Development of laser-plasma X-ray sources provides a new route to high brightness and small source size somewhere in the middle of low cost micro-focus X-rays and large scale synchrotron facilities. We explore one application of this new type of sources with emphasis on the stability of the source at high repetition rate and the advantage over similar conventional sources. In this paper we report the development and application of a micro-focus X-ray source for phase contrast imaging. The X-ray source produced at the Laser Laboratory for Acceleration and Applications (L2A2) of the University of Santiago de Compostela (USC), is made by focusing a 1 mJ, 35 fs, 1kHz pulses at 800 nm wavelength on metallic plates close to the diffraction limit. The X-ray spectra of this source are characterized by the K-α peaks which can be 'tuned' by changing the target material and a Bremsstrahlung continuum up to several tens of keV. The stability of the source is achieved by optimizing the positioning system of the metallic target which refresh and keep the surface within the small the Rayleigh length allowing the development of applications.
Non linear propagation of ultra short pulses in air is studied. By preparing an initial field distribution by an amplitude mask we can obtain a Townes soliton (self similar channel of coherent radiation) in air. Experimental observation can be described accurately by the numerical integration of the Non Linear Schroedinger Equation (NLSE) and allow us to explain the origin of the remarkable stability of this soliton as a balance between diffraction and Kerr effect. We further explore on the role of coherence by revisiting the two slit Young's experiment but now in the non linear regime.
We report the observation of self-guided propagation of 120 fs, 0.56 mJ infrared pulse in air for distances greater
than a meter (more than thirty Rayleigh Lengths). The numerical simulations demonstrates the this localized
structure corresponds to a Townes soliton, specially stable under these conditions.
In the non-relativistic limit, the dynamics of the interaction of light with matter is described via a Hamiltonian
that does not include spin operators. However, the actual spin configuration of the interacting particles still
plays a fundamental role, via the Pauli's exclusion principle, by forcing a particular symmetry of the spatial
part of the wavefunction. In this paper we analyze the role of symmetry in the process of ionization of two and