Shielding of a slowly moving test charge in a dusty plasma with dynamical grain charging

Raadu, Michael A.; Shafiq, Muhammad

doi:10.1063/1.1598433

Cited by 9 publications

(7 citation statements)

References 36 publications

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“…If T c <τ in we can argue that the dust charge is at all times derived from local equilibrium conditions in the plasma, while in the opposite case, T c >τ in , there is a "memory" in the system, and the actual charged state of the dust will depend on the preceeding motion through the plasma. Assuming that the dust is moving in a stationary electrostatic field, the forces on a dust grain are generally not conservative when the charged state of a dust grain depends on its path (Raadu and Shafiq, 2003;Shafiq and Raadu, 2004;Zhdanov et al, 2005).…”

Section: Figmentioning

confidence: 99%

Numerical simulations of the charging of dust particles by contact with hot plasmas

Miloch

Pécseli

Trulsen

2007

Nonlin. Processes Geophys.

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Abstract.Charging of individual dust particles in contact with hot plasmas is studied by numerical methods. The dust particle is treated as a rigid solid body, composed by either perfectly insulating or conducting material. The collisionless plasma, consisting of electrons and singly charged ions, is simulated by Particle-in-Cell methods in two spatial dimensions. It is demonstrated that the surface conditions, i.e. roughness, of the dust particles are significant for the charging. In a streaming plasma, a dust grain develops an electric dipole moment which varies systematically with the relative plasma flow. The strength and direction of this dipole moment depends critically on the material. We observe also Langmuir oscillations excited in the vicinity of the particles, and analyze the spatial variation of their spectral distribution.

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Section: Figmentioning

confidence: 99%

Numerical simulations of the charging of dust particles by contact with hot plasmas

Miloch

Pécseli

Trulsen

2007

Nonlin. Processes Geophys.

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“…͑42͒ may be shown to reduce to the known results 8,9 for a monosized distribution with a charge relaxation time 0 . ͑43͒-͑45͒ the combination of terms ␣ De / ␦ u0 pi is equal to 1 / 0 ͑␣ −1 ͒ ͓from Eq.…”

Section: ͑49͒mentioning

confidence: 77%

“…[2][3][4][5] The inclusion of a dust component in normal electron-ion plasmas has led to a renewed interest in the test charge response problem. 8,9 The delayed shielding effect due to dynamical charging has also been reported. An important consequence of the potential excited by a moving charge is the energy loss and braking of the velocity due to the resultant electric field at the moving charge.…”

Section: Introductionmentioning

confidence: 92%

“…These may be written 9 as Here ⍀ u0 ϵ 0 ͑a͒ is the grain charge relaxation rate so that 0 ϵ 1/ 0 is the time scale for the grain charge to come into equilibrium with the undisturbed plasma.…”

Section: B Charging Dynamicsmentioning

confidence: 99%

“…9 For the class of size distributions used here, we may write Eq. This generalizes previous results for a single-sized distribution with a unique grain size.…”

Section: ͑22͒mentioning

confidence: 99%

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Test charge response for a dusty plasma with both grain size distribution and dynamical charging

Raadu

Shafiq

2007

Physics of Plasmas

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The form of the grain size distribution strongly influences the linear dielectric response of a dusty plasma. For a class of size distributions and a thermal velocity distribution, there is an equivalence to a Lorentzian distribution of monosized particles. The electrostatic response to a slowly moving test charge can then be found. Dynamical charging of grains in a dusty plasma leads to an enhanced time-dependent shielding of a test charge. Here the combined effect of both grain size distribution and dynamical grain charging on the response to a slowly moving test charge is analyzed. The dynamical charging contribution to the plasma dielectric has a complicated dependence on the parameters for the size distribution and on the charging rate. However, this dependence can be expressed in terms of known functions. Series expansions are used to derive the potential response to a slowly moving test charge. Previously known results may be recovered as special limiting cases of this investigation. The analytical expression for the plasma dielectric may be used for more general cases and is applicable to the study of electrostatic waves.

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Effect of grain charging dynamics on the wake potential of a moving test charge in a dusty plasma

Shafiq

Raadu

2007

Physics of Plasmas

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The response potential of a dusty (complex) plasma to a moving test charge strongly depends on its velocity. For a test charge moving with a velocity exceeding the dust-acoustic speed, a distinctive wake-field is produced trailing behind the test charge. Here the response to a fast moving test charge, when dispersion effects are small and the dust behaves as a cold plasma component, is considered. The effects of dynamical grain charging are included, and the cases with and without these effects are analyzed and compared. The plasma dielectric function is chosen assuming that all grains are of the same size and includes a response term for charging dynamics. The wake field potential is found either explicitly in terms of known functions or by using numerical methods for the integral expression. Maximum response is found on the wake cone with apex angle determined by the ratio between the dust acoustic velocity and the test charge velocity. The structure of the wake field stretches in the direction of the test charge velocity when this increases. The functional form of the field is given by separately changing the length scales parallel and perpendicular to the velocity. The potential on the axis gives an electric field close behind the test charge that can attract charges with the same sign. The grain charging dynamics leads to a spatial damping and a phase shift in the potential response.

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Shielding of a slowly moving test charge in a dusty plasma with dynamical grain charging

Cited by 9 publications

References 36 publications

Numerical simulations of the charging of dust particles by contact with hot plasmas

Numerical simulations of the charging of dust particles by contact with hot plasmas

Test charge response for a dusty plasma with both grain size distribution and dynamical charging

Effect of grain charging dynamics on the wake potential of a moving test charge in a dusty plasma

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