Multibody-plasma interactions - Charging in the wake

Wang, J.; Leung, P.; Murphy, G. B.; Ruff, Bernhard

doi:10.2514/6.1993-564

Cited by 6 publications

(11 citation statements)

References 2 publications

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“…(4), VPS-7V (5), TR-SO-11 (6), stainless steel (7), and quartz (8); points 9 are the results calculated in [4] for W eh = 5 keV.…”

Section: High-voltage Charging Of the Leeward Surfaces Of A Solid By mentioning

confidence: 99%

“…The distribution of ions of group I is determined by the regime of a supersonic flow with −Φ w < 10; ions of group II penetrate into the near wake owing to their acceleration by the electric field of the charge −Φ w 10 transported by high-energy electrons. As was estimated in [4], the flow around a solid with −Φ w < 10 is described by the parameter ξ sh = d sh /R = 0.8Φ −Φ w 10 is ξ sh 1. For an isolated two-sided (metal-dielectric) model (plate or disk), the "thin layer" regime is observed if there are no high-energy electrons (−Φ w < 10).…”

Section: High-voltage Charging Of the Leeward Surfaces Of A Solid By mentioning

confidence: 99%

“…A dielectric coating was applied to one side of the plate made of aluminum (length l = 45 cm, width 2R = 16 cm, and thickness δ ≈ 0.1 cm). An aluminum coating was applied (sprayed) onto the surface of the disk (made of quartz) 15 [4] for Sei ≈ 8, R ds ≈ 40, and −Φw ≈ 0 (5) and 20 (6); points 7-9 are the results measured in [12] in the ionosphere on the Explorer-C (AE-C) artificial satellite for 5.9 Sei 8.04, −Φw ≈ 10, and R ds ≈ 116.3 (7), 135.7 (8), and 162.5 (9); points 10 are the results measured in [13] in the ionosphere on the S3-2 artificial satellite for Sei ≈ 8, R ds 45, and −Φw ≈ 10; points 11 are the results measured in [14] in the wake behind the Space Shuttle for Sei ≈ 3.35 and R ds 2 · 10 3 ; (b) angular distribution of ion density nis(θ) at t = 0.192: points 1 are the results measured in [12] on the Explorer-C (AE-C) artificial satellite for Sei ≈ 7.83, R ds ≈ 73.4, −Φw ≈ 8.8, and ξei = 1.14; points 2 are the results measured in the present work (wake behind a cylinder for Sei ≈ 5.1, R ds ≈ 78, −Φw ≈ 6.7, and ξei = 4); curve 3 is the solution of Eq. (7) with the dependence nis(Φ) from [6] for Sei ≈ 5.1, R ds ≈ 80, and −Φw ≈ 6.7; points 4 are the results of the discrete flow model [11].…”

Section: High-voltage Charging Of the Leeward Surfaces Of A Solid By mentioning

confidence: 99%

“…The current density of high-energy electrons in the polar plasma is j eh = 1-10 nA/cm 2 [1]. The current density of high-energy electrons in the near wake behind the solid remains almost constant [4]. Their energy is substantially greater than the energy of ions and electrons of the "cold" plasma in the ionosphere.…”

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confidence: 98%

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Charge transfer by high-energy electrons onto the leeward surfaces of a solid in a supersonic rarefied plasma flow

Shuvalov

Priimak

Bandel

et al. 2008

J Appl Mech Tech Phys

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Numerical and experimental dependence of equilibrium potentials of the leeward surfaces on the ratio of concentrations of high-energy electrons and positive ions in a supersonic rarefied plasma flow around a solid are obtained.Introduction. Electrodynamic interaction of solids with the polar ionosphere in the Earth's shadow is a superposition of two effects: irradiation by high-energy electrons and the flow of a "cold" rarefied plasma. If the concentration of positive ions near the body surface is N iw 10 4 cm −3 , negative charges up to a voltage of 1 kV are collected on the dielectric [1]. The main role in charging the solid surfaces in the polar ionosphere in the Earth's shadow belongs to hot electrons with energy from 1 to 35 keV (captured in radiation belts and propagating along the lines of magnetic force toward the Earth surface) and positive ions of the "cold" ionospheric plasma. The effects and consequences of high-voltage differential charging are most hazardous for the leeward surfaces of extended and electrodynamically large solids (R/λ ds > 10) and also for small solids in the near wake behind them [R is the characteristic size of the solid; λ ds = kT es /(4πe 2 N es ) is the Debye screening length of the undisturbed plasma, k is the Boltzmann constant, e is the electron charge, T es 0.3 eV is the temperature, and N es is the concentration of electrons in the "cold" plasma].The numerical study of high-voltage charging of the leeward surfaces of a solid in a polar plasma involves the solution of nonlinear integrodifferential Vlasov-Poisson equations for a supersonic flow and current-balance equations on the irradiated surface. The values of the coefficients of interaction between the charged particles and the surface for a particular material are determined experimentally.In the experimental study of high-voltage charging, it is necessary to reproduce the current density distribution in the near wake behind the solid in a supersonic rarefied plasma flow and simultaneous irradiation of the leeward surfaces by high-energy electrons with energy from 1 to 35 keV [1]. The test set designed for such studies has to combine the characteristics of a plasma gas-dynamic tunnel and an electrodynamic facility. The conditions of charging of dielectric solids in a polar plasma can be modeled (simulated) in a closed volume of such a test set. The difficulties of such studies are caused by the necessity of simultaneous implementation of conditions of plasma-gas-dynamic and electrophysical interactions in the solid-plasma system. The accuracy and reliability of the predicted level of charging of the leeward surfaces are determined by the agreement between the calculated values of the solid potentials and the data of ionospheric and test-set measurements.In the near wake behind an electrodynamically large solid, the concentration of positive ions of the "cold" plasma N is is several orders lower than its value N i∞ in the undisturbed plasma with an almost unchanged concentration of high-energy electrons N eh . This fact...

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“…(4), VPS-7V (5), TR-SO-11 (6), stainless steel (7), and quartz (8); points 9 are the results calculated in [4] for W eh = 5 keV.…”

Section: High-voltage Charging Of the Leeward Surfaces Of A Solid By mentioning

confidence: 99%

Section: High-voltage Charging Of the Leeward Surfaces Of A Solid By mentioning

confidence: 99%

Section: High-voltage Charging Of the Leeward Surfaces Of A Solid By mentioning

confidence: 99%

mentioning

confidence: 98%

See 2 more Smart Citations

Charge transfer by high-energy electrons onto the leeward surfaces of a solid in a supersonic rarefied plasma flow

Shuvalov

Priimak

Bandel

et al. 2008

J Appl Mech Tech Phys

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“…In the auroral zones, where there is a significant population of high-energy electrons, charging levels of kilovolts are possible unless mitigated by ion collection. A first-order look at ion collection indicated that charging of the order of 100 V is attainable before significant ion collection occurs [Wang et al, 1993;Mandell et al, 1995;Biasca and Wang, 1995]. The predicted thresholds for ion collection drop dramatically, however, if a small fraction of ions have a small Mach number Mo (Mo = Vo/Cs, where Cs is the ion acoustic speed) and can enter the wake [Mandell et al, 1995].…”

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confidence: 99%

High‐voltage interactions in plasma wakes: Results from the charging hazards and wake studies (CHAWS) flight experiments

Enloe¹,

Cooke²,

Pakula³

et al. 1997

J. Geophys. Res.

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Abstract. Data from the charging hazards and wake studies (CHAWS) flight experiments on board space shuttle missions STS-60 and STS-69, during which a negatively biased, high-voltage (0-5 kV) probe was placed in a plasma wake in low Earth orbit, are presented. For these experiments the source of the wake was the 4-m-diameter Wake Shield Facility (WSF), which was operated both as a free-flying spacecraft and attached to the shuttle orbiter's robot arm. Current collection by the biased probe is investigated as a function of the density and temperature of the ambient plasma and the probe's location in the plasma wake. Current collection behavior is determined by the expansion of the highvoltage sheath into the ambient plasma stream. Consistent with preflight predictions, current collection on the probe is highly nonuniform, varying by more than 5 orders of magnitude across the surface of the probe. The onset of current collection, however, begins at voltages that are an order of magnitude lower than anticipated. This is likely due to the low-energy, turbulent plasma (typically 2-5% of the ambient density and up to 40% on occasion) observed in the ambient environment. This important minority constituent of the plasma was observed in the vicinity of the shuttle Orbiter and observed while the WSF was free-flying.

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The Breakdown of the Fluid Approximation for Electrons in a Plasma Wake

Wang

2018

JGR Space Physics

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A comparative study using a fluid-based analytic solution, hybrid particle-ion fluid-electron particle-in-cell (PIC), and fully kinetic PIC is carried out to examine a collisionless, mesothermal plasma flow over a large, unbiased plate. We find that the plasma wake may be characterized into two regions based on the electron characteristics: a fluid electron expansion region and a kinetic electron expansion region. In the fluid electron expansion region, the electrons may be considered to be an equilibrium fluid and all the three approaches lead to a similar result. In the kinetic electron expansion region, the local electron velocity distributions are strongly non-Maxwellian and the commonly used fluid approximation for electrons breaks down. The results also show that the error of the hybrid PIC simulation strongly correlates with a nonequilibrium parameter based on the weighted deviation of the electron velocity distribution from the equilibrium. Plain Language SummaryThe formation of a plasma wake behind a large moving object is applicable to many problems in space science and engineering, ranging from the ionospheric plasma flow around spacecrafts to the solar wind flow around asteroids. A common approach used in almost all previous studies of plasma wakes is to assume that electrons can be modeled as a fluid, in order to simplify analyses and save on computational time in simulations. While the assumption of fluid electrons has been widely adopted, its validity has never been carefully examined. This paper presents the first study on the validity of the fluid approximation of electrons when applied to a collisionless plasma wake. The results show that these wakes consist of two regions: a fluid electron expansion region and a kinetic electron expansion region. The electrons in the kinetic expansion region are in a nonequilibrium state, and their microscopic characteristics lead to anisotropic and complex macroscopic properties. Thus, the commonly used fluid approximation for electrons breaks down in this region. The conclusions of this study will have an immediate impact on all ongoing studies of space plasma interactions with spacecraft and solar wind interactions with small asteroids. Key Points:• The validity of the commonly used fluid electron model in a collisionless plasma wake is investigated • The plasma wake consists of a fluid electron expansion region and a kinetic electron expansion region • The fluid electron model breaks down in the kinetic expansion region due to nonequilibrium electrons

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Multibody-plasma interactions - Charging in the wake

Cited by 6 publications

References 2 publications

Charge transfer by high-energy electrons onto the leeward surfaces of a solid in a supersonic rarefied plasma flow

Charge transfer by high-energy electrons onto the leeward surfaces of a solid in a supersonic rarefied plasma flow

High‐voltage interactions in plasma wakes: Results from the charging hazards and wake studies (CHAWS) flight experiments

The Breakdown of the Fluid Approximation for Electrons in a Plasma Wake

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