Special Issue "Physics and Applications of High Brightness Beams"

A special issue of Instruments (ISSN 2410-390X).

Deadline for manuscript submissions: closed (15 September 2019).

Special Issue Editors

Prof. Dr. Alessandro Cianchi
E-Mail Website
Guest Editor
University of Rome Tor Vergata, 1-00133 Rome, Italy
Interests: high brightness electron beam diagnostics; plasma acceleration diagnostics
Prof. Dr. Young-Kee Kim
E-Mail Website
Guest Editor
Department of Physics, The University of Chicago, Chicago, IL 60637, USA
Interests: experimental particle physics; accelerator physics

Special Issue Information

Dear Colleagues,

This special issue will publish the selected papers from the HBB 2019 Conference (Physics and Applications of High Brightness Beams, Rethimno, Crete, April 8-12, 2019). This proceedings issue will document the rapid developments achieved during the last several years in the high brightness beam community.

To learn more details about HBB 2019, please visit the conference website, https://conferences.pa.ucla.edu/hbb-2019/index.html.

Prof. Dr. Alessandro Cianchi
Prof. Dr. Young-Kee Kim
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Instruments is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (13 papers)

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Open AccessArticle
Molybdenum Oxides Coatings for High Demanding Accelerator Components
Instruments 2019, 3(4), 61; https://doi.org/10.3390/instruments3040061 - 12 Nov 2019
Abstract
Large electric gradients are required for a variety of new applications, notably including the extreme high brightness electron sources for X-ray free electron lasers (FELs), radio-frequency (RF) photo-injectors, industrial and medical accelerators, and linear accelerators for particle physics colliders. In the framework of [...] Read more.
Large electric gradients are required for a variety of new applications, notably including the extreme high brightness electron sources for X-ray free electron lasers (FELs), radio-frequency (RF) photo-injectors, industrial and medical accelerators, and linear accelerators for particle physics colliders. In the framework of the INFN-LNF, SLAC (USA), KEK (Japan), UCLA (Los Angeles) collaboration, the Frascati National Laboratories (LNF) are involved in the modelling, development, and testing of RF structures devoted to particles acceleration by high gradient electric fields of particles through metal devices. In order to improve the maximum sustainable gradients in normal-conducting RF-accelerating structures, both the RF breakdown and dark current should be minimized. To this purpose, studying new materials as well as manufacturing techniques are mandatory to identify better solutions to such extremely requested applications. In this contribution, we discuss the possibility of using a dedicated coating on a solid copper sample (and other metals) with a relatively thick film to improve and optimize breakdown performances and to minimize the dark current. We present here the first characterization of MoO3 films deposited on copper by pulsed-laser deposition (PLD). Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Open AccessArticle
1D Quantum Simulations of Electron Rescattering with Metallic Nanoblades
Instruments 2019, 3(4), 59; https://doi.org/10.3390/instruments3040059 - 05 Nov 2019
Abstract
Electron rescattering has been well studied and simulated for cases with ponderomotive energies of the quasi-free electrons, derived from laser–gas and laser–surface interactions, lower than 50 eV. However, with advents in longer wavelengths and laser field enhancement metallic surfaces, previous simulations no longer [...] Read more.
Electron rescattering has been well studied and simulated for cases with ponderomotive energies of the quasi-free electrons, derived from laser–gas and laser–surface interactions, lower than 50 eV. However, with advents in longer wavelengths and laser field enhancement metallic surfaces, previous simulations no longer suffice to describe more recent strong field and high yield experiments. We present a brief introduction to and some of the theoretical and empirical background of electron rescattering emissions from a metal. We set upon using the Jellium potential with a shielded atomic surface potential to model the metal. We then explore how the electron energy spectra are obtained in the quantum simulation, which is performed using a custom computationally intensive time-dependent Schrödinger equation solver via the Crank–Nicolson method. Finally, we discuss the results of the simulation and examine the effects of the incident laser’s wavelength, peak electric field strength, and field penetration on electron spectra and yields. Future simulations will investigate a more accurate density functional theory metallic model with a system of several non-interacting electrons. Eventually, we will move to a full time-dependent density functional theory approach. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Open AccessArticle
Design of Comb Fabricated Halbach Undulators
Instruments 2019, 3(4), 58; https://doi.org/10.3390/instruments3040058 - 19 Oct 2019
Abstract
An approach to fabricating Halbach array undulators using “combs” machined from single magnets is introduced. This technique is especially relevant to the fabrication of short period micro-undulators with period lengths considerably less than the few-centimeter-scale typical of current undulators. Manual, magnet-by-magnet assembly of [...] Read more.
An approach to fabricating Halbach array undulators using “combs” machined from single magnets is introduced. This technique is especially relevant to the fabrication of short period micro-undulators with period lengths considerably less than the few-centimeter-scale typical of current undulators. Manual, magnet-by-magnet assembly of micro-undulators would require the manipulation and alignment of thousands of magnets smaller than a grain of rice: comb fabrication dramatically increases the size of the basic unit cell of assembly with no increase in undulator period by creating many periods from a single piece, in a single machining modality. Further, as these comb teeth are intrinsically indexed to each other, tolerances are dictated by a single manufacturing step rather than accumulating errors by assembling many tiny magnets relative to each other. Different Halbach geometries, including M = 2 , M = 4 , isosceles triangle, and hybrid, are examined both from a theoretical perspective and with 3D magnetostatic simulations. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Open AccessArticle
Electron Diagnostics for Extreme High Brightness Nano-Blade Field Emission Cathodes
Instruments 2019, 3(4), 57; https://doi.org/10.3390/instruments3040057 - 16 Oct 2019
Abstract
Electron beams are essential tools in modern science. They are ubiquitous in fields ranging from microscopy to the creation of coherent ultra-fast X-rays to lithography. To keep pace with demand, electron beam brightness must be continually increased. One of the main strategic aims [...] Read more.
Electron beams are essential tools in modern science. They are ubiquitous in fields ranging from microscopy to the creation of coherent ultra-fast X-rays to lithography. To keep pace with demand, electron beam brightness must be continually increased. One of the main strategic aims of the Center for Bright Beams (CBB), a National Science Foundation Science and Technology Center, is to increase brightness from photocathodes by two orders of magnitude. Improving the state-of-the-art for photoemission-based cathodes is one possibility. Several factors have led to an alternative design becoming an increasing necessity; the nanoscale structure. Field emission sources from nano-tips would be an ideal candidate were it not for their low current and damage threshold. A 1-dimensional extended nano-fabricated blade, i.e., a projected tip, can solve the problems inherent in both designs. The novel geometry has been demonstrated to produce extremely high brightness electron beam bunches and is significantly more robust and easier to manufacture than traditional photocathodes. Theory indicates electron emission up to keV energies. We thus present a system of diagnostics capable of analyzing the cathodes and assessing their viability. The diagnostics are designed to measure the electron spectrum up to keV energies, with sub meV resolution at <100 eV, mean transverse energy (MTE), emission uniformity, and cathode lifetime. We also report preliminary data on total extracted charge and maximum detectable electron energy with a simplified retarding field spectrometer. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Open AccessArticle
Capabilities of Terahertz Cyclotron and Undulator Radiation from Short Ultrarelativistic Electron Bunches
Instruments 2019, 3(4), 55; https://doi.org/10.3390/instruments3040055 - 11 Oct 2019
Abstract
Mechanisms of coherent spontaneous cyclotron and undulator radiations of short dense bunches, in which electrons move along the same stationary helical trajectories, but have different dynamic properties, have been compared in detail. The results are based on the simplest 1D model in the [...] Read more.
Mechanisms of coherent spontaneous cyclotron and undulator radiations of short dense bunches, in which electrons move along the same stationary helical trajectories, but have different dynamic properties, have been compared in detail. The results are based on the simplest 1D model in the form of a plane consisting of uniformly distributed synchronously moving and in-phase emitting particles, as well as numerical 3D codes developed to study the dynamics of bunches in waveguides taking into account the effects of the radiation and spatial charge fields. For cyclotron radiation under group synchronism conditions, the Coulomb expansion of a bunch occurs along the surface of a constant wave phase with the formation of an effectively radiating coherent structure. A significantly higher radiation frequency, but with a lower efficiency, can be obtained in the regime of simultaneous excitation of high-frequency (autoresonant) and low-frequency waves; in the field of the latter, stabilization of the bunch phase size can be achieved. Such a two-wave generation is much more efficient when the bunches radiate in the combined undulator and strong guiding magnetic fields under conditions of the negative mass instability, when both the Coulomb interaction of the particles and the radiation field stabilize the longitudinal size of the bunch. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Open AccessArticle
GeV-Class Two-Fold CW Linac Driven by an Arc-Compressor
Instruments 2019, 3(4), 54; https://doi.org/10.3390/instruments3040054 - 10 Oct 2019
Abstract
We present a study of an innovative scheme to generate high repetition rate (MHz-class) GeV electron beams by adopting a two-pass two-way acceleration in a super-conducting Linac operated in Continuous Wave (CW) mode. The beam is accelerated twice in the Linac by being [...] Read more.
We present a study of an innovative scheme to generate high repetition rate (MHz-class) GeV electron beams by adopting a two-pass two-way acceleration in a super-conducting Linac operated in Continuous Wave (CW) mode. The beam is accelerated twice in the Linac by being re-injected, after the first pass, in opposite direction of propagation. The task of recirculating the electron beam is performed by an arc compressor composed by 14 Double Bend Achromat (DBA). In this paper, we study the main issues of the two-fold acceleration scheme, the electron beam quality parameters preservation (emittance, energy spread), together with the bunch compression performance of the arc compressor, aiming to operate an X-ray Free Electron Laser. The requested power to supply the cryogenic plant and the RF sources is also significantly reduced w.r.t a conventional one-pass SC Linac for the same final energy. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Open AccessFeature PaperArticle
Compression of Ultra-High Brightness Beams for a Compact X-ray Free-Electron Laser
Instruments 2019, 3(4), 53; https://doi.org/10.3390/instruments3040053 - 01 Oct 2019
Abstract
The creation of the first X-ray free-electron laser at SLAC in 2009 introduced the scientific community to coherent photons of unprecedented high brightness. These photons were produced, however, at the cost of billion-dollar-class price tags and kilometer-scale machine footprints. This has meant that [...] Read more.
The creation of the first X-ray free-electron laser at SLAC in 2009 introduced the scientific community to coherent photons of unprecedented high brightness. These photons were produced, however, at the cost of billion-dollar-class price tags and kilometer-scale machine footprints. This has meant that getting access to these photons is very difficult, and those who do get access do so with a strict time budget. Now, the development of critical enabling technologies, in particular high-field cryogenically cooled accelerating cavities and short-period, high-field undulator magnets, opens the door to an X-ray free-electron laser less than 30 m in length. We present here critical potential design elements for such a soft X-ray free-electron laser. To this end, simulation results are presented focusing on the problems associated with the process of bunch compression and novel ways in which those problems can be resolved. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Open AccessArticle
High-Brightness Beam Technology Development for a Future Dynamic Mesoscale Materials Science Capability
Instruments 2019, 3(4), 52; https://doi.org/10.3390/instruments3040052 - 29 Sep 2019
Abstract
A future capability in dynamic mesoscale materials science is needed to study the limitations of materials under irreversible and extreme conditions, where these limitations are caused by nonuniformities and defects in the mesoscale. This capability gap could potentially be closed with an X-ray [...] Read more.
A future capability in dynamic mesoscale materials science is needed to study the limitations of materials under irreversible and extreme conditions, where these limitations are caused by nonuniformities and defects in the mesoscale. This capability gap could potentially be closed with an X-ray free-electron laser (XFEL), producing 5 × 1010 photons with an energy of 42 keV, known as the Matter–Radiation Interactions in Extremes (MaRIE) XFEL. Over the last few years, researchers at the Los Alamos National Laboratory have developed a preconceptual design for a MaRIE-class XFEL based on existing high-brightness beam technologies, including superconducting L-band cryomodules. However, the performance of a MaRIE-class XFEL can be improved and the risk of its operation reduced by investing in emerging high-brightness beam technologies, such as the development of high-gradient normal conducting radio frequency (RF) structures. Additionally, an alternative XFEL architecture, which generates a series of high-current microbunches instead of a single bunch with uniformly high current along it, may suppress the most important emittance degradation effects in the accelerator and in the XFEL undulator. In this paper, we describe the needed dynamic mesoscale materials science capability, a MaRIE-class XFEL, and the proposed microbunched XFEL accelerator architecture in detail. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Open AccessFeature PaperArticle
BriXs Ultra High Flux Inverse Compton Source Based on Modified Push-Pull Energy Recovery Linacs
Instruments 2019, 3(3), 49; https://doi.org/10.3390/instruments3030049 - 10 Sep 2019
Abstract
We present a conceptual design for a compact X-ray Source BriXS (Bright and compact X-ray Source). BriXS, the first stage of the Marix project, is an Inverse Compton Source (ICS) of X-ray based on superconducting cavities technology for the electron beam with energy [...] Read more.
We present a conceptual design for a compact X-ray Source BriXS (Bright and compact X-ray Source). BriXS, the first stage of the Marix project, is an Inverse Compton Source (ICS) of X-ray based on superconducting cavities technology for the electron beam with energy recirculation and on a laser system in Fabry-Pérot cavity at a repetition rate of 100 MHz, producing 20–180 keV monochromatic X-Rays devoted mainly to medical applications. An energy recovery scheme based on a modified folded push-pull CW-SC twin Energy Recovery Linac (ERL) ensemble allows us to sustain an MW-class beam power with almost one hundred kW active power dissipation/consumption. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Open AccessFeature PaperArticle
Externally Heated Hollow Cathode Arc Plasma Source for Experiments in Plasma Wakefield Acceleration
Instruments 2019, 3(3), 48; https://doi.org/10.3390/instruments3030048 - 10 Sep 2019
Abstract
An externally heated, hollow cathode arc source was recommissioned at UCLA for use in experiments to drive plasma wakefields with shaped beams at the Argonne Wakefield Accelerator. The hollow cathode arc source provides a robust plasma column with a density in the 10 [...] Read more.
An externally heated, hollow cathode arc source was recommissioned at UCLA for use in experiments to drive plasma wakefields with shaped beams at the Argonne Wakefield Accelerator. The hollow cathode arc source provides a robust plasma column with a density in the 10 13 10 14 cm 3 range while external heating of the cathode allows the plasma arc regime to be accessed with applied voltages down to 20 V. Overall source operating principals are described, along with time-resolved plasma current measurements and plasma density characterization with the use of a triple Langumir probe. The results show that relevant plasma densities that match facility beam parameters are readily achievable. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Open AccessArticle
High Repetition Rate and Coherent Free-Electron Laser in the X-Rays Range Tailored for Linear Spectroscopy
Instruments 2019, 3(3), 47; https://doi.org/10.3390/instruments3030047 - 09 Sep 2019
Abstract
Fine time-resolved analysis of matter—i.e., spectroscopy and photon scattering—in the linear response regime requires fs-scale pulsed, high repetition rate, fully coherent X-ray sources. A seeded Free Electron Laser (FEL) driven by a Linac based on Super Conducting cavities, generating 10 8 10 [...] Read more.
Fine time-resolved analysis of matter—i.e., spectroscopy and photon scattering—in the linear response regime requires fs-scale pulsed, high repetition rate, fully coherent X-ray sources. A seeded Free Electron Laser (FEL) driven by a Linac based on Super Conducting cavities, generating 10 8 10 10 coherent photons at 2–5 keV with 0.2–1 MHz of repetition rate, can address this need. Three different seeding schemes, reaching the X-ray range, are described hereafter. The first two are multi-stage cascades upshifting the radiation frequency by a factor of 10–30 starting from a seed represented by a coherent flash of extreme ultraviolet light. This radiation can be provided either by the High Harmonic Generation of an optical laser or by an FEL Oscillator operating at 12–14 nm. The third scheme is a regenerative amplifier working with X-ray mirrors. The whole chain of the X-ray generation is here described by means of start-to-end simulations. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Open AccessArticle
From SPARC_LAB to [email protected]_LAB
Instruments 2019, 3(3), 45; https://doi.org/10.3390/instruments3030045 - 28 Aug 2019
Abstract
Following the promising results obtained at the SPARC_LAB test-facility in Frascati (Italy), we have recently submitted a proposal to develop a new facility driven by a plasma accelerator module for extended and user-oriented applications. The new multi-disciplinary user-facility will be equipped with a [...] Read more.
Following the promising results obtained at the SPARC_LAB test-facility in Frascati (Italy), we have recently submitted a proposal to develop a new facility driven by a plasma accelerator module for extended and user-oriented applications. The new multi-disciplinary user-facility will be equipped with a soft X-ray Free Electron Laser (FEL) operating with energies larger than 1 GeV. This design study is performed to be fully compatible with the EuPRAXIA design study. Here, the latest layout and beam parameters are presented. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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Other

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Open AccessProject Report
Light Sources in Europe—Case Study: The COMPACTLIGHT Collaboration
Instruments 2019, 3(3), 43; https://doi.org/10.3390/instruments3030043 - 18 Aug 2019
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Physics and Applications of High Brightness Beams)
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