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M. Lazar

Publications and source records attributed to M. Lazar.

62 records · Page 4Linked to original sources
arXiv2007

Fast magnetization in counterstreaming plasmas with temperature anisotropies

Counterstreaming plasmas exhibits an electromagnetic unstable mode of filamentation type, which is responsible for the magnetization of plasma system. It is shown that filamentation instability becomes significantly faster when plasma is hotter in the streaming direction. This is relevant for astrophysical sources, where strong magnetic fields are expected to exist and explain the nothermal emission observed.

physics.plasm-ph↗
arXiv2007

Surface waves on a quantum plasma half-space

Surface modes are coupled electromagnetic/electrostatic excitations of free electrons near the vacuum-plasma interface and can be excited on a sufficiently dense plasma half-space. They propagate along the surface plane and decay in either sides of the boundary. In such dense plasma models, which are of interest in electronic signal transmission or in some astrophysical applications, the dynamics of the electrons is certainly affected by the quantum effects. Thus, the dispersion relation for the surface wave on a quantum electron plasma half-space is derived by employing the quantum hydrodynamical (QHD) and Maxwell-Poison equations. The QHD include quantum forces involving the Fermi electron temperature and the quantum Bohm potential. It is found that, at room temperature, the quantum effects are mainly relevant for the electrostatic surface plasma waves in a dense gold metallic plasma.

physics.plasm-ph↗
arXiv2007

Collapse of the N=28 shell closure in $^{42}$Si

The energies of the excited states in very neutron-rich $^{42}$Si and $^{41,43}$P have been measured using in-beam $γ$-ray spectroscopy from the fragmentation of secondary beams of $^{42,44}$S at 39 A.MeV. The low 2$^+$ energy of $^{42}$Si, 770(19) keV, together with the level schemes of $^{41,43}$P provide evidence for the disappearance of the Z=14 and N=28 spherical shell closures, which is ascribed mainly to the action of proton-neutron tensor forces. New shell model calculations indicate that $^{42}$Si is best described as a well deformed oblate rotor.

nucl-ex↗
arXiv2005

Covariant kinetic theory of nonlinear plasma waves interaction

A rigorous and most general covariant kinetic formalism is developed to study the nonlinear waves interaction in relativistic Vlasov plasmas. The typical nonlinear plasma reaction is a nonlinear current measured by the nonlinear plasma conductivity, and these quantities are derived here on the basis of relativistic Vlasov-Maxwell equations. Knowing the nonlinear plasma conductivity allows us to determine all plasma modes nonlinearly excited in plasma. The general covariant form of nonlinear conductivity is provided first for any value of plasma temperature and for the whole complex frequency plane by a correct analytical continuation. The further analysis is restricted to a correct relativistic particle distribution which is vanishing for particle speeds greater than speed of light. In the limit of nonrelativistic plasma temperatures the covariant nonlinear conductivity is significantly different from the standard noncovariant nonrelativistic results which are reached only in the formal limit of an infinitely large speed of light $c \to \infty$.

physics.plasm-ph↗
arXiv2005

On Dislocations in a Special Class of Generalized Elasticity

In this paper we consider and compare special classes of static theories of gradient elasticity, nonlocal elasticity, gradient micropolar elasticity and nonlocal micropolar elasticity with only one gradient coefficient. Equilibrium equations are discussed. The relationship between the gradient theory and the nonlocal theory is discussed for elasticity as well as for micropolar elasticity. Nonsingular solutions for the elastic fields of screw and edge dislocations are given. Both the elastic deformation (distortion, strain, bend-twist) and the force and couple stress tensors do not possess any singularity unlike `classical' theories.

cond-mat.mtrl-sci↗
arXiv1999

Decomposition of nonlocal light-cone operators into harmonic operators of definite twist

Bilocal light-ray operators which are Lorentz scalars, vectors or antisymmetric tensors, and which appear in various hard scattering QCD processes, are decomposed into operators of definite twist. These operators are harmonic tensor functions and their Taylor expansion consists of (traceless) local light-cone operators with span irreducible representations of the Lorentz group with definite spin j and common geometric twist (= dimension - spin). Some applications concerning the nonforward matrix elements of these operators and the generalization fo conformal light-cone operators of definite twist is considered. The group theoretical background of the method has been made clear.

hep-th↗