scholarly journals Using irregularly spaced current peaks to generate an isolated attosecond X-ray pulse in free-electron lasers

2016 ◽  
Vol 23 (6) ◽  
pp. 1273-1281 ◽  
Author(s):  
Takashi Tanaka ◽  
Yong Woon Parc ◽  
Yuichiro Kida ◽  
Ryota Kinjo ◽  
Chi Hyun Shim ◽  
...  
Keyword(s):  
Electron Beam ◽  
Free Electron ◽  
Peak Power ◽  
Short Pulse ◽  
Pulse Length ◽  
Free Electron Lasers ◽  
X Ray ◽  
Similar Scheme ◽  
Irregular Arrangement ◽  
Optical Laser

A method is proposed to generate an isolated attosecond X-ray pulse in free-electron lasers, using irregularly spaced current peaks induced in an electron beam through interaction with an intense short-pulse optical laser. In comparison with a similar scheme proposed in a previous paper, the irregular arrangement of current peaks significantly improves the contrast between the main and satellite pulses, enhances the attainable peak power and simplifies the accelerator layout. Three different methods are proposed for this purpose and achievable performances are computed under realistic conditions. Numerical simulations carried out with the best configuration show that an isolated 7.7 keV X-ray pulse with a peak power of 1.7 TW and pulse length of 70 as can be generated. In this particular example, the contrast is improved by two orders of magnitude and the peak power is enhanced by a factor of three, when compared with the previous scheme.

The advent of X-ray free electron lasers

Photoniques ◽  
2021 ◽  
pp. 22-26
Author(s):  
Marie-Emmanuelle Couprie
Keyword(s):  
Free Electron ◽  
Peak Power ◽  
Short Pulse ◽  
Far Infrared ◽  
Gain Medium ◽  
High Peak Power ◽  
X Rays ◽  
Free Electron Lasers ◽  
Free Electrons ◽  
X Ray

Free Electron Lasers (FEL) use free electrons in the periodic permanent magnetic field of an undulator as a gain medium. They extend from far infrared to X-rays, they are easily tunable and provide a high peak power. The advent of tunable intense (few mJ) short pulse (down to the attosecond regime) FELs with record multi GW peak power in the X-ray domain enables to explore new scientific areas. These unprecedent X-ray sources come along with versatile performance.

Crystal plasticity in shock-compressed hcp-iron

2021 ◽  
Author(s):  
Sébastien Merkel ◽  
Sovanndara Hok ◽  
Cynthia Bolme ◽  
Wendy Mao ◽  
Arianna Gleason
Keyword(s):  
Free Electron ◽  
Deformation Mechanisms ◽  
Free Electron Lasers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hexagonal Close Packed ◽  
Planetary Cores ◽  
Materials Behavior ◽  
Optical Laser

<p>Iron is a key constituent of planetary core and an important technological material. Here, we combine <em>in situ</em> ultrafast X-ray diffraction at free electron lasers with optical-laser-induced shock compression experiments on polycrystalline Fe to study the plasticity of hexagonal close-packed (hcp)-Fe under extreme loading states. We identifiy the deformation mechanisms that controls the Fe microstructures and  observe a significant time-evolution of stress over the few nanoseconds of the experiments. These observations illustrate how ultrafast plasticity studies can reveal distinctive materials behavior under extreme loading states and will help constraining the pressure, temperature, and strain rate dependence of materials behavior in planetary cores.</p>

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 Science at X-ray Free Electron Lasers

2021 ◽  
Vol 11 (22) ◽  
pp. 10622
Author(s):  
Kiyoshi Ueda
Keyword(s):  
Free Electron ◽  
Short Pulse ◽  
Free Electron Lasers ◽  
X Ray ◽  
Power Densities

X-ray Free Electron Lasers (FELs) deliver coherent X-ray pulses, combining unprecedented power densities of up to 1020 W/cm2 and extremely short pulse durations down to hundreds of attoseconds [...]

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.

scholarly journals Laser-Driven Modulation of Electron Beams in a Dielectric Micro-Structure for X-Ray Free-Electron Lasers

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Benedikt Hermann ◽  
Simona Bettoni ◽  
Thilo Egenolf ◽  
Uwe Niedermayer ◽  
Eduard Prat ◽  
...  
Keyword(s):  
Electron Beam ◽  
Free Electron ◽  
Modulation Scheme ◽  
Dielectric Structure ◽  
Free Electron Lasers ◽  
Micro Structure ◽  
X Ray ◽  
Beam Parameters ◽  
The Individual ◽  
Micrometer Scale

AbstractWe describe an application of laser-driven modulation in a dielectric micro-structure for the electron beam in a free-electron laser (FEL). The energy modulation is transferred into longitudinal bunching via compression in a magnetic chicane before entering the undulator section of the FEL. The bunched electron beam comprises a series of enhanced current spikes separated by the wavelength of the modulating laser. For beam parameters of SwissFEL at a total bunch charge of 30 pC, the individual spikes are expected to be as short as 140 as (FWHM) with peak currents exceeding 4 kA. The proposed modulation scheme requires the electron beam to be focused into the micrometer scale aperture of the dielectric structure, which imposes strict emittance and charge limitations, but, due to the small interaction region, the scheme is expected to require ten times less laser power as compared to laser modulation in a wiggler magnet, which is the conventional approach to create a pulse train in FELs.

scholarly journals Chemical interactions and dynamics with femtosecond X-ray spectroscopy and the role of X-ray free-electron lasers

2019 ◽  
Vol 377 (2145) ◽  
pp. 20170464 ◽  
Author(s):  
Philippe Wernet
Keyword(s):  
Structural Dynamics ◽  
Free Electron ◽  
Short Pulse ◽  
Exchange Interactions ◽  
X Rays ◽  
Free Electron Lasers ◽  
Substitution Reactions ◽  
X Ray ◽  
Orbital Interactions

X-ray free-electron lasers with intense, tuneable and short-pulse X-ray radiation are transformative tools for the investigation of transition-metal complexes and metalloproteins. This becomes apparent in particular when combining the experimental observables from X-ray spectroscopy with modern theoretical tools for calculations of electronic structures and X-ray spectra from first principles. The combination gives new insights into how charge and spin densities change in chemical reactions and how they determine reactivity. This is demonstrated for the investigations of structural dynamics with metal K-edge absorption spectroscopy, spin states in excited-state dynamics with metal 3p-3d exchange interactions, the frontier-orbital interactions in dissociation and substitution reactions with metal-specific X-ray spectroscopy, and studies of metal oxidation states with femtosecond pulses for ‘probe-before-destroy’ spectroscopy. The role of X-ray free-electron lasers is addressed with thoughts about how they enable ‘bringing back together’ different aspects of the same problem and this is thought to go beyond a conventional review paper where these aspects are formulated in italic font type in a prequel, an interlude and in a sequel. This article is part of the theme issue ‘Measurement of ultrafast electronic and structural dynamics with X-rays'.

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