摘要:

The rate of ionization and the omnidirectional flux of charged particle radiation were measured near Venus by an integrating ionization chamber and two Geiger‐Müller counters on Mariner 2. The instruments detected protons withE≥10 Mev and electrons withE≥0.5 Mev by direct penetration; lower‐energy electrons were detected through the bremsstrahlung process. Mariner approached within 41,200 km of Venus center, and no increase of radiation above the interplanetary level was measured. Upper limits to the increased fluxes of various species of particles in the vicinity of Venus are 0.04 penetrating particle/cm2sec, 1.3×105/cm2sec electrons withE≃40 kev, or 8.0×103/cm2sec electrons withE≃100 kev. It is concluded that no magnetosphere comparable to the earth's was penetrated. Assuming that dipole moments scale as the cube of the dimensions of the magnetosphere and that Venus' dipole moment is perpendicular to the plane of the ecliptic, we calculate that Venus moment is no greater than 20 per cent

ISSN:0148-0227    

DOI:10.1029/JZ069i013p02651

年代:1964

数据来源: WILEY

摘要:

The presence of an interplanetary magnetic field in the vicinity of the earth is now fairly well established, and several authors have proposed that the long duration of solar proton events is due to the storage of protons in the tubes of force of this field, which we shall assume to be of solar origin. According to one model, protons emitted by a flare diffuse through the solar atmosphere, gradually leaking off into the interplanetary field where they are stored for comparatively long periods. The early anisotropic phase of a solar proton event presumably represents the filling of the earth's local tube of force by this mechanism. An attempt is made to treat the diffusion through the solar atmosphere in a quantitative fashion, and the results are applied to measurements carried out by Explorer 12 on September 28, 1961. These data appear to fit the theory and permit a determination of the diffusion constant. Application of classical diffusion theory, though admittedly of dubious validity, yields a mean free path of about 600 km for protons of a few hundred Mev energy.

ISSN:0148-0227    

DOI:10.1029/JZ069i013p02659

年代:1964

数据来源: WILEY

摘要:

Explorer 6 satellite data and surface magnetograms are used to study the gradual and sudden commencement geomagnetic storms of August 16–18, 1959. Analysis of these data provides the following conclusions: (1) The geomagnetic field was strongly perturbed but retained its essentially dipolar character out to geocentric distances of 8 earth radii. (2) A long‐period variation in the distant field coincided withDstat the surface. The magnitude of the main‐phase decrease at ∼4REwas ∼2.5 times larger than at the surface. Variations in the field direction at ∼7REcorrelate with half‐day variations in (a) the horizontal component at the surface and (b) the 3‐hourKindex. (3) Large irregular field fluctuations with periods exceeding one minute were characteristic of the storm period. (4)The large‐scale storm field was qualitatively similar to the disturbance field observed previously on nonstorm days. The disturbance field appeared to evolve from quiet to disturbed conditions and then to

ISSN:0148-0227    

DOI:10.1029/JZ069i013p02669

年代:1964

数据来源: WILEY

摘要:

An empirical formula giving attenuation as a function ofF2peak ion density and hydromagnetic‐wave frequency has been applied to a nine‐month data sample of hydromagnetic emissions (quasi‐sinusoidal oscillations of the earth's magnetic field in the frequency interval around 1 cps). Under the hypothesis that these signals are attenuated as they propagate downward through the ionosphere as hydromagnetic waves, the amplitude and frequency spectrum above the ionosphere at middle latitudes has been de

ISSN:0148-0227    

DOI:10.1029/JZ069i013p02689

年代:1964

数据来源: WILEY

摘要:

The results of part 1 concerning attenuation as a function ofF2peak ion density and hydromagnetic‐wave frequency have been applied to correct a number of studies of times of occurrence of hydromagnetic emissions at middle and upper latitudes. It is shown that most of these studies then roughly agree with the recent study by Heacock and Hessler of data from College, Alaska, which implies a daytime predominance of occurrence. It is concluded that hydromagnetic emissions are preferentially present above the ionosphere at middle and upper latitudes during the afternoon with relative morning: afternoon: night occurrence rates of approximately 3 : 4 :

ISSN:0148-0227    

DOI:10.1029/JZ069i013p02699

年代:1964

数据来源: WILEY

摘要:

The problem of the stability of the interface between the solar wind and the magnetosphere is investigated by means of hydromagnetic equations. An explicit criterion of instability is written for the special case in which both the solar plasma and the magnetospheric medium are supposed to be of the same density and carry a uniform magnetic field in the direction of streaming. It is concluded that the magnetospheric boundary is likely to be unstable toward the tail and under comparatively quiet solar conditions. It is suggested that the characteristic effects of instability should be observed toward the night side, preferably with space exploration vehicles.

ISSN:0148-0227    

DOI:10.1029/JZ069i013p02707

年代:1964

数据来源: WILEY

摘要:

From the conventional expansion of a scalar magnetic potential (such as the earth's), an expansion of the vector potential is obtained. This expansion is used for analyzing the motion of charged particles in axisymmetric magnetic fields, with special attention to such fields that do not deviate far from a dipole. The results are compared with those of Quenby and Webber. Finally, the relation between Störmer's first integral and the third adiabatic invariant is traced

ISSN:0148-0227    

DOI:10.1029/JZ069i013p02715

年代:1964

数据来源: WILEY

摘要:

Particle flux measurements and radio and optical measurements on auroras were made concurrently with detectors aboard a polar orbiting satellite near the northern auroral zone. The incident particle energy deposition was measured in two shielded plastic scintillators with electron thresholds of 2 and 28 kev. Data were obtained for six satellite passes over the auroral zone, and for parts of four passes incident particle information was acquired simultaneously with optical and radio measurements. Large variations in the energy distribution of the precipitating particles were observed. On the basis of the assumption that the incident particles were all electrons, the maximum flux observed in the downward direction was determined to be approximately 100 ergs/cm2sec ster of electrons with energy greater than 2 kev. The dominant energy contribution to the auroras was from electrons with energies less than 28 kev. Correlations with ground‐based measurements showed that, in at least one rather unusual auroral form and in the regions of low‐level luminosity outside discrete forms, electrons of energies less than a few kev carried a significant fraction of the precipitated ene

ISSN:0148-0227    

DOI:10.1029/JZ069i013p02721

年代:1964

数据来源: WILEY

摘要:

A study of observations of auroral returns at 19.4 Mc/s made with a low‐powered transmitter from a geomagnetic latitude of 54°N (dip angle 73°) over a period of three years has quite consistently indicated the presence of field‐aligned ionization. Shortly after ground sunset the reflections have been observed on 25 to 95 per cent of the days of each month during the period 1961–1963. Although the auroral echoes occur more frequently with increasing magnetic index, they are also recorded during quiet days. Frequency of occurrence shows a peak shortly after sunset throughout the year. The time of maximum activity, the presence of reflections without magnetic storms, and the direction of the echoes lead to the hypothesis that this field‐aligned ionization occurs during periods of magnetic field changes. The altitude of the field‐aligned variations tends to be 200–400 km during quiet periods and 100 km during disturbed magnet

ISSN:0148-0227    

DOI:10.1029/JZ069i013p02731

年代:1964

数据来源: WILEY

摘要:

The equivalent brightness temperatures of the radio frequency radiation produced by the high‐altitude nuclear explosion of July 9,1962, have been calculated. These calculations extend the work of Nakada in three principal respects. They deal with the intensity to be expected (a) by ground‐based stations at high geomagnetic latitudes, (b) by a satellite whose orbit crosses the equatorial plane, and (c) at high frequencies. The results of these calculations are compared with the limiting intensities measurable by modern radio‐astronomical techniques. It is shown that at frequencies of a few megacycles per second the artificial radiation must be very near the limits of detection of modern satellite‐borne receivers and that it may be a hazard to accurate work on the galactic spectrum below

ISSN:0148-0227    

DOI:10.1029/JZ069i013p02737

年代:1964

数据来源: WILEY