Strong-field effects induced in the extreme ultraviolet domain

The Extreme-ultraviolet Continuum of a Strong Stellar Flare

We present the serendipitous detection of an extreme-ultraviolet flare on EUVE J0613 23.9B. The flare showed over a 200-fold increase above the quiescent emission in the DS/Lexan 60–200 Å wavelength band. Optical spectroscopy revealed that the event was associated with an active dM3.5e star. The EUVE spectra are dominated by emission lines formed at temperatures in excess of 10 K. The observati...

Coherent extreme ultraviolet light amplification by strong-field-enhanced forward scattering.

We theoretically study the response of He atoms exposed simultaneously to an intense IR pulse and a weak extreme ultraviolet (XUV) pulse with photon energies far from the principal atomic He resonances. We find that XUV forward scattering from the nonstationary electronic wave packet promoted by the intense IR driving field is strongly enhanced as compared with the normal weak scattering from b...

Extreme ultraviolet frequency combs for precision measurement and strong-field physics

the effects of changing roughness on the flow structure in the bends

flow in natural river bends is a complex and turbulent phenomenon which affects the scour and sedimentations and causes an irregular bed topography on the bed. for the reason, the flow hydralics and the parameters which affect the flow to be studied and understand. in this study the effect of bed and wall roughness using the software fluent discussed in a sharp 90-degree flume bend with 40.3cm ...

Strong far-field coherent scattering of ultraviolet radiation by holococcolithophores.

By considering the structure of holococcoliths (calcite plates that cover holococcolithophores, a haploid phase of the coccolithophore life cycle) as a photonic structure, we apply a discrete dipolar approximation to study the light backscattering properties of these algae. We show that some holococcolith structures have the ability to scatter the ultraviolet radiation. This property may repres...