Temperature distribution within the friction stir welding tool

This purpose, experimental measurements of the temperature distribution within the welding tool were used for finite element modelin

Nonlocal stabilization of nonlinear beams in a self-focusing atomic vapor

We show that ballistic transport of optically excited atoms in an atomic vapor provides a nonlocal nonlinearity which stabilizes the propagation of vortex beams and higher order modes in the presence of a self-focusing nonlinearity. Numerical experiments demonstrate stable propagation of lowest and higher order vortices over a hundred diffraction lengths, before dissipation leads to decay of these structures.Comment: 3 figure

The study of second harmonic generation of the femtosecond laser pulses with a 950 nm central wavelength

The paper presents the results of theoretical and experimental studies of the second harmonic generation process in the Ti:sapphire femtosecond complex, which includes a generator of the femtosecond pulse, stretcher, regenerative amplifier, two multi-pass amplifiers, compressor and second-harmonic generator. This complex provides the 50-fs pulses with energy of 20 mJ and it is used as a master oscillator in THL-100 hybrid laser system, which operates in the visible region at a wavelength of 475 nm. Experiments and calculations for various beam parameters of the fundamental harmonic, such as radiation intensity, spatial profile of the beam and the level of the noise component were performed. It is theoretically shown that in the absence of the noise component in the beam of the fundamental wave a good uniformity of the second harmonic should be observed. When making the amplitude heterogeneities in the first harmonic even greater heterogeneities in the second harmonic are appeared. It is experimentally shown that with increasing of energy beam the inhomogeneity of the second harmonic beam increases

M-Theory of Matrix Models

Small M-theories unify various models of a given family in the same way as the M-theory unifies a variety of superstring models. We consider this idea in application to the family of eigenvalue matrix models: their M-theory unifies various branches of Hermitean matrix model (including Dijkgraaf-Vafa partition functions) with Kontsevich tau-function. Moreover, the corresponding duality relations look like direct analogues of instanton and meron decompositions, familiar from Yang-Mills theory.Comment: 12 pages, contribution to the Proceedings of the Workshop "Classical and Quantum Integrable Systems", Protvino, Russia, January, 200

Vanishing Meissner effect as a hallmark of in-plane FFLO instability in superconductor - ferromagnet layered systems

We demonstrate that in a wide class of multilayered superconductor - ferromagnet structures (e.g., S/F, S/F/N and S/F/F') the vanishing Meissner effect signals the appearance of the in-plane Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) modulated superconducting phase. In contrast to the bulk superconductors the FFLO instability in these systems can emerge at temperatures close to the critical one and is effectively controlled by the S layer thickness and the angle between magnetization vectors in the F/F' bilayers. The predicted FFLO state reveals through the critical temperature oscillations vs the perpendicular magnetic field component.Comment: 5 pages, 5 figure