HR: 0830h
AN: SM31C-1126    [PDF]
TI: The Electron Density in the Jovian Magnetosphere from Galileo Plasma Wave Measurements
AU: * Richards, B H
EM: benjamin-richards@uiowa.edu
AF: University of Iowa, Dept. of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Gurnett, D A
EM: donald-gurnett@uiowa.edu
AF: University of Iowa, Dept. of Physics and Astronomy, Iowa City, IA 52242 United States
AB: An overview of Jovian magnetospheric electron density is presented from data gathered by the Galileo plasma wave instrument. Two techniques are employed. The first uses the low-frequency cutoff of trapped continuum radiation existing at the local electron plasma frequency, f$_{\rm p} = 8980 \sqrt{({\rm N}_{\rm e}})$ Hz, where N${_{\rm e}}$ is the electron density in cm$^{-3}$. The second uses a narrowband emission at the upper hybrid resonance frequency, f$_{\rm uh} = \sqrt{({\rm f}_p^2 + f_c^2)}$, where f$_{\rm c} =$ 28B Hz defines the electron cyclotron frequency, and is primarily used inside approximately 15 R$_{\rm J}$, where the first method fails. Analyzed data covers between December 1995 and November 2002. Covered radial distances range approximately from 4 R$_{\rm J}$, near the inner edge of the cold torus, to 145 R$_{\rm J}$, and local times approximately extend from 0400 hours local morning to 2000 hours local evening via local midnight. Electron densities vary from approximately 4 $\times$ $10^{3}$ cm$^{-3}$ in the Io torus' most dense region to $10^{-2}$ cm$^{-3}$ in the distant magnetotail. The radial electron density profile has a distinct break at approximately 25 R$_{\rm J}$ and varies as approximately (1/R)$^{6.5}$ inside 25 R$_{\rm J}$ and (1/R)$^{2.1}$ beyond 25 R$_{\rm J}$. The north-south thickness of the plasma sheet is usually well resolved at radial distances from 25 R$_{\rm J}$ to 50 R$_{\rm J}$, and is typically within the range of 4 to 8 R$_{\rm J}$. The plasma sheet broadens considerably, however, beyond 50 R$_{\rm J}$ to an irresolvable state. Efforts are currently focused on investigating the local time dependence of the plasma sheet thickness.
DE: 2740 Magnetospheric configuration and dynamics
DE: 2744 Magnetotail
DE: 2772 Plasma waves and instabilities
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting