Low-energy charged particle environment at Jupiter: a first look

Journal Article · Fri Jun 01 00:00:00 EDT 1979 · Science; (United States)

DOI:https://doi.org/10.1126/science.204.4396.998· OSTI ID:5755597

Krimigis, S M ^[1]; Armstrong, T P; Axford, W I

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1. Johns Hopkins Univ., Laurel, MD

The low-energy charged particle instrument on Voyager was designed to measure the hot plasma (electron and ion energies greater than or equal to 15 and greater than or equal to 30 kiloelectron volts, respectively) component of the Jovian magnetosphere. Protons, heavier ions, and electrons at these energies were detected nearly a third of an astronomical unit before encounter with the planet. The hot plasma near the magnetosphere boundary is predominantly composed of protons, oxygen, and sulfur in comparable proportions and a nonthermal power-law tail; its temperature is about 3 x 10/sup 8/K, density about 5 x 10/sup -3/ per cubic centimeter, and energy density comparable to that of the magnetic field. The plasma appears to be corotating throughout the magnetosphere; no hot plasma outflow, as suggested by planetary wind theories, is observed. The main constituents of the energetic particle population (greater than or equal to 200 kiloelectron volts per nucleon) are protons, helium, oxygen, sulfur, and some sodium observed throughout the outer magnetosphere; it is probable that the sulfur, sodium, and possibly oxygen originate at Io. Fluxes in the outbound trajectory appear to be enhanced from approx. 90/sup 0/ to approx. 130/sup 0/ longitude (System III). Consistent low-energy particle flux periodicities were not observed on the inbound trajectory; both 5- and 10-hour periodicities were observed on the outbound trajectory. Partial absorption of > 10 million electron volts electrons is observed in the vicinity of the Io flux tube.

• OSTI ID: 5755597
• Journal Information: Science; (United States), Journal Name: Science; (United States) Vol. 204; ISSN SCIEA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
ATOMIC IONS
BARYONS
CHARGED PARTICLES
CHEMICAL COMPOSITION
ELECTRONS
ELEMENTARY PARTICLES
ENERGY RANGE
ENERGY SPECTRA
FERMIONS
HADRONS
HELIUM IONS
HOT PLASMA
ION DENSITY
IONS
JUPITER PLANET
KEV RANGE
KEV RANGE 10-100
LEPTONS
NUCLEONS
OXYGEN IONS
PLANETARY ATMOSPHERES
PLANETARY MAGNETOSPHERES
PLANETS
PLASMA
PROTONS
SODIUM IONS
SPACE VEHICLES
SPECTRA
SULFUR IONS
VOYAGER SPACE PROBES