Plasmons carrying orbital angular momentum in quantum plasmas

Khan, S. A.; Ali, S.; Mendonça, J. T.

doi:10.1017/s0022377813000809

Cited by 19 publications

(7 citation statements)

References 43 publications

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“…They showed that quantum mechanical effects as well as LG mode functions significantly alter the spectrum of the waves and their growth rates. In particular, Khan et al examined the impact of electron degenerate pressure on the profiles of twisted plasmons by deriving a paraxial equation in terms of density fluctuations in a strongly degenerate dense plasma. The modified expressions for electrostatic potential, energy flux, and angular momentum density were computed, which were found have significant variations through the radial and angular mode numbers.…”

Section: Introductionmentioning

confidence: 99%

Twisted electrostatic waves in a self‐gravitating dusty plasma

Bukhari

Ali

Rafique

et al. 2017

Contrib. Plasma Phys

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A generalized response (dielectric) function for twisted electrostatic waves is derived for an un-magnetized self-gravitating thermal dusty plasma, whose constituents are the Boltzmann-distributed electrons and positive ions in the presence of negatively charged micrometre-sized massive dust particulates. For this purpose, a set of Vlasov-Poisson coupled equations is solved along with the perturbed Laguerre-Gauss distribution function, as well as the electrostatic and gravitational potentials in the limit of paraxial approximation. For plane wave solution, the wavefronts of the dust-acoustic (DA) wave are assumed to have a constant phase with electric and gravitational field lines propagating straight along the propagation axis. On the other hand, non-planar wave solutions show helical (twisted) wavefronts, in which field lines spiral around the propagation axis owing to the azimuthal velocity component to account for the finite orbital angular momentum (OAM) states. The dispersion relation and damping rate for twisted DA waves are studied both analytically and numerically. It is shown that finite OAM states, the dust to electron temperature ratio, and dust self-gravitation effects significantly affect the linear dispersion and Landau damping frequencies. In particular, the phase speed of twisted DA waves is reduced with the variation of the twist parameter (= k/lq ), dust concentration (= n d0 /n i0 ), and dust self-gravitation (= Jd / pd ). The relevance of our findings to interstellar dust clouds is also discussed for micrometre-sized massive dust grains. KEYWORDS dusty plasma, electrostatic twisted waves, landau damping, orbital angular momentum INTRODUCTIONLight beam exchanges its energy and momentum [1] with matter upon interaction with it. The total angular momentum of the light beam can be composed of spin and orbital parts due to planar and helical wavefronts, respectively. In other words, the spin and orbital angular momenta have their origin from the polarization states and azimuthal phase structure, which are the well-known properties of polarized light beams. Using a specific experimental set-up, Beth [2] was the first to verify Poynting's idea and measure the mechanical torque of circularly polarized light by transferring the angular momentum to a half-wave plate. Later, Allen et al. [3] ) discussed a theoretical model for calculating the average angular momentum density per unit power and studied the well-defined orbital angular momentum (OAM) states due to the Laguerre-Gaussian (LG) light beams. In 2011, Yao and Padgett [4] presented a historical background of the angular momentum to explain various aspects of the OAM states, e.g. the generation of helical beams, the origin and behaviour of OAM, its transformation and possible applications, mode conversion and beam coherence, etc. Recently, several investigations [5][6][7][8][9][10][11][12] have been made with reference to the plasma physics to study the importance of the plasma modes and instabilities with finite OAM, e.g. nonlinear wave couplin...

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Section: Introductionmentioning

confidence: 99%

Twisted electrostatic waves in a self‐gravitating dusty plasma

Bukhari

Ali

Rafique

et al. 2017

Contrib. Plasma Phys

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“…Mendonca et al. also investigated electron plasma waves carrying orbital angular momentum in an unmagnetized collisionless plasma (Mendonca, Ali & Thidé 2009 a ; Mendonca 2012) and quantum plasmas (Khan, Ali & Mendonca 2013). One knows that the electron plasma waves can be described by a paraxial equation (Mendonca et al.…”

Section: Introductionmentioning

confidence: 99%

“…Mendonca et al investigated the exchange of angular momentum between electromagnetic and electrostatic waves in stimulated Raman and Brillouin backscattering processes in plasma (Mendonca, Thidé & Then 2009b) and showed that there is conservation of the angular momentum in the laser-plasma interaction. Mendonca et al also investigated electron plasma waves carrying orbital angular momentum in an unmagnetized collisionless plasma (Mendonca, Ali & Thidé 2009a;Mendonca 2012) and quantum plasmas (Khan, Ali & Mendonca 2013). One knows that the electron plasma waves can be described by a paraxial equation (Mendonca et al 2009a,b), which is like the optical beams being described by the Helmholtz equation in the paraxial approximation.…”

Section: Introductionmentioning

confidence: 99%

Airy-like electron plasma wave

Wang

2016

J. Plasma Phys.

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In this paper, an Airy-like electron plasma wave is investigated in an unmagnetized collisionless plasma consisting of inertial electrons and static ions. Just like the optical Airy beam, the Airy-like electron plasma wave also has two interesting propagation characteristics: it has transverse acceleration and is diffraction-free, which display that the Airy-like electron plasma wave propagates along a curved trajectory and retains the basic structure for longer distances in the propagation direction, respectively. We give a numerical simulation for the electrostatic potential of the Airy-like electron plasma wave and show that, with the increase of the propagation distance, the electrostatic potential decreases in the propagation direction but increases in the transverse direction.

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“…In this way, we used a sectional model to simulate the growth of nanoparticles in a RF acetylene discharge, which self-consistently coupled to a plasma fluid model, including a solution of Poisson's equation for the electric field. In recent years, the quantum hydrodynamics model has received wide attention for the important applications in laser-plasmas, [17] thin metal films, [18] and electrons in metals. [19] However, compared to the quantum hydrodynamics model, the fluid model has the advantages of short time consumption and high precision, which is of important for nanoparticle formation.…”

Section: Theoretical Modelmentioning

confidence: 99%

Simulation of nanoparticle coagulation in radio-frequency capacitively coupled C ₂ H ₂ discharges

Liu

2014

Chinese Phys. B

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A self-consistent fluid model is employed to investigate the coagulation stage of nanoparticle formation, growth, charging, and transport in a radio-frequency capacitively coupled parallel-plate acetylene (C 2 H 2 ) discharge. In our simulation, the distribution of neutral species across the electrode gap is determined by mass continuity, momentum balance, and energy balance equations. Since a thermal gradient in the gas temperature induced by the flow of the neutral gas, a careful study of the thermophoretic force on the spatial distribution of the nanoparticle density profiles is indispensable. In the present paper, we mainly focus on the influences of the gas flow rate, voltage, and gas pressure on the spatial distribution of the nanoparticle density. It appears that the resulting density profile of the 10-nm particles experiences a significant shift towards the upper showerhead electrode once the neutral equations are applied, and a serious shift is observed when increasing the gas flow rate. Thus, the flow of neutral gas can strongly influence the spatial distribution of the particles in the plasma.

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Plasmons carrying orbital angular momentum in quantum plasmas

Cited by 19 publications

References 43 publications

Twisted electrostatic waves in a self‐gravitating dusty plasma

Twisted electrostatic waves in a self‐gravitating dusty plasma

Airy-like electron plasma wave

Simulation of nanoparticle coagulation in radio-frequency capacitively coupled C ₂ H ₂ discharges

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Plasmons carrying orbital angular momentum in quantum plasmas

Cited by 19 publications

References 43 publications

Twisted electrostatic waves in a self‐gravitating dusty plasma

Twisted electrostatic waves in a self‐gravitating dusty plasma

Airy-like electron plasma wave

Simulation of nanoparticle coagulation in radio-frequency capacitively coupled C 2 H 2 discharges

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Simulation of nanoparticle coagulation in radio-frequency capacitively coupled C ₂ H ₂ discharges