Simultaneous Observation of Negatively and Positively Charged Nanograins at Comet 67P/Churyumov‐Gerasimenko

LLera, Kristie; Burch, J. L.; Goldstein, R.; Goetz, Charlotte

doi:10.1029/2019gl086147

Cited by 7 publications

(3 citation statements)

References 38 publications

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“…The latter is particularly clear in the simultaneous detection of positive as well as negative nanograins by LLera et al. ( 2020 ), where the deviation from antisunward motion is opposite for oppositely charged grains (Fig. 17 ).…”

Section: Plasmamentioning

confidence: 72%

The Plasma Environment of Comet 67P/Churyumov-Gerasimenko

et al. 2022

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The environment of a comet is a fascinating and unique laboratory to study plasma processes and the formation of structures such as shocks and discontinuities from electron scales to ion scales and above. The European Space Agency’s Rosetta mission collected data for more than two years, from the rendezvous with comet 67P/Churyumov-Gerasimenko in August 2014 until the final touch-down of the spacecraft end of September 2016. This escort phase spanned a large arc of the comet’s orbit around the Sun, including its perihelion and corresponding to heliocentric distances between 3.8 AU and 1.24 AU. The length of the active mission together with this span in heliocentric and cometocentric distances make the Rosetta data set unique and much richer than sets obtained with previous cometary probes. Here, we review the results from the Rosetta mission that pertain to the plasma environment. We detail all known sources and losses of the plasma and typical processes within it. The findings from in-situ plasma measurements are complemented by remote observations of emissions from the plasma. Overviews of the methods and instruments used in the study are given as well as a short review of the Rosetta mission. The long duration of the Rosetta mission provides the opportunity to better understand how the importance of these processes changes depending on parameters like the outgassing rate and the solar wind conditions. We discuss how the shape and existence of large scale structures depend on these parameters and how the plasma within different regions of the plasma environment can be characterised. We end with a non-exhaustive list of still open questions, as well as suggestions on how to answer them in the future.

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Section: Plasmamentioning

confidence: 72%

The Plasma Environment of Comet 67P/Churyumov-Gerasimenko

et al. 2022

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“…The presence of positively and negatively charged nanometer-sized grains at 67P/C-G have been reported by LLera et al (2020) based on measurements of Ion Electron Sensor (IES), which was part of the Rosetta Plasma Consortium (Burch et al 2007). These IES observations of the grains showed that their arrival direction did not come from the nucleus but was instead more scattered.…”

Section: Discussionmentioning

confidence: 94%

Refractory elements in the gas phase for comet 67P/Churyumov-Gerasimenko

Rubin

Altwegg

Berthelier

et al. 2022

A&A

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Context. Gas-phase sodium, silicon, potassium, and calcium were previously identified in mass spectra recorded in the coma of comet 67P/Churyumov-Gerasimenko, the target of the European Space Agency’s Rosetta mission. The major release process for these atoms was identified as sputtering by the solar wind. More recently, remote observations of numerous comets over a range in heliocentric distances revealed the presence of metal atoms of iron and nickel that had been released either from the nucleus or from a distributed source with a short scale length. Sputtering, however, has been dismissed as a major release process due to the attenuation of the solar wind in the comae of some of the observed targets. Aims. We investigated the presence of refractory species in the gas phase of the coma of 67P/Churyumov-Gerasimenko. This investigation includes a period close to perihelion when the solar wind was likely absent from the near-nucleus region due to the increased cometary activity. Additionally, we extended our search to iron and nickel. Methods. We analyzed in situ data from the Rosetta/ROSINA Double Focusing Mass Spectrometer DFMS. Results. We found that gas-phase silicon was present throughout the Rosetta mission. Furthermore, the presence of sodium and iron atoms near the comet’s perihelion confirms that sputtering cannot be the sole release process for refractory elements into the gas phase. Nickel was found to be below the detection limit. The search for parent species of any of the identified gas phase refractories has not been successful. Upper limits for a suite of possible fragment species (SiH, SiC, NaH, etc.) of larger parent and daughter species have been obtained. Furthermore, Si did not exhibit the same drop in signal as do common cometary gases when the spacecraft is pointed away from the nucleus. The combined results suggest that a direct release of elemental species from small grains on the surface of the nucleus or from small grains in the surrounding coma is a more likely explanation than the previous assumption of release via the dissociation of gaseous parent molecules.

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“…Dual chevron MCP performance for singly charged species under numerous detection conditions have been extensively studied and generally find that as m/q increases, the detection efficiency decreases (Gilmore & Seah 2000;Fraser 2002;Liu, Li & Smith 2014). Large mass, highly charged species, on the other hand, have been found to have relatively constant detection efficiencies in event counting mode (Fontanese et al 2018;Gemer et al 2020;Llera et al 2020). For a specific example, highly charged iron dust particles in the size range of 100 to 2000 nm with 20 to 300 m s −1 velocities were detected with a 6 ± 1 % efficiency (Fontanese et al 2018).…”

Section: Methodsmentioning

confidence: 99%

Capillary ionic liquid electrospray: beam compositional analysis by orthogonal time-of-flight mass spectrometry

Miller¹,

Ulibarri-Sanchez

Prince

et al. 2021

J. Fluid Mech.

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Orthogonal time-of-flight mass spectrometry has been used to characterize the kinetic energy and charged species distributions from an in vacuo electrospray ion source for four different ionic liquids at volumetric flow rates between 0.3 and 3.3 nanolitres per second. In all cases, the mass spectra revealed charged species consisting of singly charged and multiply charged ions as well as two broad, unresolved droplet distributions occurring in the 104 to 106 atomic mass unit per charge range. The mean jet velocity and mean jet breakup potential were established from analysis of the energy profile of the high mass-to-charge droplets. At the jet breakup point, we find the energy loss and the jet diameter flow rate dependence of the electrospray beam to be similar to that determined by Gamero-Castaño (Phys. Fluids, vol. 20, 2008, 032103; Phys. Rev. Fluids, vol. 8, 2021, 013701) for 1-ethyl-3-methylimidazolium bis(trifluromethylsulfonyl)imide at similar volumetric flow rates. Similar trends are observed for all four liquids over the flow regime. A jet instability analysis revealed that jet electrification and viscous effects drive the jet breakup from the case of an uncharged, inviscid jet; jet breakup occurs at droplet and jet radius ratios that deviate from 1.89. Using the analytically determined ratio and the beam profile, different species are modelled to reconstruct the mass spectra; primary droplets constitute only a fraction of the total species present. The populations of the species are discussed.

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Simultaneous Observation of Negatively and Positively Charged Nanograins at Comet 67P/Churyumov‐Gerasimenko

Cited by 7 publications

References 38 publications

The Plasma Environment of Comet 67P/Churyumov-Gerasimenko

The Plasma Environment of Comet 67P/Churyumov-Gerasimenko

Refractory elements in the gas phase for comet 67P/Churyumov-Gerasimenko

Capillary ionic liquid electrospray: beam compositional analysis by orthogonal time-of-flight mass spectrometry

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