Voyager 2 electron observations in the magnetosphere of Neptune

Abstract

This paper describes electron data obtained during the Neptune encounter by the Voyager 2 plasma science experiment. We derive the densities and temperatures of low‐energy (10–5950 eV) electrons and the electrostatic potential of the spacecraft near Neptune. The data indicate that the escape of charged particles from Triton and the local ionization of atoms in the neutral torus originating from Triton are the major plasma sources. We infer that this neutral torus of hydrogen atoms has a density of about 300 cm‐3 and an inner boundary at 8RN. The data near Neptune exhibit signatures suggesting that both precipitation into Neptune's atmosphere and ring absorption are important plasma loss mechanisms. Plasma transport in the magnetosphere appears to be very fast; the diffusion coefficient is xl0−7L3 RN2 s−1.