Energetic oxygen and sulfur ions in the Jovian magnetosphere

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6213098

Gehrels, N

Observations of 1 to 20 MeV/nuc oxygen, sodium, and sulfur ions in the Jovian magnetosphere are reported. Measurements made by the Cosmic Ray Subsystem on Voyager 1 and 2 are used to calculate abundances and energy spectra in the region from 5 to 20 Jovian radii (R/sub J/). The phase space density of the oxygen ions calculated from the spectra has a positive radial gradient between 6 and 17 R/sub J/, indicating an inward diffusive flow. The diffusion coefficient upper limit at 9 R/sub J/ is approx. 10/sup -5/s/sup -1/. This limit, combined with the analysis of voyager plasma observations by Siscoe et al. (1981), implies an upper limit to the mass loading rate near lo of approx. 10/sup 28/ ions/s. The energetic oxygen lifetime is within an order of magnitude of the strong pitch-angle diffusion lifetime in this region, with the largest total numbers of particles lost between 7.5 and 12.5 R/sub J/. It is shown that the losses are not due to geometric absorption by lo, absorption by dust grains, or energy loss in the plasma of the inner magnetosphere, and it is therefore postulated that the primary loss mechanism is pitch-angle scattering into the loss cone. The power delivered to the Jovian atmosphere by oxygen and sulfur ions with magnetic moments greater than 70 MeV/nuc-G (E greater than or equal to 0.3 MeV/nuc at 10 R/sub j/), scattered into the loss cone between 6 and 17 R/sub j/, is approx. 5 x 10/sup 12/ W; a power comparable to the approx. 1.2 x 10/sup 13/W required to produce the auroral emission observed by the ultraviolet spectrometer on Voyager. The measured dependence of the input power on magnetic moment threshold indicates that additional power is contributed by oxygen and sulfur ions with magnetic moments less than 70 meV/nuc-G.

• Research Organization: California Inst. of Tech., Pasadena (USA)
• OSTI ID: 6213098
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CHARGED PARTICLES
CHEMICAL COMPOSITION
ENERGY SPECTRA
IONS
JUPITER PLANET
LIFETIME
LIMITING VALUES
LOSS CONE
MAGNETIC MOMENTS
OXYGEN IONS
PLANETARY ATMOSPHERES
PLANETARY MAGNETOSPHERES
PLANETS
SODIUM IONS
SPACE VEHICLES
SPECTRA
SULFUR IONS
VEHICLES
VOYAGER SPACE PROBES