Measurements of freely-expanding plasma from hypervelocity impacts

Lee, Nicolas; Close, Sigrid; Lauben, D.; Linscott, I. R.; Goel, Ashish; Johnson, Taylor K.; Yee, Jonathan; Fletcher, Alex; Srama, R.; Bugiel, S.; Mocker, A.; Colestock, P.L.; Green, S.

doi:10.1016/j.ijimpeng.2012.01.002

Cited by 60 publications

(31 citation statements)

References 29 publications

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“…Crater volume measurements also conflict with laboratory measurements of expansion speed of the emitted cloud. Lee et al [] found cloud expansion speeds from 10 to 30 km/s. Ratcliff et al [] found ion energies of 10–40 eV.…”

Section: Impact Physics—laboratory Measurements and Simulationsmentioning

confidence: 99%

Dust impact signals on the wind spacecraft

2016

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We analyze waveforms recorded by the Time Domain Sampler of the WAVES experiment on Wind which are similar to impulsive waveforms observed by the S/WAVES experiment on STEREO. These have been interpreted as dust impacts by Meyer‐Vernet et al. and M. L. Kaiser and K. Goetz and extensively analyzed by Zaslavsky et al. The mechanism for coupling the emission to the antennas to produce an electrical signal is still not well understood, however. One suggested mechanism for coupling of the impact to the antenna is that the spacecraft body changes potential with respect to the surrounding plasma but the antennas do not (the body mechanism). Another class of mechanisms, with several forms, is that the charge of the emitted cloud interacts with the antennas. The Wind data show that both are operating. The time domain shapes of the dust pulses are highly variable but we have little understanding of what provides these shapes. One feature of the STEREO data has been interpreted as impacts from high velocity nanoparticles entrained by the solar wind. We have not found evidence for fast nanodust in the Wind data. An appreciable fraction of the impacts observed on Wind is consistent with interstellar dust. The impact rates do not follow a Poisson distribution, expected for random independent events, and this is interpreted as bunching. We have not succeeded in relating this bunching to known meteor showers, and they do not repeat from 1 year to the next. The data suggest bunching by fields in the heliosphere.

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Section: Impact Physics—laboratory Measurements and Simulationsmentioning

confidence: 99%

Dust impact signals on the wind spacecraft

2016

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“…Lee et al . [, ] in their laboratory experiments showed that impact‐generated ions with different masses were detected by the charge collector at different delay times. Pantellini et al .…”

Section: Rpws Dust Detection Mechanismmentioning

confidence: 99%

Properties of dust particles near Saturn inferred from voltage pulses induced by dust impacts on Cassini spacecraft

Gurnett

Kŭrth

et al. 2014

JGR Space Physics

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The Cassini Radio and Plasma Wave Science (RPWS) instrument can detect dust particles when voltage pulses induced by the dust impacts are observed in the wideband receiver. The size of the voltage pulse is proportional to the mass of the impacting dust particle. For the first time, the dust impacts signals measured by dipole and monopole electric antennas are compared, from which the effective impact area of the spacecraft is estimated to be 4 m 2 . In the monopole mode, the polarity of the dust impact signal is determined by the spacecraft potential and the location of the impact (on the spacecraft body or the antenna), which can be used to statistically infer the charge state of the spacecraft. It is shown that the differential number density of the dust particles near Saturn can be characterized as a power law dn/dr ∝ r μ , where μ~À 4 and r is the particle size. No peak is observed in the size distribution, contrary to the narrow size distribution found by previous studies. The RPWS cumulative dust density is compared with the Cosmic Dust Analyzer High Rate Detector measurement. The differences between the two instruments are within the range of uncertainty estimated for RPWS measurement. The RPWS onboard dust recorder and counter data are used to map the dust density and spacecraft charging state within Saturn's magnetosphere.

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“…Impacts in the hypervelocity regime often produce weakly ionized vapor or plasma which has been proposed to produce several effects: (1) the plasma provides a significant perturbation to the ambient magnetic field and can produce spontaneous magnetic fields due to non-aligned electron density and temperature gradients [1][2][3][4][5]; (2) it supports the production of transient radiofrequency electromagnetic fields [6][7][8]; and (3) it charges ejected debris which, because of inertial separation, leads to significant electrostatic and magnetostatic field production [9]. In prior work with experiments performed at the NASA Ames Vertical Gun Range (AVGR), electrostatic charge separation during hypervelocity impact was characterized for different impactor and target geometries [9].…”

Section: Introductionmentioning

confidence: 99%

Computational Modeling of Electrostatic Charge and Fields Produced by Hypervelocity Impact

Crawford

2015

Procedia Engineering

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Following prior experimental evidence of electrostatic charge separation, electric and magnetic fields produced by hypervelocity impact, we have developed a model of electrostatic charge separation based on plasma sheath theory and implemented it into the CTH shock physics code. Preliminary assessment of the model shows good qualitative and quantitative agreement between the model and prior experiments at least in the hypervelocity regime for the porous carbonate material tested. Moreover, the model agrees with the scaling analysis of experimental data performed in the prior work, suggesting that electric charge separation and the resulting electric and magnetic fields can be a substantial effect at larger scales, higher impact velocities, or both.

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Measurements of freely-expanding plasma from hypervelocity impacts

Cited by 60 publications

References 29 publications

Dust impact signals on the wind spacecraft

Dust impact signals on the wind spacecraft

Properties of dust particles near Saturn inferred from voltage pulses induced by dust impacts on Cassini spacecraft

Computational Modeling of Electrostatic Charge and Fields Produced by Hypervelocity Impact

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