摘要:

We present evidence for the existence of a hitherto unrecognized flux of nuclei of a charge of 6 ≲Z≲ 26 and kinetic energies of35. This flux is in qualitative agreement with estimates of the flux expected from re‐entrant albedo, produced by interactions of primary Fe group nuclei in the atmosphere. We consider the implications of these findings for observations of the flux of very heavy primary c

ISSN:0148-0227    

DOI:10.1029/JA077i031p06037

年代:1972

数据来源: WILEY

摘要:

Ionization of the lunar atmosphere by solar photons and solar‐wind particles will create perturbations in the solar wind. Observations by lunar‐orbiting Explorer 35 show that any such perturbations are generally10%. The perturbations occasionally observed may be due to transient increases in the atmosphere or to some other cause. Upper limits on the steady‐state atmosphere, which correspond to a perturbation of 10%, can be determined if the coupling between the ionized atmosphere and the solar wind is known. Upper limits are given here for two coupling limits: a single‐fluid limit, in which the ions instantly join the solar‐wind flow, and a two‐fluid limit, in which the ions are coupled to the wind by the steady solar‐wind electric and magnetic fields. The results give upper limits on the surface density of between 10³ and 105cm−3for H, H2, He, Ne, A, O, O2, N, N2, H2O, OH, NO, N2O,

ISSN:0148-0227    

DOI:10.1029/JA077i031p06042

年代:1972

数据来源: WILEY

摘要:

Numerical simulations have provided detailed information of the microscopic processes that occur in a high Mach number oblique shock wave such as the bow shock. The gross feature of the ion dissipation is a strong interaction of the reflected ions with the whistler precursor, which can be explained by a nonlinear ion‐ion counterstreaming instability. The instability simultaneously amplifies the magnetic oscillations of the whistler, which supports the strong magnetic turbulence at the bow shock. In addition, electrostatic substructures have been observed that significantly enhance the thermalization of the ion distribution on the Debye scal

ISSN:0148-0227    

DOI:10.1029/JA077i031p06052

年代:1972

数据来源: WILEY

摘要:

This paper re‐examines and reinterprets the interesting bow shock crossing of Pioneer 6 on December 16, 1965, by combining the high‐resolution data for the magnetic field measurements and all the available plasma data. It is shown that, although a small correction of the magnetic field data improves the validity test of the MHD Rankine‐Hugoniot (R‐H) conditions, it is the plasma density measurements that are the principal source of the remaining inconsistencies. With the exception of the densities, the best agreement between the measurements and the R‐H relations is obtained when the specific heat ratio γ is slightly less than the classical value of 5/3 expected for a magnetized plasma in the magnetosheath. A more accurate shock normal determination has been made, and it is found that the shock itself is possibly in motion with respect to the earth and that locally it may be approximated as a no

ISSN:0148-0227    

DOI:10.1029/JA077i031p06060

年代:1972

数据来源: WILEY

摘要:

From solar‐wind plasma observations on the lunar orbiting Explorer 35 satellite, multiple boundary crossings have been analyzed to give statistical information on the tail boundary motions at lunar distance. In eleven months of observations, more than twice as many crossings occurred on the dawn side as on the dusk side, indicating a dawn‐dusk asymmetry. The amplitude of boundary motion, given by the standard deviation of the observed positions around the average value, is 4.9REon the dawn side and 2.8REon the dusk side. Histograms of the time intervals between boundary crossings indicate two time scales are simultaneously present (16.7 min and 63.3 min, dawn‐side values). A fit of the number of crossings and the histogram data to models of the motion indicates that the amplitude of the long‐period motion is 2 to 3 times larger than that of the short‐period motion. The inferred speeds for both motions lie in the range 10 to 20 km / sec. The models estimate the thickness of the plasma boundary layer

ISSN:0148-0227    

DOI:10.1029/JA077i031p06071

年代:1972

数据来源: WILEY

摘要:

The equation governing the distribution function of high‐energy protons in the earth's radiation belt has been modified to include the effects of the secular change of the earth's magnetic dipole moment in addition to the effects of albedo neutron decay, collisional energy loss, and radial diffusion, which have been studied in the past. Because the time scale of the magnetic‐field change (∼2000 years) is much longer than the time scale of proton trapping (∼200 years) an approximate solution of the equation can be obtained. This solution indicates that the shrinking dipole increases the distribution function at the geomagnetic equator for 1.15

ISSN:0148-0227    

DOI:10.1029/JA077i031p06087

年代:1972

数据来源: WILEY

摘要:

The ΔBdistribution deduced from the Ogo 3 and 5 satellites shows large field depressions in the equatorial region inside the plasmasphere. The existence of this −ΔBregion is established by demonstrating that contours of differential ΔB, derived by ΔB(Kp= 2–3) − ΔB(Kp= 0–1), have characteristics similar to those of ΔBcontours, and thus the possibility is eliminated that the ΔBdistribution in question may have arisen from errors in the reference fields used to calculate ΔBor systematic errors in the orbit determination. On the basis of the ΔBdistribution it is shown that what is usually considered the quiet‐time ring current is an equatorial sheet current that is an extension of the neutral sheet current in the magnetospheric tail. The primary source of the large field reductions inside the plasmasphere is a population of protons with energies of 0.1–1 Mev initially detected by Davis and Williamson (1963) and Davis (1965) on Explorer 12, 14, and 15. Low‐energy protons extensively measured on Ogo 3 by Frank (1967, 1971) are primarily responsible for the current near and outside the plasmapause. Although the sources of the current are identified with the workers who discovered protons in these two different energy ranges, the division of the sheet current into two separate current belts is arbitrary and inadvisable unless future experiments indicate the necessity for such a division. The presently available magnetic‐field data are concordant with a sheet current continuous from the tail to 2.5RE. It is suggested that from the standpoint of particle dynamics in the magnetosphere an equatorial charged‐particle sheet including all energies may be a more useful concept than the conventional concepts of the plasma

ISSN:0148-0227    

DOI:10.1029/JA077i031p06093

年代:1972

数据来源: WILEY

摘要:

Large fluxes of energetic heavy ions (M/q≈ 16) were observed in the inner magnetosphere during the geomagnetic storm of December 17, 1971. The observations were made by a set of energetic‐ion mass spectrometers covering the energy range 0.7–12 kev on board the polar‐orbiting satellite 1971‐089A (800‐km altitude, ≈0300 LT). Significant heavy‐ion fluxes were observed for a period of approximately 48 hours during the main phase of the storm. The heavy‐ion fluxes frequently exceeded the proton fluxes in the 0.7‐ to 12‐kev energy range. The heavy‐ion spectrums were highly variable and frequently contained a peak of several kev. The heavy ions were observed over a wide latitudinal range (2.4 ≲L≲ 9) and generally extended to somewhat lower latitudes than the protons. The peak energy flux of these ions was approximately 0.4 erg/cm² sec ster, which is substantial in terms of expected observable ionospheric effects. They may also contribute significantly to the storm‐time magnetic‐field depression (Dst), since at the same flux they represent an energy density greater by a fact

ISSN:0148-0227    

DOI:10.1029/JA077i031p06104

年代:1972

数据来源: WILEY

摘要:

Auroral particle fluxes have been measured by detectors aboard the low‐altitude, polar‐orbiting satellite OVI 18. Electron pitch‐angle distributions in the energy range 0.8 to 16 kev are presented for a 3‐month period in 1969. The distributions at all energies were found to be predominantly isotropic for intensities above a few times 106(cm² sec ster kev)−1, independent of latitude and geomagnetic conditions. This result suggests that strong pitch‐angle diffusion is almost always operating on auroral field lines at higher electron intensities. At lower intensities and energies above a few kev, fluxes in the loss cone on the average were found to decrease with decreasing pitch angles, indicating an intensity dependence of the diffusion strength. Occasionally field‐aligned angular distributions were observed at electron energies below a few kev. These anisotropies are discussed on the basis of parallel electric fields in conjunction with pitch‐

ISSN:0148-0227    

DOI:10.1029/JA077i031p06111

年代:1972

数据来源: WILEY

摘要:

The Isis 1 satellite has made measurements of several ionospheric and related parameters, and the results of the various measurements have been compared in detail for two north transpolar passes during the geomagnetic storm of February 3, 1969. Simultaneous measurements were made of local electron and ion densities and temperatures, electron density between the satellite and the peak of theFlayer, radio noise, and particle fluxes over a wide energy range extending down to 10 ev. Several features of the ionosphere (in particular, enhancements of radio noise, scale height, and plasma temperatures) appear to be due to soft‐particle (100 ev to 1 kev) precipitation, which is related to magnetospheric structure as delineated by the observation of more energetic particles. The magnetosheath particles precipitating on the dayside of the polar cap are particularly effective. Although soft particles appear to exert an important influence on the topside ionosphere, they alone cannot account for the observed distribution of ionization, and ionization transport may also be importan

ISSN:0148-0227    

DOI:10.1029/JA077i031p06121

年代:1972

数据来源: WILEY