53 research outputs found
Dispersion and damping of potential surface waves in a degenerate plasma
Potential (electrostatic) surface waves in plasma half-space with degenerate
electrons are studied using the quasi-classical mean-field kinetic model. The
wave spectrum and the collisionless damping rate are obtained numerically for a
wide range of wavelengths. In the limit of long wavelengths, the wave frequency
approaches the cold-plasma limit with
being the plasma frequency, while at short wavelengths, the wave
spectrum asymptotically approaches the spectrum of zero-sound mode propagating
along the boundary. It is shown that the surface waves in this system remain
weakly damped at all wavelengths (in contrast to strongly damped surface waves
in Maxwellian electron plasmas), and the damping rate nonmonotonically depends
on the wavelength, with the maximum (yet small) damping occuring for surface
waves with wavelength of , where is the
Thomas-Fermi length.Comment: 22 pages, 6 figure
QED cascades induced by circularly polarized laser fields
The results of Monte-Carlo simulations of electron-positron-photon cascades
initiated by slow electrons in circularly polarized fields of ultra-high
strength are presented and discussed. Our results confirm previous qualitative
estimations [A.M. Fedotov, et al., PRL 105, 080402 (2010)] of the formation of
cascades. This sort of cascades has revealed the new property of the
restoration of energy and dynamical quantum parameter due to the acceleration
of electrons and positrons by the field and may become a dominating feature of
laser-matter interactions at ultra-high intensities. Our approach incorporates
radiation friction acting on individual electrons and positrons.Comment: 13 pages, 10 figure
Survival law in a potential model
The radial equation of a simple potential model has long been known to yield
an exponential decay law in lowest order (Breit-Wigner) approximation. We
demonstrate that if the calculation is extended to fourth order the decay law
exhibits the quantum Zeno effect. This model has further been studied
numerically to characterize the extra exponential time parameter which
compliments the lifetime. We also investigate the inverse Zeno effect.Comment: 16 pages, 2 tables, 3 figures, AMS-Te
A new class of coherent states with Meixner-Pollaczek polynomials for the Gol'dman-Krivchenkov Hamiltonian
A class of generalized coherent states with a new type of the identity
resolution are constructed by replacing the labeling parameter zn/n! of the
canonical coherent states by Meixner-Pollaczek polynomials with specific
parameters. The constructed coherent states belong to the state Hilbert space
of the Gol'dman-Krivchenkov Hamiltonian.Comment: 10 pages, Submitte
Modulational Instability in Nonlinearity-Managed Optical Media
We investigate analytically, numerically, and experimentally the modulational
instability in a layered, cubically-nonlinear (Kerr) optical medium that
consists of alternating layers of glass and air. We model this setting using a
nonlinear Schr\"odinger (NLS) equation with a piecewise constant nonlinearity
coefficient and conduct a theoretical analysis of its linear stability,
obtaining a Kronig-Penney equation whose forbidden bands correspond to the
modulationally unstable regimes. We find very good {\it quantitative} agreement
between the theoretical analysis of the Kronig-Penney equation, numerical
simulations of the NLS equation, and the experimental results for the
modulational instability. Because of the periodicity in the evolution variable
arising from the layered medium, we find multiple instability regions rather
than just the one that would occur in uniform media.Comment: 13 pages, 12 figures (several with multiple parts); some important
changes from the page proof stage implemented in this preprint versio
Bremsstrahlung Suppression due to the LPM and Dielectric Effects in a Variety of Materials
The cross section for bremsstrahlung from highly relativistic particles is
suppressed due to interference caused by multiple scattering in dense media,
and due to photon interactions with the electrons in all materials. We present
here a detailed study of bremsstrahlung production of 200 keV to 500 MeV
photons from 8 and 25 GeV electrons traversing a variety of target materials.
For most targets, we observe the expected suppressions to a good accuracy. We
observe that finite thickness effects are important for thin targets.Comment: 52 pages, 13 figures (incorporated in the revtex LaTeX file
The theory of the Landau, Pomeranchuk, Migdal effect
Bremsstrahlung of photons from highly relativistic electrons is investigated.
The cross section of the processes, which is suppressed due to a multiple
scattering of an emitting electron in dense media (LPM effect) and due to
photon interaction with electrons of a medium, is calculated with an accuracy
up to "next to leading logarithm" and with the Coulomb corrections taken into
account. Making allowances for a multiple scattering and a polarization of a
medium an analysis of radiation on a target boundary is carried out. The method
of consideration of radiation in a thin target under influence of the LPM
effect is developed. Interrelation with the recent experiment is discussed.Comment: 36 pages, LaTeX, 3 eps figure
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