Entry of solar protons to the plasma sheet and lobe of the magnetotail AT r=18 R/sub E/ in the event of April 22, 1971

Journal Article · Fri Jun 01 04:00:00 EDT 1979 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA084iA06p02630· OSTI ID:6248765

Palmer, I D; Jackson, J C; Hones, Jr, E W

Vela satellites of orbit r=18 R/sub E/ measured the intensity of < or approx. = 1-MeV solar protons at two points in the plasma sheet and one in the north tail lobe during an 8-hour period on April 22, 1971. Intensities were isotropic, except when a sharp gradient was convected past a satellite. Several such gradients have been interpreted as the boundary between plasma sheet and north lobe. Movement of this plasma sheet surface has been observed in coincidence with substorm and geomagnetic storm activity. It is inferred that the region of open field lines at Vela orbit was very small in this event. A prolonged intensity difference by a factor of almost 2 existed across the surface between plasma sheet and lobe for >8 hours, implying very little cross-field transport of < or approx. =1-MeV protons. One gradient-induced anisotropy was anomalous in direction and has been explained by a tongue-shaped distortion in the surface separating plasma sheet and lobe. A second case of anomalous anisotropy from another event has been explained in a similar way. Intercomparison between Vela and Imp 6, the latter in interplanetary space, suggests the following. Access of < or approx. =1-MeV solar protons to the north tail lobe was delayed by 3-4 hours, giving an access point 602-872 R/sub E/ from earth. The intensity there was a little higher than the mean of the interplanetary distribution. The intensity in the dusk plasma sheet lay between the mean in interplanetary space and the integrated intensity of the backward moving interplanetary particles (-1<..mu..<0). The intensity in the dawn plasma sheet was lower and tracked the integrated intensity of the backward moving particles in interplanetary space. This gradient across the plasma sheet at r=18 R/sub E/ implies that there was not a thorough mixing of < or approx. =1-MeV protons, at least on a time scale of hours.

• Research Organization: Oral Roberts University, Tulsa, Oklahoma 74171
• OSTI ID: 6248765
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 84:A6; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640203* -- Atmospheric Physics-- Magnetospheric Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANISOTROPY
BARYONS
EARTH ATMOSPHERE
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
HADRONS
IMP SATELLITES
INTERPLANETARY SPACE
KEV RANGE
MAGNETOSPHERE
MAGNETOTAIL
NUCLEONS
PLASMA DENSITY
PLASMA SHEET
PROTONS
RADIATIONS
SATELLITES
SOLAR PARTICLES
SOLAR PROTONS
SOLAR RADIATION
SPACE
STELLAR RADIATION