title: First plasma wave observations at neptune.
abstract: The Voyager 2 plasma wave instrument detected many familiar plasma waves during the encounter with Neptune, including electron plasma oscillations in the solar wind upstream of the bow shock, electrostatic turbulence at the bow shock, and chorus, hiss, electron cyclotron waves, and upper hybrid resonance waves in the inner magnetosphere. Low-frequency radio emissions, believed to be generated by mode conversion from the upper hybrid resonance emissions, were also observed propagating outward in a disklike beam along the magnetic equatorial plane. At the two ring plane crossings many small micrometer-sized dust particles were detected striking the spacecraft. The maximum impact rates were about 280 impacts per second at the inbound ring plane crossing, and about 110 impacts per second at the outbound ring plane crossing. Most of the particles are concentrated in a dense disk, about 1000 kilometers thick, centered on the equatorial plane. However, a broader, more tenuous distribution also extends many tens of thousands of kilometers from the equatorial plane, including over the northern polar region.
authors.forename: D A
authors.initials: DA
authors.lastname: Gurnett
authors.forename: W S
authors.initials: WS
authors.lastname: Kurth
authors.forename: R L
authors.initials: RL
authors.lastname: Poynter
authors.forename: L J
authors.initials: LJ
authors.lastname: Granroth
authors.forename: I H
authors.initials: IH
authors.lastname: Cairns
authors.forename: W M
authors.initials: WM
authors.lastname: Macek
authors.forename: S L
authors.initials: SL
authors.lastname: Moses
authors.forename: F V
authors.initials: FV
authors.lastname: Coroniti
authors.forename: C F
authors.initials: CF
authors.lastname: Kennel
authors.forename: D D
authors.initials: DD
authors.lastname: Barbosa