laser
MOZD2
EuPRAXIA and its italian construction site
27
The European Eupraxia project has recently been included in the ESFRI roadmap. EuPRAXIA is a world-wide first, new kind of compact facility and will be constructed at two European sites. One of the two sites for Eupraxia will be the INFN LNF at Frascati. The facility will be integrated with the already planned 1GeV linear accelerator. This talk will cover the status of the technical design of the accelerator, general infrastructure plans and future pilot applications in the user community.
Paper: MOZD2
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOZD2
About: Received: 21 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
MOOG2
Characterisation of microbunching instability at the FERMI Free Electron Laser
47
A systematic study of microbunching instability is being carried out in the FERMI free-electron laser linac driver. This talk will report about modelling and experiments related to the instability, including the development of an infrared (IR) spectrometer for the diagnostic of microbunching-induced coherent emission in the IR spectral range.
Paper: MOOG2
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOOG2
About: Received: 10 May 2023 — Revised: 12 Jun 2023 — Accepted: 12 Jun 2023 — Issue date: 26 Sep 2023
MOOG3
Additive manufacturing of copper RF structures for particle accelerator applications
53
Particle accelerators, relevant to LANL’s mission spaces will rely on the use of copper based rf structure for charged particle acceleration. Additively manufactured (AM) copper structures offer the usual well-known advantages in terms of relaxation of physical design (shape) constraints, and thus hold the promise of making complex shaped rf structures. To rapidly demonstrate the potential to additively manufacture accelerator structures with existing technology, a bound metal deposition (BMD) metal 3D printer will be used to build a scaled design and the results of this effort will be presented.
Paper: MOOG3
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOOG3
About: Received: 03 May 2023 — Revised: 15 Jun 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPA062
Technological features and status of the new heavy ions synchrotron SIS100 at FAIR
165
SIS100 is a new superconducting heavy ion synchrotron optimized for the acceleration of high intensity heavy ion beams. Most crucial intensity limitation for heavy ion beams in SIS100 is the dynamic vacuum and corresponding beam loss by projectile ionization. Ionization loss and ion induced desorption drive the residual gas pressure into an instability, generating an intensity barrier at much lower intensity levels than any space charge limit. Technologies for stabilizing the dynamic vacuum, such as extensive charge separator lattice, pumping by cryogenic magnet chambers, cryo-adsorption pumps and cryo-ion catchers had to be implemented. SIS100 will also be the first user synchrotron comprising a laser cooling system for cooling at relativistic beam energies. Combined with a strong bunch compression system, laser cooling will support the generation of short ion bunches. Meanwhile, a large amount of the SIS100 components have been delivered and preparations for installation are launched. The shell construction of SIS100 underground tunnel is completed. Installation of the technical building infrastructure and the cryogenic distribution system are ongoing.
Paper: MOPA062
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA062
About: Received: 02 May 2023 — Revised: 08 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
MOPA063
Light source developments at UVSOR BL1U
169
UVSOR, a low energy synchrotron light source, has been operational for about 40 years. It has been providing high brightness VUV radiation to users but also providing a research environment for light source technology developments. In this paper, first, we briefly review the history of the light source developments at UVSOR. Then, we describe a beamline BL1U, which is currently used for developments and applications of novel light source technologies. The beamline is equipped with two variable polarized undulators with a phase-shifter magnet and with a femto-second laser system which is synchronized with the RF acceleration. We have been developing resonator free electron laser, coherent harmonic generation, coherent synchrotron radiation, inverse Compton scattering, spatiotemporal-structured light and have been exploring their applications, in collaboration with researchers from universities and research institutes. We present the present status of BL1U and some recent results.
Paper: MOPA063
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA063
About: Received: 08 May 2023 — Revised: 08 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPA074
Optimizing the beam intensity control by Compton back-scattering in e+/e- Future Circular Collider
199
In this paper, we present the possible use of laser Compton back scattering (CBS) to adjust and tune the bunch intensity. In the future circular electron-positron collider “FCC-ee”, the intensity of the colliding bunches should be tightly controlled, with a maximum charge imbalance between collision partner bunches of less than 3–5%. The control of such tolerance is necessary due to the strong effect of beamstrahlung on the bunch length and “flip-flop” instability. We show a realistic beam optical line and simulation results of CBS in the "FCC-ee", including the distribution of scattered positrons.
Paper: MOPA074
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA074
About: Received: 03 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
MOPA076
Modernization of the laser-optical system of the X-ray generator NESTOR
206
Modernization of the NESTOR hard X-ray generator storage ring for switching to the operating frequency of the accelerator of 2.856 GHz requires corresponding changes in the design of the high-frequency system, and this, in turn, leads to the need to modernize the laser-optical system. The necessary calculations were carried out to determine the new characteristics of the pulsed laser, the Fabry-Perot cavity, and the lens optical system matching the beam geometry. The obtained results confirm the possibility to use an already existing laser-optical system at a new operating frequency of the accelerator with some changes in the design.
Paper: MOPA076
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA076
About: Received: 09 May 2023 — Revised: 10 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPA081
Data analysis and control of an MeV ultrafast electron diffraction system and a photocathode laser and gun system using machine learning
222
An MeV ultrafast electron diffraction (MUED) instrument system, such as is located at the Accelerator Test Facility (ATF) of Brookhaven National Laboratory, is a structural characterization technique suited to investigate dynamics in the ultrashort range in a variety of materials via a laser pump method. It is a unique characterization technique especially suitable for highly correlated materials. This technology can be advanced further into a turnkey instrument by using data science and artificial intelligence (AI) mechanisms in conjunction with high-performance computing. This can facilitate automated operation, data acquisition, and real-time or near-real-time processing. The AI-based system controls can provide real-time feedback on the electron beam or provide virtual diagnostics of the beam. Deep learning can be applied to the MUED diffraction patterns to recover valuable information on subtle lattice variations that can lead to a greater understanding of a wide range of material systems. A data-science-enabled MUED facility will also facilitate the application of this technique, expand its user base, and provide a fully automated state-of-the-art instrument. Another beamline enhancement planned is the extension of the beamline sample area to include additional instrumentation for simultaneous measurement of a standard baseline sample. EM modeling of the beamline components facilitates this. Updates on research and development for the MUED instrument are presented.
Paper: MOPA081
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA081
About: Received: 08 May 2023 — Revised: 12 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
MOPA141
Preliminary design of the FCC-ee vacuum chamber absorbers
382
In the FCC-ee study, it is proposed that electron and positron beams circulate at high current and high energy in a 92-km circumference ring. The present operational scenario foresees a first running step at an energy of 45.6 GeV and around 1.4 A current, which would generate copious amounts of synchrotron radiation (SR) power and flux. To guarantee a quick decrease of the photon desorption yields and so a fast vacuum conditioning, it has been proposed to use localized SR absorbers along the vacuum chamber, spaced about 6 m apart. This would also help contain the high-energy Compton-scattered secondaries once the beam energy is increased up to 182.5 GeV, later in the experimental program. In the preliminary design of FCC-ee vacuum chamber absorbers presented in this work, the SR thermal power is intercepted along around 100 mm of slanted surface. The temperature distribution in the adsorbers is estimated by Finite Element Analysis (FEA) and needs to be assessed to avoid any liquid-gas phase change within the water-cooling circuit. The cooling channels contain a twisted tape that increases the turbulence of water. This results in the desired heat transfer coefficient. The mechanical deformations due to the non-uniform temperature map are presented and analyzed as well.
Paper: MOPA141
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA141
About: Received: 10 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
MOPA175
Improved signal detection of the steady-state microbunching experiment at the Metrology Light Source
461
The concept of steady-state microbunching (SSMB) as a new scheme for the production of high power synchrotron radiation has been demonstrated at the Metrology Light Source in Berlin-Adlershof (MLS) [1]. At the MLS the same undulator section is used for the generation of the micro-structures onto the electron bunch as well as for the detection of the resulting coherent radiation from the micro-bunches one turn later. Due to the enormous difference in the pulse energy of the micro-bucket generating laser and the coherent undulator pulses showing up 160 ns later, the detection is not straightforward. We show in detail the detection scheme, mostly based on fast optical shutters, and the triggering scheme of the experiment. Ideas for further improvements are discussed. [1] X. Deng et al., Nature, Volume 590, Issue 7847
Paper: MOPA175
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA175
About: Received: 25 Apr 2023 — Revised: 16 Jun 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPA176
Exploring the necessary conditions for steady-state microbunching at the Metrology Light Source
464
Steady-state microbunching (SSMB) is envisioned to enable the generation of high-power coherent synchrotron radiation at an electron storage ring for wavelengths up to the extreme ultraviolet. The underlying mechanism has been shown to be viable in a proof-of-principle (PoP) experiment at the Metrology Light Source (MLS) in Berlin\*. An enhanced detection scheme allows systematic studies of the conditions needed for the creation of microbunches within the continuing PoP experiment\*\*. It was found that the generation of coherent radiation from microbunches is favored in specific nonlinear longitudinal phase space structures, known as “alpha buckets”, which arise when the momentum compaction function becomes dominated by higher order terms. We present the most recent experimental results and their interpretation as well as accompanying simulation results.
Paper: MOPA176
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPA176
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL068
Dark sector searches based on dielectric laser acceleration
702
We discuss the beam requirements for indirect searches of dark matter and feebly coupled particles using advanced accelerator concepts. A parameter comparison reveals dielectric laser acceleration as a promising candidate for delivering the needed single-electron beams in the 5-100 GeV energy range or beyond. We suggest a parameter set for a baseline DLA-based dark sector accelerator. Enhancements through combining dielectric laser deflectors with a segmented detector or by making the dielectric structure be part of the laser oscillator could offer a performance significantly exceeding the ``Extended LDMX'' proposal based on LCLS-II.
Paper: MOPL068
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL068
About: Received: 26 Apr 2023 — Revised: 05 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
MOPL147
Ultra-thin film yttria enhanced gold photocathodes
883
The performance requirements for next generation electron accelerators put ever increasing demand on the photocathode performance, where it fundamentally limits the achievable beam quality. Metal photocathodes are limited by their high work function and relatively low quantum efficiency, necessitating the use of high powered deep UV lasers. Metal oxide thin film interfaces have been shown to reduce the work function of the underlying metal photocathode, whilst maintaining the ease of use, high durability and fast response time. This leads to an improvement in quantum efficiency and spectral response to desirable incident laser sources. We present the characterisation of a thin film yttria (Y2O3) enhanced Au photocathode at various film thicknesses. Quantum efficiencies were measured at 265 nm along with surface compositions via X-ray photoelectron spectroscopy.
Paper: MOPL147
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL147
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPM032
SPEED: Worldwide first EEHG implementation at a storage ring
1057
At DELTA, a 1.5-GeV synchrotron radiation source at TU Dortmund University, ultrashort radiation pulses are generated using CHG (coherent harmonic generation), where the interaction with laser pulses in an undulator (modulator) causes a periodic electron energy modulation within a 50-fs slice of a 2000-times longer electron bunch. A dispersive chicane creates a density modulation giving rise to the coherent emission of ultrashort pulses at harmonics of the seed pulse in a second undulator (radiator) exceeding the incoherent background from the whole bunch. In summer 2022, the electromagnetic insertion device U250, which included both undulators and the chicane, was reconfigured to demonstrate EEHG (echo-enabled harmonic generation, originally proposed for linac-based free-electron lasers) at a storage ring and to reach higher harmonics. The U250 coils were rewired to create two modulators for a twofold laser-electron interaction, two chicanes to manipulate the electron density, and the radiator, each comprising only a few undulator periods. The two seeds are a frequency-doubled Ti:sapphire laser pulse at 400 nm and its residual at 800 nm wavelength. EEHG pulses are detected using an in-vacuum grating spectrometer. In addition, the coherent emission of THz radiation is monitored. The paper presents first results of this project termed SPEED (Short-Pulse Emission via Echo at DELTA) which, to our knowledge, is the worldwide first attempt to perform EEHG at a storage ring.
Paper: MOPM032
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM032
About: Received: 03 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
MOPM065
Generalized longitudinal strong focusing in a storage ring for coherent EUV radiation
1134
A laser-driven storage ring is proposed to generate steady-state, nanometer-long electron bunches. A ring of this type can produce coherent EUV radiation with greatly enhanced power and photon flux, benefiting a wide range of scientific and industrial communities, including condensed matter physics and computer chip fabrication. The underlying mechanism is called generalized longitudinal strong focusing (GLSF), which invokes precise transverse-longitudinal coupling dynamics and lowers the required laser power significantly by exploiting the ultrasmall vertical beam emittance. A practical instance indicates that kW-level coherent EUV radiation is attainable in a GLSF ring with a modulation laser power as low as 1 MW, allowing for continuous-wave operation of up-to-date optical cavities.
Paper: MOPM065
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM065
About: Received: 03 May 2023 — Revised: 25 May 2023 — Accepted: 25 May 2023 — Issue date: 26 Sep 2023
MOPM091
Magnetic Measurement of Tapered Gap U50 Undulator
1188
The Tapered undulator provides interesting possibilities for keeping the undulator in resonance with the electron beam along the length of the undulator. The U50-II [1,2] undulator at Laser and Insertion Device Application Laboratory of DAVV, India is a 1000mm length, 50mm period length undulator. The four heavy-duty precise lead screw attached to the mechanical girder allows its gap to be tapered. In this paper, we report the field integral, phase error measurement of the tapered U50-II PPM undulator by Hall probe method and compare its accuracy by stretched wire result [3].
Paper: MOPM091
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM091
About: Received: 09 Apr 2023 — Revised: 05 Jul 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPM095
An in-vacuum measurement system for CPMUs at Diamond Light Source
1196
An in-vacuum Hall probe measurement bench was designed, built, and used to measure four Cryogenic Permanent Magnet Undulators (CPMUs) at 77 K at Diamond Light Source. The devices were tuned to correct the phase error at cold temperatures based on the measurements from the in-vacuum bench. The in-vacuum bench consists of a stretched wire system supplied by Danfysik and the in-house Hall probe bench. The Hall probe bench has gone through two iterations: the first was prone to deforming with temperature changes; the second was made thicker following design changes to the magnet holders and girders of the CPMUs which allowed more space for the bench inside the vacuum vessel. The design and commissioning of the bench will be presented, along with some measurements of the CPMUs at room temperature and at 77 K. Details such as height compensation, temperature compensation, and triggering of the Hall probe measurements will be covered.
Paper: MOPM095
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM095
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPM101
Status update on SUNADAE2 magnetic field test facility at European XFEL
1215
The implementation and further improvements of superconducting undulators is part of the European XFEL facility development program. Within this program, a magnetic field test facility is being developed. Named SUNDAE2 (Superconducting UNDulAtor Experiment 2), it aims to perform in-vacuum magnetic field measurements of superconducting undulators (SCUs) with three techniques: Hall probe, moving wire, and pulsed wire. This contribution presents the updates and status of SUNDAE2.
Paper: MOPM101
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM101
About: Received: 31 Mar 2023 — Revised: 28 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
MOPM111
Pulsed wire magnetic field measurements for an in-vacuum undulator
1236
An in-vacuum undulator is important for synchrotron radiation. An in-vacuum undulator with a permanent-magnet is used by the Taiwan Photon Source (TPS) in the National Synchrotron Radiation Research Center (NSRRC). Before installation in the storage ring, the magnetic field of the undulator is measured at the oper-ational gaps. The magnetic-field for an in-vacuum un-dulator is measured using a Hall-probe and a stretched-wire measurement system. This study uses a pulsed wire magnetic field measurement system for an in-vacuum undulator. A reference magnet with a known magnetic field is used to determine the magnetic field profile for an in-vacuum undulator and it is demonstrat-ed that the oil dampers crucial to eliminating dispersion waves for the pulsed wire measurement. The results are used to compare the magnetic field measurements that use a pulsed wire with those that use a Hall probe.
Paper: MOPM111
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM111
About: Received: 27 Apr 2023 — Revised: 07 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPM112
Strongly tapered helical undulator system for FAST-GREENS installation
1240
RadiaBeam, in collaboration with UCLA and Fermilab, is developing a strongly tapered helical undulator system for the Tapering Enhanced Stimulated Superradiant Amplification experiment at 515 nm (TESSA-515). The experiment will be carried out at the FAST facility at Fermilab as a Gamma-Ray high Efficiency ENhanced Source (FAST-GREENS). The undulator system was designed by UCLA, engineered by RadiaBeam, and will be installed on the beamline at Fermilab. The design is based on a permanent magnet Halbach scheme of four 1-meter long undulator sections; two of which have been completed and installed. The undulator period is fixed at 32 mm and the magnetic field amplitude can be tapered by tuning the gap along the interaction. Each magnet can be individually adjusted by 1 mm, offering up to 25% magnetic field tunability with a minimum gap of 5.58 mm. This paper discusses the design and engineering of the undulator system and the stage 0 installation status.
Paper: MOPM112
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM112
About: Received: 08 May 2023 — Revised: 10 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPM123
Cavity mirror development for optical enhancement cavity of steady-state microbunching light source
1254
Optical enhancement cavity (OEC) provides the high intensity and high stability modulation laser field in steady-state microbunching (SSMB) light source. An SSMB extreme ultraviolet (EUV) light source targeted for lithography application is currently being developed at Tsinghua University, which demands for megawatt scale intra-cavity power for OEC. Cavity mirrors are the key components of the OEC to realize its designed parameters. Here we report the development progress of the cavity mirrors.
Paper: MOPM123
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM123
About: Received: 02 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
MOPM125
Study on a self-resonating optical cavity for high-brightness Laser-Compton Scattering X-ray sources
1257
Laser Compton Scattering (LCS) is a technique to produce quasi-monochromatic X-rays and gamma rays by colliding a laser with a high-energy electron beam produced by an accelerator. Although LCS light sources are expected to produce photons of the same quality in a small (6m x 8m) device as those from large synchrotron radiation facilities , the low number of scattered photons is an issue for practical use. To solve this problem, we have developed an optical cavity to generate colliding lasers with high repetition rate and high peak power. However, the operation of an optical cavity in an accelerator environment with high noise limits the stored optical power by maintaining resonance through resonator length control. Therefore, we have devised and are developing a self-resonating optical cavity in which the resonance is maintained spontaneously by connecting the optical storage resonator and the laser oscillator in a closed loop. In this talk, I will report on the current status of self-resonating optical cavity and its temperature dependence.
Paper: MOPM125
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM125
About: Received: 24 Apr 2023 — Revised: 05 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPM126
Tunable monochromatic gamma ray source design using Inverse Compton Scattering at Daresbury Laboratory
1260
Inverse Compton Scattering (ICS) is an ideal source of tunable monochromatic gamma rays. These gammas have uses for Nuclear Resonance Fluorescence, and production of novel medical radioisotopes. The gamma energy can be tuned by changing the electron energy. An ICS source can be made quasi-monochromatic by using low energy spread electron and laser beams, and using a collimator. Currently ICS gammas are only available from large synchrotron driven electron sources. These sources suffer from a smaller flux in the desired bandwidth than ERLs or linacs. A new planned gamma source is under consideration as part of the proposed UK-XFEL project, this would involve part of the XFEL linac being enabled for an energy recovery mode. A demonstrator experiment to support the UK-XFEL project is being discussed for the upgraded CLARA facility at Daresbury Laboratory. The experiment will scatter Ti:Sapphire laser pulses at 800 nm off 250 MeV electrons. The gammas will be collimated. This experiment will characterise the source to determine the bandwidth and flux of the source. The maximum energy of the gamma photons in this experiment is 1.48 MeV and the bandwidth of the collimated source is 3.2%. In this work I will present simulations of the planned experiment, showing the scattered gamma energy, bandwidth and tunability of the source.
Paper: MOPM126
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM126
About: Received: 02 May 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPM132
Recent progress of Shanghai laser electron gamma source (SLEGS) beamline in SSRF
1271
Shanghai Laser Electron Gamma Source (SLEGS) beamline, based on laser Compton scattering (LCS), as one of beamlines of Shanghai Synchrotron Radiation Facility (SSRF) in phase II project, has been construct-ed and started test commissioning from July 2021. The results of the commissioning already show a steady experimental proof that SLEGS can produce gamma rays with adjustable maximum energy by consecutive-ly changing the interaction angle between laser beam and electron bunches. In this paper, the recent progress of SLEGS is given. The newly measured gamma-ray’s spectra and flux are presented. The resolution of the gamma-rays is im-proved with the application of external collimator. A gamma spot monitor is setup to measure the spatial distribution of LCS gamma ray. A 4π flat-efficiency 3He neutron detector (FED) array and the neutron time-of-fight (TOF) spectrometer are also designed and installed. Some preliminary results of these devices is introduced.
Paper: MOPM132
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPM132
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUOGA1
Laser assisted charge exchange injection into the ring at the SNS
1311
A realistic laser assisted charge exchange (LACE) scheme for 1.3~GeV H- beam injection into the Ring for Spallation Neutron Source is under development. The design considered here is supposed to demonstrate the possibility of H$^-$ charge exchange injection into the SNS ring as an alternative to carbon foil stripping. A realistic stripping magnet design is considered as an integrated part of the injection area. Beam dynamics at the injection area are optimised. Laser assisted stripping, painting and beam dynamics of protons in the ring is simulated. Several alternative stripping schemes are evaluated.
Paper: TUOGA1
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUOGA1
About: Received: 04 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
TUOGA2
Laser cooling taken to the extreme: cold relativistic intense beams of highly-charged heavy ions
1314
Recent storage ring experiments have demonstrated the power and the potential of laser cooling of bunched relativistic ion beams. Encouraged by this, the heavy-ion synchrotron SIS100 at FAIR (Darmstadt, Germany) will be equipped with a truly unique laser cooling facility. A sophisticated combination of 3 newly developed UV (257 nm) laser systems and modest rf-bunching will allow for fast cooling of injected intense heavy-ion beams. There will be two powerful pulsed laser systems with MHz repetition rates and variable pulse duration (1-50 ps and 50-740 ps) and one powerful tunable cw laser system. The picosecond laser pulses are broad in frequency and will enable fast cooling of injected ion beams with a large initial longitudinal momentum spread. The cw laser can be rapidly tuned over a large frequency range and has high spectral power density, forcing the ion beams to remain cold during storage. This combination of 3 UV laser beams should be up to the challenge of suppressing intra-beam scattering and space charge effects. We will present new experimental results from the ESR storage ring and the status of the SIS100 laser cooling facility.
Paper: TUOGA2
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUOGA2
About: Received: 02 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
TUODB2
Dielectric laser acceleration for dark sector studies
1332
For the purpose of indirect search of dark matter, we designed laterally driven Dielectric Laser Acceleration (DLA) structure that achieves 1.2 MeV energy gain in 6 mm length together with 6D confinement. The design originated from a relativistic DLA structure and was supplemented with non-homogeneous shapes following the APF segments and optimized using a genetic algorithm together with the DLAtrack6D tracker. The achieved throughput could be increased to 98%.
Paper: TUODB2
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUODB2
About: Received: 03 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
TUPA001
Copper surface treatment with deep UV ultrafast laser for improved photocathode photoemissive properties
1350
Surface nanostructuring is a promising approach when it comes to improving the quantum efficiency (QE) of materials for electron accelerator purposes at CERN. This is due to the plasmonic effect taking place in metallic materials at the nanoscale, when an electromagnetic wave interacts with a sub-wavelength feature. Ultrafast laser surface nanopatterning can be an efficient and times saving method for producing such nanostructures. We conducted a study of nanostructuring of copper surfaces with a deep-UV femtosecond laser. A wide range of fabrication parameters (speed, laser fluence and repetition rate) were tested. At different energy regimes we were able to produce Laser Induced Periodic Surface Structures (LIPSS), as well as spherical nanoparticles of tunable size and other types of periodic nanoscale features. Sub-wavelength periodic structures yield higher exaltation of surface plasmons under matching excitation wavelength, resulting in a potentially significant increase in QE of copper photocathodes. Moreover, by using the same laser source for nanomachining and photoemission, one can easily integrate the technology in and existing photoinjector.
Paper: TUPA001
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA001
About: Received: 13 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
TUPA002
Simulation of plasmonic effects in nanostructured copper surfaces for field-assisted photoemission
1354
We propose a simulation model of the field enhancement and quantum efficiency (QE) increase of metallic surfaces as a result of a surface nanostructuring. In the framework of photoinjector facilities for electron accelerators at CERN, achieving optimal nanostructuring parameters may become a significant asset. The presence of a well-designed periodic surface topography can give rise to plasmonic resonance and coupling effects within the structures, which yields a local increase in electron density and an electric field enhancement. This model is used to provide a deeper insight into these effects. We investigate the dependency of the electron emission enhancement on the nanopattern geometry and incident wavelength on the plasmonic resonance. We examine, based on former experimental results, the performance of Laser Induced Periodic Surface Structures (LIPSS) and other types of periodic nanoscale features, but we also demonstrate the surprisingly strong contribution of nanoparticles in the global field enhancement of the surface. These particles are a common side effect of ultrafast laser surface processing and themselves exhibit unique plasmonic resonance properties.
Paper: TUPA002
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA002
About: Received: 04 May 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUPA003
Prformance of laser patterned copper plasmonic photocathodes
1358
We study ultrafast laser surface nanopatterning as an alternative to improve the photo-emissive properties of metallic photocathodes. By tailoring the physical dimensions of these surface nanostructures, one can localize the optical field intensity and exploit plasmonic effects occurring in such nanostructures. As a result, this surface nanopatterning technique can become a great tool for improving metallic photocathodes photoemission behavior enabling their use for next generation high brightness electron sources. Our goal is to investigate such surface-plasmon assisted photoemission processes with a view on simplifying the photocathode production at CERN while extending the lifetime of existing photoinjectors. The performance of two different femtosecond laser nanopatterned plasmonic photocathodes was analyzed by measuring the quantum yield with a 65kV DC electron gun utilizing 266nm laser excitation generated by a nanosecond laser with 5ns pulse duration and 10Hz repetition rate. By comparing the electron emission of the copper surface nanostructured areas with that of a flat area, our results suggest quantum yield enhancements of up to 5 times.
Paper: TUPA003
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA003
About: Received: 07 May 2023 — Revised: 08 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
TUPA020
Test of a DC-photogun Injector for the Lighthouse facility
1390
Worldwide there is a push for producing medical isotopes using particle accelerators rather than fission reactions. Here we report on the operation of a DC-photogun designed for producing Mo-99 in the Lighthouse facility and commissioned by the Institute for Radio Elements (IRE, Belgium). The gun is based on the successful CBETA design by Cornell University. It is installed at the RI site in Bergisch Gladbach, Germany. As innovative components it contains a photocathode deposition system allowing an automatic transfer of photocathodes into the gun and it uses Novec 4710, a gas developed by 3M as a sustainable replacement for SF6. The injector was installed at the RI site in Bergisch Gladbach, Germany and has produced first e-beam in April 2022. Currently we are ramping up the e-beam power and optimizing the photocathodes. The high-voltage has been conditioned up to >400kV and we see no negative impact of the NOVEC gas. The laser produces 40W at 515nm and 1.3GHz repetition rate and adjustable pulse length. It can deliver pulse trains of 100ns up to CW with variable pulse power onto the cathode. In the MBE system we routinely prepare photocathodes with at least 5% quantum efficiency, well sufficient for the design current of 40mA.The beam diagnostics is currently used to optimize the electron beam. The current focus is on ramping up the power to the design value of 40mA at 350kV.
Paper: TUPA020
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA020
About: Received: 11 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPA035
Negative electron-affinity activation procedures for GaAs photocathodes at Photo-CATCH
1415
State-of-the-art spin-polarized photo-electron sources use GaAs-based photocathodes to provide electron beams with high degrees of spin-polarization. Such photo-guns are required to operate with both quantum efficiency and cathode lifetime as high as possible in order to meet the requirements of high-current applications such as energy-recovery linacs and colliders. Both quantum efficiency and lifetime are determined by the quality of the thin surface layer, typically consisting of Cs in combination with an oxidant, required for GaAs photocathodes to achieve negative electron affinity. This layer is applied during a so-called activation process. It is therefore of great interest to optimize and standardize this procedure in order to provide the best possible conditions for reliable photo-gun operation. This contribution presents the analysis of bulk-GaAs activations using Cs and O conducted at the Photo-CATCH test stand. The effects of Cs and O partial pressures on final quantum efficiency and lifetime, as well as the duration of the activation process were scrutinized in order to find an optimal partial pressure ratio at a reasonable duration of the procedure.
Paper: TUPA035
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA035
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPA041
Ionization of the muonium using the electron
1432
The muonium is the bound state of the positive muon and the electron. The muoium can be ionized using a dedicated laser to produce the ultra-slow muon beam. It is one idea that the dense electrons may be used as a substitute of the ionization laser for the muonium. The preliminary study is reported for the ionization of the muonium using the electron.
Paper: TUPA041
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA041
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUPA045
High-energy single-cycle terahertz sources for compact particle accelerators and manipulators
1440
Novel accelerator concepts such as all-optical terahertz (THz) based compact accelerators demand high-power THz sources that are robust in order to enable reliable testing. THz sources based on the tilted-pulse front scheme have become the method of choice for table-top, high-energy, single-cycle (SC) THz generation due to both their versatility and scalability. However, due to the noncollinear interaction geometry, fine-tuning of the performance and tailoring of the THz beam properties requires a detailed understanding of the dependences on the setup parameters. Here, we present on the use of multi-dimensional parameter scans to systematically map out sensitivities of such THz sources on the primary interaction parameters and show experimental characterization of a robust, high-energy, single-cycle THz source designed and constructed based on these findings. This setup delivers pulses centered at 300 GHz with pulse energies exceeding 400 µJ at 52 Hz repetition rate and a shot-to-shot rms stability < 3.8%. Such robust, high-energy THz sources are crucial for the development of next generation THz-driven particle accelerators and manipulators.
Paper: TUPA045
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA045
About: Received: 10 May 2023 — Revised: 10 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
TUPA047
3D polarisation of a structured laser beam and prospects for its application to charged particle acceleration
1443
A Structured Laser Beam (SLB) is a type of optical beam with spatially inhomogeneous 3D polarisation structures. Generating SLBs from vector beams allows the creation of Hollow Structured Laser Beams (HSLB) with a dark central core. In this way, atypical electric and magnetic field vectors, which are purely longitudinally polarized in the dark zones of the beam, are obtained. The SLB spatial distribution can also include regions with both the electric and magnetic fields longitudinally polarized and oriented in the same or opposite directions. The SLB has a transverse distribution similar to that of a Bessel beam but can theoretically propagate to infinity, therefore giving the potential to generate strong, longitudinally oriented electric fields over long distances, which could possibly allow the acceleration of charged particles. The results of the study of this phenomenon, including simulations of the spatial distribution of the electromagnetic field components, are presented in this paper.
Paper: TUPA047
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA047
About: Received: 10 May 2023 — Revised: 11 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
TUPA051
TeV/m acceleration in laser-graphene interactions
1454
Electron acceleration in solid-state plasmas is of interest within the Laser Wakefield Acceleration (LWFA) research. Layered nanostructures such as graphene nanoribbons can be used as targets for intense UV lasers to generate and accelerate electron bunches. We present numerical Particle in Cell (PIC) simulations of a novel sub-femtosecond self-injection scheme which relies on edge-plasma oscillations in a layered graphene target. The scheme delivers 0.4 fs-long electron bunches of 2.5 pC total charge with an energy gain rate of 4.8 TeV/m. These parameters are unprecedented and, if confirmed experimentally, may have an impact on fundamental femtosecond research.
Paper: TUPA051
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA051
About: Received: 01 May 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUPA060
Laser source and Gabor lens for use within LhARA
1465
The ‘Laser-hybrid Accelerator for Radiobiological Applications’, LhARA*, facility is conceived to study the biological response to ionising radiation, specifically focussing upon the co-called ‘FLASH’ (>40 Gy/min) regime. A high repetition laser, directed at a thin target, will generate high intensity, ultra-short, particle bunches, at up to 15 MeV/u (and subsequent acceleration up to 127 MeV/u, as required). These particles will be guided to one of several end-stations, whereby the effects can be studied via in-vitro or in-vivo experiments using newly developed detectors, existing phantoms, and test samples. The laser driven ion source and capture systems are key technologies for LhARA. We will discuss ongoing R&D into delivery of a laser driven ion source with the required beam parameters, stability and repetition rate. Following the idea originally outlined by Gabor**, the current plan and status of using large volume, high-density, low-temperature, non-neutral plasmas as beam optics within the capture system will also be presented.
Paper: TUPA060
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA060
About: Received: 12 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
TUPA064
Simulations and experimental studies for an X-band short-pulse ultra-high gradient photoinjector
1476
A program is under way at the Argonne Wakefield Accelerator (AWA) facility, in collaboration with Euclid Techlabs and Northern Illinois University (NIU) to develop a GV/m-scale photocathode gun, with the goal of producing bright electron bunches. The novel X-band (11.7 GHz) photo-gun (Xgun) is powered by high-power, short rf pulses (9 ns), which are generated by the AWA drive beam in a wakefield structure. In the first series of experiments, the Xgun produced ~400 MV/m peak field on the photocathode surface. The Xgun has also shown exceptional robustness, with no noticeable breakdown observed after being fully conditioned. As a first step towards achieving a complete understanding of the Xgun's performance, we aim to investigate the fundamentals of photoemission in the high-gradient regime. Systematic simulations will be presented for the near-future photocathode thermal emittance measurements.
Paper: TUPA064
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA064
About: Received: 04 May 2023 — Revised: 19 May 2023 — Accepted: 19 May 2023 — Issue date: 26 Sep 2023
TUPA070
MeV-scale simulations and fabrication tests of woodpile-based waveguide for dielectric laser accelerators
1484
Hollow-core dielectric Electromagnetic Band Gap (EBG) microstructures powered by lasers represent a new and promising area of accelerator research since, thanks to the short optical wavelength and to the dielectric's high damage threshold greater accelerating gradients, with respect to the metallic counterparts, can be achieved. In this paper, we present MeV-scale beam-dynamics simulations and fabrication results relative to a silicon, woodpile-based travelling-wave structure operating at the wavelength 𝜆0 = 5 μm. The simulated CST and HFSS electric field has been evaluated and used as input for a space charge tracking code, in order to perform beam-dynamics evaluations on the beam injection and extraction into the proposed structure as well as the evolution of the main beam parameters. We also report on the fabrication of first Si prototypes of the woodpile structure that are obtained by the innovative Two Photon Polymerization fabrication process. This technique allows to reach resolutions down to hundreds of nanometers, offering the possibility to print Si-rich structures, or woodpile skeletons to be infiltrated with Si by CVD technique.
Paper: TUPA070
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA070
About: Received: 28 Apr 2023 — Revised: 11 May 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
TUPA071
Simulation of tapered co-propagating structures for dielectric laser accelerator
1488
One of the key aspects to provide on chip acceleration in Dielectric Laser Accelerators (DLA) from tens of keV up to MeV energies is the phase velocity tapering. This paper presents the simulated performance of sub-relativistic structures, based on tapered slot waveguides. We engineered channel/defect modification in order to obtain a variable phase velocity matched to the increasing velocity of the accelerated particles. Additionally, we present a hollow-core relativistic electromagnetic band gap (EGB) accelerating waveguide. In DLA structures co-propagating schemes are employed for higher efficiency and smaller footprint compared to the cross-propagating schemes. In this respect, we envisage tapered continuous copropagating structures that simultaneously allow wave launching/coupling, beam acceleration, and transverse focusing. The main figures of merit, such as the accelerating gradient, the total energy gain, and the transverse focusing/defocusing forces, are evaluated and used to guide the optimization of the channel/defect modification. Index terms: Dielectric Laser Accelerators (DLA), Photonic Crystal, Dielectric Waveguides
Paper: TUPA071
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA071
About: Received: 04 May 2023 — Revised: 09 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPA077
Design and modeling of dielectric a wakefield accelerator with plasma ionized witness bunch
1499
A planned experiment at the Argonne Wakefield Accelerator (AWA) facility will demonstrate the plasma photocathode concept, wherein precise laser-based ionization of neutral gas within the wakefield driven by a relativistic particle beam generates a high brightness witness beam, which is accelerated in the wakefield. Replacing the plasma wakefield acceleration component with a dielectric wakefield acceleration scheme can simplify experimental realization by relaxing requirements on synchronization and alignment at the expense of accelerating gradient. However, this places rigorous constraints on drive beam dynamics, specifically charge, size, and relative separation. This paper presents progress on the design of such a hybrid scheme, including improved simulations accounting for anticipated beam properties and revised structure characteristics.
Paper: TUPA077
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA077
About: Received: 04 May 2023 — Revised: 19 May 2023 — Accepted: 19 May 2023 — Issue date: 26 Sep 2023
TUPA083
Transport studies of low energy radioactive ion beams produced by photofission at ALTO-LEB
1514
The ALTO research platform at the Laboratoire de physique des 2 infinis Irène Joliot Curie (IJCLab) is dedicated to wide-ranging research in nuclear physics, nuclear astrophysics and interdisciplinary activities such as health physics. ALTO-LEB is the low energy beam area of ALTO where neutrons rich exotic nuclei are studied. A new precision experiment is being installed at the ALTOLEB facility : a double Penning trap mass spectrometer MLLTRAP coupled with a RadioFrequency Quadrupole Cooler and Buncher (RFQCB). This last device requires low energy beams with low emittance, low energy dispersion and with few contaminants. This paper focuses on the beam transport at ALTO-LEB, from the target-ion source vault to the RFQCB. Simulations of the ions extraction from the ion source and beam transport calculations are being presented in this work. Those results are also directly connected to the reliability of ALTO-LEB beam lines initiated at IJCLab in 2018.
Paper: TUPA083
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA083
About: Received: 11 Apr 2023 — Revised: 05 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUPA089
EARLI: design of a laser wakefield accelerator for AWAKE
1529
Following the successful Run 1 experiment, AWAKE has developed a program for Run2 that requires designing and implementing a compact electron source (150 MeV, >= 100 pC) for external injection. The baseline design uses a S- and X-band RF photo-injector gun system. The project EARLI investigates the feasibility of an alternative electron source system using a laser wakefield accelerator (LWFA) to produce this electron bunch. Currently, the EARLI project is in the design phase backed by the preparation of experimental demonstrations to prove the feasibility of this accelerator. The main originality of the chosen approach is that the focus is made exclusively on the final beam-targeted characteristics and the reliability and repeatability of the beam quality. EARLI is a stand-alone injector that consists of three main parts: a laser system, a plasma cell and a transfer line, at the end of which the electron beam is injected in a plasma wave driven by a self-modulated proton bunch. Methods from conventional accelerators are applied to LWFA physics. Each part requires specific expertise, that must be investigated in close coupling with the others. A massive campaign of simulations and optimizations with PIC codes is ongoing while the design of the transfer line, the plasma chamber, diagnostics and the laser are carried out in parallel.
Paper: TUPA089
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA089
About: Received: 08 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
TUPA093
Efficient simulation of multistage plasma accelerators
1533
Plasma accelerators can sustain accelerating gradients of up to ~100 GeV/m. However, reaching the high energies required for future particle colliders requires the acceleration to be performed in multiple plasma stages. Solving the challenges posed by multistage acceleration, such a beam quality preservation, requires the capability of simulating large chains of accelerating stages, something that is typically limited by the high cost of full 3D particle-in-cell codes. Thus, there is a growing need for the development of more efficient models that allow for inexpensive collider studies with reduced physics or dimensionality. Here, we present the implementation of a novel gridless quasistatic algorithm in the Wake-T code that, coupled with a laser envelope solver, allows for accurate and efficient simulations of multistage laser-plasma accelerators with axial symmetry, a critical step toward their realization.
Paper: TUPA093
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA093
About: Received: 03 May 2023 — Revised: 19 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPA104
Status and first results from FACET-II towards the demonstration of plasma wakefield acceleration, coherent radiation generation, and probing strong-field QED
1549
FACET-II is a National User Facility at SLAC National Accelerator Laboratory with the goal to develop advanced acceleration and coherent radiation techniques using a 10 GeV electron beam of unprecedented beam intensity with >100 kA peak current and <10 µm spot size, a 10 TW experimental laser system, and a variety of solid, gas and plasma targets. A diverse experimental program will investigate beam-driven plasma wakefield acceleration (PWFA), injection, and control with the aim of demonstrating efficient multi-GeV/m PWFA while preserving emittance and narrow energy spread – as is required to reach the beam parameters for a future linear collider. Complimentary research programs into the application of machine learning for accelerator diagnostics and control, novel techniques for the generation of intense coherent radiation, and probing strong-field quantum electrodynamics (QED) also make use of the facility’s unique beam intensity and laser capabilities. The first year of beam delivery to experiments has focused on user assisted commissioning of beam delivery and experimental systems, including a novel EOS BPM with 10 fs bunch length and 5 µm transverse resolution. This contribution will describe the status of the facility, experimental systems, and novel diagnostics, in addition to reviewing the first scientific developments from User programs including initial progress towards beam-driven PWFA.
Paper: TUPA104
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA104
About: Received: 07 May 2023 — Revised: 14 Jun 2023 — Accepted: 14 Jun 2023 — Issue date: 26 Sep 2023
TUPA105
The EPAC electron transport beamline - physics considerations and design
1553
The Extreme Photonics application Centre (EPAC) is a planned UK national facility. The current intention is for EPAC to use a 1 PW 10Hz laser system to drive laser plasma acceleration with output energies ranging from 100 MeV up to, at least, 5 GeV. The initial design for the electron beam transport of the EPAC facility is presented in this paper. This includes some initial considerations on which type of beam line could be used in order to accommodate as many of the different energies as possible. Subsequently, the 1 GeV option is examined in considerable detail. Field errors as well as misalignments for all magnets in the beam line are examined, both individually and together, as well as multipole errors. Finally, a complete layout of the beam line is produced, this includes all diagnostic locations together with the position of a tape system to remove the laser light post-acceleration.
Paper: TUPA105
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA105
About: Received: 03 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
TUPA109
EuPRAXIA doctoral network
1567
EuPRAXIA is the first European project that develops a dedicated particle accelerator research infrastructure based on novel plasma acceleration concepts and laser technology. It focuses on the development of electron accelerators and underlying technologies, their user communities, and the exploitation of existing accelerator infrastructures in Europe. It was accepted onto the ESFRI roadmap for strategically important research infrastructures in June 2021 as a European priority. To fully exploit the potential of this breakthrough facility, advances are urgently required in plasma and laser R&D, studies into facility design and optimization, along a coordinated push for novel applications. EuPRAXIA-DN is a new MSCA Doctoral Network for a cohort of 12 Fellows between universities, research centers and industry that will carry out an interdisciplinary and cross-sector plasma accelerator research and training program for this new research infrastructure. This contribution gives an overview of this interdisciplinary network and its research.
Paper: TUPA109
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA109
About: Received: 30 Apr 2023 — Revised: 12 Jun 2023 — Accepted: 12 Jun 2023 — Issue date: 26 Sep 2023
TUPA132
Ultra thin Cs3Sb photocathodes with anomalously high quantum efficiency
1605
In this proceeding, we demonstrate the synthesis of epitaxial Cs$_3$Sb films with a high degree of crystallinity on silicon carbide substrates. Films less than 10 nm thin are grown in vacuum and exhibit percent level quantum efficiencies at 532 nm. We find a positive correlation between quantum efficiency and improved crystallinity of the photocathode film, particularly in the longer wavelengths of the visible spectrum. We present a model describing the optical interference effects observed in the SiC - Si substrate multilayer that enhance quantum efficiency of the thin film photocathodes by almost a factor of two at particular wavelengths. Additionally, we characterize the surface and bulk crystallinity of epitaxial Cs$_3$Sb films using both X-ray diffraction (XRD) and reflection high energy electron diffraction (RHEED) in an endeavor to identify relationships between crystalline phases and photocathode performance.
Paper: TUPA132
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA132
About: Received: 05 May 2023 — Revised: 19 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPA138
Characterisation of a Cs-implanted Cu photocathode
1611
The generation of high--brightness electron beams is a crucial area of particle accelerator research and development. Photocathodes which offer high levels of quantum efficiency when illuminated at visible wavelengths are attractive as the drive laser technology is greatly simplified. The higher laser power levels available at longer wavelengths create headroom allowing use of manipulation techniques to optimise the longitudinal* and transverse** beam profiles, and so minimise electron beam emittance. An example of this are bi-alkali photocathodes which offer quantum efficiency ~ 10% under illumination at 532 nm. Another solution is the use of modified photoemissive surfaces. Caesium has a low workfunction and readily photoemits when illuminated at green wavelengths (~532nm). Caesium oxide has an even lower workfunction and emits at red wavelengths (~635nm). We present data on our work to create a hybrid copper photocathode surface modified by implantation of caesium ions, measuring the surface roughness and probing its structure using MEIS. We measure the energy spread of photoemitted electrons, the QE as a function of illumination wavelength, and the practicality of this surface as a photocathode by assessing its lifetime on exposure to oxygen.
Paper: TUPA138
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA138
About: Received: 10 May 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
TUPA140
Thermodynamic study of ultrafast laser-field emission at nanostructured cathodes
1618
Strong laser-field electron emission enhanced by nanostructures is a growing topic of study, owing to its ability to generate high brightness beams. Experiments have shown that the nanoblade structure, a wedge shape, notably outperforms nanotips in the peak fields achieved. These higher fields result in a brighter emission. In this paper we study the thermodynamics of the electron system restricted to a nanostructure. Thermal diffusion of deposited energy near the apex of the structure is dominated by the electronic distribution on the electron-phonon timescale. We show analytically through use of the temperature-squared heat equation that the nanoblade, owing to its larger opening angle and higher dimensionality, thermomechanically outperforms the nanotip.
Paper: TUPA140
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA140
About: Received: 03 May 2023 — Revised: 07 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPA143
Theoretical investigation of real supply current distributions for metallic field emission
1625
Electron field emission and the related process of strong laser-field emission are promising mechanisms for the creation of high brightness beams. These processes deviate from the photoelectric effect in that the normal energy – not the total energy – is the predominant factor determining the likelihood for an electron to ionize. In this paper we continue our investigation of the material normal energy distribution (MNED), which is the supply current as a function of the normal energy. We derive analytical expressions for the MNED and mean transverse energy (MTE) for two cases: that of a smooth Fermi surface, and that of a Bragg plane intersecting Fermi surface in a weakly binding potential. We compare these analytical expressions to results calculated using density-functional theory (DFT) for tungsten and copper surfaces. We find explainable discrepancies between our analytical results and the DFT results for the W(100) direction and the Cu(111) direction, associated with the Fermi surface intersecting a Bragg plane, but otherwise find general agreement.
Paper: TUPA143
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA143
About: Received: 03 May 2023 — Revised: 07 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPA185
Development of a 704.4 MHz CH cavity using additive manufacturing
1744
A novel 704.4 MHz CH structure is under develop-ment. Due to its relatively small spatial dimensions (22 cm in diameter and 33.7 cm in length), the additive manufacturing (AM) technology is an attractive choice for the construction. For a proof of concept, a simplified model with one stem, one drift tube, and a small part of another stem was printed with copper. This structure was also foreseen for CW operation, so the design of the water-cooling channels inside the drift tubes and stems have been optimized and checked by the Ansys simulation. The progress with the realization of the 704.4 MHz CH structure will be presented.
Paper: TUPA185
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPA185
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPL004
Optimization of Echo-Enabled Harmonic Generation toward coherent soft X-ray free-electron laser in current and future synchrotron light sources
1778
For storage-ring-based free-electron lasers (FELs), prebunching via echo-enabled harmonic generation (EEHG) is an efficient way to reduce the radiator length and improve the longitudinal coherence as well as output stability. We propose a conceptual design, which uses two straight sections of a synchrotron to seed coherent soft X-ray emission. This scheme requires no change of the storage ring lattice and is fully compatible with other beamlines. To take the large energy spread (of the order of 10-3) of a storage ring electron beam into account, we developed a new modelling tool (EEHG optimizer) and successfully applied it to maximize the prebunching from harmonic 50 to 200 for nearly any synchrotron light source, with significant benefits. We developed a generalized EEHG model based on the critical parameters (momentum compaction, beam emittances, and Twiss functions) determining EEHG performances, which is applicable to nearly any synchrotron light source. We show by numerical simulations that for most of the currently operated and future light sources, the EEHG scheme can produce a significant prebunching up to harmonic 200, and thus generate a few MW scale peak power at 1.25 nm wavelength.
Paper: TUPL004
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL004
About: Received: 17 Apr 2023 — Revised: 27 Jun 2023 — Accepted: 27 Jun 2023 — Issue date: 26 Sep 2023
TUPL014
Sensitivity of the optical-klystron-based high-gain harmonic generation on the electron beam energy profile
1790
Externally seeded free electron lasers (FELs) offer fully coherent and stable FEL radiation in the soft x-ray regime. While electron bunches of superconducting-based FELs are available at MHz repetition rates, seeded radiation is limited by the repetition rate of the seed laser used in the process. Combining standard seeding schemes with an optical klystron is a simple and promising trick to reduce the seed laser power requirements and allow externally seeded radiation at higher repetition rates. To ensure optimum operation, we study the combined effect of a linear and a quadratic electron beam energy chirp on the properties of the output FEL radiation.
Paper: TUPL014
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL014
About: Received: 03 May 2023 — Revised: 16 Jun 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
TUPL016
Photocathodes for the electron sources at FLASH and European XFEL
1798
The photoinjectors of FLASH at DESY (Hamburg, Germany) and the European XFEL are operated by laser driven RF-guns. In both facilities cesium telluride (Cs$_2$Te) photocathodes are successfully used since several years. We present recent data on the lifetime and quantum efficiency (QE) of the current photocathode at FLASH \#105.2, operated before and after a long shutdown. In addition, data for the cathodes that recently have been exchanged at the European XFEL will be presented.
Paper: TUPL016
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL016
About: Received: 03 May 2023 — Revised: 05 Jun 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
TUPL020
Status of the free-electron laser user facility FLASH
1809
The free-electron laser user facility at DESY – FLASH – is operating two undulator beamlines simultaneously and delivers XUV and soft X-ray radiation for photon experiments. It is driven by a superconducting linear accelerator. In a shutdown from November 2021 to August 2022 FLASH underwent a comprehensive refurbishment and a substantial upgrade (FLASH2020+). In this paper we summarize the recommissioning of FLASH and its upgraded injector as well as the restart of user operation in 2022. The year 2023 focuses on user operation in order to establish as much as possible beamtime before the next shutdown in 2024.
Paper: TUPL020
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL020
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
TUPL022
Recommissioning of the FLASH injector and linac
1816
FLASH, the <strong>F</strong>ree electron <strong>LAS</strong>er in <strong>H</strong>amburg is currently undergoing a substantial refurbishment and upgrade project (FLASH2020+). A major stage was the 9 month shutdown in 2021/22. During this shutdown key components of the injector/linac where inserted, moved, rebuild or upgraded to enable the efficient and reliable preparation of electron bunches for HGHG and EEHG seeding in the FLASH1 beamline and simultaneous SASE operation in the FLASH2 beamline. In particular we have, added a new injector laser system, installed a laser heater system, moved the 1st bunch compression chicane downstream to generate space for the laser heater, replaced two old acceleration modules with modern high-gradient modules (thereby gained an additional 100 MeV of energy), replaced the 2nd bunch compression chicane with a more fancy movable one that enables variable longitudinal dispersion while allowing the compensation of bunch tilts, and saves space for an additional matching section section at the entrance to the main linac. Here we describe the more general aspects of the re-commissioning of the machine with beam which started early October 2022.
Paper: TUPL022
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL022
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
TUPL023
Using the LHeC ERL to generate high-energy photons
1820
The Large Hadron electron Collider (LHeC) is proposed as a future particle physics project colliding 60 GeV electrons from a six-pass recirculating energy-recovery linac (ERL) with 7 TeV protons stored in the LHC. The ERL technology allows for much higher beam current and, therefore, higher luminosity than a traditional Linac. The high-current, high-energy electron beam can also be used to drive a free electron laser (FEL). In this presentation, we examine how the LHeC ERL can serve as a source of high-energy photons for studies in nuclear physics, high energy physics, axion detection, dark energy and protein crystallography. In the first section, we discuss the performance of an LHeC-based FEL, operated in the SASE mode for generating pulses of X- and gamma rays at wavelengths ranging from 5 Å to 3 pm [1]. In the second section, we investigate photon production via inverse Compton scattering (ICS). [1] Physical Review Accelerators and Beams 24, 10 (2021)
Paper: TUPL023
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL023
About: Received: 02 May 2023 — Revised: 24 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPL025
Slice energy spread measurements in the european XFEL injector
1824
Optimising the slice energy spread in X-ray free electron lasers (XFELs) is key to their effective operation, and must be considered from the photoinjector at the very beginning of the machine. The standard approach, in which the measured beam size is entirely attributed to the product of the dispersion and the energy spread, has only a resolution on the order of several keV, meaning that a precise measurement in photoinjectors where the energy spread is predicted to be on the order of a few keV is challenging. However, recent techniques developed at SwissFEL, the Photo Injector Test Facility (PITZ) and at the European XFEL (EuXFEL) enable the slice energy spread to be determined with sub-keV precision. In this paper recent slice energy spread measurements at the EuXFEL are presented and contrasted with previous results. Furthermore its dependence on beamline parameters is explored. Finally, recent developments in the automation and simplification of the measurement procedure at the EuXFEL that allow for a broader investigation of the slice energy spread and its dependence on the beamline configuration are stated.
Paper: TUPL025
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL025
About: Received: 03 May 2023 — Revised: 22 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPL027
A CBXFEL demonstrator setup at the European XFEL
1828
A cavity based free-electron laser (CBXFEL) is a next generation X-ray source promising radiation with full three-dimensional coherence, nearly constant pulse to pulse stability and more than an order of magnitude higher spectral flux compared to SASE FELs. In this contribution, an R&D project for installation of a CBXFEL demonstrator experiment at the European XFEL facility is conceptually presented. It is composed of an X-ray cavity design in backscattering geometry of 133 m round trip length with four undulator sections of 20 m total length producing the FEL radiation. It uses cryocooled diamond crystals and employs the concept of retroreflection to reduce the sensitivity to vibrations. Start to end simulations were carried out which account for realistic electron bunch distributions, inter RF-pulse bunch fluctuations, various possible errors of the X-ray optics as well as the impact of heat load on the diamond crystals. The current state of the project shall be presented in this contribution.
Paper: TUPL027
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL027
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPL032
Laser plasma accelerator-based soft X-ray FEL development at ELI-Beamlines
1831
Modern linac-based free electron lasers (FEL) opened a new area of scientific research in physics, chemistry, biology and material sciences. In recent years laser plasma accelerator (LPA) technology has made great progress towards compact electron ‘GeV-energy scale’ accelerators. Combination of compact LPA accelerator with well-established technologies to build dedicated electron beam transport and undulator beam-line opens a possibility to extend ability of existing FEL facilities delivering a photon beam with unique and novel properties for the worldwide photon user community. Development of the laser-plasma accelerator based soft X-ray FEL at ELI-Beamlines (Czech Republic) will extend ERIC-ELI capabilities in multiple science fields such as laser technology, plasma accelerators and photon science technology. In the frame of this report we will present a conceptual solution of the entire setup from the high-power high-repetition rate laser up to the photon beamline aiming to deliver to the user area the coherent photon beam with the wavelength in the soft X-ray range (3÷4.5 nm for the fundamental harmonic) and the peak brilliance, comparable with existing soft X-ray FELs. Challenges, R&D program needed in order to develop such user-oriented setup and connection with the EuPRAXIA (European Plasma Research Accelerator with eXcellence in Applications) project will be discussed.
Paper: TUPL032
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL032
About: Received: 02 May 2023 — Revised: 11 May 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
TUPL037
Polarization based out-coupling for cavity based x-ray FELs
1839
Cavity based X-ray free-electron lasers (CBXFEL) are next generation X-ray sources promising radiation with full three-dimensional coherence, nearly constant pulse to pulse stability and more than an order of magnitude higher spectral flux compared to SASE FELs. However, especially for the low gain X-ray free-electron laser oscillator (XFELO), the outcoupling of the radiation stored inside the cavity remains an issue, as only small outcoupling coefficients are tolerable. In this contribution, a scheme is proposed which exploits the polarization dependence of the crystal based X-ray diffraction, which poses the main reflection mechanism for forming the X-ray cavity. Especially for reflections close to a 45° Bragg-angle, as is proposed for the proof of concept experiment at the *Linac Coherent Light Source* (LCLS) at the *Stanford Linear Accelerator* (SLAC)"*", the polarization dependence of the reflection coefficient becomes very strong. By properly setting up the polarization of the FEL radiation with respect to the reflection direction, a very simple, yet potent and tunable outcoupling mechanism can be realized.
Paper: TUPL037
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL037
About: Received: 10 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPL043
Physical design for Shenzhen superconducting soft X-Ray free-electron laser (S3FEL)
1852
Shenzhen Superconducting Soft X-Ray Free-electron Laser (S3FEL) is a newly proposed high repetition-rate X-ray FEL facility. It will be located at Guangming Science City in Shenzhen with a total length of 1.7 km. The electron beam is generated from a VHF photocathode gun and accelerated to 2.5 GeV through a superconducting RF linac. At initial phase, it is planned to build four undulator lines with two of them working at the principle of SASE and another two working at EEHG. S3FEL aims at generating X-rays and EUV FELs between 1 and 30 nm at a rate up to 1 MHz to facilitate various scientific applications. This paper describes the physical design of S3FEL.
Paper: TUPL043
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL043
About: Received: 03 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
TUPL044
High-power and femtosecond free-electron laser pulse generation with chirped pulse amplification in EEHG
1856
Ultrafast science has developed rapidly nowadays thanks to the development of optical and laser technologies, like chirped pulse amplification and high-harmonic generation. In this work, a simulation has been performed to generate high-power femtosecond free-electron laser pulses with chirp pulse amplification in echo-enable harmonic generation. Numerical modeling shows that the peak power reaches tens of gigawatts and pulse duration is about several femtosecond.
Paper: TUPL044
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL044
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
TUPL052
Calculation for a compact laser plasma undulator beamline based on the experimental beam parameters at NCU
1870
Laser-wake field accelerators (LWFAs) are potential candidates to produce intense relativistic electron beams to drive compact free electron lasers (FELs) in VUV and X-ray regions. In High-Field Physics and Ultrafast Technology Laboratory at National Central University (NCU), an LWFA is being developed to produce a 250 MeV high-brightness electron beam by their 100-TW laser system. An FEL seeded by a 266-nm UV laser is under design to generate extreme ultraviolet (EUV) radiation. The initial phase of the project is to develop a beam energy modulator through the interaction of the LFWA-produced electron beam with the 266-nm seed laser in a 10-period planar undulator of 35-mm period length. An electron beamline has been designed based on linear optics to deliver the intense electron pulse from LWFA to the undulator and focus properly. However, due to the large energy spread of the beam, chromatic effects on beam transportation may be severe. In this work, we perform a detailed simulation of the LWFA FEL from experimental data of the NCU LWFA electron source. A 6D phase space analysis of multi-particle dynamics using IMPACT code [1] is to determine how significant the effects of beam energy spread on beam properties along the beamline are. The electron beam is then transferred to GENESIS [2] and Puffin [3] to see the laser beam interaction in the undulator. Further study of the HGHG scheme is evaluated using both FEL codes to see the influence of ultra-short electron bunch.
Paper: TUPL052
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL052
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
TUPL054
Carrier-envelope phase stabilization in FEL oscillators
1874
FEL oscillators can produce few-cycle optical pulses with a high-extraction efficiency when the oscillators are operated in the superradiant regime*. Such FEL oscillators are unique light sources to explore intense light field science, especially in mid-infrared and longwave infrared where ultrashort pulses are difficult to produce from conventional lasers. Since the laser-matter interaction in the intense field regime is described in terms of the oscillating electric field rather than the instantaneous intensity, the carrier-envelope phase (CEP) must be stabilized in many applications of few-cycle optical pulses to the intense light field science. Stabilization of CEP in FEL oscillators has been proposed with an external seed laser* and coherent radiation of electron bunches **. In this paper, we study CEP stabilization in FEL oscillators with numerical simulations and discuss applications of CEP-stable FEL pulses in the intense light field science.
Paper: TUPL054
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL054
About: Received: 09 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPL068
Design and construction of a population inversion x-ray laser at LCLS
1905
We report our recent results on the project (XLO) to build, characterize and operate a population inversion x-ray laser at the copper $K{\alpha_1}$ line, using LCLS x-ray pulses as a pump. The results include: gain measurement; design, alignment and focusing elements for the optical bow-tie cavity; copper target measurement of damage caused by the pump pulses; development of a fast system to provide a fresh solid copper target for pump pulses separated in time by 35 ns; development of the generation and control of two electron bunches in LCLS to generate two X-ray pump pulses. All the results obtained and discussed in this paper support the feasibility of XLO and the unique role it would have for scientific research in atomic and molecular science.
Paper: TUPL068
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL068
About: Received: 09 May 2023 — Revised: 29 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPL071
An introduction to the UK XFEL conceptual design and options analysis
1909
In October 2022, the UK XFEL project entered a new phase to explore how best to deliver the advanced XFEL capabilities identified in the project's Science Case. This phase includes developing a conceptual design for a unique new machine to fulfil the required capabilities and more. It also examines the possibility of investment opportunities at existing XFELs to deliver the same aims, and a comparison of the various options will be made. The desired next-generation capabilities include transform limited operation across the entire X-ray range with pulse durations ranging from 100 as to 100 fs; evenly spaced high repetition rate pulses for enhanced data acquisition rates; optimised multi-colour FEL pulse delivery and a full array of synchronised sources (XUV-THz sources, electron beams and high power/high energy lasers). The project also incorporates sustainability as a key criteria. This contribution gives an overview of progress to date and future plans.
Paper: TUPL071
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL071
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPL073
Improving the performance of the SXFEL through Proximal Policy Optimization
1916
Free-electron lasers (FEL) producing ultra-short X-ray pulses with high brightness and continuously tunable wavelength have been playing an indispensable role in the field of materials, energy catalysis, biomedicine, and atomic physics. A core challenge is to maintain and improve the transverse overlap of the electron and laser beams. This requires high-dimensional, high-frequency, closed-loop control with magnetic elements, further complicated by the diverse requirements across a wide range of wavelength configurations. In this work, we introduce a proximal policy optimization architecture for FEL commissioning that autonomously learns to control the set of magnetic elements. We experimentally demonstrated the feasibility of this technique on the alignment of electron beams and laser beams automatically in Shanghai Soft X-Ray Free Electron Laser User Facility, by adjusting groups of corrector magnets to maximize the FEL output power.
Paper: TUPL073
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL073
About: Received: 03 May 2023 — Revised: 15 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
TUPL078
Feasibility verification of ultrafast FEL generation experimental scheme based on SXFEL
1920
The photon energy in the soft X-ray range corresponds to the fundamental absorption edges of matter. Ultrashort X-ray pulses can be used to observe the breaking of chemical bonds in biochemical reactions and capture the transfer process of electrons in ultrafast physical phenomena, which is of great significance for the research of the next generation of semiconductor materials, such as diamond and graphene. In this paper, the feasibility of ESASE experiments on Shanghai Soft X-ray Free Electron Laser Facility (SXFEL) is theoretically verified. The results show that the ESASE scheme can produce ultrafast light pulses on the order of attosecond, with a peak power of 450 MW. At the same time, the simulation results in this paper verify the feasibility of chirped enhanced SASE schenme based on SXFEL. The results show that compared with the ESASE scheme, the power of the radiation pulse can be greatly improved by this scheme. A relatively low energy electron beam (1.5 GeV) was used to generate about 40 GW of radiation, and the length of the radiation pulse was significantly shortened.
Paper: TUPL078
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL078
About: Received: 08 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
TUPL079
Enhanced harmonic generation for high-repetition-rate soft X-ray free-electron laser
1924
Externally seeded free-electron lasers are promising for generating intense, stable, and fully coherent soft X-ray pulses. An earlier study demonstrates that high brightness and coherent soft X-ray radiation can be produced based on coherent harmonic generation and superradiant principles, termed high-brightness high-gain harmonic generation (HB-HGHG). However, due to the limitations of state-of-the-art laser systems, seed lasers in the ultraviolet region cannot induce sufficient energy modulation at high repetition rates. A recently suggested self-modulation scheme shows that the peak power requirement of a seed laser can be reduced by around one order of magnitude in an HGHG setup. In this paper, we present start-to-end simulation results to estimate the feasibility of the self-modulation-enhanced HB-HGHG scheme.
Paper: TUPL079
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL079
About: Received: 01 Apr 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
TUPL081
High-gain free-electron laser with orbital angular momentum seeded by an x-ray regenerative amplifier
1931
Cavity-based FELs, including x-ray free electron laser oscillators (XFELO) and x-ray regenerative amplifiers (RAFEL), have been proposed to generate fully coherent x-rays at high repetition rates. Among them, the oscillator-amplifier scheme can be used to generate high-brightness x-ray beams. Motivated by this technique, we propose a promising scheme to generate a fully coherent x-ray seed laser for the HGHMG system. In this scheme, an x-ray regenerative amplifier is used to offer a fully coherent x-ray seed laser to modulate the electron beam in a helical undulator. With an energy-chirped electron beam, one part electron beam will not lase in the regenerative amplifier since the FELs resonance relationship is not satisfied. This part of the electron beam will be helically modulated in a helical undulator by the coherent x-ray from the previous regenerative amplifier. With the proposed technique, high power and high repetition rate x-ray with OAM can be produced, which will open routes to scientific research in x-ray science.
Paper: TUPL081
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL081
About: Received: 01 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
TUPL089
A novel scheme based on angular dispersion-induced microbunching mechanism for harmonic generation in storage ring
1935
Angular dispersion-induced microbunching (ADM) scheme was proposed to generate high harmonic coherent radiation in the storage ring with weak energy modulation amplitude. However, it is still difficult to convert the external UV seed laser into the sub-nanometer wavelength. In this paper, we proposed a novel scheme based on ADM mechanism. By properly choosing the parameters, theory and one order simulation demonstrate that it is possible to produce ultrahigh harmonic coherent radiation in the storage ring. The high harmonic conversion efficiency of the proposed scheme may open up a new opportunity to produce sub-nanometer X-ray coherent radiation in the storage ring.
Paper: TUPL089
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL089
About: Received: 11 Apr 2023 — Revised: 12 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUPL090
An Active Q-switched X-ray Regenerative Amplifier Free-Electron Laser
1939
We describe active Q-switched X-ray regenerative amplifier FEL scheme to produce fully-coherent, high-brightness hard X-rays. In this scheme, a moderate energy chirp is introduced to the electron beams to shift the Free Electron Laser (FEL) radiation frequency outside the reflectivity bandwidth of the Bragg crystal. By actively controlling the chirp of the electron beam, the ratio of the out-coupled and recirculated pulse energy can be manipulated flexibly. This allows hard X-ray cavities driven by electron beams with reduced beam repetition rate, relatively low beam energy, and short cavity length. In contrast to typical XRAFEL outcoupling designs involving X-ray optics manipulation, this approach only requires the control of energy chirp of the electron beams, which can be simple and straightforward to implement. We report theoretical and numerical studies as well as error tolerance analysis on this scheme. We further discuss the experimental plans based on self-seeding or cavity-based XFELs on LCLS-II.
Paper: TUPL090
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL090
About: Received: 02 May 2023 — Revised: 16 Jun 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
TUPL098
First beam heating with the laser heater for FLASH2020+
1950
Within the framework of FLASH2020+, substantial parts of the injector of the FEL user facility FLASH have been upgraded during a nine-month shutdown in 2022 to improve the electron bunch properties in preparation for FEL operation with external seeding starting in 2025. As part of the injector upgrade, a laser heater has been installed upstream of the first bunch compression chicane to control the microbunching instability in the linear accelerator by a defined increase of the uncorrelated energy spread in the electron bunches. In this paper, we present first results of beam heating studies at FLASH. Measurements of the induced energy spread are compared to results obtained by particle tracking simulations.
Paper: TUPL098
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL098
About: Received: 03 May 2023 — Revised: 16 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
TUPL099
Accurate control of seed and free-electron laser chirp with bunching spectral analysis
1954
The spectro-temporal characteristics of free-electron laser (FEL) radiation emerging from external seeding schemes such as high-gain harmonic generation are shaped by the properties of the initial seed laser. Accurate control of the seed laser envelope and phase is essential to allow for precise manipulation of the FEL output. Based on experimental data obtained at the seeded FEL user facility FERMI, it is shown that detailed bunching spectral analysis enables monitoring of the seed and FEL frequency chirp. The bunching model is extended to be capable of also reproducing the FEL power.
Paper: TUPL099
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL099
About: Received: 03 May 2023 — Revised: 06 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPL101
Preliminary design on the accelerator of an infrared free electron laser oscillator
1961
We are building a new infrared Free Electron Laser (FEL) facility in China that will produce infrared laser covering the spectral range from 2.5 um to 200 um. It is made up of two oscillators generating middle infrared and far infrared laser respectively, which are driven by a single RF linear accelerator (linac) with a tunable beam energy from 12 MeV to 60 MeV. According to the requirement of the FEL physics, the linac is designed with an rms energy spread of less than 0.5%, a transverse rms emittance of less than 40 mm-mrad and a micro bunch length of 4-10 ps with a charge of 1 nC inside. In this manuscript, we present the preliminary design of the accelerator, from the electron gun through the transport line's terminus.
Paper: TUPL101
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL101
About: Received: 02 May 2023 — Revised: 16 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPL102
Waveguide FEL oscillator simulation with toroidal mirror
1964
FEL oscillator is the main working mode to produce infrared and THz radiation. However, in the long wavelength range, the waveguide is essential to suppress the diffraction losses. We have developed a method to study this effect by wGenesis that is modified with Genesis in combination with OPC code. However, this method is limited by the optical elements given in OPC. In this paper, we tried to give a more general optical element case based on the ABCD matrix. Then the simulation based on FELiChEM parameter is done to reduce the truncation loss at the waveguide port by choosing proper toroidal curvature radius. The results show that output power can be increased about 6.4 times than spherical mirror.
Paper: TUPL102
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL102
About: Received: 28 Apr 2023 — Revised: 13 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPL103
Study of the laser manipulation on relativistic electron beam for terahertz emission
1967
Terahertz radiation plays an important role in cutting-edge scientific research. Terahertz radiation source based on relativistic electron beam can provide excellent terahertz radiation source. The performance of such radiation is closely related to the distribution of the electron beam. Therein, the laser modulation technology based on the undulator is widely used to manipulate the distribution of the electron beam, thereby manipulating the radiation characteristics, such as improving coherence, tuning spectrum and controlling pulse width. In this paper, we analytically discuss the effects of various non-ideal factors during the process of dual-laser difference frequency modulation, such as finite laser pulse width, laser frequency chirp, and electron beam phase space distribution distortion. This will help to further understand the laser modulation technology of relativistic electron beams in the terahertz band, thus promoting the development of terahertz photonic science.
Paper: TUPL103
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL103
About: Received: 03 May 2023 — Revised: 14 Jun 2023 — Accepted: 14 Jun 2023 — Issue date: 26 Sep 2023
TUPL116
Photocathode charge map measurements at ARES
2002
The ARES linac at DESY (Deutsches Elektronen-Synchrotron) is a dedicated accelerator research and development facility for advanced accelerator technologies and applications, including high gradient accelerating schemes, high-resolution diagnostics and medical applications. It provides ultra-short, high quality electron beams with charges between a few femtocoulombs and a few hundred picocoulombs, with energies up to 155 MeV, characterized by high reproducibility and stability. The electron bunches are generated in a photoinjector comprising a UV laser and a normal conducting S-band gun with an exchangeable cathode material, enabling the required wide charge range and temporal bunch profile. A set of movable mirrors allows to change the position of the laser spot on the cathode, which in combination with bunch charge diagnostics downstream of the gun can be used for measuring the extracted charge as a function of the laser position. With this method the emission homogeneity and changes of the cathode can be studied and different cathode materials can be compared. We present the first results using this technique at ARES, including charge map and quantum efficiency (QE) measurements.
Paper: TUPL116
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL116
About: Received: 03 May 2023 — Revised: 15 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
TUPL119
Experimental generation of the transversely uniform electron bunches at the CLEAR facility at CERN
2009
Electron beams with a flat-top transverse distribution are highly desired for uniform dose delivery in irradiation applications, like studies of radiation damage to electronics and radiotherapy, as well as for potential applications in the improvement of light sources. In this work, we report on the optimization of the electron photocathode injector parameters which allow such uniform distributions to be reached. This can be achieved starting from a standard Gaussian transverse distribution of the laser, by tailoring the space charge forces and the magnetic field of the solenoid. We report on the first experimental demonstration of this method at the CLEAR facility at CERN.
Paper: TUPL119
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL119
About: Received: 02 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
TUPL144
Establishing a relativistic ultrafast electron diffraction & imaging (RUEDI) UK national facility
2075
RUEDI (Relativistic Ultrafast Electron Diffraction & Imaging) is a proposed facility which will deliver single-shot, time-resolved, imaging with MeV electrons, and ultrafast electron diffraction down to 10 fs timescales. RUEDI is being designed to enable the following science themes: dynamics of chemical change; materials in ex-treme conditions; quantum materials; energy generation, storage, and conversion; and in vivo biosciences. RUEDI is proposed to be built at STFC’s Daresbury Laboratory in the UK. The Conceptual Design Review and Outline Instrument Design reports were published in November 2022 and summarised in this paper, with a Technical Design Review report to follow in November 2023.
Paper: TUPL144
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL144
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
TUPL152
A high brightness electron beam research and application beamline at Tsinghua University
2093
In this paper we report on the status and performance of a newly commissioned high brightness electron beamline at Tsinghua University. The beamline is dedicated to research on the physics and technologies of multi-MeV, low charge, high brightness electron beams, as well as applications including MeV ultrafast electron diffraction and imaging. The layout, simulation and measurement results of the beam parameters and the stability performance of the beamline will be discussed. A liquid-phase UED sample delivery system and experiment methodology have recently been commissioned and established. Near-term upgrade to a variety of key components, including the high power rf source, laser-to-rf timing system, electro-optic lenses, together with the modeled performance improvements will also be presented.
Paper: TUPL152
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL152
About: Received: 03 May 2023 — Revised: 07 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
TUPL158
Longitudinal laser shaping at the EIC cooler injector
2112
Intra-beam scattering and other mechanisms can degrade the beam quality in the EIC Hadron Storage Ring. Strong hadron cooling will maintain the beam brightness and high luminosity during long collision experiments. An Energy Recovery Linac is used to deliver the high-current high-brightness electron beam for cooling. The best cooling rate is realized when the electron beam has low emittance, small energy spread, and uniform longitudinal distribution in the cooling section. Therefore, the initial distribution needs must be optimized to achieve a good cooling distribution. The longitudinal beam distribution at the cathode can be shaped by varying the temporal profile of the laser. The cathode distribution is tracked numerically through the cooler lattice to find the resulting cooling distribution. In this work, we demonstrate the optimization of the cathode longitudinal beam distribution to achieve a uniform longitudinal cooling distribution while maintaining a small emittance. Space charge and cathode image fields are included in the beam tracking.
Paper: TUPL158
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL158
About: Received: 03 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
TUPL162
Brixsino high-flux dual X-ray and THz radiation source based on energy recovery linacs
2123
We present the conceptual design of a compact light source named BriXSinO. BriXSinO was born as a demonstrator of the Marix project, but contains also a dual high flux radiation source Inverse Compton Source (ICS) of X-ray and a Free-Electron Laser Oscillator of THz spectral range radiation conceived for medica applications and general applied research. The accelerator is a push-pull CW-SC Energy Recovery Linac (ERL) based on the technology of superconducting cavities and allows to sustain MW-class beam power with al-most just one hundred kW active power dissipation/consumption. ICS line produces 33 keV monochromatic X-Rays via Compton scattering of the electron beam with a laser system in Fabry-Pérot cavity at a repetition rate of 100 MHz. The THz FEL oscillator is based on an undulator imbedded in optical cavity and generates THz wavelengths from 15 to 50 micron. The possibility of generating in the FEL cavity also synchronized X radiation is also shown.
Paper: TUPL162
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL162
About: Received: 03 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
TUPL164
A high brightness beam test facility for ERL applications
2127
A High Brightness Beams Test Facility has been recently funded at the INFN-LASA laboratory in Segrate (Milan- Italy). The Test Facility will allow to perform developments in ERL construction and design and to carry out experiments with the high current CW electron beam in frontier areas of accelerator physics. The Test Facility setup will comprise a high-performance laser driven DC Gun followed by a normal conducting RF buncher-acceleration section to provide 1 MeV 5 mA CW electron beam. A Superconducting RF booster linac able to increase the electron energies up to 5-10 MeV maintaining beam current up to 2.5 mA is part of the proposal for further funding.
Paper: TUPL164
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL164
About: Received: 02 May 2023 — Revised: 16 Jun 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
TUPL165
Dosimetry and first radiobiological assay of multi-Gy, multi-MeV TNSA proton beam with ultrahigh dose-rate
2131
Background and aim: The potential of a compact, laser-based ion accelerator for radiobiological and medical applications relies heavily on the control of the laser-target source and on the use of custom beam transport and delivery to the final target. Here we show the results of an experimental campaign dedicated to the dosimetry of the beam at the crosswire and the first radiobiological micronuclei (MN) assay study in the regime of ultra-high dose rate at selected proton energies at multi-MeV. Methods: We have developed a proton beamline based on the so-called Target Normal Sheath Acceleration (TNSA) to deliver a proton beam radiobiological applications. We use TNSA driven by a 200 TW ultra intense laser to accelerate protons with a cut-off energy of up to 10 MeV. We use permanent magnet quadrupoles to select protons at 6 MeV and transport them, in the form of a collimated beam, to the final target position in air. Results: We measured the spectrum and the deliverable dose of the proton beam at the sample position for each shot. We also evaluated uniformity across the beam and shot by shot fluctuations. We carried out dosimetric measurements that show a ultra-high instantaneous dose rate, with good uniformity over a cm-scale dimension and good shot to shot reproducibility. A preliminary measurement of radiation damage vs dose based on the MN assay was successfully carried out and compared with conventional X-ray source.
Paper: TUPL165
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL165
About: Received: 03 May 2023 — Revised: 25 Jul 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
TUPL167
Fully coherent soft X-ray pulse generation based on ERL
2135
Energy recovery linacs (ERLs) possess bright prospect of the fully coherent x-ray generation. Recently, we designed a 600 MeV energy recovery linac capable of producing high power fully coherent radiation pulses at 13.5 nm with a relatively low-intensity 256.5 nm seed laser profited from the employment of angular-dispersion-induced microbunching (ADM) technology. We also designed a matched multiplexed system that can deflect each radiator by 8 mrad with a carefully choreographed multi-bend achromat (MBA) scheme. As a result of downstream MBA’s dispersion compensation, bunching factors will be enhanced both at fundamental wavelength and high harmonics. The bunching factor of the 19th harmonic increased from 10% to 26%, and that of the 57th harmonic became 7.8%, which is sufficient to generate fully coherent radiation in the soft X-ray range.
Paper: TUPL167
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL167
About: Received: 10 Apr 2023 — Revised: 10 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
TUPL168
Development of a setup for laser-Compton backscattering at the S-DALINAC
2139
Non-destructive beam diagnostics as well as experiments and light sources that have a low impact on the beam are important for the operation and applications of an Energy-Recovery LINAC (ERL). Compton backscattering can provide a quasi-monochromatic highly polarized X-ray or gamma-ray beam without strongly affecting the electron beam due to the small cross- section of the Compton scattering. Highest energies of the scattered photons are obtained for photon-scattering angles of 180°, i. e., backscattering. A project at TU Darmstadt foresees to synchronize a highly repetitive high-power laser with the electron beam from the Superconducting DArmstadt electron LINear ACcelerator (S-DALINAC). First, the Laser-Compton Bachscattering (LCB) source will be uses as diagnostic tool for determining the electron beam energy and the energy spread. From the results, optimal design considerations for LCB sources under ERL operations will be deduced. An overview over the design concept and the status of the LCB source at the S-DALINAC will be given.
Paper: TUPL168
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL168
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPL177
Increasing the flux of a Thomson source while maintaining a narrow bandwidth by using large energy spread primary particles
2158
Thomson/Compton scattering is a method to produce high energy photons through the collision of low energy photons in a laser pulse onto relativistic electrons. In the linear (incoherent) Thomson/Compton regime, the flux scales linearly with the number of primary particles and the bandwidth of the produced photons depend, amongst other factors, on the energy spread of them. In general, an increase of the primary particles is connected to a larger energy spread (e.g.non-constant acceleration gradients, collective effects, etc). Therefore their number is restricted by the desired bandwidth, and thus limits the flux. In our previous (theoretical) studies we showed that the ideal Thomson spectrum can be retrieved when an electron bunch with a linear energy correlation of several percent collides with a matched linearly chirped laser pulse. Here we extend the scheme to allow for higher order energy correlations and quantify how the electron distribution influences the bandwidth. Furthermore we discuss the practical viability to maximize the primary particles, with the focus on linear accelerators (LINACS) for the electrons and laser pulses based on the chirped pulse amplification (CPA) scheme. These could potentially provide up to tens of nano-Coulomb electron bunches and tens, or even over a hundred, Joule lasers pulses respectively.
Paper: TUPL177
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL177
About: Received: 08 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
TUPL180
A start-to-end optimisation of CLEAR for an inverse Compton scattering experiment, using RF-Track
2162
The CERN Linear Electron Accelerator for Research (CLEAR) has been operating since 2017 as a user facility providing beams for various experiments. We created a start-to-end model of the CLEAR setup in RF-Track, aiming to optimise the CLEAR accelerator as a driver for an X-ray source based on inverse-Compton scattering. RF-Track, a CERN-developed particle tracking code, can simulate the generation, acceleration, and tracking of the electron beam from the cathode to the interaction point, across the entire accelerator. Additionally, RF-Track can compute the ICS interaction with an input laser beam, allowing for the first start-to-end optimisation of an ICS source using a single code. The optimisation was aimed to maximise the flux of the outcoming x-rays, while minimising the impact of static and dynamic imperfections. Sensitivity studies were performed, with an estimate of the effect of the jitter on the scattered photon flux.
Paper: TUPL180
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL180
About: Received: 07 May 2023 — Revised: 08 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUPL181
Scattered spectra from inverse Compton sources operating at high laser fields and high electron energies
2166
As Compton X-ray and gamma-ray sources become more prevalent, to understand their performance in a precise way it becomes important to be able to compute the distribution of scattered photons precisely. An ideal model would: (1) include the full Compton effect frequency relations between incident and scattered photons, (2) allow the field strength to be large enough that nonlinear effects are captured, and (3) incoroprate the effects of electron beam emittance. Various authors have considered various pieces of this problem, but until now no analytical or numerical procedure is known to us that captures these three effects simultaneously. Here we present a model for spectrum calculations that does simultaneously cover these aspects. The model is compared to a published full quantum mechanical calculation and found to agree for a case where both full Compton effect and nonlinear field strength are present. We use this model to investigate chirping prescriptions to mitigate ponderomotive broadening.
Paper: TUPL181
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL181
About: Received: 28 Apr 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
TUPL188
Study of nano-structured electron sources using photoemission electron microscope
2174
Nanostructured electron sources exhibiting simultaneous spatio-temporal confinement to nanometer and femtosecond level along with a low emittance can be used for developing future ordered electron sources to generate unprecedented electron beam brightness and can revolutionize stroboscopic ultrafast electron scattering and steady-state electron microscopy applications. In addition, high current density electron beams generated from nanostructured electron sources can be used for applications that include nanoelectronics and dielectric laser accelerators. In this work, we report our efforts to develop and characterize two kinds of nanostructured electron sources: (i) nitrogen incorporated ultrananocrystalline diamond [(N)UNCD] tips and (ii) plasmonic Archimedean spiral focusing lens. We demonstrate the ability to fabricate these cathodes and characterize them using a photoemission electron microscope under femtosecond laser illumination thereby demonstrating the ability of these structures to be used for next generation electron sources.
Paper: TUPL188
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPL188
About: Received: 02 May 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
TUPM012
High-energy beamline for delivering H- laser stripped proton beam to LANSCE experimental area
2216
A unique feature of the current LANSCE accelerator facility is acceleration of four H- beams (differing in time structure) and one H+ beam. This is achieved by utilization of an injector system based on two ion sources (H+/H-), and a combination of chopper and RF bunchers in the Low Energy Beam Transports. Since the end of 1990’s, the large LANSCE experimental, Area-A, has been largely unused. In order to restore usage of Area-A, we have been exploring the possibilities of bringing low-intensity power beams into Area-A*. The proposal is based on partial stripping of the 800 MeV H- beam that is transported to the Weapons Neutron Research Facility, and to deliver the resulting 10 – 100 nA proton beam to Area-A. The appropriate place for generating proton beam was found to be the beginning of Line D after LANSCE Switchyard by first neutralizing the beam from H- to neutral hydrogen beam ahead of the bending magnet using a laser, and then by fully stripping the neutral hydrogen beam to protons utilizing a stripper foil. The paper discusses design details of the proposed high-energy beamline and beam parameters.
Paper: TUPM012
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM012
About: Received: 01 May 2023 — Revised: 17 May 2023 — Accepted: 17 May 2023 — Issue date: 26 Sep 2023
TUPM018
Implementation of the Additive Manufacturing for metals approach: the production of the acceleration grids for DTT NBI project
2230
Acceleration grids of the Neutral Beam Injector in nuclear fusion reactors must be extremely accurate and satisfy specific geometrical requirements to work properly. The implementation of the additive manufacturing technology was proposed since 2017 starting the characterization of pure copper up to the recent excellent results in terms of density, process reliability and repeatability. To assure the required performance and maximize the beam optics and the overall system efficiency, an intense study of the geometry of these components was performed, adopting a spherical aspect of planes. The material selection was also an important step of the work. An integrated cooling system, peculiar of the AM technology, was optimized, ensuring a relevant reduction of temperature peaks. Pure copper and CuCrZr alloy were investigated for reaching the best material properties: parameters optimization was executed using different machines and laser beams, and several post processes were assessed, such as surface treatments to smooth the cooling ducts. After the material characterization, which was focused on the evaluation of density, thermal conductivity and mechanical strength of the AMed parts. Lastly, several prototypes were produced and power tests were carried out.
Paper: TUPM018
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM018
About: Received: 05 May 2023 — Revised: 05 Jun 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
TUPM062
Status of the laser manipulations of H- beam at J-PARC
2335
The laser manipulations of H- ion beam by single or double neutralization is a very promising technique and highly essential to utilized in accelerator processes such as stripping, pulse chopping, collimation, extraction, and beam diagnostics for the present and future high-intensity proton accelerators. At J-PARC, we are preparing for a POP (Proof-of-Principle) demonstration 400 MeV H- stripping by using only lasers. A prototype YAG laser system and a laser cavity system to reduce the laser power are being developed through 3 MeV H- neutralization studies. Fermilab utilizes H- neutralization at 0.75 MeV by establishing a laser Notcher system for a gap in the H- pulse needed for a clean beam extraction from the ring. To minimize the laser power and maximize the interaction efficiency are common issue at both laboratories. Under the US-Japan collaboration for high-intensity neutrino beam, we are closely working to establish recycling/reusing of seed laser pulses to reduce a size of the laser system. In parallel, we have also developed non-destructive beam diagnostic systems at lower H- energy of 3 MeV, which will be implemented to the 400 MeV as well as easily applicable to the Fermilab linac including PIP-II linac. Installation of the laser system at J-PARC linac for 400 MeV H- stripping is ongoing to start the POP experimental study in 2023.
Paper: TUPM062
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-TUPM062
About: Received: 02 May 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEODB2
5D phase-space reconstruction of an electron beam
2605
The complete knowledge of electron bunch properties is of great interest to understand and optimize the performance of accelerators and their applications. A new tomographic beam diagnostics method to reconstruct the full 5-dimensional phase space (x, x', y, y', t) of bunches has recently been proposed. This method combines a quadrupole-based transverse phase-space tomography with the variable streaking angle of a polarizable X-band transverse deflection structure (PolariX TDS). In this contribution, we show preliminary data of the first experimental demonstration of the method including the reconstruction of the full 5-dimensional phase space distribution of an electron bunch at FLASHForward.
Paper: WEODB2
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEODB2
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEODC1
A short-length transport line for laser-plasma accelerators using HTS periodic magnets
2627
In laser-plasma accelerators (LPA), due to extremely high accelerating gradients, electron bunches are accelerated to high energies in only a few millimeters to centimeters of acceleration length. To efficiently capture and transport the LPA-generated bunches in a compact transport line, beam line designs employing high-strength combined-function magnets based on high-temperature superconductor technology have been studied. Moreover, to overcome coil winding challenges in fabricating miniature HTS magnets, novel periodic magnets have been designed, which can collimate and guide the electron beams in a well-controlled short-length transport line. In this contribution, we present the beam dynamics calculations as well as the magnet designs for a 1.4 m transport line matching the LPA-generated electron beams to a transverse-gradient undulator.
Paper: WEODC1
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEODC1
About: Received: 03 May 2023 — Revised: 24 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPA042
Emittance compensation in a high charge TOPGUN photoinjector
2747
A simple acceleration of a high charge, needle-shaped electron bunch from a cathode is affected by strong correlated emittance growth due to current-dependent transverse space-charge forces. It was shown that such emittance growth could be reversed by focusing the bunch soon after it emerges from the cathode, and that one can expect to retrieve the emittance the beam was born with – the intrinsic emittance. We present a space charge emittance compensation study for a 250 pC radiofrequency photoinjector based on a 100 pC design developed by the UCLA team. We expect that a bright electron beam with an order of magnitude improvement over currently operating photoinjectors can be achieved with 250 pC electron bunches that maintain their emittance below 100 nm-rad.
Paper: WEPA042
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA042
About: Received: 03 May 2023 — Revised: 02 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPA079
Simulations of radiation reaction in inverse Compton scattering
2829
The effect of radiation reaction is often negligible in inverse Compton scattering. However, in the nonlinear Compton regime, at high laser fields and high electron beam energies where electron recoil must be properly accounted for, there is experimental data which demonstrates the onset of radiation reaction * . We model the radiation reaction as a series of emissions from individual electrons with decreasing energy. This allows us to use the code we previously developed for simulating single-emission inverse Compton scattering events ** . We use the new code to simulate the experiment reported in Cole et al. 2018, and to compare it to other models of radiation reaction.
Paper: WEPA079
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA079
About: Received: 03 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
WEPA101
Hybrid beamline element ML-training for surrogates in the impactX beam-dynamics code
2885
The modeling of current and next-generation particle accelerators is a complex endeavour, ranging from the simulation-guided exploration of advanced lattice elements, over design, to commissioning and operations. This paper explores hybrid beamline modeling, towards coupling s-based particle-in-cell beam dynamics with machine-learning (ML) surrogate models. As a first example, we train a surrogate model of an advanced accelerator element, a laser-wakefield accelerator stage, via the time-based particle-in-cell code WarpX [1]. A second example trains trains a model for the IOTA nonlinear lens via the s-based code ImpactX [2].
Paper: WEPA101
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPA101
About: Received: 04 May 2023 — Revised: 18 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
WEPL050
Design, fabrication and measurement of a normal conducting quadrupole for a laser-plasma-accelerator-based beam transport line
3227
For an experimental setup at the laser plasma accelerator (LPA) at the JETi Laser at Jena, Germany, an energy upgrade of a linear beam transport line has been studied. The transport line, originally designed to match the LPA beam to a transverse gradient undulator (TGU) at 120 MeV and successfully experimentally tested in 2014, will be upgraded to up to 300 MeV by employing stronger focusing quadrupoles. For these high strength quadrupoles, magnetic simulations as well as cooling and electrical calculations have been done. To develop fabrication procedures and magnetic measurement techniques, a prototype of the quadrupole magnet has been manufactured and tested at Karlsruhe Institute of Technology, Germany. This paper is presenting the design, fabrication and magnetic measurement of the first prototype quadrupole magnet.
Paper: WEPL050
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL050
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL054
CEBAF Injector Model for K-Long bunch charge at 200 kV
3236
The upcoming Jefferson Lab K-Long experiment at Hall D will require unique beam conditions with a much lower bunch repetition rate and atypically high bunch charge. To optimize the Continuous Electron Beam Accelerator Facility (CEBAF) injector for this experiment, we performed Multi-Objective Genetic Optimization (MGO) using General Particle Tracer (GPT) to determine the magnetic elements and RF settings necessary for the K-long bunch charge (0.64 pC) at 200 kV. We also investigated the transmission and beam characteristics of low to high charge per bunch electron beams through the injector for simultaneous operations of all four CEBAF Halls and characterized the transmission as a function of the photocathode laser spot size and pulse length. Our findings provide valuable insights into optimizing the CEBAF injector for the Jefferson Lab K-Long experiment, as well as for other experiments with similar beam conditions.
Paper: WEPL054
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL054
About: Received: 02 May 2023 — Revised: 04 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL084
Benchmarking for CODAL beam dynamics code: laser-plasma accelerator case study
3298
Laser-plasma electron beams are known for their large divergence and energy spread while having ultra-short bunches, which differentiate them from standard RF accelerated beams. To study the laser-plasma beam dynamics and to design a transport line, simulations with *CODAL* [1], a code developed by SOLEIL in collaboration with IJCLab, have been used. *CODAL* is a 6D 'kick' tracking code based on the symplectic integration of the local hamiltonian for each element of the lattice. *CODAL* also includes collective effects simulations such as space charge, wakefield and coherent synchrotron radiation. To validate the studies in the framework of Laser-Plasma Acceleratior developpement, results from *CODAL* have been compared to *TraceWin* [2], a well-known tracking code developed by CEA. The comparison has been made using the outcome of Laser WakeField Acceleration (LWFA) particle-in-cell simulations as initial start particle coordinates from a case study of PALLAS project, a Laser-Plasma Accelerator test facility at IJCLab.
Paper: WEPL084
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL084
About: Received: 03 May 2023 — Revised: 02 Jun 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
WEPL125
General method of short-range wakefield calculation for corrugated structures of arbitrary shape
3405
Corrugated structures have been used widely in X-ray free-electron laser facilities for chirp control, fresh-slice applications, and diagnostics. In this paper, we present a general method for calculating the short-bunch wakefield of corrugated structures with arbitrary shapes. At zeroth order, we give analytical solutions via the method of conformal mapping. At first order, we give steady-state wake calculation by solving a set of integral equations.
Paper: WEPL125
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL125
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL133
A space charge forces analytical model for emittance compensation
3417
Space charge forces represent main induced effects in an RF-injector that degrade the beam quality. In this scenario the laser distribution sent on the photocathode acquires an important role in the emittance compensation process, as the slice analysis shows. A novel model of space charge forces is proposed for bunch with arbitrary charge distribution to derive expressions of self-induced forces. As the performance of the fields near the cathode is under present analysis, we can investigate use of this model in low charge regime. Further, the model has been benchmarked with the behavior of the distributions present in the literature and studied for new ones. It has also been applied for the study of the optimization of a C-band hybrid photoinjector now being commissioned, thus explaining the factor two reduction of the emittance observed at the exit of the gun by changing the initial distribution at the cathode.
Paper: WEPL133
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL133
About: Received: 31 Mar 2023 — Revised: 12 Jun 2023 — Accepted: 12 Jun 2023 — Issue date: 26 Sep 2023
WEPM041
Magnetic measurements of the ALS-U magnets
3650
he Advanced Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBL) is going through an upgrade (ALS-U) where the ALS triple-bend achromat will be replaced by a nine-bend achromat storage ring (SR) with an on-axis injection using beam swapping from a triple-bend achromat accumulator ring (AR). About 700 magnets will be used for the ALS-U accelerator systems. The paper gives an overview of the stretched wire and rotating coil systems used for the magnetic measurements of the ALS-U magnets. We are also describing the fiducialization process, i.e. the mechanical and magnetic alignment of the magnets.
Paper: WEPM041
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPM041
About: Received: 03 May 2023 — Revised: 04 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPM101
Progress in development and measurement of an asymmetric magnet pole undulator
3801
The Insertion device development and measurement laboratory of Devi Ahilya University, Indore, India has ongoing activities on undulator design, development and measurements. A new type of undulator known as Asymmetric magnet pole with upper and lower structure having different period lengths will be designed and fabricated. Asymmetric magnet pole undulator has a special demanding field quality for suppressing the higher harmonic components of radiation and reducing on axis heat load from radiation. The undulator will be a variable gap undulator with upper structure consist of 25mm period having NdFeB magnets of rectangular cross section 6.25 mm, 6.25 mm and 50mm and lower structure will be with 50mm period length with the same magnet material but having rectangular cross section of 12.5mm, 12.5mm and 50mm. In this paper the design details for an asymmetric magnet pole undulator will be presented.
Paper: WEPM101
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPM101
About: Received: 10 May 2023 — Revised: 15 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPM106
Development of Hall probe system for accurate field mapping at NSRRC
3815
After 20 years of use, the Hall-probe system at the Na-tional Synchrotron Radiation Research Center (NSRRC) has poor measurement reproducibility. The granite bench is 6m long and is robust but the Hall-probe stage with air bearings has deteriorated. To create a reasonable operat-ing space for field correction for an insertion device (ID), the distance between the ID and the measurement system must be increased so a more stable and accurate stage is required. The developed system has a new structure to isolate the imbalance in the forces that act on it when the Hall probe stage is moving and the cable drags. An opti-cal position sensitive detector (PSD) is also fitted to measure the change in the position of the hall probe in space. The positional error in space for the Hall probe is now less than 15um. This is achieved by measuring and correcting the position in real time.
Paper: WEPM106
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPM106
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
WEPM110
Research on hydrostatic leveling system to provide elevation constraints for control network adjustment
3826
As the precise sensor system for monitoring the rela-tive altitude changes among multiple points, the capacity hydrostatic leveling system (HLS) is widely used in particle accelerators. To expand its application in provid-ing the elevation constraint for the control network ad-justment, the research on the issue of the HLS for alti-tude difference measurement between multiple points is carried out. Based on the working principle of the HLS sensor, a comparison system composed of dual-frequency laser interferometer, high-precision Z stage, HLS sensors and others is designed and manufactured. The system is used to control multiple sensors to observe the same liquid level in the same coordinate system. The zero-position difference among sensors can be obtained by comparison. Then the altitude difference measure-ment can be realized, and it is verified that the measure-ment accuracy is better than 5 μm. In addition, a simula-tion experiment for 3D control network measurement is run, in which the HLS system provides the elevation constraint for the adjustment processing. The results show that for the 100m linear tunnel, the errors accumu-lation in the elevation direction is significantly improved compared to the classics adjustment.
Paper: WEPM110
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPM110
About: Received: 27 Apr 2023 — Revised: 05 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPM122
Reverse Engineering, a key and challenging step before the integration studies for old accelerators at CERN
3848
The accelerators constituting the LHC injectors chain have been gradually built and commissioned since the CERN foundation in the fifties. The operation of the Proton Synchrotron, the Proton Synchrotron Booster and the Super Proton Synchrotron started in 1959, 1972 and 1976 respectively. During the Long Shutdown 2 (LS2) of the CERN accelerator complex in 2019 and 2020, a large upgrade of these machines has been performed in the context of the LHC Injector Upgrade (LIU) Project and consolidation programme. This paper presents the process of reverse engineering performed by the Integration Office within 3D CAD environment during the preparation phase of the LS2 to allow the spatial integration studies of the upgrades and ensure the reliability of the installations. It describes the methodologies and technologies used from 2D drawings to 3D models and data consistency check processes in accordance with reality. Process remains ongoing to treat the enormous quantity of data.
Paper: WEPM122
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPM122
About: Received: 27 Apr 2023 — Revised: 25 May 2023 — Accepted: 25 May 2023 — Issue date: 26 Sep 2023
WEPM124
The high luminosity Large Hadron Collider project: from project to reality at CERN
3855
The High Luminosity Large Hadron Collider (HL-LHC) project is an upgrade of the LHC aiming to increase by a factor 10 the harvested integrated luminosity foreseen early 40s. During Long Shutdown 3, scheduled to begin at the end of 2025, nearly 1.2 km of accelerator components, including a range of services spread across surface and underground facilities, will be replaced with new equipment deploying innovative key technologies. Two 300-meter-long tunnels, with access shafts and large service caverns, were excavated in parallel to the LHC machine tunnel to house the new power converters, cryogenics, and other key systems. Ten buildings were constructed on the surface to house all the necessary new services. The civil engineering design, the system definition and equipment design phase have been managed in close synergy with the HL-LHC Integration Team, responsible for optimizing the allocation of volumes between the different stakeholders in order to guarantee the efficiency of installation, the maintainability, and the operability of the different systems. This work describes the process and the challenges that had to be overcome in the integration studies to meet the targets of maturity of the project, allowing the installation phase to start on a sound and solid basis.
Paper: WEPM124
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPM124
About: Received: 02 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THXD1
Towards the COXINEL seeded Free Electron Laser with a laser plasma accelerator at HZDR
3903
Developing Free Electron Lasers using Laser Plasma Acceleration open great hopes for compact laboratory scale light sources. The COXINEL line developed at Synchrotron SOLEIL (France) has been moved at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Germany) for using high-quality electron beam generated by the 150 TW DRACO laser. After proper electron beam transport, seed and undulator radiation temporal, spectral and spatial overlaps, the seeded Free Electron Laser driven by the DRACO laser plasma accelerator has been observed in the UV. Good agreement is found between measurements and simulations.
Paper: THXD1
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THXD1
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPA009
Optical pepper-pots: developing single-shot emittance diagnostics
3966
Emittance measurements are a universal requirement when operating particle accelerators. Many techniques exist to achieve these measurements, each suiting the specific requirements of a machine. Most are multi-shot or invasive, and struggle to function with low energy beams or where space-charge effects are dominant. Generally, these limitations can be restricting, but especially so in emerging sectors such as novel acceleration or energy recovery linacs. To this end, two all-optical single-shot emittance measurements are being developed. In both cases the measurement is analogous to an optical version of the common pepper-pot diagnostic. The two methods are complementary: the first uses a micro-lens array (MLA); the second a digital micro-mirror device (DMD). Both systems can operate away from a beam waist and separate the optical beam radiation into beamlets rather than the beam itself; leaving potential for a non-invasive measurement. The benefits of using optical beam radiation are reduced beam scattering, simple designs, and suitability for low-energy/space-charge dominant beams. Presented is a series of benchmarking measurements and simulations with laser sources. Initial beam simulations, plans for first measurements, and the application to a machine learning virtual diagnostic are also discussed.
Paper: THPA009
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA009
About: Received: 03 May 2023 — Revised: 24 May 2023 — Accepted: 24 May 2023 — Issue date: 26 Sep 2023
THPA041
The potential contribution of a structured laser beam to accelerator alignment technology
4044
The Structured Laser Beam (SLB) is a type of optical beam characterized by an intense, sharply defined, low divergence core at its center, similar in its transverse intensity distribution to a Bessel beam. The SLB can propagate over a theoretically infinite distance, and has recently been tested up to a distance of 900 m. This test confirmed the low divergence of the SLB core, of about 0.01 mrad in this case. Furthermore, a hollow SLB (HSLB) can be created by feeding the generator with vector beams. These properties open the possibility of creating new types of optical alignment systems that could be used over long distances, for example for particle accelerators. Investigations are on-going to optimize the SLB and fully evaluate its alignment potential. Methods are under development to accurately detect the center of the SLB, based either on the beam intensity distribution or on the measurement of particular polarization states of the HSLB. Moreover, in order to deal with alignment in harsh environment, systems based on passive elements are also of interest. This paper summarize these studies and includes a discussion of phenomena such as the straightness of the SLB.
Paper: THPA041
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA041
About: Received: 21 Apr 2023 — Revised: 11 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
THPA064
Eom-based bunch arrival monitor development at the Argonne wakefield accelerator facility
4112
To better understand the beam-RF jitter at the Argonne Wakefield Accelerator Facility, a high-resolution bunch arrival monitor (BAM) is being developed. The BAM take advantages of a commercial, electro-optic modulator (EOM) to measure the bunch timing though optical modulation. This non-descructive technique is far superior and the resolution can be as high as several femto-second. A prototype has been developed.
Paper: THPA064
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA064
About: Received: 27 Apr 2023 — Revised: 07 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
THPA073
Developing a two-colour all-fibre balanced optical cross-correlator for sub-femtosecond synchronisation
4135
In modern accelerator facilities, femtosecond synchronisation between an optical master oscillator (OMO) that provides facility-wide timing pulses and an external experiment laser is needed to achieve the few-fs resolution required for experiments such as pump-probe spectroscopy. This can be achieved with a balanced optical cross-correlator (BOXC), which determines the timing delay between two laser pulses via the generation of sum-frequency radiation in a nonlinear crystal. In this paper, a design for a two-colour fibre-coupled BOXC using waveguided periodically-poled lithium niobate (PPLN) crystals is presented. An all-fibre two-colour BOXC is highly desirable as it would be more robust against environment fluctuations, easier to implement, and can achieve greater synchronisation performance compared to free-space coupled BOXCs that are currently used in accelerator facilities. This proposed design can theoretically achieve 5 - 10 times greater sensitivity to relative timing changes between laser pulses than current free-space two-colour BOXCs, which can make sub-fs synchronisation between an OMO and an external experiment laser of different wavelength achievable.
Paper: THPA073
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA073
About: Received: 28 Apr 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPA076
Application of low-energy, tunable-delay ultrashort electron bunch pairs for irradiation experiments
4142
On AREAL RF photogun linac at CANDLE, time-separated ultrashort electron bunch pairs are generated by means of temporal shaping of the laser pulses driving the photocathode. The free-space interferometric delay line method used for the laser pulse shaping provides the means for tailoring the beam characteristics such as the charge contrast and relative delay of the bunch pairs in the train. In this contribution, the details on generation and characterization of temporally modulated beams will be presented along with the description of the set of available control parameters for various applications. In addition, results of ongoing studies of the effects of high-dose rate irradiation on structural and optical properties of transparent thin films and glasses will be presented and discussed.
Paper: THPA076
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA076
About: Received: 03 May 2023 — Revised: 07 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPA078
PRAGUE (Proton Range Measurement Using Silicon Carbide): a detector to measure online the proton beam range with laser-driven proton beams
4146
Laser-driven proton beams are characterized by very high intensities per pulse with a very short duration, extremely high dose rates, and broad energy spectra. These specific features do not allow the use of the conventional dosimeters typically suggested by the international dosimetry protocols for conventional proton beams. Precise dosimetry for laser-accelerated protons is an ambitious task as well as a crucial prerequisite for successful radiobiological experiments. We will present the work done within the PRAGUE project funded by the H2020 in the framework of the MSCA-IF IV program and by the INFN. The main goal of PRAGUE was the design, simulation, realization, and characterization of a real-time depth-dose distribution detector system based on thin Silicon Carbide multilayers for conventional and laser-accelerated proton beams in the energy range between 30 MeV to 150 MeV. The detector developed was designed to work at the regime of extremely high dose rate beams and it allows the retrieval of real-time and shot-to-shot depth dose distributions with a high spatial resolution thanks to the development and use of a 10 μm, fully depleted 15x15 mm2 square SiC detector. A detector prototype was already realized, simulated, and tested with 30 and 70 MeV conventional proton beams. Potentially this newly developed detector could enable new detector technology capable of providing online information of dose delivered at a biological sample with a laser-driven proton beam.
Paper: THPA078
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA078
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPA079
Characterization and optimization of laser-generated THz beam for THz based streaking
4149
At the Ferninfrarot Linac- und Test-Experiment (FLUTE) at the Karlsruhe Institute of Technology (KIT) a new and compact method for longitudinal diagnostics of ultrashort electron bunches is being developed. For this technique, which is based on THz streaking, strong electromagnetic pulses with frequencies around 240 GHz are required. Therefore, a setup for laser-generated THz radiation using tilted-pulse-front pumping in lithium niobate was designed, delivering up to 1 µJ of THz pulse energy with a conversion efficiency of up to 0.03 %. In this contribution we study the optimization of the THz beam transport and environment.
Paper: THPA079
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA079
About: Received: 02 May 2023 — Revised: 05 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPA081
A UV Pump laser System for micro-UED at Cornell
4153
Ultrafast Electron Diffraction (UED) probes the dynamics of material structures which are triggered by a fs pump laser pulse. Some materials of interest for UED study, such as wide-bandgap insulators, require the use of UV pump lasers. Furthermore, UED with a probe size on the single micron scale requires high stability in the position, power, and size of the pump laser, which demands feedback systems and real time monitoring integrated in the full accelerator control system. Here we discuss a system currently implemented at a UED beamline at Cornell University for producing, monitoring, and stabilizing a UV pump lasers for UED with few micron probe beam sizes.
Paper: THPA081
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA081
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
THPA137
RF characterisation of laser treated copper surfaces for the mitigation of electron cloud in accelerators
4275
In accelerator beam chambers and RF waveguides, electron cloud and multipacting can be mitigated effectively by reducing the secondary electron yield (SEY). In recent years, it has been established that laser surface structuring is a very efficient method to create a copper surface with SEY close to or even below unity. Different laser pulse durations, from nanoseconds to picoseconds, can be used to change surface morphology. Conversely, the characteristics that minimise the SEY, such as the moderately deep grooves and the redeposited nanoparticles, might have unfavourable consequences, including increased RF surface resistance. In this study, we describe the techniques used to measure the surface resistance of laser-treated copper samples using an enhanced dielectric resonator with 12 cm diameter sample sizes operating in the GHz range. The quantification basis lies in a non-contact measurement of the high-frequency losses, focusing on understanding the variation of surface resistance levels depending on the specifics of the treatment and possible post-treatment cleaning procedures.
Paper: THPA137
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA137
About: Received: 10 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPA157
Study on the vacuum properties of laser-etched oxygen-free copper
4328
The performance of operating particle accelerators has been seriously affected by the electron cloud (e-cloud) effect. The secondary electron emission (SEE) and the e-cloud can be effectively suppressed through laser-etching the inner surface of the vacuum chamber. Oxygen-free copper (OFC) has become the first choice for the vacuum chambers of modern accelerators due to its high electric and thermal conductivity and effective radiation shield-ing property. It is necessary to study the vacuum proper-ties of the laser-etched OFC for the application in the particle accelerators. In this paper, the photon stimulated desorption (PSD) yield and the outgassing rate of the laser-etched OFC were measured. The results show that the laser-etched OFC presents lower PSD yield compared to the untreated OFC, while the outgassing rates of the laser-etched and unetched samples are similar.
Paper: THPA157
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA157
About: Received: 27 Apr 2023 — Revised: 05 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPA177
Multi-terawatt, sub-picosecond long-wave infrared laser for next-generation particle accelerators
4381
Lambda-squared scaling of the ponderomotive potential makes long wavelengths preferable for certain regimes of laser-based particle acceleration, including the laser-wakefield acceleration of electrons at low plasma densities and the acceleration of ions from gaseous targets. Currently, multi-terawatt levels of peak power at long-wave infrared (LWIR) wavelengths around 10 μm can only be achieved via the amplification of a picosecond laser pulse in high-pressure CO2 laser amplifiers. Our state-of-the-art LWIR laser system employs chirped-pulse amplification in a mixed-isotope CO2 active medium (Oxygen-16 : Oxygen-18 ≈ 50:50) at a pressure of ~10 atmospheres to deliver up to 5 TW peak power in 2-picosecond pulses. This laser system has enabled several promising parameter-space optimization studies and proof-of-principle demonstrations of advanced techniques of particle acceleration and x-ray generation in recent years. A next-generation LWIR laser is currently under active development. It will provide a sub-picosecond pulse duration (100 fs and 500 fs with and without post-compression, respectively) and ≥15 TW of peak power. Theoretical models predict that these laser parameters will enable new acceleration regimes, such as the blow-out regime of laser-wakefield acceleration with millimeter-scale accelerating plasma structures.
Paper: THPA177
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA177
About: Received: 12 May 2023 — Revised: 04 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPA178
Study on the laser treatment of NB and Nb3Sn thin films on copper substrate with a kW nanosecond fiber laser
4384
Surface annealing using intense nanosecond laser pulses is an emerging technique for SRF cavities. This technique can effectively reduce the cavities’ surface defects and improve their RF performance. However, previous studies in this field limited themselves on solid state lasers or gas lasers, which have very low average power and are not practical for processing actual SRF cavities with ~m2 inner surface area. IMP innovatively built a practical whole-cavity processing system with a kW-level nanosecond fiber laser, which is designed to process an SRF cavity within a working day. In this work, the system design and feasibility analysis will be given, together with the comparison between pristine Nb thin film samples on copper substrates and their fiber laser processed counterparts. The results show that our fiber laser system can deliver comparable surface treatment as that from the solid-state laser system, but with higher efficiency. The authors believe such results could boost the application of laser surface annealing technique in the particle accelerator community.
Paper: THPA178
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA178
About: Received: 09 May 2023 — Revised: 12 Jun 2023 — Accepted: 12 Jun 2023 — Issue date: 26 Sep 2023
THPA179
Ion acceleration by laser-matter interaction: status and perspective with the upcoming I-LUCE facility at INFN-LNS
4386
The potential for developing compact, high-brightness particle and radiation sources has given a strong impetus to the development of the underpinning laser technology, including increasing the efficiency and repetition rate of the lasers. A result of this technological development can be seen in the new generation of ultrafast high-power laser systems working at a high repetition rate which have been built across Europe. A new high-power laser facility called I-LUCE (INFN Laser indUced radiation acCEleration) will be realized at LNS-INFN in 2024. The facility realization is funded by both EuAPS (EuPRAXIA Advanced Photon Sources) and Samothrace (Sicilian MicronanOTecH. Research And Innovation) projects financed by the PNRR Italian program. The Ti:Sapphire laser will have two outputs: the first one will be a 1 TW beam line (25fs,25-30mJ,10Hz) while the main beam line will be a 500 TW laser (25fs,10J,10Hz). I-LUCE will serve two experimental areas called E1 and E2. E2 will provide the unique worldwide combination of intense laser radiation with heavy ion beams generated with the Superconductive Cyclotron and Tandem (already installed at LNS) opening the door for interesting experiments in the field of plasma physics, nuclear physics and atomic physics. In addition, stand-alone experiments with intense laser beams will be carried out for several studies such as proton/ion acceleration laser generation. Instead, the E1 experimental room will be dedicated to electron acceleration.
Paper: THPA179
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPA179
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPL028
Bayesian Optimization for SASE Tuning at the European XFEL
4483
Parameter tuning is a regular task and takes considerable time for daily operations at FEL facilities. In this contribution, we demonstrate SASE pulse energy optimization at the European XFEL with Bayesian optimization (BO) as an alternative approach to the widely used simplex method. Preliminary experimental results show that BO could reach a comparable performance as the simplex method, even with an out-of-the-box implementation. Compared to previous attempts, our version of BO does not require setting hyperparameters via additional measurements, thus effectively reducing the required effort for machine operators to use it during operation. On the other hand, BO has the potential to be further improved by introducing prior physical knowledge about the task and fine-tuning the algorithm to specific tasks. This makes BO a promising candidate for routine tuning tasks at particle accelerators in the future.
Paper: THPL028
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL028
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL034
Machine learning for laser pulse shaping
4495
The temporal profile of the electron bunch is of critical importance in accelerator areas such as free-electron lasers and novel acceleration. In FELs, it strongly influences factors including efficiency and the profile of the photon pulse generated for user experiments, while in novel acceleration techniques it contributes to enhanced interaction of the witness beam with the driving electric field. Work is in progress at the CLARA facility at Daresbury Laboratory on temporal shaping of the ultraviolet photoinjector laser, using a fused-silica acousto-optic modulator. Generating a user-defined (programmable) time-domain target profile requires finding the corresponding spectral phase configuration of the shaper; this is a non-trivial problem for complex pulse shapes. Using a physically informed machine learning model, we demonstrate accurate and rapid shaping of the photo-injector laser to a wide range of arbitrary target temporal intensity profiles on the CLARA PI laser. Additionally, we discuss the utility of this expanded range of laser pulse shapes to potential applications in FELs and novel acceleration.
Paper: THPL034
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL034
About: Received: 04 May 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPL037
Gradient descent optimization and resonance control of superconducting RF cavities
4507
Presently, superconducting radio frequency (SRF) cavities with high intrinsic quality factors are used in particle accelerators, as a high intrinsic quality factor allows for increased energy efficiency. As such, this technology benefits new research into light source linacs such as in the new LCLS-II system. However, due to the narrow bandwidth attributed to large quality factors, the use of these SRF cavities requires more accurate control to mitigate the effects of vibrations within the cavity and maintain a fixed frequency. In a paper by Banerjee et al., it was proposed that the current practice of actively suppressing such vibrations using fast tuners may be improved through the implementation of a narrowband active noise control algorithm (NANC) that makes use of gradient descent. It is the aim of this research to explore which gradient descent methods work best for active resonance control
Paper: THPL037
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL037
About: Received: 04 May 2023 — Revised: 11 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
THPL063
Design of an electron energy spectrometer and energy selector for laser-plasma driven beams at EPAC
4568
The Extreme Photonics application Centre (EPAC) is a new national facility to support UK science, technology, innovation and industry currently under construction at the Rutherford Appleton Laboratory, UK. EPAC is designed to facilitate a wide variety of user experiments with 1PW 10Hz laser systems. It is anticipated that early experiments will include laser-plasma acceleration of electrons to energies ranging from 100 MeV up to 10 GeV, with later experiments using these electrons as a beam once stable generation is achieved. EPAC is designed to be flexible, allowing users to select the relevant central electron energy for their experiment. To achieve this goal EPAC and the Accelerator Science & Technology Centre (ASTeC) at STFC Daresbury Laboratory have been working on the design of a beamline to capture laser-plasma driven electrons with broad energy spread, measure their energy spectrum, perform selection of specific energies if necessary and deliver these electrons to a user interaction point. We present here the conceptual design of the proposed spectrometer and energy selection system.
Paper: THPL063
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL063
About: Received: 27 Apr 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
THPL068
Characterisation and analysis of supersonic gas jets using interferometric measurement methods
4588
Supersonic gas jets are useful tools in particle accelerators used in both scientific and medical applications. They can provide real-time, longitudinal and transverse beam profile measurements for charged particle beams in accelerators and are also being used as a plasma source in wakefield accelerators. For gas jets to be used effectively as beam profile monitors, the density profile of the jet must also be well-known. This can be calculated by measuring the phase shift produced by the gas jet inside a laser beam due to the difference in density between the gas and the surrounding vacuum environment from the Lorentz-Lorenz relation. In this contribution, multiple techniques for measuring gas jet profile and density will be compared and analysed; Mach-Zehnder and Nomarski interferometry. A 532 nm laser will be used for both of these methods, with a gas jet backing pressure of 7 bar. Multi-pass interferometry will also be used to increase the phase shifts by a factor of 4, and therefore sensitivity to lower density gas jets. This method involves retro-reflecting the interferometry beams, passing them through the gas jet multiple times. These techniques will be compared and their suitability for gas jet density characterisation will be assessed.
Paper: THPL068
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL068
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
THPL070
Exploring time-of-flight energy filtering possibilities for ultrafast electron single-pixel imaging
4592
Achieving a high signal-to-noise ratio is challenging in electron scattering experiments that require low average probe current or low total electron dose, e.g., time resolved hard-matter or radiation-sensitive soft matter experiments. A promising method for improving the signal-to-noise ratio when electron counts are low is to structure the electron wavefunction with optical fields and then retrieve the image via reconstruction algorithms in a single pixel imaging approach. When the electron-optical interaction is inelastic, such a scheme requires an electron energy filter. Here, we present numerical simulations of a time-of-flight energy filtering scheme for use in ultrafast electron microscopy, where a radiofrequency deflector cavity placed at the bottom of an electron microscope column provides a time-dependent momentum kick, dispersing the energy bands of the beam on a downstream detector. We estimate the filtering performance for electron single pixel imaging with an electron beam wavefunction shaped by a high intensity, highly coherent ultrafast light pulse and discuss future practical aspects.
Paper: THPL070
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL070
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
THPL071
Reconstructing 4D source momentum space via aperture scans
4595
The brightness of the beam in any linear accelerator can be no greater than at its source. Thus characterization of source initial conditions, including spatial and momentum distributions, is then critical to understand brightness evolution in a linac. Often measurement of the initial momentum distribution is hampered by imperfect knowledge of either the spatial source distribution or the downstream particle optics. Here we describe a method of recovering the transverse momentum space of a beam at the particle source without prior knowledge of the electron optics used to obtain the phase space or any source parameters; only linearity of the transport is assumed. We then demonstrate this method experimentally by measuring a 4D phase space using an aperture scan and subsequently recover the transverse phase space of a beam emitted by an alkali antimonide photocathode.
Paper: THPL071
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL071
About: Received: 03 May 2023 — Revised: 24 May 2023 — Accepted: 24 May 2023 — Issue date: 26 Sep 2023
THPL073
Improvements in longitudinal phase space tomography at PITZ
4601
Methodical studies to improve the existing e-beam Longitudinal Phase Space (LPS) tomography were performed at the Photo Injector Test facility at DESY in Zeuthen. Proof-of-principle simulations were done to address some core concerns e.g. booster phase range, space charge effects and noisy artefacts in results. Phase advance analysis was done with the help of an analytical model that determined the booster phase range and step size. A slit was introduced before the booster to truncate the beam and reduce space charge forces. The reconstruction method adopted was image space reconstruction algorithm owing to its assurance of non-negative solution. An initial scientific presumption of LPS from low energy momentum measurements was established to reduce artefacts in the phase space. This paper will explain the proof-of-principle simulations highlighting the key aspects to obtain accurate results. Reconstructed LPS for different experimental cases will be presented to demonstrate the diagnostic capability.
Paper: THPL073
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL073
About: Received: 29 Mar 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPL120
Enhancing the sensitivity of the electro-optical far-field experiment for measuring CSR at KARA
4753
At the KIT storage ring KARA (Karlsruhe Research Accelerator), a far-field electro-optical (EO) experimental setup to measure the temporal profile of the coherent synchrotron radiation (CSR) is implemented. Here, the EOSD (electro-optical spectral decoding) technique will be used to obtain single-shot measurements of the temporal CSR profile in the terahertz frequency domain. To keep the crucial high signal-to-noise ratio a setup based on balanced detection is under commission. Therefore, simulations are performed for an optimized beam path and the setup is characterized. In this contribution, the upgraded setup and first measurements are presented.
Paper: THPL120
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL120
About: Received: 02 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
THPL121
First two-bunch measurements using the electro-optical near-field monitor at KARA
4756
The Karlsruhe Research Accelerator (KARA) is an electron storage ring, which features an electro-optical near-field monitor within the beam pipe in vacuum as a tool for longitudinal bunch profile measurements. The device performs very well in single-shot turn-by-turn measurements during single-bunch operation and over the years. The design has been optimized to be prepared for measurements in multi-bunch operation. The ability to work with multiple bunches and short bunch spacing is an important step to make the device suitable for more application purposes such as a diagnostics tool for the Future Ciruclar Collider for electrons and positrons (FCC-ee). This contribution provides first tests of the monitor during two-bunch operation with minimum 2 ns bunch spacing. Challenges like crystal heating due to an increased beam current are discussed and strategies for mitigation are presented.
Paper: THPL121
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL121
About: Received: 02 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
THPL122
Split-ring resonator experiments and data analysis at FLUTE
4760
FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact linac-based test facility for accelerator and diagnostics R&D located at the Karlsruher Institute of Technology (KIT). A new accelerator diagnostics tool, called the split-ring resonator (SRR), was tested at FLUTE, which aims at measuring the longitudinal bunch profile of fs-scale electron bunches. Laser-generated THz radiation is used to excite a high frequency oscillating electromagnetic field in the SRR. Electrons passing through the 20 µm x 20 µm SRR gap are time-dependently deflected in the vertical plane, leading to a vertical streaking of the electron bunch. During the commissioning of the SRR at FLUTE, large series of streaking attempts with varying machine parameters and set-ups were investigated in an automatized way. The recorded beam screen images during this experiment have been analyzed and evaluated. This contribution motivates and presents the automatized experiment and discusses the data analysis.
Paper: THPL122
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL122
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL147
Developments and characterization of a gas jet ionization imaging optical column
4810
Standard methods of measuring the transverse beam profile are not adaptable for sufficiently high-intensity beams. Therefore, the development of non-invasive techniques for extracting beam parameters is necessary. Here we present experimental progress on developing a transverse profile diagnostic that reconstructs beam parameters based on images of an ion distribution generated by beam-induced ionization. Laser-based ionization is used as an initial step to validate the electrostatic column focusing characteristics, and different modalities, including velocity map imaging. This paper focuses on measurements of the ion imaging performance, as well as the dependence of Ion intensity on gas density and incident beam current for low-energy electron beams (<10 MeV).
Paper: THPL147
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL147
About: Received: 03 May 2023 — Revised: 19 May 2023 — Accepted: 19 May 2023 — Issue date: 26 Sep 2023
THPL153
Corrugated wakefield structures at SwissFEL
4828
Dedicated wakefield-generating structures are capable of measuring the electron beam current profile, and of removing residual energy chirps (dechirping). Furthermore, at Free-Electron Laser (FEL) facilities they can be used to measure* or shape the photon pulse power profile. We motivate and present the mechanical design of the rectangular, double-sided corrugated structures used at SwissFEL, and compare it to similar designs employed at other facilities.
Paper: THPL153
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL153
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPL160
High-bandwidth Electro-Optic BPMs and an optical time-stretch technique
4839
An electro-optic beam position monitor is in development for the HL-LHC to enable high-bandwidth monitoring of crabbed bunch rotation and intra-bunch instabilities. Following in-air beam tests of a prototype at HiRadMat and the Clear facilities at CERN in 2021 and 2022, a new in-vacuum version is being prepared for operation in the SPS during LHC Run 3. We report on progress toward the design aims and investigate a novel method of readout of single shot pulsed bunch signals at high bandwidth, while acquiring data at lower bandwidths using an optical time-stretch technique.
Paper: THPL160
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL160
About: Received: 07 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
THPL161
Detector parametrisation for the front end test stand laserwire diagnostic using GEANT4
4843
Comprehensive simulations for the FETS laserwire have been made with the developed Geant4 laser package. Feasibility of the longitudinal mode laser to provide full 6D beam characterisation has been made. Simulation results have been used to outline minimum detector requirements. The detector necessary for measuring the 6D phase space requires a drift distance of at least 2.5m between interaction point and detection plane, a 1mm2 spatial resolution, across a total transverse area of 40mm2 for the transverse measurements. To include longitudinal data the time resolution of the detector would need to be 200ps or less. The Timepix4 is proposed as a candidate detector due to its tile structure enabling custom size detector, a <100 μm spatial resolution, and a 195 ps time resolution.
Paper: THPL161
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL161
About: Received: 03 May 2023 — Revised: 31 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
THPL171
Demonstration of an electro-optic spectral interferometry longitudinal profile monitor at Clara
4855
Electro-optic diagnostics are able to non-destructively resolve the longitudinal charge profile of highly relativistic bunches without complicated calibrations and ambiguous phase recovery techniques. The most implemented technique is EO spectral decoding as it is simple and reliable, and has an easy to interpret output. However, its resolution is limited to the geometric mean of the transform limited and stretched probe laser durations. Until very recently, efforts to improve on this have resulted in designs that lose the attractive properties of spectral decoding. On the CLARA accelerator at Daresbury Laboratory we have demonstrated a new EO system that exploits common-path spectral interferometry, 'EOSI', which removes the geometric mean limitation. The system was used to measure 35 MeV/c bunches live at 10 Hz, ranging from 150 pC down to 2 pC, and at a range of compressions from several ps down to ~300 fs rms. We explain the technique, describe the measurements, and outline issues and improvements. The technique differs from a spectral decoding system by only a single optical element, potentially allowing current EO systems to be upgraded.
Paper: THPL171
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL171
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPL190
Tolerance analysis of a bunch arrival-time monitor design with rod-shaped pickups on a printed circuit board for the European XFEL and FELBE
4879
For arrival-time monitors of the electro-optical synchronization system at the European XFEL, FELBE and other free-electron laser facilities, a novel concept based on rod-shaped pickups mounted on a printed circuit board is proposed. New simulation results show the huge potential for low charge applications foreseen at the European XFEL and FELBE for future operation modes. A theoretical jitter-charge product 𝜎t × 𝑄B of 9 fs pC was estimated for this pickup structure in combination with tailor-made ultra-wideband low-pi-voltage electro-optical modulators. The design meets the desired criteria for 1 pC operation, so it is planned to produce a prototype for first tests in FELBE. The structure is assumed to be sensitive to the production accuracy, manufacturing tolerances for different components of the pickup-structure are analyzed in this work. The results allow to identify critical dimensions and will help to predict the effect of inevitable geometric deviations.
Paper: THPL190
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPL190
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
THPM005
Design of the ESS DTL mechanical supports
4899
The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is composed of 5 independent Tanks, each of which of 8 t in weight and 8 m in length, is made of 4 modules and is positioned and aligned to the Nominal Beam Line with 2 mechanical supports. The supports are designed to perform the iso-statical alignment of the tank, and to allow its longitudinal displacement for the installation and maintenance of the Intertanks. Presently, 4 of 5 Tanks have been successfully installed and aligned with respect to the Nominal Beam Line, using a Laser Tracker to monitor the position with a tolerance of 0.1 mm. This paper details the chosen kinematic configuration, the supports design, the calculation and simulations for design validation, the procedures for regulation and alignment and the achieved results.
Paper: THPM005
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM005
About: Received: 03 May 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
THPM021
Laser powder bed fusion of pure niobium for particle accelerator applications
4935
Niobium is particularly appreciated for its superconductive properties. One of the main applications of this metal in Nuclear Physics is the production of superconducting radiofrequency (SRF) cavities for particle accelerators. Additive Manufacturing (AM) gives the chance to fabricate objects with very complex shapes; also, high melting temperature and hard-to-machine materials can be easily processed. However, AM is not free from challenges, and the creation of devices such as the SRF cavities is not trivial. In this work, the characterization of pure niobium produced by Laser Powder Bed Fusion (LPBF) and a fine-tuning of the printing parameters have been carried out. Much emphasis was put on the development of innovative contactless supporting structures for improving the quality of downward-facing surfaces with very small inclination angles. A relative density higher than 99.8% was achieved and the efficiency of such innovative supports was demonstrated, as they made the fabrication of seamless SRF cavities possible. Smoothing surface treatments and performance tests on AMed cavities were also performed.
Paper: THPM021
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM021
About: Received: 04 May 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPM022
Predictive capabilities in CFD simulations of additively manufactured extraction grid cooling channels for the DTT NBI system
4939
Recently, Metal Additive Manufacturing technology enables the possibility to realize cooling systems in accelerator components during the manufacturing process phase, obtaining extremely high density, high thermal, and mechanical properties in metals. In the Neutral Beam Injection for the Divertor Tokamak Test facility, the beam acceleration components are submitted to extremely high-power loads. A tailored cooling channel shape for the acceleration grids is proposed and tested. However, the roughness issue in MAM manufacturing is a problem that can strongly affect the pressure drop in long and small-section channels. CFD is a valid tool that, if properly calibrated, predicts the pressure drop and efficiency of the cooling system. In this work, different single-channel samples have been manufactured via MAM and they have been tested to characterize the pressure drop behaviour. The single-channel samples have been internally smoothed via a chemical process to reduce the pressure drop and tested again. CFD models, using Ansys Fluent software, have been calibrated to properly predict the pressure drop of the single-channel samples. The CFD models have been implemented to optimize the channel design of the Extraction Grid cooling system. The optimized shape of the EG channels has been adopted to produce different scaled AM prototypes and tested with a thermal power map, which is similar to the nominal one.
Paper: THPM022
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM022
About: Received: 05 May 2023 — Revised: 07 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
THPM023
Additive Manufacturing of 6 GHz seamless SRF copper cavities: printing, surface treatments and performance investigations
4943
Traditionally produced SRF cavities are characterized by many limiting drawbacks, such as welding lines and poor reproducibility of their properties. Additive Manufacturing, and in particular Laser Powder Bed Fusion (LPBF), may overcome these issues: with this technology, it is possible to create seamless components with reproducible characteristics. But 6 GHz cavities cannot see internal supports because they would not be easily removable. On the other hand, the down-skin self-supporting surfaces are extremely rough and unsuitable for the intended application. Indeed, very smooth surfaces are required since copper cavities are internally coated with superconducting materials (like Nb or Nb alloys): several surface treatments have been performed and studied; tests like tightness, resonant frequency and internal inspections have also been carried out before and after the post-printing smoothening and coating stages. Results are very promising and they will be shown in this work.
Paper: THPM023
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM023
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPM024
Laser powder bed fusion of CuCrZr for nuclear fusion acceleration components
4947
Copper and copper alloys are widely used in the Nuclear Fusion field for their outstanding characteristics, especially in terms of thermal and electrical conductivities. CuCrZr is peculiarly suitable and well-known in High Energy applications because it combines good conductivity and good mechanical properties. Moreover, the material properties can be tuned with thermal treatments to fit the application requirements even more. Additive manufacturing is then a revolutionizing process that permits the creation of geometrically optimized components. This near-net-shape process allows to produce seamless parts reducing material waste and saving time. We investigate the application of the Laser Powder Bed Fusion technology to produce the acceleration grids of a Neutral Beam Injector. In this work, the authors analyzed different CuCrZr powders and investigated the material properties obtained after the printing parameters optimization, in as-built conditions and after several heat treatments. The high density and high mechanical and thermal properties allowed us to proceed with the creation of the first prototypes of the acceleration components.
Paper: THPM024
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM024
About: Received: 05 May 2023 — Revised: 10 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPM026
Additively manufactured tantalum cathode for FEBIAD type ion sources: production, geometric measurements, and high temperature test
4950
The Laser Powder Bed Fusion (LPBF) is an AM technology suitable to produce almost free-form metallic components. At Legnaro National Laboratories of the Italian National Institute for Nuclear Physics, the LPBF process was recently used to produce parts of the Forced Electron Beam Induced Arc Discharge (FEBIAD) ion source for the SPES Isotope Separation On-Line (ISOL) facility. Such device is a critical component for the ISOL process, as its correct functioning is fundamental to ensure the availability of the radioactive ion beam to the experimental users. One of the main parts of the ion source is the tantalum cathode, a component that is electrically heated up to 2200°C and is subjected to thermal stresses. Currently, the cathode is produced by subtractive manufacturing processes and TIG welding, which are not trivial in the case of Tantalum. Therefore, the cathode lacks dimensional/geometrical precision, affecting the performance repeatability and reliability of the ion source. The LPBF technology allows to perform a morphological/topological optimization of the cathode aiming to overcome the intrinsic assembly limits of the present design and making more repeatable and reliable the ion source performance. In this work, the production of the prototypical cathodes via AM, the results of dimensional–geometrical measurements, and the endurance high-temperature test are presented.
Paper: THPM026
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM026
About: Received: 08 May 2023 — Revised: 23 Jun 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
THPM031
Evaluation of green laser source additive manufacturing technology for accelerator applications with ultra-high vacuum requirements
4960
Additive Manufacturing (AM) offers different benefits such as efficient material usage, reduced production time and design freedom. Moreover, with continuous technological developments, AM expands in versatility and different material usage capabilities. Recently new energy sources have been developed for AM – green wavelength lasers, which provide better energy absorption for pure copper. Due to high thermal and electrical conductivity of copper, this novel AM technology is highly promising for various industries, particularly, there is a huge interest to use it for accelerator applications. In particular, these AM produced accelerator components should reach the associated Ultra High Vacuum (UHV) requirements. In this study, vacuum membranes of pure copper were produced by AM using a green laser source, in different thicknesses and built angles. Furthermore, a vacuum membrane helium leak tightness test was performed at room temperature by using a high-sensitivity mass spectrometer. Comparison of these test results was performed with previously established results. Through this study, novel knowledge and initial results are provided for green laser source AM technology usage for applications for UHV accelerator components.
Paper: THPM031
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM031
About: Received: 07 May 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
THPM059
Development of reliable VHEE/FLASH passive dosimetry methods and procedures at CLEAR
5028
The electron beam at CERN Linear Accelerator for Research (CLEAR) has been intensively used to study the potential use of Very High Energy Electrons (VHEE) for radiotherapy, including the so-called FLASH regime. An important part of these studies revolves around the development of reliable dosimetry methods, given that generally accepted standards are partly lacking for electron beams in the 100 MeV range and even more so in the ultra-high dose rates (UHDR) conditions needed for FLASH. Passive dosimetry methods, such as radiochromic films and alanine pellets are presumed to be energy- and dose-rate independent and constitute an indispensable tool for VHEE studies. Furthermore, the development and testing of new modalities for active UHDR dosimetry relies heavily on them for validation and cross-calibration. In this context, efforts have been made to establish reliable and systematic approaches for passive dosimetry at CLEAR. This paper describes studies related to the processing of radiochromic films, the energy dependence of the dose measurements and comparisons with alanine pellets and other media.
Paper: THPM059
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM059
About: Received: 03 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
THPM066
LhARA, the laser-hybrid accelerator for radiobiological applications
5049
LhARA*, the ‘Laser-hybrid Accelerator for Radiobiological Applications’, will be a novel, uniquely flexible, facility dedicated to the study of radiobiology. LhARA will use a high-power pulsed laser to generate a short burst of protons or light ions. These will be captured using strong-focusing electron-plasma (Gabor) lenses. Acceleration using a fixed-field alternating-gradient accelerator will deliver proton beams with energies up to 127 MeV and ion beams, such as C^6+, with energies up to 33.4 MeV/nucleon. The laser-hybrid source allows high instantaneous dose rates of up to 10^9 Gy/s to be delivered in short (10–40 ns) pulses. The laser-hybrid approach will allow the exploration of the vast “terra incognita” of the mechanisms by which the biological response to radiation is modulated by the beam’s characteristics. The technologies to be demonstrated in LhARA have the potential to allow particle-beam therapy to be delivered in completely new regimens, providing a variety of ion species in a range of spatial configurations and exploiting ultra-high dose rates**. This contribution describes the status of the LhARA project in the context of the Ion Therapy Research Facility***.
Paper: THPM066
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM066
About: Received: 11 May 2023 — Revised: 05 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
THPM083
Progress on the conceptual design of the laser-hybrid accelerator for radiobiological applications (LhARA)
5071
LhARA, the Laser-hybrid Accelerator for Radiobiological Applications, is a proposed novel facility capable of delivering high intensity beams of protons and ions that will enable radiobiological research to be carried out in completely new regimes. A two-stage facility, the first stage utilizes laser-target acceleration to produce proton bunches of energies up to 15 MeV. A series of Gabor plasma lenses will efficiently capture the beam which will be delivered to an in-vitro end station. The second stage will accelerate protons in a fixed-field alternating-gradient ring up to 127 MeV, and ions up to 33.4 MeV/nucleon. The beams will subsequently be deliverable to either an in-vivo end station or a second in-vitro end station. The technologies demonstrated in LhARA have the potential to underpin the future of hadron therapy accelerators and will be capable of delivering a wide variety of time structures and spatial configurations at instantaneous dose rates up to and significantly beyond the ultra-high dose rate FLASH regime. We present here recent progress and the current status of the LhARA accelerator as we work towards a full conceptual design.
Paper: THPM083
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM083
About: Received: 03 May 2023 — Revised: 19 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
THPM108
Generation and NRF application of Flat-Laser Compton Scattering gamma-ray beam in UVSOR
5121
Laser Compton Scattering Gamma-ray beam (F-LCS), which has a flat distribution in the energy spectrum and the special distribution, has been developed to study an isotope selective CT Imaging application in the beamline BL1U in UVSOR*. The generation of F-LCS beam has been demonstrated by using the Apple-II undulator installed in BL1U in UVSOR**. The principle of F-LCS generation, EGS5 simulation which takes into account the distribution of the laser-electron interaction region and detailed measurement results will be presented at the conference. In addition, the application of F-LCS beam to Nuclear Resonance Fluorescence (NRF) experiment has been performed in UVSOR and the result will be discussed.
Paper: THPM108
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-THPM108
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023