Two-component proton spectra in the inner Saturnian magnetosphere

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

DOI:https://doi.org/10.1029/GL009i010p01143· OSTI ID:6574194

Krimigis, S M; Armstrong, T P

The Low Energy Charged Particle (LECP) experiment onboard the Voyager-2 spacecraft performed extensive measurements of energetic (approx.28 keV< or approx. =E/sub p/< or approx. =150 MeV; approx.22 keV< or approx. =E/sub e/< or approx. =20 MeV) protons and electrons during spacecraft passage through the inner magnetosphere of Saturn in August 1981. Analysis of the measurements inside the orbits of Enceladus and Mimas reveals the presence of a two-component proton spectrum consisting of a low-energy population at < or approx. =500 keV identified for the first time and described by dj/dE = KE/sup 2.5/, and a high-energy part at E> or approx. =16 MeV whose spectral form is similar to that expected from cosmic ray neutron albedo decay (CRAND), as previously inferred by the Pioneer-11 investigators from integral measurements. In addition, there exist large fluxes of high (> or approx. =1.5 MeV) and low (22 to 35 keV) energy electrons (approx.3.5 x 10/sup 5/ and approx.1.1 x 10/sup 5/ cm/sup -2/sec/sup -1/sr/sup -1/, respectively) throughout this region. The pitch angle distribution of low energy protons changes from a simple sin/sup 2/3/ ..cap alpha.. dependence to one where intensities near 90/sup 0/ become depleted as the spacecraft approached the planet's ring plane at approx.2.88 R/sub S/. It is likely that the pitch angle depletion is due to proton interactions with the tenuous G-ring. These observations also resolve a number of uncertainties regarding the presence of energetic protons and electrons inside the orbits of Enceladus and Mimas, arising from the analysis of Pioneer-11 measurements.

• Research Organization: Applied Physics Laboratory, The Johns Hopkins University, Laurel, Maryland 20707
• OSTI ID: 6574194
• Journal Information: Geophys. Res. Lett.; (United States), Journal Name: Geophys. Res. Lett.; (United States) Vol. 9:10; ISSN GPRLA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics &amp; Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
ELECTRONS
ELEMENTARY PARTICLES
ENERGY SPECTRA
FERMIONS
FLUX DENSITY
INCLINATION
LEPTONS
PLANETARY ATMOSPHERES
PLANETARY MAGNETOSPHERES
PLANETS
PROTON SPECTRA
SATURN PLANET
SPACE VEHICLES
SPECTRA
VEHICLES
VOYAGER SPACE PROBES