Engineering topics

Carbary, J. F.

Publications and source records attributed to Carbary, J. F..

24 records · Page 2

NASA NTRS1979

Energetic particle activity at 5-min and 10-s time resolution in the magnetotail and its relation to auroral activity

The paper examines several energetic particle bursts associated with substorm events in the magnetotail using data from the Imp 7 and 8 spacecraft experiments. Individual proton and electron bursts observed by the spacecraft do not always coincide nor does magnetotail activity correlate strongly with auroral activity on time scales less than 1 hr. The pitch angle distributions were determined with a time resolution of 10 s by combining magnetic field and particle measurements on Imp 8; during intense particle bursts the 0.3-MeV protons exhibit unidirectional or bidirectional anisotropies along the magnetic field. The data suggest the presence of small localized acceleration regions in the magnetotail observable when magnetically connected to the spacecraft; little evidence is found for a single neutral line extending across the width of the magnetotail.

Carbary, J. F.↗

NASA NTRS1979

Hot plasma environment at Jupiter - Voyager 2 results

Preliminary results are reported from measurements made with the low-energy charged particle (LECP) instrument on Voyager 2 as it approached and traversed the Jovian magnetosphere. The primary objectives of the LECP instrument were to make measurements of the hot plasma (no less than about 20 keV and no less than about 28 keV for electrons and ions, respectively), to characterize the composition of the hot plasma and energetic-particle population, and to determine the particle flows and spatial distributions. In addition, the effects associated with the possible wake of Ganymede are discussed. Attention is given to inbound and outbound passes, along with Jovian plasma characteristics. The results suggest that the Jovian magnetosphere is confined by a plasma boundary rather than a conventional magnetopause. Inside the plasma boundary there exists a discontinuity at about 50-60 Jupiter radii, and the region inside this discontinuity is termed the 'inner plasmasphere'.

Krimigis, S. M.↗

NASA NTRS1979

Low-energy charged particle environment at Jupiter - A first look

Preliminary results of measurements obtained by the low energy charged particle instrument on board the Voyager 1 spacecraft during its traversal of the Jovian magnetosphere are reported. The instrument consists of the low energy particle telescope and the low energy magnetospheric particle analyzer, designed to perform measurements in the inner and outer magnetosphere respectively. Ions and electrons comprising the Jovian magnetosphere were first detected at a distance of about 600 Jupiter radii from the planet, with the first bow shock crossing at 85.6 Jupiter radii. Upon crossing the magnetopause at about 67 Jupiter radii, the flows of electrons and ions were observed to change direction from away from the planet to the corotational direction. The hot plasma near the magnetosphere boundary is comprised predominantly of protons, sulfur and oxygen. Selective particle absorption near the Io flux tube indicates some form of particle deflection by Io. Fluxes in the outbound region were found to be enhanced from 90 to 160 deg longitude, and 5- and 10-hour low energy particle flux periodicities were observed.

Krimigis, S. M.↗

NASA NTRS1978

A self-consistent model of a corotating Jovian magnetosphere

In the rotation-dominated model of the Jovian magnetosphere, proposed in the present paper, the plasma current distribution is dynamically consistent with the magnetic field. The model is constructed under the assumptions of an ionospheric plasma source without pitch angle scattering; loss-free radiation transport through flux tube interchange diffusion; and a static balance between centrifugal force and magnetic stress. Using these assumptions, a dynamic equation is derived for a self-consistent field configuration having a single adjustable parameter that is related to the plasma source strength. The equation is solved by an iterative technique. The self-consistent field resembles a radially distorted dipole field, rather than the flat magnetodisk configuration inferred from Pioneer data. The implication is that such a magnetodisk field would require an equatorial plasma source rather than a source at the feet of the field lines.

Carbary, J. F.↗

NASA NTRS1976

Planetary spin period acceleration of particles in the Jovian magnetosphere

A four-step mechanism is proposed for the acceleration of energetic protons and relativistic electrons in Jupiter's magnetosphere. According to this mechanism, photoelectrons and ions from the Jovian ionosphere are: (1) ejected along magnetic-field lines toward the equator by the centrifugal force of corotation; (2) accelerated by magnetic-field annihiliation in the magnetotail, which process is modulated at Jupiter's rotational frequency; (3) trapped on closed field lines in the reconnection process, convected inward toward Jupiter from the merging region, and subjected to adiabatic compression; and (4) diffused inward by the conventional radial-diffusion process through a violation of the third adiabatic invariant. It is shown that the proposed mechanism produces magnetic moments much larger than those available from inward diffusion of solar-wind particles or motional emf acceleration at the Galilean satellites, provides a natural explanation for the 10-hr periodicity of the energetic particle fluxes observed inside the magnetosphere by the Pioneer spacecraft, and also produces a 10-hr periodicity in the energetic particle flux from the magnetosphere into interplanetary space in such a way that the phase of interplanetary flux variations is locked to the rotational phase of Jupiter

Carbary, J. F.↗

NASA NTRS1974

Periodic escape of relativistic electrons from the Jovian magnetosphere

We adopt a model in which the Jovian magnetospheric tail is forced open by plasma that is accelerated out of the ionosphere by the centrifugal force of corotation. Any longitudinal asymmetry that exists in the ionospheric plasma source and/or the planetary magnetic field will cause a diurnal variation in the radial extent of the trapping region for energetic electrons. This diurnal variation in the extent of the particle trapping region can result in a time-dependent loss of relativistic electrons from the Jovian magnetosphere, modulated at the planetary rotation period. The diurnal trapping process may be relevant to the observation of electron pulses in interplanetary space during the Pioneer 10 approach to Jupiter.

Hill, T. W.↗