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

Ye, Shengyi; Gurnett, D. A.; Kŭrth, W. S.; Averkamp, T. F.; Kempf, S.; Hsu, Hsiang-Wen; Srama, R.; Grün, E.

doi:10.1002/2014ja020024

Cited by 48 publications

(67 citation statements)

References 78 publications

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“…In Figures a and c, the timings of the density peaks E7 a , E7 b , E7 d , E18 a , and E18 c of the ELS nanograin data are generally consistent with some density peaks in INMS water vapor and RPWS dust data (see the dashed blue lines). As shown by Ye et al [], the E7 CDA data share similar density variations with the RPWS dust data. These similarities between INMS, CAPS, and RPWS data may imply some dust (nanograin and micrograin) jets associated with the water vapor jets.…”

Section: Cassini Observationssupporting

confidence: 76%

“…Calibrated with the CDA data, the RPWS is able to measure the density and size distribution of the impacting dust grains [ Kurth et al, ; Wang et al, ; Ye et al, ]. During the flybys E2 to E19, the RPWS measured a power law size distribution of the dust in the plume similar to that of the E2 CDA data [ Kempf et al, ]:

\frac{normald n}{normald a} = n_{0} a^{- κ}

where a is the grain radius and the exponent κ is ~4 [ Ye et al, , ]. In equation , d n/ d a , n 0 , and a have units of m −3 /µm, m − 3 µm κ − 1 , and µm.…”

Section: Cassini Observationsmentioning

confidence: 99%

“…Figures a and b show the comparison of the INMS water vapor densities n (H 2 O) [ Teolis et al, ], the RPWS‐LP cold plasma ion and electron densities n i and n e [ Morooka et al, ], the CAPS ELS and IMS nanograin densities n (‐ nanograin) and n (+ nanograin) [ Hill et al, ], and the RPWS dust density n d ( a > 2 µm) [ Ye et al, ] during E3 and E5. These data sets imply a nontrivial problem with charge balance in the plume.…”

Section: Cassini Observationsmentioning

confidence: 99%

“…α and β are two dimensionless parameters that control the shape of the d n /d a curve near the peak and at a < a 0 . For the ice grains in the plume, the power law exponent κ is from the RPWS data [ Ye et al, ], which also gives the dust density as n d ( a > a min ) with a min = 2 µm ≫ a 0 . From the relation

n_{d} ((), a > a_{\min}) = true {true\int}_{a_{normalmin}} \frac{normald n}{normald a} normald a

and equation , the scale factor C of the composite size distribution is determined by the RPWS data of κ and n d ( a > a min ) for any given α , β , and a 0 :

C = n_{d} ((), a > a_{normalm normali normaln}) ((), κ - 1) {(\frac{α}{κ})}^{\frac{α + κ}{β}} \frac{{a_{normalm normali normaln}}^{κ - 1}}{{a_{0}}^{α + κ}}

…”

Section: Size Distributionsmentioning

confidence: 99%

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Characteristics of ice grains in the Enceladus plume from Cassini observations

Dong

Hill

2015

JGR Space Physics

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Ice grains in the Enceladus plume have been observed by several Cassini instruments during many Enceladus encounters. In this paper we study the ice grains ranging from less than one nanometer to micrometers in size based on multiple instrument observations. We have analyzed the nanograin data from the E17 and E18 Cassini Plasma Spectrometer (CAPS) energy spectra using the approach of Hill et al. (2012) and studied the charging of the grains using the E3-E6 Radio and Plasma Wave Spectrometer (RPWS)-Langmuir Probe (LP) data presented by Morooka et al. (2011). To bridge the gap between CAPS nanograin observations and Cosmic Dust Analyzer and RPWS micrograin observations, we propose a composite size distribution and fit it to the E3, E5, E17, and E18 CAPS and RPWS data. The resulting size distribution peaks at~2 nm and provides a total grain mass density~20% that of the water vapor measured by Ion and Neutral Mass Spectrometer at the densest part of the plume and a total grain charge density much smaller than that inferred from the RPWS-LP plasma data. Charge balance with the RPWS-LP plasma data would require many more grains than provided by the best fit composite distribution to the CAPS and RPWS data and would provide a grain mass density comparable to that of the water vapor. On the basis of these results, we study the subsequent motion of the ice grains and estimate the resulting grain current (~10 4 tõ 10 5 A) and grain mass production rate (~15-65 kg/s).

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Section: Cassini Observationssupporting

confidence: 76%

\frac{normald n}{normald a} = n_{0} a^{- κ}

where a is the grain radius and the exponent κ is ~4 [ Ye et al, , ]. In equation , d n/ d a , n 0 , and a have units of m −3 /µm, m − 3 µm κ − 1 , and µm.…”

Section: Cassini Observationsmentioning

confidence: 99%

Section: Cassini Observationsmentioning

confidence: 99%

n_{d} ((), a > a_{\min}) = true {true\int}_{a_{normalmin}} \frac{normald n}{normald a} normald a

and equation , the scale factor C of the composite size distribution is determined by the RPWS data of κ and n d ( a > a min ) for any given α , β , and a 0 :

C = n_{d} ((), a > a_{normalm normali normaln}) ((), κ - 1) {(\frac{α}{κ})}^{\frac{α + κ}{β}} \frac{{a_{normalm normali normaln}}^{κ - 1}}{{a_{0}}^{α + κ}}

…”

Section: Size Distributionsmentioning

confidence: 99%

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Characteristics of ice grains in the Enceladus plume from Cassini observations

Dong

Hill

2015

JGR Space Physics

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“…Besides the dedicated Cosmic Dust Analyzer, the Radio and Plasma Waves Science (RPWS) instrument also performed in situ dust detection (Dong et al, 2015;Gurnett et al, 2004;Hill et al, 2012;Kempf et al, 2008Kempf et al, , 2010Kurth et al, 2006;Spahn et al, 2006;Srama et al, 2006;Wang et al, 2006;Ye et al, 2014;. Besides the dedicated Cosmic Dust Analyzer, the Radio and Plasma Waves Science (RPWS) instrument also performed in situ dust detection (Dong et al, 2015;Gurnett et al, 2004;Hill et al, 2012;Kempf et al, 2008Kempf et al, , 2010Kurth et al, 2006;Spahn et al, 2006;Srama et al, 2006;Wang et al, 2006;Ye et al, 2014;.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Field Effect on Antenna Signals Induced by Dust Particle Impacts

et al. 2020

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The Radio and Plasma Wave Science instrument on Cassini has observed fewer than expected dust particle impacts during the mission's Grand Finale orbits. The relatively strong magnetic field in the close vicinity of the planet has been suggested to affect the intensity of the dust impact generated signals. A laboratory investigation is performed using dust particles accelerated to ≥20 km/s speed impacting onto a previously developed model of the spacecraft and the Radio and Plasma Wave Science antennas. The external magnetic field is generated by two sets of magnetic coils. The recorded antenna waveforms are decomposed into contributions from the electrons and ions of the dust impact generated plasma cloud. A good qualitative understanding of the waveforms is achieved by dividing the electron and ion population into two portions: one that is escaping from the spacecraft and another that is collected by the spacecraft. The experimental results show that the part of the signal corresponding to escaping electrons is affected by the magnetic field and that dust impact signals can be significantly reduced for spacecraft floating potentials close to zero.

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Floating potential perturbations due to micrometeoroid impacts: Theory and application to S/WAVES data

Zaslavsky

2015

JGR Space Physics

128

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In situ observation of dust grains from various origins is routinely performed by space missions equipped with radio instruments. These measurements consist in observations of voltage pulses or their spectral signature. It has for long been proposed that one of the mechanisms able to produce these pulses is the collection by the spacecraft of electric charges generated by impact ionization. Here for the first time, a complete theoretical model of how pulses are generated by charge collection is proposed. In the solar wind at 1 AU, the pulses are shown to be shaped by local plasma and photoelectron parameters. However, the situation can be different in hotter or denser plasma environments. We use the data provided by the STEREO/WAVES (S/WAVES) radio instrument onboard the twin STEREO spacecraft to validate our model. We find that the observations indeed strongly support the theory. The proposed model is an important step forward, since it makes it possible to reproduce the shape, timescales, and amplitudes of pulses generated by dust impacts in various space environments. Such a model can be used to infer the dust detection abilities of radio instruments onboard different spacecraft and can help the design of dust detection optimized radio instruments for future missions.

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

Cited by 48 publications

References 78 publications

Characteristics of ice grains in the Enceladus plume from Cassini observations

Characteristics of ice grains in the Enceladus plume from Cassini observations

Magnetic Field Effect on Antenna Signals Induced by Dust Particle Impacts

Floating potential perturbations due to micrometeoroid impacts: Theory and application to S/WAVES data

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