Orbital-motion-limited theory of dust charging and plasma response

Tang, Xian-Zhu; Delzanno, Gian Luca

doi:10.1063/1.4904404

Cited by 54 publications

(45 citation statements)

References 24 publications

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“…15 and explained in more details in Ref. 16. For clarity, we repeat this equation in the present work.…”

Section: Nonlinear Screening Theorymentioning

confidence: 97%

“…(16) and the screening factor (19) as a new approximate expression for the solution of the Poisson equation (1) with the boundary conditions (5).…”

Section: A Preliminary Considerationsmentioning

confidence: 99%

“…15,16 Since the nonlinear Poisson equation can be solved only numerically, approximate expressions are usually applied to predict the potential distribution with certain accuracy. The common approach in this case is to use an analytical solution of the linearized Poisson equation.…”

mentioning

confidence: 99%

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Approximate expression for the electric potential around an absorbing particle in isotropic collisionless plasma

2015

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A new approximate expression for the potential distribution around an absorbing particle in isotropic collisionless plasma is proposed. The approximate expression is given by the sum of the Debye-H€ uckel potential with an effective screening length and the far-field asymptote obtained from the solution of the linearized Poisson equation. In contrast to analogous models, the effective screening length is not fixed but depends on the distance from the particle. This allows us to obtain a more accurate approximation for the potential distribution in the entire range of distances. The dependence of the screening length on the distance is predicted from the analysis of the charge density distribution function. This dependence contains two adjustable parameters, which are calculated by applying the procedure based on charge balance considerations. Using the obtained results, simple expressions for the parameters of the model are proposed. In addition, a simple expression for the characteristic screening length, which can be used to approximate the potential distribution near the particle, is obtained. The developed model potential is shown to be in excellent agreement with the solution of the nonlinear Poisson equation for typical conditions used in experiments with complex plasmas. V C 2015 AIP Publishing LLC.

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“…15 and explained in more details in Ref. 16. For clarity, we repeat this equation in the present work.…”

Section: Nonlinear Screening Theorymentioning

confidence: 97%

“…(16) and the screening factor (19) as a new approximate expression for the solution of the Poisson equation (1) with the boundary conditions (5).…”

Section: A Preliminary Considerationsmentioning

confidence: 99%

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Approximate expression for the electric potential around an absorbing particle in isotropic collisionless plasma

2015

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“…wherev d is the ion drift velocity,  i = m i ∕m ev 2 d ∕2 is the ion kinetic energy related tov d and sc = (r 1 ) = (r qn ) is the spacecraft potential. For electrons, we assume a Maxwellian distribution at the quasi-neutral 10.1029/2017JA024926 surface and we apply the kinetic theory derived by Delzanno and Tang (2016) in the OML approximation (see also Tang & Delzanno, 2014)…”

Section: Equation For the Spacecraft Potentialmentioning

confidence: 99%

Spacecraft‐Charging Mitigation of a High‐Power Electron Beam Emitted by a Magnetospheric Spacecraft: Simple Theoretical Model for the Transient of the Spacecraft Potential

et al. 2018

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A spacecraft‐charging mitigation scheme necessary for the operation of a high‐power electron beam in the low‐density magnetosphere is analyzed. The scheme is based on a plasma contactor, that is, a high‐density charge‐neutral plasma emitted prior to and during beam emission and its ability to emit high ion currents without strong space‐charge limitations. A simple theoretical model for the transient of the spacecraft potential and contactor expansion during beam emission is presented. The model focuses on the contactor ion dynamics and is valid in the limit when the ion contactor current is equal to the beam current. The model is found in very good agreement with particle‐in‐cell simulations over a large parametric study that varies the initial expansion time of the contactor, the contactor current, and the ion mass. The model highlights the physics of the spacecraft‐charging mitigation scheme, indicating that the most important part of the dynamics is the evolution of the outermost ion front, which is pushed away by the charge accumulated in the system by the beam. The model can be also used to estimate the long‐time evolution of the spacecraft potential. For a short contactor expansion (0.3‐ or 0.6‐ms helium plasma or 0.8‐ms argon plasma, both with 1‐mA current) it yields a peak spacecraft potential of the order of 1–3 kV. This implies that a 1‐mA relativistic electron beam would be easily emitted by the spacecraft.

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“…It takes into account the collisional ion drag which depends on the plasma jet speed, the plasma density and the dust radius and mass. Since the dust particles are much larger than the plasma screening length (r d D l  ) the orbital ion drag force which arises from the long range Coulomb interactions of ions with a charged dust particle is neglected [42]. In fact 1 m D l m < and r 5 m d  m for 99% of the dust inventory, as shown in table 1.…”

Section: Plasma Diagnosticsmentioning

confidence: 99%

A pulsed ‘plasma broom’ for dusting off surfaces on Mars

2017

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Dust is a challenge for the design and operation of equipment on the Martian surface, particularly for solar cells. An efficient and robust technique for removing dust and sand from surfaces immersed in CO 2 at low pressure is presented. The working principle is based on a pulsed plasma jet produced between two coaxial electrodes biased at voltages between 1 and 2 kV. A demonstration is presented using dust particles whose chemical composition mimic the Mars soil. An array of connected photovoltaic cells fully covered with dust and sand is exposed to the plasma jet. The cells open circuit voltage is monitored in real-time thus providing the means to measure the dust removal efficiency. A good cleaning efficiency is attained after a few shots in a geometry where the plasma jet is directed perpendicularly to the dusty surface. The main advantage of this approach lies in the opportunity to apply it directly at about 5 Torr, the pressure of the Martian environment. A numerical evaluation shows that the plasma drag force on a dust particle is orders of magnitude higher than its weight depending on plasma density and flow speed, hence validating the principles of this cleaning technique.

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Orbital-motion-limited theory of dust charging and plasma response

Cited by 54 publications

References 24 publications

Approximate expression for the electric potential around an absorbing particle in isotropic collisionless plasma

Approximate expression for the electric potential around an absorbing particle in isotropic collisionless plasma

Spacecraft‐Charging Mitigation of a High‐Power Electron Beam Emitted by a Magnetospheric Spacecraft: Simple Theoretical Model for the Transient of the Spacecraft Potential

A pulsed ‘plasma broom’ for dusting off surfaces on Mars

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