scholarly journals X-ray Spectroscopic Studies of a Solid-Density Germanium Plasma Created by a Free Electron Laser

2020 ◽  
Vol 10 (22) ◽  
pp. 8153
Author(s):  
Gabriel Pérez-Callejo ◽  
Sam M. Vinko ◽  
Shenyuan Ren ◽  
Ryan Royle ◽  
Oliver Humphries ◽  
...  
Keyword(s):  
Photon Energy ◽  
Free Electron ◽  
Free Electron Laser ◽  
Emission Spectra ◽  
Spectroscopic Studies ◽  
Coupled Systems ◽  
Heating Process ◽  
Strongly Coupled ◽  
X Ray ◽  
Solid Density

The generation of solid-density plasmas in a controlled manner using an X-ray free electron laser (XFEL) has opened up the possibility of diagnosing the atomic properties of hot, strongly coupled systems in novel ways. Previous work has concentrated on K-shell emission spectroscopy of low Z (<= 14) elements. Here, we extend these studies to the mid-Z(=32) element Germanium, where the XFEL creates copious L-shell holes, and the plasma conditions are interrogated by recording of the associated L-shell X-ray emission spectra. Given the desirability of generating as uniform a plasma as possible, we present here a study of the effects of the FEL photon energy on the temperatures and electron densities created, and their uniformity in the FEL beam propagation direction. We show that good uniformity can be achieved by tuning the photon energy of the XFEL such that it does not overlap significantly with L-shell to M-shell bound-bound transitions, and lies below the L-edges of the ions formed during the heating process. Reasonable agreement between experiment and simulations is found for the emitted X-ray spectra, demonstrating that for these higher Z elements, the selection of appropriate XFEL parameters is important for achieving uniformity in the plasma conditions.

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.

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.

Spectroscopic studies of hard x-ray free-electron laser-heated foils at 1016Wcm-2irradiances

2011 ◽  
Author(s):  
J. Dunn ◽  
R. Shepherd ◽  
A. Graf ◽  
A. Steel ◽  
J. Park ◽  
...  
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
Spectroscopic Studies ◽  
X Ray ◽  
Laser Heated

scholarly journals Intense sub-micrometre focusing of soft X-ray free-electron laser beyond 1016 W cm−2 with an ellipsoidal mirror

2019 ◽  
Vol 26 (5) ◽  
pp. 1406-1411 ◽  
Author(s):  
Hiroto Motoyama ◽  
Shigeki Owada ◽  
Gota Yamaguchi ◽  
Takehiro Kume ◽  
Satoru Egawa ◽  
...  
Keyword(s):  
Photon Energy ◽  
Free Electron ◽  
High Intensity ◽  
Free Electron Laser ◽  
Numerical Aperture ◽  
Saturable Absorption ◽  
X Ray ◽  
High Numerical Aperture ◽  
Ellipsoidal Mirror ◽  
Drastic Increase

Intense sub-micrometre focusing of a soft X-ray free-electron laser (FEL) was achieved by using an ellipsoidal mirror with a high numerical aperture. A hybrid focusing system in combination with a Kirkpatrick–Baez mirror was applied for compensation of a small spatial acceptance of the ellipsoidal mirror. With this system, the soft X-ray FEL pulses were focused down to 480 nm × 680 nm with an extremely high intensity of 8.8×1016 W cm−2 at a photon energy of 120 eV, which yielded saturable absorption at the L-edge of Si (99.8 eV) with a drastic increase of transmittance from 8% to 48%.

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.

Creation and diagnosis of a solid-density plasma with an X-ray free-electron laser

Nature ◽  
2012 ◽  
Vol 482 (7383) ◽  
pp. 59-62 ◽  
Author(s):  
S. M. Vinko ◽  
O. Ciricosta ◽  
B. I. Cho ◽  
K. Engelhorn ◽  
H.-K. Chung ◽  
...  
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
X Ray ◽  
Solid Density ◽  
Density Plasma

scholarly journals Characterization of temporal coherence of hard X-ray free-electron laser pulses with single-shot interferograms

IUCrJ ◽  
2017 ◽  
Vol 4 (6) ◽  
pp. 728-733 ◽  
Author(s):  
Taito Osaka ◽  
Takashi Hirano ◽  
Yuki Morioka ◽  
Yasuhisa Sano ◽  
Yuichi Inubushi ◽  
...  
Keyword(s):  
Photon Energy ◽  
Free Electron ◽  
Free Electron Laser ◽  
Dynamic Properties ◽  
Spatial Scales ◽  
Temporal Coherence ◽  
High Energy ◽  
Spectral Information ◽  
Single Shot ◽  
X Ray

Temporal coherence is one of the most fundamental characteristics of light, connecting to spectral information through the Fourier transform relationship between time and frequency. Interferometers with a variable path-length difference (PLD) between the two branches have widely been employed to characterize temporal coherence properties for broad spectral regimes. Hard X-ray interferometers reported previously, however, have strict limitations in their operational photon energies, due to the specific optical layouts utilized to satisfy the stringent requirement for extreme stability of the PLD at sub-ångström scales. The work presented here characterizes the temporal coherence of hard X-ray free-electron laser (XFEL) pulses by capturing single-shot interferograms. Since the stability requirement is drastically relieved with this approach, it was possible to build a versatile hard X-ray interferometer composed of six separate optical elements to cover a wide photon energy range from 6.5 to 11.5 keV while providing a large variable delay time of up to 47 ps at 10 keV. A high visibility of up to 0.55 was observed at a photon energy of 10 keV. The visibility measurement as a function of time delay reveals a mean coherence time of 5.9 ± 0.7 fs, which agrees with that expected from the single-shot spectral information. This is the first result of characterizing the temporal coherence of XFEL pulses in the hard X-ray regime and is an important milestone towards ultra-high energy resolutions at micro-electronvolt levels in time-domain X-ray spectroscopy, which will open up new opportunities for revealing dynamic properties in diverse systems on timescales from femtoseconds to nanoseconds, associated with fluctuations from ångström to nanometre spatial scales.

scholarly journals Observation of Ultrafast Solid-Density Plasma Dynamics Using Femtosecond X-Ray Pulses from a Free-Electron Laser

2018 ◽  
Vol 8 (3) ◽  
Author(s):  
Thomas Kluge ◽  
Melanie Rödel ◽  
Josefine Metzkes-Ng ◽  
Alexander Pelka ◽  
Alejandro Laso Garcia ◽  
...  
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
Plasma Dynamics ◽  
X Ray ◽  
Solid Density ◽  
Density Plasma

scholarly journals Saturable Absorption of an X-Ray Free-Electron-Laser Heated Solid-Density Aluminum Plasma

2015 ◽  
Vol 114 (1) ◽  
Author(s):  
D. S. Rackstraw ◽  
O. Ciricosta ◽  
S. M. Vinko ◽  
B. Barbrel ◽  
T. Burian ◽  
...  
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
Saturable Absorption ◽  
X Ray ◽  
Solid Density ◽  
Aluminum Plasma ◽  
Laser Heated
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