HR: 0800h
AN: P41B-06 [Abstracts]
TI: 1D Hybrid Simulations of Ion Cyclotron Waves Generation by Mass Loading at Io
AU: * Cowee, M M
EM: mcowee@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, UCLA, 405 Hilgard Ave, Los Angeles, CA
90095, United States
AU: Russell, C T
EM: ctrussel@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, UCLA, 405 Hilgard Ave, Los Angeles, CA
90095, United States
AU: Strangeway, R J
EM: strange@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, UCLA, 405 Hilgard Ave, Los Angeles, CA
90095, United States
AB:
Ion cyclotron waves were detected by the Galileo spacecraft as it flew by the Jovian moon, Io, in 1995-2002.
These waves are generated by populations of newborn sulfur monoxide and sulfur dioxide ions mass loaded
from Io's atmosphere. Because the wave amplitudes are proportional to the number of ions generating them, the
observed waves can be used to estimate the mass loading rate at Io. Using a 1D hybrid technique (kinetic ions,
fluid electrons), we simulate the addition of newborn molecular sulfur ions to an Io torus-like plasma and
examine the generated waves. The generated waves are narrowly peaked just below the newborn ion
gyrofrequency and show little change over time for a uniform mass loading rate. Typically, the newborn ions lose
~30% of their initial energy as they scatter on the self-generated waves. Some of this energy is lost by
transferring it other ion components in the plasma and some resides in the ion cyclotron waves. This disagrees
with previous estimates of mass loading rates at Io assumed that the newborn ions would lose 50% of their
initial energy to wave growth. Because the ions lose less energy than this, more ions are necessary in order to
generate the observed wave amplitudes, so the previous mass loading rate estimates are too low.
DE: 2152 Pickup ions
DE: 2753 Numerical modeling
DE: 6218 Jovian satellites
DE: 6219 Io
DE: 7829 Kinetic waves and instabilities
SC: Planetary Sciences [P]
MN: 2007 Joint Assembly