Backscattered supercontinuum emission from high-intensity laser-plasma interactions.
We performed high-intensity subpicosecond laser-plasma interaction experiments to examine nonlinear scattering mechanisms in underdense plasmas. At incident laser intensities of 2 x 10(18) W/cm(2) the stimulated-Raman-backscattered spectrum exhibited an extremely broad, supercontinuumlike structure (Deltaomega/omega(0) > 1) extending from ~500 to >1200 nm (limited only by detector sensitivity). Large-amplitude modulations in the spectrum of the backscattered light were measured and are attributed to an interaction of the stimulated-Raman-scattered radiation with ion plasma waves.
Self-focusing and frequency broadening of an intense short-pulse laser in plasmas.
An intense ultrafast laser pulse propagating through a plasma undergoes self-focusing and self-phase-modulation as a result of relativistic mass nonlinearity. The inclusion of a quartic (r4) term in the expansion of the eikonal in the radial coordinate r allows the modification of the shape of the radial intensity profile. The front of the pulse, under the combined effects of time-dependent self-focusing and frequency downshifting, acquires a severely distorted temporal shape. The radial profile for I(lambda)2(mu) < 2.8 x 1018 W/cm2, where I is the axial laser intensity and lambda(mu), is the laser wavelength in micrometers, is transformed from a Gaussian to a super-Gaussian because of the faster convergence of the marginal rays than the paraxial rays. In the opposite case of I(lambda)(2)(mu) > 2.8 x 10(18) W/cm2 when nonlinear plasma permittivity approaches saturation, the radial profile in the axial region becomes broader than the Gaussian.
Corpus Linguistics in Legal Discourse
There are many different ways in which modern Corpus Linguistics can be used to enrich and broaden our understanding of legal discourse. Based on the central principle of co-occurrence and co-selection in language construction, this paper reviews current applications of Corpus Linguistics in the area of legal discourse focusing on issues ranging from phraseology, variation in legal discourse, legal translation, register and genre perspectives on legal discourse, legal discourse in forensic contexts to evaluative language in judicial settings. It revisits the notion of ‘corpus’ and it highlights the relevance of various types of legal corpora and computer tools in legal linguistic research.