Physics of collective attraction of negatively charged dust particles

Цытович, В. Н.

doi:10.1134/1.1664000

Cited by 22 publications

(50 citation statements)

References 15 publications

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“…A minimum in the screening potential is also known from non-relativistic, complex plasmas, where an attractive potential even between equal charges can be found if the finite extension of the charges is considered [25]. A similar screening potential was found for a color charge at rest in Ref.…”

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confidence: 70%

Screening of a moving parton in the quark-gluon plasma

2005

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The screening potential of a parton moving through a quark-gluon plasma is calculated using the semi-classical transport theory. An anisotropic potential showing a minimum in the direction of the parton velocity is found. As consequences possible new bound states in the quark-gluon plasma and J/ψ dissociation are discussed.Screening of charges in a plasma is one of the most important collective effects in plasma physics. In the classical limit in an isotropic and homogeneous plasma the screening potential of a point-like test charge Q at rest can be derived from the linearized Poisson equation, resulting in Debye screening. In this way the Coulomb potential of a charge in the plasma is modified into a Debye-Hückel or Yukawa potential [1]with the Debye mass (inverse screening length) m D (h = c = k B = 1). A special kind of plasma is the so-called quark-gluon plasma (QGP), where the electric charges in a plasma are replaced by the color charges of quarks and gluons, mediating the strong interactions between them. Such a state of matter is expected to exist at extreme temperatures, above 150 MeV, or densities, above about 10 times nuclear density. These conditions could be fulfilled in the early Universe for the first few microseconds or in the interior of neutron stars. In accelerator experiments high-energy nucleus-nucleus collisions are used to search for the QGP. In these collisions a hot and dense fireball is created which might consist of a QGP in an early stage (less than about 10 fm/c) [2]. Since the masses of the lightest quarks and of the actually massless gluons are much less than the temperature of the system, the QGP is an ultrarelativistic plasma. To achieve a theoretical understanding of the QGP, methods from quantum field theory (QCD) at finite temperature are adopted [3]. Perturbative QCD should work at high temperatures far above the phase transition where the interaction between the quarks and gluons becomes weak due to a specific property of QCD called asymptotic freedom. An important quantity which can be derived in this way is the polarization tensor describing the behavior of interacting gluons in the QGP. From the polarization tensor important properties of the QGP, such as the dispersion relation and damping of the plasma modes or the Debye screening of color charges in the QGP can be derived [4].In the QGP the Debye mass of a chromoelectric charge follows from the static limit of the longitudinal polarization tensor in the high-temperature limit [4],where g is the strong coupling constant and n f the number of light quark flavors in the QGP with m q ≪ T . The high-temperature limit of the polarization tensor corresponds to the classical approximation. For instance, it is closely related to the dielectric function following from the semi-classical Vlasov equation describing a collisionless plasma. E.g., the longitudinal dielectric function following from the Vlasov equation is given by [5][6][7] (The only non-classical inputs here are Fermi and Bose distributions instead of the Boltzmann d...

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confidence: 70%

Screening of a moving parton in the quark-gluon plasma

2005

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“…The absorption flux in these conditions is collective (created and absorbed by many grains simultaneously) and therefore the attraction has a collective nature. This effect was considered first in [7,8] for β 1 and the aim of the present consideration is to generalize these results for β 1. The major physics for β 1 is the same as in [7,8] and is related to substantial change of the polarization charge close to the grains by presence of absorption flux.…”

Section: Major Physics Of Collective Effectsmentioning

confidence: 96%

“…This effect was considered first in [7,8] for β 1 and the aim of the present consideration is to generalize these results for β 1. The major physics for β 1 is the same as in [7,8] and is related to substantial change of the polarization charge close to the grains by presence of absorption flux. The consideration of polarization should include in this case two vector field, the electrostatic field E described by the electrostatic potential φ and by the plasma flux field Φ described by its potential.…”

Section: Major Physics Of Collective Effectsmentioning

confidence: 96%

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Collective Grain Interaction I. New Paradigm for Plasma Crystal Formation

Цытович

2005

Contrib. Plasma Phys.

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The concept of collective grain interaction in complex plasmas is developed for large non-linearity in grain screening. It is shown that for the case where the characteristic collective radius exceeds the non-linear screening radius the collective interactions can fully determine the non-linear collective attraction well. Based on the physics of collective non-linear grain attraction a new paradigm for plasma crystal formation is formulated according to which the plasma crystal formation is related with localization of grains in non-linear collective attraction wells. Nonlinearity in screening is an important feature of new paradigm and takes into account that the grain charges are large in accordance with most experiments where the plasma crystals where observed. The physical consequence of large non-linearity is the presence of relative large potential well at distances only several times larger then the non-linear screening radius. The calculated location of the potential well is of the order of the observed inter-grain distances in plasma crystals and the deepness of the potential well is close to observed temperature of phase transition. The new paradigm considers formation of plasma crystal as result of grain trapping in the collective non-linear potential well. The grain interactions close to the position of the potential well are in this paradigm relatively weak contrary to previous paradigm relating the plasma crystal formation with strong grain interactions. This new approach opens the possibility for direct calculation of the deepness of the attraction collective well, the critical value of the coupling constant. Results of these calculations show a reasonable agreement with both the observations of crystals in low pressure high-frequency discharges and in large pressure discharges.

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“…The collective attraction of grains in plasmas was previously considered in [1][2][3][4] for the ionization source proportional to the electron density using the linear perturbation approach. This case is often met in High Frequency (HF) discharges used in experiments in dusty complex plasmas [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%