Injection and loss mechanisms for energetic ions in the inner Jovian magnetosphere

Journal Article · Fri Oct 01 04:00:00 EDT 1982 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA087iA10p08105· OSTI ID:6574236

Thorne, R M

The pronounced depletion of energetic ions observed by Voyager outside the orbit of Io can be understood as a steady state balance between particle loss and inward diffusion. For ions above 1 MeV/nuc (nucleon) G sweeping loss by Io itself is unimportant; rather the removal mechanisms involve processes associated with the extensive torus of neutral and ionized gas emanating from the satellite. There is compelling evidence to suggest that losses throughout an extended region in the outer torus, exterior to the orbit of Io, occur at a rate comparable to the upper limit imposed by strong pitch angle diffusion; although the plasma wves responsible for such scattering have yet to be detected. This is by far the dominant process for removing energy from the inner Jovian magnetosphere, and it also provides a viable energy source for exciting intense Jovian auroral emissions. Charge exchange removal of equatorially trapped lower-energy (< or approx. =10 MeV/nuc G) heavy ions (e.g., O/sup +/ or S/sup +/) can become significant over a limited region near and just inside the orbit of lo, but this process appears to have little overall effect on the energetics of the Jovian system. The trapped particle distribution function in fact exhibits little evidence for effective loss inside the orbit of lo, presumably due to the absence of intense plasma waves. An equilibrium solution for the ion phase space density requires a pronounced increase in the rate of radial diffusion between the orbit of lo and the outer torus (L>7). In contrast, the diffusion rate near Io is substantially slower, D/sub L/L(Lapprox. =6)roughly-equal2 x 10-/sup 7/R/sub J//sup 2//s.

• Research Organization: Department of Atmospheric Sciences, University of California, Los Angeles, California 90024
• OSTI ID: 6574236
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 87:A10; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics &amp; Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CHARGED PARTICLES
IONS
JUPITER PLANET
PLANETARY ATMOSPHERES
PLANETARY MAGNETOSPHERES
PLANETS
SPACE VEHICLES
STEADY-STATE CONDITIONS
VEHICLES
VOYAGER SPACE PROBES