The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Avraham Gover - One of the best experts on this subject based on the ideXlab platform.
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effects of azimuthal and radial spreads of Canonical Momentum on electron beam focusing characteristics in the presence of space charge forces
Journal of Applied Physics, 1995Co-Authors: Moshe Cohen, Avraham GoverAbstract:A theoretical and numerical investigation of the effects of azimuthal and radial spreads of Canonical Momentum on an electron beam focused by a magnetic lens in the presence of space‐charge forces is presented. The particles are inserted with an initial Gaussian distribution in the transverse space and in the Momentum coordinates or with a uniform initial current distribution. The particle trajectory equation is derived for parameters of an arbitrary applied fields configuration with cylindrical symmetry, and a nonvanishing initial Canonical Momentum. In the absence of an initial Momentum spread particles launched above a critical radial distance from the axis exhibit a phase‐space tearing effect in the electron distribution. The inclusion of initial Canonical Momentum spread in the model allows for skewed trajectories with strong centrifugal force which prevents the appearance and overshadows the effect of strong space‐charge forces near the axis, which are responsible for the phase‐space tearing effect.
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Effects of azimuthal and radial spreads of Canonical Momentum on electron‐beam focusing characteristics in the presence of space‐charge forces
Journal of Applied Physics, 1995Co-Authors: Moshe Cohen, Avraham GoverAbstract:A theoretical and numerical investigation of the effects of azimuthal and radial spreads of Canonical Momentum on an electron beam focused by a magnetic lens in the presence of space‐charge forces is presented. The particles are inserted with an initial Gaussian distribution in the transverse space and in the Momentum coordinates or with a uniform initial current distribution. The particle trajectory equation is derived for parameters of an arbitrary applied fields configuration with cylindrical symmetry, and a nonvanishing initial Canonical Momentum. In the absence of an initial Momentum spread particles launched above a critical radial distance from the axis exhibit a phase‐space tearing effect in the electron distribution. The inclusion of initial Canonical Momentum spread in the model allows for skewed trajectories with strong centrifugal force which prevents the appearance and overshadows the effect of strong space‐charge forces near the axis, which are responsible for the phase‐space tearing effect.
Alain J. Brizard - One of the best experts on this subject based on the ideXlab platform.
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Momentum conservation in dissipationless reduced-fluid dynamics
arXiv: Plasma Physics, 2010Co-Authors: Alain J. BrizardAbstract:The Momentum conservation law for general dissipationless reduced-fluid (e.g., gyrofluid) models is derived by Noether method from a variational principle. The reduced-fluid Momentum density and the reduced-fluid Canonical Momentum-stress tensor both exhibit polarization and magnetization effects as well as an internal torque associated with dynamical reduction. As an application, we derive an explicit gyrofluid toroidal angular-Momentum conservation law for axisymmetric toroidal magnetized plasmas.
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Noether derivation of exact conservation laws for dissipationless reduced-fluid models
Physics of Plasmas, 2010Co-Authors: Alain J. BrizardAbstract:The energy-Momentum conservation laws for general reduced-fluid (e.g., gyrofluid) models are derived by Noether method from a general reduced variational principle. The reduced Canonical energy-Momentum tensor (which is explicitly asymmetric and has the Minkowski form) exhibits polarization and magnetization effects associated with dynamical reduction. In particular, the asymmetry in the reduced Canonical Momentum-stress tensor produces a nonvanishing reduced intrinsic torque that can drive spontaneous toroidal rotation in axisymmetric tokamak plasmas.
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A new Lagrangian formulation for laser-plasma interactions
Physics of Plasmas, 1998Co-Authors: Alain J. BrizardAbstract:A new Lagrangian structure for cold relativistic plasma electrodynamics is presented. This new formulation uses the fluid velocity v instead of the Canonical-Momentum Clebsch potential ψ [X. L. Chen and R. N. Sudan, Phys. Fluids B 5, 1336 (1993)]. As a simple application, it is used to derive (through the Noether method) new exact conservation laws associated with nonlinear laser wake-field equations in the multi-dimensional quasi-static approximation.
Moshe Cohen - One of the best experts on this subject based on the ideXlab platform.
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effects of azimuthal and radial spreads of Canonical Momentum on electron beam focusing characteristics in the presence of space charge forces
Journal of Applied Physics, 1995Co-Authors: Moshe Cohen, Avraham GoverAbstract:A theoretical and numerical investigation of the effects of azimuthal and radial spreads of Canonical Momentum on an electron beam focused by a magnetic lens in the presence of space‐charge forces is presented. The particles are inserted with an initial Gaussian distribution in the transverse space and in the Momentum coordinates or with a uniform initial current distribution. The particle trajectory equation is derived for parameters of an arbitrary applied fields configuration with cylindrical symmetry, and a nonvanishing initial Canonical Momentum. In the absence of an initial Momentum spread particles launched above a critical radial distance from the axis exhibit a phase‐space tearing effect in the electron distribution. The inclusion of initial Canonical Momentum spread in the model allows for skewed trajectories with strong centrifugal force which prevents the appearance and overshadows the effect of strong space‐charge forces near the axis, which are responsible for the phase‐space tearing effect.
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Effects of azimuthal and radial spreads of Canonical Momentum on electron‐beam focusing characteristics in the presence of space‐charge forces
Journal of Applied Physics, 1995Co-Authors: Moshe Cohen, Avraham GoverAbstract:A theoretical and numerical investigation of the effects of azimuthal and radial spreads of Canonical Momentum on an electron beam focused by a magnetic lens in the presence of space‐charge forces is presented. The particles are inserted with an initial Gaussian distribution in the transverse space and in the Momentum coordinates or with a uniform initial current distribution. The particle trajectory equation is derived for parameters of an arbitrary applied fields configuration with cylindrical symmetry, and a nonvanishing initial Canonical Momentum. In the absence of an initial Momentum spread particles launched above a critical radial distance from the axis exhibit a phase‐space tearing effect in the electron distribution. The inclusion of initial Canonical Momentum spread in the model allows for skewed trajectories with strong centrifugal force which prevents the appearance and overshadows the effect of strong space‐charge forces near the axis, which are responsible for the phase‐space tearing effect.
Franco Nori - One of the best experts on this subject based on the ideXlab platform.
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Acoustic Radiation Force and Torque on Small Particles as Measures of the Canonical Momentum and Spin Densities.
Physical review letters, 2019Co-Authors: Ivan Toftul, Konstantin Y. Bliokh, Mihail I. Petrov, Franco NoriAbstract:We examine acoustic radiation force and torque on a small (subwavelength) absorbing isotropic particle immersed in a monochromatic (but generally inhomogeneous) sound-wave field. We show that by introducing the monopole and dipole polarizabilities of the particle, the problem can be treated in a way similar to the well-studied optical forces and torques on dipole Rayleigh particles. We derive simple analytical expressions for the acoustic force (including both the gradient and scattering forces) and torque. Importantly, these expressions reveal intimate relations to the fundamental field properties introduced recently for acoustic fields: the Canonical Momentum and spin angular Momentum densities. We compare our analytical results with previous calculations and exact numerical simulations. We also consider an important example of a particle in an evanescent acoustic wave, which exhibits the mutually orthogonal scattering (radiation-pressure) force, gradient force, and torque from the transverse spin of the field.
Shun-qing Shen - One of the best experts on this subject based on the ideXlab platform.
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Comment on "Nonexistence of "Spin Transverse Force" for a Relativistic Electron" by Wlodek Zawadzki (cond-mat/0701387)
Physical Review Letters, 2007Co-Authors: Shun-qing ShenAbstract:This is a reply to W. Zawadzki's paper (arXiv: cond-mat/0701378) on non-exietence of spin transverse force for a relativistic electron. The force was first proposed by the present author that the spin current will experience a transverse force in an electric field as a relativistic quantum mechanical effect, and in semiconductor with Rahsba spin-orbit coupling. Zawadzki's approach is based on an incorrect relation between the velocity and Canonical Momentum, and his conclusion is not true.