AbstractThe effects of the polarized incident laser pulse on the electrons of the plasma surface and on the reflected pulse in the relativistic laser-plasma interaction is investigated. Based on the relativistic oscillating mirror and totally reflecting oscillating mirror (TROM) regimes, the interaction of the intense polarized laser pulses with over-dense plasma is considered. Based on the effect of ponderomotive force on the characteristic of generated electron nano-bunches, considerable increasing in the localization and charges of nano-bunches are realized. It is found that the circularly polarized laser pulse have Ne/Ncr of 1500 which is almost two and seven times more than the amounts for P-polarized and S-polarized, respectively.
A theoretical model is developed to determine time evolution of temperature at the surface of an opaque target placed in air for cases characterized by the formation of laser supported absorption waves (LSAW) plasmas. The model takes into account the power temporal variation throughout an incident laser pulse, (i.e. pulse shape, or simply: pulse profile).Three proposed profiles are employed and results are compared with the square pulse approximation of a constant power.
High-temperature plasmas were produced by focusing 1·05 μm, 100 psec laser pulses onto Al layer targets at a mean irradiation of 3·1013 Watt/cm2. By means of simultaneous measurements of the thermal x-ray emission and the frequency-quadrupled laser pulse we observe a 20 ± 15 psec delay of the x-ray peak relative to the peak of the incident laser pulse. In addition, modulations on the trailing edge of the driving pulse appear strongly enhanced in the x-ray signature.
AbstractPhotometric and spectroscopic observations of a very large flare on AD Leo are presented. A self consistent model of a flare corona, transition region and chromosphere is developed; in particular the chromospheric temperature distributions resulting from X-ray and EUV irradiation by coronae of various temperatures are determined. The predicted line fluxes in Hγ are compared to the observed line fluxes to find the coronal temperature as a function of time during the flare. This run of temperature with time is then compared with the predictions of an independent theoretical flare model based on a dynamic scaling law (see paper by Fisher and Hawley, these proceedings).
The rules for the lattice rotation during rolling (plane
strain) deformation of fcc polycrystals are studied with a
viscoplastic self-consistent model. Very high values of the
ratesensitivity exponent are used in order to establish Sachs-type
conditions with large local deviations from the macroscopic
strain. The lattice rotation depends on the grain shape. For
equiaxed grains the lattice rotation follows the MA rule, which is
the one normally used in solid mechanics. For elongated and flat
grains the lattice rotation follows a different rule, the PSA
rule. In the standard version the model performs a transition from
MA to PSA with increasing strain. There is avery clear difference
between the textures resulting from the two different rules. MA
leads to a copper-type texture, and PSA leads to a brass-type
texture.
The effects of circularly polarized laser pulse on generated electron nano-bunches in oscillating mirror model