| 1. |
- L'Huillier, Anne, et al.
(författare)
-
High-order Harmonics - A Coherent Source In the Xuv Range
- 1995
-
Ingår i: Journal of Nonlinear Optical Physics & Materials. - 0218-1991. ; 4:3, s. 647-665
-
Tidskriftsartikel (refereegranskat)abstract
- We review the main results concerning high-order generation processes from the point of view of a potential user of this new source of XUV radiation. The perspectives for optimizing the source, both in efficiency and in spectral range, its characteristics and in particular, its coherence properties, are discussed. Finally, we describe two experiments, which demonstrate the usefulness of the harmonics as a short-pulse, coherent source in the XUV domain.
|
|
| 2. |
- Thomas, H., et al.
(författare)
-
Explosions of Xenon Clusters in Ultraintense Femtosecond X-Ray Pulses from the LCLS Free Electron Laser
- 2012
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 108:13
-
Tidskriftsartikel (refereegranskat)abstract
- Explosions of large Xe clusters (< N > similar to 11 000) irradiated by femtosecond pulses of 850 eV x-ray photons focused to an intensity of up to 1017 W/cm(2) from the Linac Coherent Light Source were investigated experimentally. Measurements of ion charge-state distributions and energy spectra exhibit strong evidence for the formation of a Xe nanoplasma in the intense x-ray pulse. This x-ray produced Xe nanoplasma is accompanied by a three-body recombination and hydrodynamic expansion. These experimental results appear to be consistent with a model in which a spherically exploding nanoplasma is formed inside the Xe cluster and where the plasma temperature is determined by photoionization heating.
|
|
| 3. |
- Timneanu, Nicusor, et al.
(författare)
-
Fragmentation of clusters and recombination induced by intense and ultrashort X-ray laser pulses
- 2013
-
Ingår i: Damage To Vuv, Euv, And X-Ray Optics Iv; And Euv And X-Ray Optics. - : SPIE - International Society for Optical Engineering.
-
Konferensbidrag (refereegranskat)abstract
- Understanding the ultrafast dynamics of matter under extreme conditions is relevant for structural studies and plasma physics with X-ray lasers. We used the pulses from free-electron lasers (FLASH in Hamburg and LCLS in Stanford) to trigger X-ray induced explosions in atomic atoms (Xe) and molecular clusters (CH4 and CD4). The explosion dynamics depends on cluster size and the intensity of the X-ray pulse, and a transition from Coulomb explosion to hydrodynamic expansion is expected with increasing size and increasing pulse intensity. In methane clusters experiments at FLASH, the time-of-flight spectrometry shows the appearance of molecular adducts which are the result of molecular recombination between ions and molecules. The recombination depends on the cluster size and the expansion mechanism and becomes significant in larger clusters. In Xenon cluster experiments at the LCLS, measurements of the ion charge states in clusters suggest a formation of Xe nanoplasma which expands hydrodynamically. The dominance of low charge states of Xe is due to three-body recombination processes involving electron and Xe ions, and it depends on the X-ray intensity and nanoplasma formation.
|
|
| 4. |
- Salieres, P, et al.
(författare)
-
Angular distributions of high-order harmonics generated by a femtosecond laser
- 1996
-
Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075. ; 29:20, s. 4771-4786
-
Tidskriftsartikel (refereegranskat)abstract
- We present a systematic study of the angular distributions of high-order harmonics generated with a femtosecond Cr:LiSrAlF6 laser. We investigate the influence of different parameters, namely laser intensity, nonlinear order, nature of the gas and position of the laser focus relative to the generating medium. We show that when the laser is focused before the atomic medium, harmonics with regular spatial profiles can be generated with reasonable conversion efficiency. Their divergence does not depend directly on the nonlinear order, the intensity or even the nature of the generating gas, but rather on the region of the spectrum the considered harmonic belongs to, which is determined by the combination of the three preceding elements. When the focus is drawn closer to the medium, the distributions get increasingly distorted, becoming annular with a significant divergence for a focus right into-or after-the jet. We perform numerical simulations of the angular distributions. The simulated profiles reproduce remarkably well the experimental trends and are thus used to interpret them.
|
|
