scholarly journals Suppression of resonant auger effect with chirped x-ray free-electron laser pulse

2018 ◽  
Vol 51 (3) ◽  
pp. 035602 ◽  
Author(s):  
Yu-Ping Sun ◽  
Quan Miao ◽  
Ai-Ping Zhou ◽  
Rui-Jin Liu ◽  
Bo Liu ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Free Electron ◽  
Free Electron Laser ◽  
X Ray ◽  
Auger Effect

Possibility of X-ray pulse compression using an asymmetric or inclined double-crystal monochromator

2013 ◽  
Vol 20 (4) ◽  
pp. 550-554 ◽  
Author(s):  
Jaromir Hrdý ◽  
Peter Oberta
Keyword(s):  
Laser Pulse ◽  
Free Electron ◽  
Free Electron Laser ◽  
Pulse Compression ◽  
Compact Scheme ◽  
Mutual Distance ◽  
Compression Scheme ◽  
Double Crystal ◽  
X Ray ◽  
Double Crystal Monochromator

It is shown theoretically that the asymmetric or inclined double-crystal X-ray monochromator may be used for X-ray pulse compression if the pulse is properly chirped. By adjusting the mutual distance of the two asymmetric or inclined crystals it should be possible to achieve even a sub-femtosecond compression of a chirped free-electron laser pulse. The smalld-spacing of the crystal enables a more compact scheme compared with the currently used grating compression scheme. The asymmetric cut of the crystal enables the acceptance of a larger bandwidth. The inclined cut has larger tunability.

Thermomechanical optimization of the cathode design intended for the X-ray free-electron laser oscillator injector electron gun

2010 ◽  
Vol 1 (MEDSI-6) ◽  
Author(s):  
B. Brajuskovic ◽  
R. Lindberg ◽  
N. Sereno
Keyword(s):  
Thermal Analysis ◽  
Laser Pulse ◽  
Free Electron ◽  
Free Electron Laser ◽  
Thermal Stresses ◽  
Laser Oscillator ◽  
Transient Thermal Analysis ◽  
X Ray ◽  
Cathode Design ◽  
Transient Thermal

The Advanced Photon Source at Argonne National Laboratory is developing a low-emittance thermionic gun for a proposed X-ray free-electron laser oscillator (XFEL-O) that will use a laser pulse-heated cathode. The cathode must operate at or slightly above 1500 °C for several nanoseconds and then cool down several hundred °C in approximately the same amount of time, with a 1-MHz heating–cooling cycle. A transient thermal analysis was performed to optimize the laser pulse shape needed to provide the desired temperature response of the cathode for several possible cathode materials. In addition, thermal stresses developed in the cathode during heating–cooling cycles were analysed. Both transient thermal analysis and thermal stress computations were performed using the ANSYS12 code. The computed temperature distribution and thermal stresses were utilized in the optimization of the cathode design. The results of the analysis are presented.

scholarly journals X-ray multiphoton ionization dynamics of a water molecule irradiated by an x-ray free-electron laser pulse

2016 ◽  
Vol 94 (2) ◽  
Author(s):  
Ludger Inhester ◽  
Kota Hanasaki ◽  
Yajiang Hao ◽  
Sang-Kil Son ◽  
Robin Santra
Keyword(s):  
Laser Pulse ◽  
Water Molecule ◽  
Free Electron ◽  
Free Electron Laser ◽  
Multiphoton Ionization ◽  
X Ray

scholarly journals Ultrafast Dynamics of a Nucleobase Analogue Illuminated by a Short Intense X-ray Free Electron Laser Pulse

2016 ◽  
Vol 6 (2) ◽  
Author(s):  
K. Nagaya ◽  
K. Motomura ◽  
E. Kukk ◽  
H. Fukuzawa ◽  
S. Wada ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Free Electron ◽  
Free Electron Laser ◽  
Ultrafast Dynamics ◽  
X Ray

scholarly journals Increased gain of the lateral-injection free-electron laser and the use of clusters for amplication in the X-ray range

1986 ◽  
Vol 4 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Heinrich Hora ◽  
Jin-Cheng Wang ◽  
P. J. Clark ◽  
R. J. Stening
Keyword(s):  
Laser Pulse ◽  
Free Electron ◽  
Free Electron Laser ◽  
High Efficiency ◽  
High Gain ◽  
Difficult Problem ◽  
Solid Particles ◽  
Laser Amplifier ◽  
Plasma Properties ◽  
X Ray

Using radial plasma acceleration in a laser beam, an alternative type of free electron laser has been developed by radial injection of electrons. Its properties have been elaborated for a laser amplifier of 400 μtm wavelength. To overcome the difficulties of this FEL, a basically new laser amplifier concept has been developed where a laser pulse is amplified by nearly lateral injection of solid particles (clusters, pellets etc.) whose kinetic energy (at appropriate adjustment and synchronisation) is converted into 80% optical energy of the laser pulse. The mechanism of energy transfer is the radial slowing down by nonlinear ponderomotive forces of the plasma made from the cluster reaching the beam axis, and the switching-off process of the beam with regard to the transient nonlinear force processes. It is an inversion of the plasma ejection with ponderomotive self-focussing. Apart from the unusually high efficiency, a relatively high gain is expected even for such small laser wavelengths as 10 nm. Furthermore, the difficult problem of modification of phase fronts and convergence (focussing, directing of X-ray beams) should be solved by the optical plasma properties at injection.

scholarly journals Electron and fluorescence spectra of a water molecule irradiated by an x-ray free-electron laser pulse

2018 ◽  
Vol 97 (5) ◽  
Author(s):  
Julia M. Schäfer ◽  
Ludger Inhester ◽  
Sang-Kil Son ◽  
Reinhold F. Fink ◽  
Robin Santra
Keyword(s):  
Laser Pulse ◽  
Water Molecule ◽  
Free Electron ◽  
Free Electron Laser ◽  
Fluorescence Spectra ◽  
X Ray

scholarly journals Non-equilibrium modeling of the Fe XVII 3C/3D ratio for an intense X-ray free electron laser

2017 ◽  
Vol 95 (9) ◽  
pp. 869-877 ◽  
Author(s):  
Y. Li ◽  
M. Fogle ◽  
S.D. Loch ◽  
C.P. Ballance ◽  
C.J. Fontes
Keyword(s):  
Laser Pulse ◽  
Density Matrix ◽  
Line Intensity ◽  
Free Electron ◽  
Free Electron Laser ◽  
Intensity Ratio ◽  
Strength Ratio ◽  
X Ray ◽  
Expected Time ◽  
Line Intensity Ratio

We present a review of two methods used to model recent LCLS experimental results for the 3C/3D line intensity ratio of Fe XVII (S. Bernitt, et al. Nature, 492, 225 (2012)), the time-dependent collisional-radiative method and the density matrix approach. These are described and applied to a two-level atomic system excited by an X-ray free electron laser. A range of pulse parameters is explored and the effects on the predicted Fe XVII 3C and 3D line intensity ratio are calculated. To investigate the behavior of the predicted line intensity ratio, a particular pair of A-values for the 3C and 3D transitions was chosen (2.22 × 1013 s−1 and 6.02 × 1012 s−1 for 3C and 3D, respectively), but our conclusions are independent of the precise values. We also reaffirm the conclusions from Oreshkina et al. (N.S. Oreshkina, et al. Phys. Rev. Lett. 113, 143001 (2014); Ibid. J. Phys. B, 49, 094003 (2015)): the nonlinear effects in the density matrix are important and the reduction in the Fe XVII 3C/3D line intensity ratio is sensitive to the laser pulse parameters, namely, pulse duration, pulse intensity, and laser bandwidth. It is also shown that for both models the lowering of the 3C/3D line intensity ratio below the expected time-independent oscillator strength ratio has a significant contribution due to its emission from the plasma after the laser pulse has left the plasma volume. Laser intensities above ∼1 × 1012 W/cm2 are required for a reduction in the 3C/3D line intensity ratio below the expected time-independent oscillator strength ratio.

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