bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analytical energy spectra and wake effects for relativistic dielectric laser accelerators
Authors: Egenolf Thilo , Niedermayer Uwe 
Published: September 2020

Abstract
Dielectric laser acceleration (DLA) is one of the advanced concepts for more compact accelerators. DLA gratings have apertures and period lengths within the range of optical wavelengths. Phase stability and wakefield effects are thus crucial for upcoming experiments with highly relativistic electrons. For this, we present a method to analytically calculate energy spectra for comparison with measurements in order to reconstruct the phase of injection into the DLA grating structure. Knowing the injection phase is important for both alignment and interpretation of measured data. Furthermore, we estimate the effects of wakefields on bunches which are coherently accelerated in a DLA. We are calculating the energy spectrum affected by the longitudinal wake by evaluating the analytical description numerically and give estimates for the transverse kicks of an off-centered injected electron bunch.
Parameter studies on dielectric gratings as electron accelerators
Authors: Kuropka W , Aßmann R , Dorda U , Mayet F 
Published: September 2020

Abstract
Dielectric laser driven particle acceleration (DLA) is one of the candidates for novel high-gradient technologies to reduce the footprint of large scale particle acceleration facilities. On the other hand these devices can be used to interact with the particle beams of state-of-the-art photon science machines, especially with FELs, to manipulate the longitudinal phase space in a compact and cost effective way. The near-field surface modes of dielectric gratings can be used to interact with particle beams close to the surface. To achieve transversely homogeneous accelerating fields two gratings are opposed. The laser can be coupled from the side into the structure. In this work we present a study on the influence of the geometry parameters of the grating on the acceleration gradient and its transverse uniformity. Based on this study a design for production was chosen, which will be used for experiments at the ARES linac within the SINBAD facility at DESY. This work was carried out within the ACHIP project funded by the Gordon and Betty Moore Foundation (GBMF 4744).
Characterization of the Electron Beam in the ACHIP Chamber in SwissFEL
Authors: Ischebeck Rasmus , Bettoni Simona , Borrelli Simona , Calvi Marco , Dijkstal Philipp , Ferrari Eugenio , Guzenko Vitaliy , Hauenstein Dominique , Hermann Benedikt , Hürzeler Orell , Kittel Christoph , Lombosi Csaba , Orlandi Gian Luca , Prat Eduard , Reiche Sven , Rivkin Leonid , Voulot Didier , Zehnder Dominique 
Published: September 2020

Abstract
We have installed an interaction chamber in the electron beam line of SwissFEL. Electrons with a particle energy of 3 GeV are focused to a few-micrometer beam size. Samples placed in this beam can be aligned to the electron beam with a hexapod. The goal of this installation is to demonstrate laser-driven acceleration inside dielectric structures. We present here the layout of this interaction chamber as well as first measurements with the electron beam.
Initial Design of a High-Power Ka-Band Klystron
Authors: Behtouei M. , Faillace L. , Ferrario M. , Spataro B. , Variola A. 
Published: September 2020

Abstract
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 and 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.
Simulations of the millimeter wavelength accelerating structure excitation
Authors: Arsentyeva M V , Levichev A E 
Published: September 2020

Abstract
We present the work on development of the millimeter wavelength accelerating structure (also called the W-band structure). It consists of cylindrical cavities with the operating frequency of 96 GHz. The structure will be excited by the picosecond electron beam from the photocathode RF gun. In order to define exactly both the structure and the exciting beam parameters, analytical estimations and simulations of the structure excitation were performed. For the successful propagation of the exciting beam through it, focusing system is needed. It is proposed to use the permanent magnets producing solenoidal field, their preliminary design being discussed. Prototype of the millimeter wavelength structure has been manufactured, its first measurements are presented.
Laser-driven electron storage rings
Authors: Khan S 
Published: September 2020

Abstract
Advanced accelerator concepts usually address linear acceleration schemes. Storage rings, however, are often superior to linear machines regarding repetition rate, stability and efficiency. The radiative energy loss per turn in an electron storage ring is compensated by radiofrequency resonators with a wavelength of the order of 1 meter, which corresponds to the spacing between consecutive potential wells, so-called buckets, and results in a bunch length around 1 centimeter or several 10 picoseconds. As an alternative, longitudinal focusing could be performed by a laser wave co-propagating with the electrons in an undulator. Considering a continuous-wave carbon dioxide laser beam as an example, the bucket spacing would be 10.6 micrometer with a bunch length in the femtosecond range. The paper discusses chances and limitations of such a laser-driven storage ring concept with steady-state femtosecond bunches.
On the resonant properties of the THz metal-dielectric waveguide impedance
Authors: Ivanyan M , Aslyan L , Floettmann K , Lemery F , Tsakanov V 
Published: September 2020

Abstract
Various asymptotic representations for the longitudinal monopole impedance of a two-layer metal-dielectric cylindrical waveguide with finite-conducting external walls and a lossy internal dielectric layer are derived. Areas of their applicability are determined and their properties are investigated. New features for the resonance properties of the structure under consideration are revealed and described.
Injector Design for the MariX-FEL Project
Authors: Faillace L. , Bacci A. , Bosotti A. , Cialdi S. , Drebot I. , Michelato P. , Monaco L. , Petrillo V. , Conti M.Rossetti , Paparella R. , Rossi A.R. , Sertore D. , Serafini L. 
Published: September 2020

Abstract
The MariX project (Multi-disciplinary Advanced Infra-structure for Research with X-rays) is a free electron laser (FEL) light source proposed by the INFN-Milan. It will produce highly coherent X-rays, in the range 0.2-8 keV, with ultra-short pulses (10-50 fs) and a repetition rate up to 1MHz. At the same time, MariX will host a compact monochromatic X-ray source, called BriXS (Bright and compact X-ray Source), by using an inverse-Compton scattering scheme, with energies up to 180 keV and a repetition rate of 100 MHz (continuous-wave CW operation) that will generate fluxes up to 1013 photons per second. In this paper, the Radio-Frequency (RF) and beam dynamics designs of the electron injector for the MariX-FEL project are presented. The choice of the main devices, such as the electron gun and the accelerating linear accelerators, as well as the main parameters for CW operation are discussed in detail.
Towards ultra-high gradient particle acceleration in carbon nanotubes
Authors: Perera A , Bonatto A , Bontoiu C , Resta-López J , Rodin V , Welsch C , Xia G , Yadav G 
Published: September 2020

Abstract
Charged particle acceleration using solid-state nanostructures is attracting new attention in recent years as a method of achieving ultra-high acceleration gradients in the order of TV/m. The use of carbon nanotubes (CNTs) has the potential to overcome limitations of using natural crystals, e.g. channelling aperture and thermo-mechanical robustness. In this work, we present preliminary particle-in-cell simulation results of laser and beam interaction with a single CNT, modelled as 20 parallel plates of Carbon ions and electrons. This is the equivalent to a 10-layers tube in 3D. We further discuss simulation of anisotropic particles to model 2D quasi-free electrons in CNT walls. Further research ideas are outlined along with the presentation of a possible proof-of-principle experiment.
Electromagnetic and Beam Dynamics Studies for High Gradient Accelerators at Terahertz Frequencies
Authors: Marongiu M. , Chiadroni E. , Croia M. , Ferrario M. , Ficcadenti L. , Lupi S. , Martinelli V. , Mostacci A. , Pompili R. , Tofani S. 
Published: September 2020

Abstract
THz radiation is one of the most appealing portion of the electromagnetic spectrum in terms of multi-disciplinary use in basic science and technology. Beyond the numerous applications, a great interest is its potential for future, compact linear accelerators.
Conventional radio-frequency accelerating structures operating at the S and C band can reach gradients up to 30 - 50MV/m, respectively; higher accelerating gradients, of the order of 100MV/m, have been obtained with X-band cavities. THz-based accelerating structures enable operation at even higher gradient, potentially up to the GV/m scale, holding great potential for their application to free-electron lasers and linear colliders, for instance.
Here we present electromagnetic and beam dynamics studies about the use of a dielectric loaded waveguide to accelerate electron bunches by mean of a narrow-band multi-cycle THz pulse. The excitation of the accelerating structure by the THz pulse and the bunch acceleration in the excited field are investigated through CST Microwave Studio and GPT simulations.
Spatial autocorrelation study for laser beam quality estimation
Authors: Scifo Jessica , Dotto Alessio Del , Ferrario Massimo , Pompili Riccardo , Villa Fabio 
Published: September 2020

Abstract
High brightness electron beam is required by several applications in the accelerator physics field. In order to have a high brightness beam, that means a high current and a low emittance beam, it is important to study, among other things, the beams non uniformity due to the non perfect transverse laser beam uniformity. Regarding the transverse analysis of the beam, statistical tools as mean and standard deviation are usually used. In this work we will show how the autocorrelation function of a photocathode laser can be used for monitoring the spatial distribution of the beam non-uniformity, strictly connected with the high electron beam emittance: we will apply our analysis on the SPARC_LAB data.
High gradient ultra-high brightness C-band photoinjector optimization
Authors: Croia M , Alesini D , Cardelli F , Diomede M , Ferrario M , Giribono A , Romeo S , Vaccarezza C , Vannozzi A 
Published: September 2020

Abstract
Cathode, laser system, high RF peak field, and gun solenoid are fundamental aspects that have to be optimized to produce high brightness beam in photoinjectors. In order to produce ultra-high brightness beams of about one order of magnitude more than the present devices, new studies have been done in the last years. One promising approach is to increase the peak field on the cathode surface. In this paper we will present a study on a C-band gun using a cathode peak field of 240 MV/m. A first RF study to reach such very high field was done, by means of shortening the RF pulse duration. A first design of the RF structures and solenoid was carried out. If we will not reach exactly the predicted gradient during the RF tests, the impact on the beam dynamics have been simulated reducing the peak field on the cathode up to the value of 130 MV/m, maintaining the same geometry. The convenience of such gun also at a lower gradient, opened the way to possible applications on light production devices. For example, this C-band injector is one of the main options to guide the X-band linac in the CompactLight design study, where an X-ray FEL is foreseen.
Feasibility study for a THz acceleration experiment on the PHIL accelerator at LAL
Authors: Vinatier’ T , Bruni C , Assmann R W , Dorda U , Lemery F , Marchetti B 
Published: September 2020

Abstract
We present a feasibility study for an experiment aiming to post-accelerate an electron bunch, coming from the PHIL (Photo-Injecteur au LAL) photoinjector at LAL (Laboratoire de l’Accélérateur Linéaire), in a circular partially dielectric-loaded waveguide (DLW) driven by a multicycle THz pulse generated by the infrared laser coming from the LASERIX (Installation laser XUV/IR de l’Université Paris Sud) facility. We first discuss the considerations taken into account to fix the DLW design and the THz pulse properties, especially the choice of a 160 GHz THz pulse frequency, and then provide a set of values for their main parameters. We then perform start-to-end simulations of the acceleration experiment, taking into account the current achievable range of parameters at PHIL and the THz pulse properties already achieved with LASERIX with some margins for the coupling losses. They demonstrate the possibility to obtain a 1.2 MeV energy gain for a 10 pC bunch, without charge losses, with a clear shift of the energy spectrum, which would represent a significant improvement compared to the current state-of-the-art of THz acceleration. An overview of the upcoming steps towards the realization of the experiment is finally given.
Summary of Working Group 4: Application of compact and high-gradient accelerators
Authors: Brenner C M , Sarri G 
Published: September 2020

Abstract
We present here an overview of the topics presented and discussed during the Working Group 4 sessions of the European Advanced Accelerator Concepts workshop 2019 (EAAC19). The remit of Working Group 4 (WG4) is to address topics relating to all potential application areas of compact and high-gradient accelerators. This includes recent experimental results and planned demonstration experiments with relevance to radiation generation, medical, industrial, and cultural heritage sector applications, and development of advanced photon sources such as free electron lasers (FEL). Within scope of Working Group 4 is also discussions on planned facilities implementing advanced accelerator concepts that have a focus on applications, as well as beam shaping and tailoring to deliver adequate beams for applications. The topics discussed in the EAAC19 programme for Working Group 4 all fit within the following application theme areas: 1) new facilities exploiting advanced and novel accelerator concepts, 2) development of next generation photon sources, 2) imaging and spectroscopy with laser-plasma accelerator particle and photon beams, and 3) radiobiology with laser-plasma accelerator particle beams.
SINBAD-ARES - A Photo-Injector for external Injection Experiments in novel Accelerators at DESY
Authors: Marchetti Barbara , Assmann Ralph , Brinkmann Reinhard , Burkart Florian , Dorda Ulrich , Floettmann Klaus , Hartl Ingmar , Hillert Wolfgang , Huening Markus , Jafarinia Farzad , Jaster-Merz Sonja , Kellermeier Max , Kuropka Willi , Lemery Francois , Marx Daniel , Mayet Frank , Panofski Eva , Pfeiffer Sven , Schlarb Holger , Vinatier Thomas , Walker Paul Andreas , Winkelmann Lutz , Yamin Sumera 
Published: September 2020

Abstract
The accelerator R&D facility SINBAD (Short Innovative Bunches and Accelerators at DESY) will drive multiple independent experiments in the fields of production of ultra-short electron bunches and tests of advanced high gradient acceleration concepts.
The SINBAD-ARES (Accelerator Research Experiment at SINBAD) linac has been designed to allow the production of high brightness ultra-short electron bunches with excellent arrival-time stability. The accelerator will be used to study experimentally the optimization of the brightness for fs long electron bunches. Such electron bunches, with tunable characteristics, will be then injected into novel accelerators realized in the context of the ATHENA project, the ACHIP international collaboration and the ARIES program. In this paper we describe the principal characteristics of the linac design, we underline the technical challenges connected to the production and characterization of fs bunches and we report on the status of the installation and commissioning.
Progress Towards Laser Wakefield Acceleration and Applications at the Scottish Centre for the Application of Plasma-based Accelerators (SCAPA)
Authors: Holt G K , Battaglia G , Brunetti E , Feehan J , Kornaszewski A , Li W , Maitrallain A , Manahan G G , Pring W D , Reid L R , Shahzad M , Spesyvstev R , Vieux G , Wiggins S M , Jaroszynski D A 
Published: September 2020

Abstract
Laser wakefield accelerators (LWFAs) are promising sources of high brightness particle and radiation beams with many possible applications, ranging from scientific research to medicine, industry and border security. The Scottish Centre for the Application of Plasma-based Accelerators (SCAPA) is a university-based facility employing the use of two high-power, ultrashort pulse lasers to advance research, development and application of laser-plasma accelerators. Here we report on recent advancements in LWFA research at SCAPA and upcoming research programmes to demonstrate proof-of-concept applications of the LWFA.
Progress towards laser plasma based free electron laser on COXINEL
Authors: Couprie Marie-Emmanuelle , André Thomas , Blache Frédéric , Bouvet François , Dietrich Yannick , Duval Jean-Pierre , El-Ajjouri Moussa , Ghaith Amin , Herbeaux Christian , Hubert Nicolas , Kitégi Charles , Khojoyan Martin , Labat Marie , Leclercq Nicolas , Lestrade Alain , Loulergue Alexandre , Marcouillé Olivier , Marteau Fabrice , Oumbarek-Espinos Driss , Rommeluére Patrick , Sebdaoui Mourad , Tavakoli Keihan , Valléau Mathieu , Corde Sébastien , Gautier Julien , Goddet Jean Philippe , Kononenko Olena , Lambert Guillaume , Tafzi Amar , Phuoc Kim Ta , Thaury Cédric , Bielawski Serge , Roussel Eléonore , Szwaj Christophe , Andriyash Igor , Malka Victor , Smartsev Slava 
Published: September 2020

Abstract
The Free Electron Laser (FEL) application of Laser Plasma Acceleration (LPA) requires the handling of the energy spread and divergence. The COXINEL manipulation line, designed and built at SOLEIL for this purpose, consists of high gradient quadrupoles for divergence handling and a decompression chicane for energy sorting, enabling FEL amplification with baseline parameters. Installed at Laboratoire d’Optique Appliquee (LOA), it uses robust electrons generated and accelerated by ionization injection using a 30 TW laser. We report here on the work progress towards a FEL demonstration. The LPA measured electron beam characteristics deviates from the baseline reference case. After the installation of the equipment, the electron beam transport has first been optimized. The electron position and dispersion are independently adjusted. Then, undulator radiation has been measured. The spectral purity is controlled via the energy spread adjusted in the slit located in the chicane. FEL effect demonstration is within reach, with currently achieved performance on different LPA experiments.
Multi-objective optimization of the matching beamline for external injection into a laser-driven plasma accelerator
Authors: Panofski E , Assmann R W , Svystun E N 
Published: September 2020

Abstract
Accelerators based on laser plasma wakefield acceleration are of great interest for a new generation of compact machines. External injection of an electron beam from an RF injector into a plasma accelerating stage has the advantage that a well-controlled and fully characterized beam can be used. The matching of the electron bunches into an accelerating plasma wakefield places high demands on the electron beam quality. The electron beam size must be extremely small to match the field structure inside the plasma wake. The short period of the accelerating field in the plasma requires a bunch length in the (sub-)fs range. These electron beam properties result in a high electron density and strongly space charge dominated bunches. The beamline upstream of the plasma must be able to control the significant effect of space charge on the bunch and to transversely match the beam to the focusing fields of the plasma. Further constraints to the beamline design are given by the in-coupling of the high-power drive laser and the implementation of diagnostic tools. Choosing suitable settings for the beamline elements in order to match the beam thus poses a great challenge. Using multi-objective optimization, suitable settings for the beamline elements can be extracted from Pareto optimum solutions. The development of a universal multi-objective optimization algorithm for beamline matching as well as first optimization results are presented.
Summary of Working Group 5: Plasma devices, plasma and beam diagnostics
Authors: D’Arcy Richard , Delerue Nicolas 
Published: September 2020

Abstract
The presentations and proceedings of Working Group 5 (plasma devices, plasma and beam diagnostics) at the fourth European Advanced Accelerator (EAAC) Workshop reported on experimental demonstrations and simulation studies for new concepts in the field of plasma/beam diagnostics and plasma devices. New schemes, as well as the development of those already well benchmarked, were described, covering a breadth of concepts ranging from the diagnosis of how both hot and cold plasmas evolve in time to how in time they may be applied to future high-energy-physics and photon science facilities.
Plasma density profile measurements for ultra-short high power laser beam guiding experiments at SPARC _LAB
Authors: Costa G , Anania M P , Biagioni A , Bisesto F G , Brentegani E , Ferrario M , Pompili R , Romeo S , Rossi A R , Zigler A , Cianchi A 
Published: September 2020

Abstract
External injection is a promising method to achieve high accelerating gradients and to control the beam properties. The energy gain of an electron via the wakefield is proportional to the product of the accelerating field multiplied by the effective propagation distance of the laser. Therefore, in order to bring the electron energy in the order of the GeV, a longer propagation length is required, which can be obtained by guiding the laser pulse in a wave-guide. In the case of SPARC_LAB, a 500 μτη diameter hydrogen-filled capillary discharge is used; to guide the laser beam it is necessary to act on the refractive index of the plasma, depending on its density. In this work measurements of the trend over time of the longitudinal profile of the plasma density within the capillary are presented, along with openFOAM simulations of the gas profile distribution. Preliminary test of laser guiding are also shown, detecting the behaviour of the laser beam at the exit of the capillary with respect to the discharge current value.
Control of undulator radiation using a Laser Plasma Acceleration Source
Authors: Ghaith Amin , Oumbarek-Espinos Driss , André Thomas , Roussel Eléonore , Loulergue Alexandre , Labat Marie , Corde Sébastian , Kononenko Olena , Valléau Mathieu , Marcouillé Olivier , Bielawski Serge , Malka Victor , Couprie Marie-Emmanuelle 
Published: September 2020

Abstract
Spontaneous undulator radiation emission, after the COXINEL line using a Laser Plasma acceleration (LPA) source, has been observed. The line enables to manipulate the electron beam phase space such as emittance, dispersion and energy spread along a 10 m long transport. The large divergence is handled at a very early stage to mitigate the chromatic emittance, using high gradient permanent magnet based quadrupoles mounted on translation tables. The operating energy is between 161-180 MeV focused in a 2-m long cryo-ready undulator with a period of 18 mm emitting light in the Ultra-Violet range. The spectral flux is characterized using a spectrometer. The wavelength is tuned by either changing the electron beam energy or by adjusting the undulator gap. The radiation pattern signature is illustrated alongside its dependence on the energy spread that is modified by introducing a slit in a magnetic chicane where a small relative bandwidth of 5% has been achieved.