318 research outputs found
Recommended from our members
All-optical suppression of relativistic self-focusing of laser beams in plasmas
It is demonstrated that a catastrophic relativistic self-focusing (RSF) of a high-power laser pulse can be prevented all-optically by a second, much weaker, copropagating pulse. RSF suppression occurs when the difference frequency of the pulses slightly exceeds the electron plasma frequency. The mutual defocusing is caused by the three-dimensional electron density perturbation driven by the laser beat wave slightly above the plasma resonance. A bienvelope model describing the early stage of the mutual defocusing is derived and analyzed. Later stages, characterized by the presence of a strong electromagnetic cascade, are investigated numerically. Stable propagation of the laser pulse with weakly varying spot size and peak amplitude over several Rayleigh lengths is predicted.U.S. Department of Energy DE-FG02-04ER54763 DE-FG02-04ER41321 DE-FG02-07ER54945NSF PHY-0114336Physic
Complicated Scenarios of Transitions to Deterministic Chaos in Non-Ideal Dynamic Systems
Some of non-ideal dynamic systems are considered. It is discovered and described the complicated transition
scenarios from regular to chaotic regimes and transitions between different types of chaotic regimes.
Described the transition to chaos, which begins by the Feigenbaum scenario, and ends by intermittency. Also
discusses the scenario of intermittency with several laminar phases and one turbulent phase. It is discovered
and described transitions "hyperchaotic attractor of one type – hyperchaotic attractor of another type," which
are realized according to the scenario of a generalized intermittency, but only with two rough-laminar phases
Stimulated Raman backscattering of laser radiation in deep plasma channels
Stimulated Raman backscattering (RBS) of intense laser radiation confined by
a single-mode plasma channel with a radial variation of plasma frequency
greater than a homogeneous-plasma RBS bandwidth is characterized by a strong
transverse localization of resonantly-driven electron plasma waves (EPW). The
EPW localization reduces the peak growth rate of RBS and increases the
amplification bandwidth. The continuum of non-bound modes of backscattered
radiation shrinks the transverse field profile in a channel and increases the
RBS growth rate. Solution of the initial-value problem shows that an
electromagnetic pulse amplified by the RBS in the single-mode deep plasma
channel has a group velocity higher than in the case of homogeneous-plasma
Raman amplification. Implications to the design of an RBS pulse compressor in a
plasma channel are discussed.Comment: 11 pages, 3 figures; submitted to Physics of Plasma
- …