Observations of waves and plasma in the environment of comet Halley

Grard, R.; Pedersen, Å.; Trotignon, J. G.; Béghin, C.; Mogilevsky, M. M.; Mikhailov, Yu. M.; Molchanov, O. A.; Formisano, V.

doi:10.1038/321290a0

Cited by 82 publications

(32 citation statements)

References 2 publications

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“…This assures the access to the crossing point with simple experimental techniques, such as Langmuir probes [34,35]. The situation may be slightly different for Tokamak (n 0 ∼ 10 14 cm −3 ) and solid-state (n 0 ∼ 10 18 cm −3 ) plasmas, for which we respectively estimate λ Ã ∼ 0.1 mm and λ Ã ∼ 1 μm, implying the use of more sophisticated spectroscopic techniques [36][37][38].…”

Section: Physical Review Lettersmentioning

confidence: 99%

Axion-Plasmon Polaritons in Strongly Magnetized Plasmas

Terças¹,

Rodrigues²,

Mendonça³

2018

Phys. Rev. Lett.

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Axions are hypothetical particles related to the violation of the charge-parity symmetry within the strong sector of the standard model, being one of the most prone candidates for dark matter. Multiple attempts to prove their existence are currently performed in different physical systems. Here, we predict that axions may couple to the electrostatic (Langmuir) modes of a strongly magnetized plasma, and show that a new quasiparticle can be defined, the axion-plasmon polariton. The excitation of axions can be inferred from the pronounced modification of the dispersion relation of the Langmuir waves, a feature that we estimate to be accessible in state-of-the-art plasma-based experiments.

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Section: Physical Review Lettersmentioning

confidence: 99%

Axion-Plasmon Polaritons in Strongly Magnetized Plasmas

Terças¹,

Rodrigues²,

Mendonça³

2018

Phys. Rev. Lett.

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“…It may be stressed here that the present investigation may be useful for understanding the low-frequency electrostatic noise enhancement observed by the Vega and Giotto space probes [23] in the dust regions of Haley's comet and spoke-like structures revealed by the Voyager space mission [21] in Saturn's rings.…”

mentioning

confidence: 82%

“…Angelis et al [14] investigated the propagation of ion-acoustic waves in a dusty plasma, in which a spatial inhomogeneity is created by a distribution of immobile dust particles [22]. They [14] applied their results in interpreting the low frequency noise enhancement observed by the Vega and Giotto space probes in the dusty regions of Haley's comet [23].…”

mentioning

confidence: 99%

Low-frequency electrostatic dust-modes in a non-uniform magnetized dusty plasma

et al. 2004

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A self-consistent and general description of obliquely propagating low frequency electrostatic dust-modes in a inhomogeneous, magnetized dusty plasma system has been presented. A number of different situations, which correspond to different low-frequency electrostatic dust-modes, namely, dust-acoustic mode, dust-drift mode, dust-cyclotron mode, dust-lower-hybrid mode, and other associated modes (such as, accelerated and retarded dust-acoustic modes, accelerated and retarded dust-lower-hybrid modes, etc.), have also been investigated. It has been shown that the effects of obliqueness and inhomogeneities in plasma particle number densities introduce new electrostatic dust modes as well as significantly modify the dispersion properties of the other low-frequency electrostatic dust-modes. The implications of these results to some space and astrophysical dusty plasma systems, especially to planetary ring-systems and cometary tails, are briefly mentioned.

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“…Section 4 summarizes the major findings of this paper. Figure 1 shows the locations of the APV-V sensors (Grard et al, 1989) and the IKS IR-camera (Arduine et al, 1983) on the Vega spacecraft. The quasistatic (dc) and wave (ac) electric fields are measured with a double probe antenna, made of two solid spheres (sensors P1 and P2), 10 cm in diameter, located at the tips of two 2-meter long booms and separated by a distance L = 11 m. The potential differences between the probes, V 12 = V 1 − V 2 , and between probe P2 and the spacecraft structure, V 2s = V 2 − V s , are sampled at intervals of 1 s and 4 s, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…Probe L2 is biased at a fixed potential of +5V with respect to the spacecraft structure in order to detect fast fluctuations of the electron flux. The current response of probe L1 is measured while its potential is swept with a period of 32 s between −6V and +6V on Vega 1 and between −4V and +2V on Vega 2 (Grard et al, 1989).…”

Section: Introductionmentioning

confidence: 99%

Plasma and wave phenomena induced by neutral gas releases in the solar wind

et al. 2002

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Abstract. We investigate plasma and wave disturbances generated by nitrogen (N 2 ) gas releases from the cooling system of an IR-camera on board the Vega 1 and Vega 2 spacecraft, during their flybys of comet Halley in March 1986. N 2 molecules are ionized by solar UV radiation at a rate of ∼ 7 · 10 −7 s −1 and give rise to a plasma cloud expanding around the spacecraft. Strong disturbances due to the interaction of the solar wind with the N + 2 ion cloud are observed with a plasma and wave experiment (APV-V instrument). Three gas releases are accompanied by increases in cold electron density and simultaneous decreases of the spacecraft potential; this study shows that the spacecraft potential can be monitored with a reference sensor mounted on a short boom. The comparison between the model and observations suggests that the gas expands as an exhaust plume, and approximately only 1% of the ions can escape the beam within the first meters. The releases are also associated with significant increases in wave electric field emission (8 Hz-300 kHz); this phenomenon lasts for more than one hour after the end of the release, which is most likely due to the temporary contamination of the spacecraft surface by nitrogen gas. DC electric fields associated with the events are complex but interesting. No magnetic field perturbations are detected, suggesting that no significant diamagnetic effect (i.e. magnetic cavity) is associated with these events.

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Observations of waves and plasma in the environment of comet Halley

Cited by 82 publications

References 2 publications

Axion-Plasmon Polaritons in Strongly Magnetized Plasmas

Axion-Plasmon Polaritons in Strongly Magnetized Plasmas

Low-frequency electrostatic dust-modes in a non-uniform magnetized dusty plasma

Plasma and wave phenomena induced by neutral gas releases in the solar wind

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