| 1. |
- Delfin, C, et al.
(författare)
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Influence of laser pulse duration on relativistic channels
- 2002
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 9:3, s. 937-940
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Tidskriftsartikel (refereegranskat)abstract
- A high-power (10 TW) laser is employed to generate relativistic channels in an underdense plasma. The lengths of the channels are measured by imaging the Thomson-scattered light, and the gas densities are determined through the forward Raman scattered light. The laser-pulse parameters are varied and their impact on the channel formation is studied. It is found that increasing the laser pulse duration in many cases produces longer channels, even as this implies reducing the laser peak power. A theoretical discussion is presented, proposing an explanation of the experimental results. (C) 2002 American Institute of Physics.
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| 2. |
- L'Huillier, Anne, et al.
(författare)
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Applications of high-order harmonics
- 2003
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Ingår i: European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 26:1, s. 91-98
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Tidskriftsartikel (refereegranskat)abstract
- We review applications of high-order harmonic generation in different fields of physics, from spectroscopic studies of atoms and molecules, to interferometry and plasma diagnostics and nonlinear optics.
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| 3. |
- Norin, Johan, et al.
(författare)
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Time-frequency characterization of femtosecond extreme ultraviolet pulses.
- 2002
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Ingår i: Physical Review Letters. - 1079-7114. ; 88:19, s. 193901-193901
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Tidskriftsartikel (refereegranskat)abstract
- We present energy-resolved cross-correlation measurements of an extreme ultraviolet (XUV) pulse, generated as the fifth harmonic (15.5 eV) of an intense 80 fs laser pulse centered at 400 nm. Spectrally resolving the cross-correlation signal allows us to characterize the time-dependent frequency of the XUV pulse. We find that the fifth harmonic has a small negative chirp in excess of that predicted by perturbation theory. In addition, by manipulating the chirp of the driving laser we can induce and measure a positive or a negative chirp on the XUV pulse.
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| 4. |
- Robson, L, et al.
(författare)
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Volumetric intensity dependence on the formation of molecular and atomic ions within a high intensity laser focus
- 2005
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1879-1123 .- 1044-0305. ; 16:1, s. 82-89
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Tidskriftsartikel (refereegranskat)abstract
- The mechanism of atomic and molecular ionization in intense, ultra-short laser fields is a subject which continues to receive considerable attention. An inherent difficulty with techniques involving the tight focus of a laser beam is the continuous distribution of intensities contained within the focus, which can vary over several orders of magnitude. The present study adopts time of flight mass spectrometry coupled with a high intensity (8 X 10(15) Wcm(-2)), ultra-short (20 fs) pulse laser in order to investigate the ionization and dissociation of the aromatic molecule benzene-d1 (C6H5D) as a function of intensity within a focused laser beam, by scanning the laser focus in the direction of propagation, while detecting ions produced only in a "thin" slice (400 and 800 mum) of the focus. The resultant TOF mass spectra varies significantly, highlighting the dependence on the range of specific intensities accessed and their volumetric weightings on the ionization/dissociation pathways accessed.
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| 5. |
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| 6. |
- Sjögren, Anders, et al.
(författare)
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Relativistic channel formation with different pulse durations
- 2002
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Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. ; 611, s. 119-125
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Konferensbidrag (refereegranskat)abstract
- Relativistic channels are generated in an under-dense plasma by means of subpicosecond laser pulses. The channel extension is characterized via the Thomson-scattered light and the impact of the laser pulse duration and chirp are studied. It is shown that, under certain conditions, the channel extends further when the pulse duration is increased. This is in contrast to many earlier reports, where the channel grows with increasing laser power. Some theoretical arguments are presented to support the experimental findings. The number of electrons, accelerated in the forward direction, and their energies are assessed. In some cases, it is found that the channel divides and the fragments extend in different directions. This raises the question if, and how, the channel formation can be externally manipulated
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