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Latest and best measurements of physical quantities involved in complete calculation of the charge exchange lifetime of mirroring magnetospheric ions are coalesced and summarized. It is critical that the charge exchange lifetimes for ions be known as accurately as possible in order to apply the charge exchange mechanism to ion phenomena within the earth's magnetosphere.
Field-aligned currents, which are known to play an important role in the dynamics of the earth's magnetosphere, would also be expected to flow in the Jovian magnetosphere during magnetically active periods. Such currents are difficult to observe largely because of their limited spatial extent and intermittent nature, but on the Pioneer 11 inbound pass to Jupiter on day 336, 1800 GRT, near the L shell of Ganymede, the helium vector magnetometer recorded a structured perturbation with the characteristic signature of a field-aligned current. No analogous structure was found on a similar Pioneer 10 inbound pass (day 337, 1200 GRT). The perturbation could have been caused by turbulence with the wake of Ganymede through which the spacecraft was moving or the perturbation could represent the first observation of a Jovian substorm. The observations are discussed in terms of both models, and difficulties are examined.
A rotation-dominated magnetosphere is unstable to magnetic flux-tube interchange motions if and only if the plasma content of a unit magnetic flux tube is a decreasing function of distance from the spin axis. For a spin-aligned dipole field, an approximate expression is obtained for the marginally stable distribution. Plasma filling the Jovian magnetosphere from internal sources would initially violate this stability criterion so that interchange motions would act to establish the marginally stable distribution.
Examples of observed plasma flows in the dayside magnetosphere near the magnetopause, within the ring current in the local evening sector, and at two positions simultaneously in the plasma sheet are presented. These measurements were gained with plasma instruments on the IMP 6 and 7 satellites. Flow velocities inside the magnetopause in the dayside magnetosphere are typically 25 to 75 km/s and are directed generally parallel to the tangent to the nearby magnetopause with a small component directed into this boundary. Bulk flow speeds within the ring current ranged from the instrument threshold of about 20 km/s to speeds of 50 km/s. Strong tailward 'jetting' of plasma, in the range of 200 to 300 km/s, at geocentric radial distances of about 35 earth radii in the plasma sheet is found to be often associated with the occurrence of magnetic substorms.
The latitudinal width of the magnetospheric whistler duct has been estimated by the first and final invariant latitudes of whistler echoes and the conservation of the magnetic flux for the centered dipole field, using 105 whistler echoes in ISIS VLF data received at Kashima, Japan for 1972-1973. The latitudinal distribution of whistler duct occurrence shows a maximum at invariant latitudes of 40-45 degrees near the maximum occurrence latitude of ground whistlers. The radial width of magnetospheric whistler duct in the geomagnetically equatorial plane increases with invariant latitude of the geomagnetic flux tube in which whistlers propagate.
Some of the natural analogs of proposed seeding experiments in the magnetosphere are: electric charged particle injections during substorms; lightning-induced whistlers providing wave injections; 'detachment' of plasma from the plasmapause, which is equivalent to light-ion seeding in the outer magnetosphere. In the present paper, the characteristics of some natural precedents to active experiments are reviewed, and their relative advantages and drawbacks are examined. One of these precedents - wave generation in detached plasma regions - is then discussed in some detail; the discussion reveals the generation of ELF electromagnetic noise when the energetic electrons exceed the stably trapped limit, and also indicates that a critical dimension for the seeded volume exists transverse to the geomagnetic field.
A mechanism for heavy ion circulation in the magnetosphere is proposed. Singly charged ions heavy ions from the plasmasphere are convected intermittently to the dayside magnetopause, accelerated there, swept into the distant tail lobes and boundary layer, and convected earthward in the plasma sheet to reenter the magnetosphere.
Plasma wave measurements from the IMP-6, IMP-8 and Hawkeye-1 satellites show that a broad region of intense low-frequency electric field turbulence occurs on the high latitude auroral field lines at altitudes ranging from a few thousand kilometers in the ionosphere to many earth radii in the distant magnetosphere. A qualitatively similar, but less intense, type of electric field turbulence is also observed at the plasmapause during magnetic storms. In the auroral regions the turbulence occurs in an essentially continuous band on the auroral L-shells at all local times around the earth and is most intense during periods of auroral activity. In this paper we summarize the basic characteristics of this electric field turbulence and consider the possible role this turbulence may play in the heating and acceleration of plasma in the magnetosphere.
Data on Mercury's magnetosphere and on the plasma, planetomagnetic, and energetic particle environment of the planet obtained in three encounters (Mariner 10 flybys) are compared, and tasks for future research are outlined. The Mercury bow shock and magnetopause are much closer to the planet than the earth counterparts are to the earth. The magnetotail with embedded plasma sheet-field reversal region, global deflection of the solar wind by an intrinsic dipolar magnetic field, variations in solar wind momentum flux, and absence of such features as ionosphere, plasmasphere, and radiation belts, are described. Energetic electrons are accelerated in the magnetotail, however, and the interplanetary magnetic field variations distort Mercury's magnetosphere to produce a southward field associated with substorm-like disturbances.
The configuration of high-latitude electric and magnetic fields is reviewed. Various results suggest that high-latitude magnetic field lines from the outermost regions of the dayside magnetosphere converge toward a point near the noon meridian. Plasma flows, the midday cusp, and a dawn-dusk electric field across the polar cap are characterized. The electric fields associated with plasma flows produce Hall currents on the polar cap which vary with sector structure. Some evidence indicates that polar cap convection may reverse during intervals of strong northward interplanetary field. It is concluded that most observations are consistent with an open field magnetosphere model.
Assuming that the solar wind plasma is usually nonuniform over distances of 10,000 km or less, it is shown that filamentary plasma elements stretched out from the sun can penetrate impulsively and become engulfed into the magnetosphere. The diamagnetic effects associated with these plasma inhomogeneities are observed in outer magnetospheres and magnetosheaths as dips or directional discontinuities in the magnetic field measurements. From the mean penetration distances of these diamagnetic plasma elements one can deduce a mean deceleration time, as well as an approximate value of the integrated Pedersen conductivity in the polar cusp of the earth and Jupiter.
A geometrically explicit three-dimensional model of the magnetosphere is proposed and compared with existing models. The proposed model is a bimodal combination of the classical open and closed magnetosphere. The plasma sheet is topologically contained in a closed field line volume which is exposed to the magnetosheath along the flanks. Boundary layer plasma at the flanks of the closed field line volume freely flows along field lines to the ionosphere and forms a complete border to the plasma sheet. The plasma sheet derives from the closed boundary layer plasma, which is in the same topological volume. The closed boundary layer between the clefts on the dayside is covered by plasma hood (the open field line equatorward extension of the mantle) when dayside merging occurs.
The passage of debris from a high altitude ( 400 km) nuclear burst over the ionospheric plasma is found to be capable of exciting large amplitude whistler waves which can act to structure a collisionless shock. This instability will occur in the loss cone exits of the nuclear debris bubble, and the accelerated ambient ions will freestream along the magnetic field lines into the magnetosphere. Using Starfish-like parameters and accounting for plasma diffusion and thermalization of the propagating plasma mass, it is found that synchronous orbit plasma fluxes of high temperature electrons (near 10 keV) will be significantly greater than those encountered during magnetospheric substorms. These fluxes will last for sufficiently long periods of time so as to charge immersed bodies to high potentials and arc discharges to take place.
The effects of the Satellite Solar Power System (SSPS) on the life support functions of the earth's magnetosphere were investigated. Topics considered include: (1) thruster effluent effects on the magnetosphere; (2) biological consequences of SSPS reflected light; (3) impact on earth bound astronomy; (4) catastrophic failure and debris; (5) satellite induced processes; and (6) microwave power transmission. Several impacts are identified and recommendations for further studies are provided.
Cyclotron emission from a strong magnetic field, has been proposed to identify line feature observed in the hard X-ray spectrum of the neutron star Hercules X-1. If this interpretation is indeed correct, and if the model wherein the 1.24 second hard X-ray pulse is due to the occultation of a more isotropic X-ray flux by an opaque magnetospheric shell is accepted then these observations can be used to place strict limits on the total source luminosity of the cyclotron emission. The observational fate of cyclotron line photons that have emerged from the region near the neutron star surface, but have yet to encounter an opaque shell at the magnetosphere is discussed. It is shown that if a narrow line is incident on such a shell, then a residual narrow feature can emerge from the shell.
The structure of pulsar magnetospheres and the acceleration mechanism for charged particles in the magnetosphere was studied using a pulsar model which required large acceleration of the particles near the surface of the star. A theorem was developed which showed that particle acceleration cannot be expected when the angle between the magnetic field lines and the rotation axis is constant (e.g. radial field lines). If this angle is not constant, however, acceleration must occur. The more realistic model of an axisymmetric neutron star with a strong dipole magnetic field aligned with the rotation axis was investigated. In this case, acceleration occurred at large distances from the surface of the star. The magnitude of the current can be determined using the model presented. In the case of nonaxisymmetric systems, the acceleration is expected to occur nearer to the surface of the star.
The interplanetary magnetic field (IMF) changes and the associated responses of the magnetosphere on November 1, 1972, are examined. IMF Bz changes consisted of a sudden southward turning, a slow northward turning, and a subsequent steady northward sense. Magnetospheric substorms occurred throughout this period.
Transient electric field events were studied by means of the long double-probe instrumentation carried by the Imp 6 satellite, and nine clearly defined exceptionally large amplitude events are described. The events were observed in the midnight sector at geocentric distances of 3.5 to 5.5 earth radii at middle latitudes within a magnetic L shell range of 4.8 to 7.5; the duration is from one to several minutes with peak power spectra amplitudes occurring at a frequency of about 0.3 Hz. The events occur under magnetically disturbed conditions and are often associated with negative dH/dt excursions. The magnetospheric motions calculated for these electric fields indicate a quasi-stochastical diffusive process rather than the general inward magnetospheric collapsing motion expected during the expansive phases of auroral substorm activity. It is likely that the transient electric fields are responsible for the impulsive acceleration and injection of plasma to populate the outer radiation belt.