摘要:

The OGO 1 satellite has yielded evidence for both ducted and nonducted modes of whistler propagation in the magnetosphere. Two new types of nonducted whistlers have been identified: the ‘magnetospherically reflected’ whistler and the ‘Nu’ whistler. These whistlers have never been observed on the ground. Their unique properties result in part from the presence of ions that permit reflection of whistler‐mode energy in the magnetosphere. These phenomena provide a new tool for study of the distribution of ionization in the magnetosphere. Ducted whistlers from OGO 1 have provided the first in situ observations of whistler ducts. NearL= 3, the equatorial separations between ducts ranged from 50 to 500 km, and the equatorial thicknesses were about 400 km. The analysis yielded independent experimental support for the diffusive equilibrium model of distribution of ionization along the field lines in the plasmasphere. Some evidence was found of distortion of the magnetic field on the nightside atL∼ 3, possibly due to oblique incidence of the solar wind on the ea

ISSN:0148-0227    

DOI:10.1029/JA073i001p00001

年代:1968

数据来源: WILEY

摘要:

In April 1967 five Nike‐Apache rockets were launched from Kiruna, Sweden, carrying barium release and electron concentration experiments. The component of the electric field transverse to the magnetic lines of force is derived from the motion of the ion clouds. The electron concentration measurements provide ionospheric conductivities. The magnitudes of the electric fields varied between 2 and 20 v/km. Their directions were northwestward for evening conditions and southwestward for morning conditions. The magnetic perturbations on the ground that would result from ionospheric currents derived on the basis of the measured fields and conductivities closely resemble the actual ground magnetometer data. The electric fields vary appreciably with space and time; they can even reverse their directions over distances of the order of 60 k

ISSN:0148-0227    

DOI:10.1029/JA073i001p00021

年代:1968

数据来源: WILEY

摘要:

A theory and methodology for investigating the ion chemistry governing mesospheric electron concentrations is presented. In this theory, macroscopic reaction coefficients are defined in terms of the microscopic chemical reactions that take place between positive ions, electrons, and negative ions. The role of minor constituents of the atmosphere, O, O3, CO2, NO, and NO2, is discussed using reaction rates measured in the laboratory. One reaction, the associative detachment of O2−by atomic oxygen, is so fast that mechanisms for inhibiting or suppressing this reaction are required. The need for such mechanisms is dictated by field data on riometer absorption induced by the nuclear explosions of the 1962 Christmas Island air drops. The importance of terminating negative ions, i.e., negative ions that withstand the attack of atomic oxygen, is emphasized. Also emphasized is the influence of the ion‐ion mutual neutralization coefficient of terminating negative ions. Four illustrative models of the ion chemistry are presented ranging from the simplest O2−model, which is certainly unrealistic, to a more complex model involving six species of negative ions. This model, which is suggested by recent measurements of reaction rates in the laboratory, does not include the effect of water vapor in the reaction scheme since little laboratory data exist on the reaction of negative ions with

ISSN:0148-0227    

DOI:10.1029/JA073i001p00027

年代:1968

数据来源: WILEY

摘要:

Interplanetary shock waves propagating through the solar wind have been observed with hemispherical plate electrostatic analyzers aboard the twin Vela 3 satellites. From the consideration of mass flux continuity, the shock velocities have been calculated; the shock velocities determined from the data in this manner are consistent with the observed temperature changes across the shocks. These velocities are significantly less than themeantransit velocities of the shocks from the sun to the earth derived from the delay times between the initiating flares and shock arrival. This result is interpreted to mean that interplanetary shock waves are decelerated as they expand and propagate through the quiescent solar plasma.

ISSN:0148-0227    

DOI:10.1029/JA073i001p00043

年代:1968

数据来源: WILEY

摘要:

Ion spectrums and magnetograms obtained simultaneously when the Vela 3A satellite crossed the earth's bow shock have been correlated. An intermediate form of ion spectrum, representing neither solar wind nor magnetosheath, but characterized by an irregular envelope and occasional large flux peaks, is found to correspond to the appearance of large‐amplitude (10‐25 γ), irregular magnetic oscillations of 4‐to 30‐sec period. The large spectral flux peaks of the shock seem to result from localized transient accelerations and decelerations of the bulk of the solar wind protons. Smaller amplitude (<5 γ), longer period (20‐60 seconds), generally more regular magnetic oscillations are seen in the solar wind outside the shock where the direction of flow of ion flux peaks is found to oscillate in close correlation with mag

ISSN:0148-0227    

DOI:10.1029/JA073i001p00051

年代:1968

数据来源: WILEY

摘要:

Power spectra from 3 × 10−4to 0.5 cps based on Mariner 4 interplanetary magnetic field data show a dependence on frequency ƒ that is roughly of the form ƒ−γwith γ typically near 3/2 and essentially always between 1 and 2 for each of the three components and for the absolute value of the field. This is based on the analysis of data for days of widely ranging degrees of activity near solar minimum. Power levels were typically a factor of 10 higher for disturbed than for quiet days and, except on quiet days, were a factor of 2 higher for the various components than for the absolute value. Data relating to frequently occurring field discontinuities show few shocks and many contact surfaces. The associated current sheets are found to be unusually thin, roughly 50% of those analyzed had thicknesses less than 3500 km and 10% less than 500 km. The structure of the current sheets that produced the cleanest discontinuities was analyzed and shown to be consistent with that of a tangential discontinuity characterized by zero normal field and normal velocity components. The directional distribution of current sheet normals strongly suggests a local latitudinal solar wind shear that prevails over one sector and can change from sector to sector. The cross sections of magnetic filaments are found to be in some cases highly elliptical rather than more‐or‐less circular, again suggesting a latitudinal sola

ISSN:0148-0227    

DOI:10.1029/JA073i001p00061

年代:1968

数据来源: WILEY

摘要:

Second adiabatic theory is used to derive an asymptotic expression for the bounce‐averaged rate of kinetic energy change experienced by charged particles trapped in electric and magnetic fields that conserve the first two invariantsMandJof their motion. The restriction that there exists no electric fieldE∥, parallel to the magnetic field, reduces by one order in the adiabatic expansion parameterm/efrom itsE∥≠ 0 value. If in addition the magnetic field arises solely from, and convects rigidly with, the arbitrary motion of a perfectly conducting magnet, we find that is smaller by yet another order inm/e. Our results generalize and confirm the conclusions of Hones and Bergeson who considerE∥= 0 and the special case of a uniformly rotating conducting magnetized sphere with nonaligned rotation and magnetiza

ISSN:0148-0227    

DOI:10.1029/JA073i001p00083

年代:1968

数据来源: WILEY

摘要:

Observation of solar protons in the 1–100 Mev interval during the solar proton event of September 2, 1966, shows that: (a) an important day‐night asymmetry in the geomagnetic cutoffs exists, with the flux starting to decrease from the polar plateau value at higher invariant latitudes nearer the noon meridian than the midnight meridian; (b) the asymmetry is more pronounced for the lower energy particles. Direct and indirect measurements of pitch‐angle distributions show that a quasi‐trapped flux of protons is established at high altitudes on the dayside of the polar cap. The nonisotropic pitch‐angle distribution at invariant latitudes less than 75° near local noon is a manifestation of limited access of solar protons to some local times and is associated with the midday absorption recoveries observed with

ISSN:0148-0227    

DOI:10.1029/JA073i001p00087

年代:1968

数据来源: WILEY

摘要:

The velocity distribution of daytime ionospheric photoelectrons in the energy range 7–20 ev has been investigated at altitudes near 600 km by measuring the intensity of radar Thomson scatter from the steady‐state level of plasma waves in the ionospheric plasma. This intensity depends on the velocity distribution through plasma wave‐particle interactions such as Landau damping. The measurements were carried out at the Arecibo Ionospheric Observatory (L≈ 1.5, geographic latitude 18°N). The experimental values for the vertically upward flux of photoelectrons are in the range (3–10) × 108cm−2sec−1, and, for the upward energy flux, (3–13) × 109ev cm−2sec−1. The experiments show that the daytime downward flux is equal to the upward flux to within experimental error (±50%) at Arecibo. Some December 1966 observations during the presunrise and postsunset periods have detected photoelectrons originating at the magnetic conjugate point. The effect of a weak (ωp>ωc) magnetic field on the Landau damping of plasma waves by a Maxwellian velocity distribution was investigated by changing the angle θ between the radar beam and the magnetic field. The theoretical prediction that the Landau damping is orders of magnitude larger than the field‐free case and depends strongly on angle

ISSN:0148-0227    

DOI:10.1029/JA073i001p00097

年代:1968

数据来源: WILEY

摘要:

The wind‐shear theory of the formation of temperate‐zone sporadicElayers is extended to take into account effects associated with a neutral wind profile having a descending phase velocity. It is shown that layers of long‐lived ions (presumably of meteoritic origin) that are formed at higher altitudes are carried down with the wind profile to a region roughly 85–95 km in altitude, where they are dumped. Above about 95‐km altitude the layers are trapped in portions of the neutral wind profile having a shear of the correct sign according to the simple (equilibrium) form of the wind‐shear theory. Below about 95 km the layers are not trapped in this manner, and their position shows no obvious correlation with the sign of the neutral wind shear. The effects of diffusion are discussed, and an expression for the equilibrium width of a sporadicElayer

ISSN:0148-0227    

DOI:10.1029/JA073i001p00111

年代:1968

数据来源: WILEY