Magnetic fields play an important role in the laser plasma interactions. Their generation mechanisms have been longtime insufficiently investigated because their diagnostics and numerical computations are a complicated task. However it is known that under the conditions previewed for the inertial fusion the anisotropy of the electron distribution function opens a possibility of magnetic field generation. In [1], we have proposed a fluid model where electron pressure is assumed to be a tensor corresponding to an anisotropic distribution function. This model describes electron response within the ten-moments approximation coupled to the equation that takes account of the magnetic field generation. Let us consider a laser beam propagating in plasma along z-axis and polarized in the x, yplane. The magnetic field is directed along z axis and it is induced by the plasma motion in the x, y-plane. The code describes the plasma heating and its motion in the hydrodynamic approximation and it accounts for the magnetic field generation due to the anisotropy of laser heating in the direction of the polarization vector. Our goal is to consider the effects of this self-magnetic field on the plasma on the energy transport and the plasma motion. One particular self-consistent
Numerous experimental and theoretical contributions in the past have stressed the detrimental effect of fractures in the generation of surface laser damage sites in fused silica illuminated at 351 nm. However, two very important steps lack for the moment on the way towards a scientific understanding of the role of fractures. 1. a physical model must be developed to predict damage events starting from real defect sites 2. a reproducible measurement must be obtained and compared with calculations.Here we present the theoretical work realized to reach the first goal. Contrary to previous discussions on fractures, the electromagnetic configuration is calculated in the case of a real material, with electronic surface states, bulk defects, and defects dynamics. Due to electromagnetic field enhancement in the fracture, surface defects absorb a sufficient part of laser energy, able to heat silica above the vaporization temperature. This is the initial event that triggers production of more excited states during the pulse, and steep increase of temperature and pressure fields. Comparisons with available experimental results are positive. Calculated fluences of damage initiation are very near those of measured events on engineered fractures, or on real defects in polished samples.
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