field well beyond the present capability. Simulation results for a 10 mm period and 4 mm magnetic gap staggered array of GdBCO bulks predict peak magnetic field above 2 T. Building on the existing working principle of undulator design and simulated performance, the first experimental results of a 5 period 6.0 mm gap short undulator measured in the new test facility available at the University of Cambridge will be presented together with details of the experimental setup and sample preparation.

The light sources currently existing or under development in Europe address needs in the Central and Northwestern regions, whereas in the Southeastern European region there is no facility of this kind. The CompactLight collaboration, an H2020 funded project, is going to deliver a Conceptual Design Report (CDR) of a novel generation X-ray Free Electron Laser (XFEL) facility which is compact, innovative, relatively cheap and to be implemented for industrial and medical applications. The CDR will facilitate technological updates of the many European region institutions and enable them to construct a novel light source. Cost and risk analysis, as well as technology transfer and market survey of the project results are also discussed.