scholarly journals Perspectives towards Sub-Ångström Working Regime of the European X-ray Free-Electron Laser with Low-Emittance Electron Beams

2021 ◽  
Vol 11 (22) ◽  
pp. 10768
Author(s):  
Ye Chen ◽  
Frank Brinker ◽  
Winfried Decking ◽  
Matthias Scholz ◽  
Lutz Winkelmann
Keyword(s):  
Electron Beam ◽  
Photon Energy ◽  
Free Electron ◽  
Free Electron Laser ◽  
Electron Beams ◽  
Energy Levels ◽  
Energetic Electron ◽  
X Rays ◽  
X Ray ◽  
Low Emittance

Sub-ångström working regime refers to a working state of free-electron lasers which allows the generation of hard X-rays at a photon wavelength of 1 ångström and below, that is, a photon energy of 12.5 keV and above. It is demonstrated that the accelerators of the European X-ray Free-Electron Laser can provide highly energetic electron beams of up to 17.5 GeV. Along with long variable-gap undulators, the facility offers superior conditions for exploring self-amplified spontaneous emission (SASE) in the sub-ångström regime. However, the overall FEL performance relies quantitatively on achievable electron beam qualities through a kilometers-long accelerator beamline. Low-emittance electron beam production and the associated start-to-end beam physics thus becomes a prerequisite to dig in the potentials of SASE performance towards higher photon energies. In this article, we present the obtained results on electron beam qualities produced with different accelerating gradients of 40 MV/m–56 MV/m at the cathode, as well as the final beam qualities in front of the undulators via start-to-end simulations considering realistic conditions. SASE studies in the sub-ångström regime, using optimized electron beams, are carried out at varied energy levels according to the present state of the facility, that is, a pulsed mode operating with a 10 Hz-repetition 0.65 ms-long bunch train energized to 14 GeV and 17.5 GeV. Millijoule-level SASE intensity is obtained at a photon energy of 25 keV at 14 GeV electron beam energy using a gain length of about 7 m. At 17.5 GeV, half-millijoule lasing is achieved at 40 keV. Lasing at up to 50 keV is demonstrated with pulse energies in the range of a few hundreds and tens of microjoules with existing undulators and currently achievable electron beam qualities.

scholarly journals Nanofocusing Optics for an X-Ray Free-Electron Laser Generating an Extreme Intensity of 100 EW/cm2 Using Total Reflection Mirrors

2020 ◽  
Vol 10 (7) ◽  
pp. 2611
Author(s):  
Hirokatsu Yumoto ◽  
Yuichi Inubushi ◽  
Taito Osaka ◽  
Ichiro Inoue ◽  
Takahisa Koyama ◽  
...  
Keyword(s):  
Photon Energy ◽  
Pulse Energy ◽  
Free Electron ◽  
Free Electron Laser ◽  
Total Reflection ◽  
Experimental Chamber ◽  
X Rays ◽  
X Ray ◽  
Set Up ◽  
Focused Beam

A nanofocusing optical system—referred to as 100 exa—for an X-ray free-electron laser (XFEL) was developed to generate an extremely high intensity of 100 EW/cm2 (1020 W/cm2) using total reflection mirrors. The system is based on Kirkpatrick-Baez geometry, with 250-mm-long elliptically figured mirrors optimized for the SPring-8 Angstrom Compact Free-Electron Laser (SACLA) XFEL facility. The nano-precision surface employed is coated with rhodium and offers a high reflectivity of 80%, with a photon energy of up to 12 keV, under total reflection conditions. Incident X-rays on the optics are reflected with a large spatial acceptance of over 900 μm. The focused beam is 210 nm × 120 nm (full width at half maximum) and was evaluated at a photon energy of 10 keV. The optics developed for 100 exa efficiently achieved an intensity of 1 × 1020 W/cm2 with a pulse duration of 7 fs and a pulse energy of 150 μJ (25% of the pulse energy generated at the light source). The experimental chamber, which can provide different stage arrangements and sample conditions, including vacuum environments and atmospheric-pressure helium, was set up with the focusing optics to meet the experimental requirements.

STUDY OF TRANSVERSE EFFECTS IN THE PRODUCTION OF X-RAYS WITH A FREE-ELECTRON LASER BASED ON AN OPTICAL UNDULATOR

2007 ◽  
Vol 22 (23) ◽  
pp. 4270-4279
Author(s):  
A. BACCI ◽  
C. MAROLI ◽  
V. PETRILLO ◽  
L. SERAFNI ◽  
M. FERRARIO
Keyword(s):  
Electron Beam ◽  
Free Electron ◽  
Free Electron Laser ◽  
Laser Energy ◽  
Laser Pulses ◽  
Collective Effects ◽  
Laser Source ◽  
X Rays ◽  
X Ray ◽  
Back Scattering

The interaction between high-brilliance electron beams and counter-propagating laser pulses produces X rays via Thomson back-scattering. If the laser source is long and intense enough, the electrons of the beam can bunch and a regime of collective effects can establish. In this case of dominating collective effects, the FEL instability can develop and the system behaves like a free-electron laser based on an optical undulator. Coherent X-rays can be irradiated, with a bandwidth very much thinner than that of the corresponding incoherent emission. The emittance of the electron beam and the distribution of the laser energy are the principal quantities that limit the growth of the X-ray signal. In this work we analyse with a 3-D code the transverse effects in the emission produced by a relativistic electron beam when it is under the action of an optical laser pulse and the X-ray spectra obtained. The scalings typical of the optical wiggler, characterized by very short gain lengths and overall time durations of the process make possible considerable emission also with emittance of the order of 1mm mrad.

scholarly journals Two-color operation of a free-electron laser with a tilted beam

2016 ◽  
Vol 23 (4) ◽  
pp. 869-873 ◽  
Author(s):  
Sven Reiche ◽  
Eduard Prat
Keyword(s):  
Electron Beam ◽  
Photon Energy ◽  
Free Electron ◽  
Free Electron Laser ◽  
Tuning Range ◽  
Free Electron Lasers ◽  
Successful Operation ◽  
X Ray ◽  
Two Photon ◽  
Gap Control

With the successful operation of free-electron lasers (FELs) as user facilities there has been a growing demand for experiments with two photon pulses with variable photon energy and time separation. A configuration of an undulator with variable-gap control and a delaying chicane in the middle of the beamline is proposed. An injected electron beam with a transverse tilt will only yield FEL radiation for the parts which are close to the undulator axis. This allows, after re-aligning and delaying the electron beam, a different part of the bunch to be used to produce a second FEL pulse. This method offers independent control in photon energy and delay. For the parameters of the soft X-ray beamline Athos at the SwissFEL facility the photon energy tuning range is a factor of five with an adjustable delay between the two pulses from −50 to 950 fs.

Two-color X-ray free-electron laser consisting of broadband and narrowband beams

2020 ◽  
Vol 27 (6) ◽  
pp. 1720-1724
Author(s):  
Ichiro Inoue ◽  
Taito Osaka ◽  
Toru Hara ◽  
Makina Yabashi
Keyword(s):  
Photon Energy ◽  
Free Electron ◽  
Free Electron Laser ◽  
Intensity Ratio ◽  
Energy Separation ◽  
Nonlinear Interactions ◽  
X Rays ◽  
Free Electron Lasers ◽  
Simple Scheme ◽  
X Ray

A simple scheme is proposed and experimentally confirmed to generate X-ray free-electron lasers (XFELs) consisting of broadband and narrowband beams with a controllable intensity ratio and a large photon-energy separation. This unique two-color XFEL beam will open new opportunities for investigation of nonlinear interactions between intense X-rays and matter.

scholarly journals High Repetition Rate and Coherent Free-Electron Laser in the X-Rays Range Tailored for Linear Spectroscopy

Instruments ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 47 ◽  
Author(s):  
Vittoria Petrillo ◽  
Michele Opromolla ◽  
Alberto Bacci ◽  
Illya Drebot ◽  
Giacomo Ghiringhelli ◽  
...  
Keyword(s):  
Free Electron ◽  
Repetition Rate ◽  
Free Electron Laser ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
High Repetition Rate ◽  
X Rays ◽  
Regenerative Amplifier ◽  
X Ray ◽  
High Repetition

Fine time-resolved analysis of matter—i.e., spectroscopy and photon scattering—in the linear response regime requires fs-scale pulsed, high repetition rate, fully coherent X-ray sources. A seeded Free Electron Laser (FEL) driven by a Linac based on Super Conducting cavities, generating 10 8 – 10 10 coherent photons at 2–5 keV with 0.2–1 MHz of repetition rate, can address this need. Three different seeding schemes, reaching the X-ray range, are described hereafter. The first two are multi-stage cascades upshifting the radiation frequency by a factor of 10–30 starting from a seed represented by a coherent flash of extreme ultraviolet light. This radiation can be provided either by the High Harmonic Generation of an optical laser or by an FEL Oscillator operating at 12–14 nm. The third scheme is a regenerative amplifier working with X-ray mirrors. The whole chain of the X-ray generation is here described by means of start-to-end simulations.

PRODUCTION OF FEMTOSECOND PULSES AND MICRON BEAM SPOTS FOR HIGH BRIGHTNESS ELECTRON BEAM APPLICATIONS

2007 ◽  
Vol 22 (22) ◽  
pp. 3726-3735
Author(s):  
S. G. ANDERSON ◽  
D. J. GIBSON ◽  
F. V. HARTEMANN ◽  
J. S. JACOB ◽  
A. M. TREMAINE ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Beams ◽  
Beam Radiation ◽  
High Brightness ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Strong Focusing ◽  
Moderate Energy ◽  
Low Emittance

Current and future applications of high brightness electron beams, which include advanced accelerators and beam-radiation interactions require both transverse and longitudinal beam sizes on the order of tens of microns. Ultra-high density beams may be produced at moderate energy (50 MeV) by compression and subsequent strong focusing of low emittance, photoinjector sources. We describe the implementation of this method used at the PLEIADES inverse-Compton scattering (ICS) x-ray source at LLNL in which the photoinjector-generated beam has been compressed to 300 fsec rms duration using the velocity bunching technique and focused to 20 μm rms size using an extremely high gradient, permanent magnet quadrupole focusing system.

scholarly journals Electron-bunch lengthening on higher-harmonic oscillations in storage-ring free-electron lasers

2017 ◽  
Vol 24 (5) ◽  
pp. 912-918 ◽  
Author(s):  
Norihiro Sei ◽  
Hiroshi Ogawa ◽  
Shuichi Okuda
Keyword(s):  
Electron Beam ◽  
Storage Ring ◽  
Free Electron ◽  
Free Electron Laser ◽  
Cavity Length ◽  
Extreme Ultraviolet ◽  
Bunch Length ◽  
Free Electron Lasers ◽  
X Ray ◽  
Higher Harmonic

The influence of higher-harmonic free-electron laser (FEL) oscillations on an electron beam have been studied by measuring its bunch length at the NIJI-IV storage ring. The bunch length and the lifetime of the electron beam were measured, and were observed to have become longer owing to harmonic lasing, which is in accord with the increase of the FEL gain. It was demonstrated that the saturated FEL power could be described by the theory of bunch heating, even for the harmonic lasing. Cavity-length detuning curves were measured for the harmonic lasing, and it was found that the width of the detuning curve was proportional to a parameter that depended on the bunch length. These experimental results will be useful for developing compact resonator-type FELs by using higher harmonics in the extreme-ultraviolet and the X-ray regions.

scholarly journals Multiple-beamline operation of SACLA

2019 ◽  
Vol 26 (2) ◽  
pp. 595-602 ◽  
Author(s):  
Kensuke Tono ◽  
Toru Hara ◽  
Makina Yabashi ◽  
Hitoshi Tanaka
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
Linear Accelerator ◽  
Electron Beams ◽  
Pulse Electron ◽  
Parallel Operation ◽  
Switching Operation ◽  
X Ray ◽  
Fast Switching ◽  
Concurrent User

The SPring-8 Ångstrom Compact free-electron LAser (SACLA) began parallel operation of three beamlines (BL1–3) in autumn 2017 to increase the user beam time of the X-ray free-electron laser. The success of the multiple-beamline operation is based on two technological achievements: (i) the fast switching operation of the SACLA main linear accelerator, which provides BL2 and BL3 with pulse-by-pulse electron beams, and (ii) the relocation and upgrade of the SPring-8 Compact SASE Source for BL1, for the generation of a soft X-ray free-electron laser. Moreover, the photon beamlines and experimental stations were upgraded to facilitate concurrent user experiments at the three beamlines and accommodate more advanced experiments.

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