摘要:

The X‐ray spectrum due to atmospheric absorption of Van Allen radiation belt electrons is calculated, on the assumption that small‐angle atmospheric scattering is the dominant loss mechanism for these electrons. It is concluded that the X‐ray flux, although highly variable, at peak intensity should be detectable above the cosmic radiation background at balloon altitudes. A detailed series of balloon measurements of the X‐ray flux at several locations around the earth, including the Capetown region, could provide quantitative data on the rate at which electrons are lost from the radiation belt and, therefore, information on the Van Allen electron source strength. Such measurements would provide an experimental test to differentiate between the neutron decay origin and the local acceleration origin for the Van Allen belt electrons. Furthermore, it should be possible from such observations to make a definitive statement whether the primary loss of outer‐zone electrons occurs through atmospheric scattering or through rapid ‘dumping’ during geomagnetic storms. Specific balloon experiments

ISSN:0148-0227    

DOI:10.1029/JZ066i002p00343

年代:1961

数据来源: WILEY

摘要:

A nuclear emulsion stack was flown through the lower part of the inner Van Allen radiation belt a few days after the intense solar flares of July 10–16, 1959. The stack ‘looked out’ through a thin window on the mounting plate at the rear of the nose cone. Protons with incident energies down to 42 Mev were recorded.The total proton flux is about ⅓ that reported by Freden and White; the difference may be due to the lower peak altitude of the flight reported here. Above 100 Mev the proton spectrum is consistent with the neutron albedo hypothesis. Below 100 Mev, however, there is evidence of structure, with a peak or plateau in the region of 80 Mev. This structure may be due to solar

ISSN:0148-0227    

DOI:10.1029/JZ066i002p00351

年代:1961

数据来源: WILEY

摘要:

The magnetic moment of a charged particle traveling through a hydromagnetic wave does not remain constant. The motion through small, static, transverse perturbations of a uniform magnetic field is calculated. The changes of the magnetic moment are not random. They depend strongly on the number of wavelengths traversed by the particle during one Larmor period and on the pitch angle of the gyration. For sinusoidal waves a resonant decrease of the moment may occur when the particle traverses 0.5 wavelength per Larmor period. For sufficiently peaked waves the moment generally decreases if the particle traverses less than about 0.3 wavelength per Larmor period.

ISSN:0148-0227    

DOI:10.1029/JZ066i002p00359

年代:1961

数据来源: WILEY

摘要:

Theoretical estimates on the nature of hydromagnetic waves in the magnetosphere are reviewed. The calculations of part 1 are applicable near the inner Van Allen belt. The magnetic moment of a fast proton may change significantly in one day. After the mirror point of a proton injected within the belt is raised or lowered by at most a few hundred kilometers the magnetic moment remains constant. A stationary velocity‐dependent distribution of mirror points is established. The existence and finite spatial extent of the inner Van Allen belt are associated with the peak in the hydromagnetic‐wave velocity in that region. Results indicate that mirror points of protons above the belt are continuously lowered into the atmosphere. The disappearance of the Argus electrons during a geomagnetic storm is discus

ISSN:0148-0227    

DOI:10.1029/JZ066i002p00363

年代:1961

数据来源: WILEY

摘要:

Impacts of micrometeorites recorded by the artificial satellite Explorer I in February 1958 have been examined statistically to determine their distribution with latitude, altitude, and longitude relative to the satellite‐earth‐sun angle (satellite local time). The latitude distribution shows an interesting peak near the equator, which is, however, not statistically significant. The distribution in longitude relative to the satellite‐earth‐sun angle corresponds to an altitude distribution and apparently contains no information that is not better shown in this latter distribution. With suitable analysis, the altitude distribution yields information on the velocity of the particles relative to the center of the earth. The conclusion is that the average particle measured by Explorer I was in a closed orbit around the earth rather than on an impact trajectory from a great distance to the surface of th

ISSN:0148-0227    

DOI:10.1029/JZ066i002p00371

年代:1961

数据来源: WILEY

摘要:

Anomalies associated with the Lyrid, δ‐Aquarid, and Perseid meteor showers were observed on the daily phase variation of the 16 kc/s transmission from Rugby, England, to Boulder, Colorado. The effective reflection heights estimated from these anomalies are 80, 81, and 83 km respective

ISSN:0148-0227    

DOI:10.1029/JZ066i002p00379

年代:1961

数据来源: WILEY

摘要:

Recent work related to the interpretation of the observed solar ultraviolet radiation is summarized from two standpoints: (1) the source of energy giving rise to the radiation, and (2) the physical conditions in the solar atmosphere where the radiation originates. Data on the ultraviolet spectrum are of great astrophysical importance for determining the energy balance and thermodynamic structure of the upper solar chromosphere and lower corona, but the lack of adequate atomic cross sections seriously limits the practical astrophysical usefulness of such data.

ISSN:0148-0227    

DOI:10.1029/JZ066i002p00385

年代:1961

数据来源: WILEY

摘要:

First the temperatureTof the corona is discussed, since the spectral distribution of the X‐ray radiation depends on the value ofT. The cross sections for electronic collisions computed by Schwartz and Zirin forswaves yield an upper limit ofTwhich is 1.3 to 1.4·106degrees Kelvin. In pursuance of earlier calculations of the author the X‐ray emission of the corona by free‐free and free‐bound as well as by line emission is discussed. The theoretical results are compared with the observations. The effect of the radiation in the atmosphere of the earth and the intensity distribution across the solar disk is summed up. The emission of the transient region to the chromosphere and of hot spots is considered. Finally the X‐ray radiation during a flare is investigated; some conclusions are drawn from the observations on the physical state of the em

ISSN:0148-0227    

DOI:10.1029/JZ066i002p00391

年代:1961

数据来源: WILEY

摘要:

The author's previous theory of the artificial satellite is derived in terms of the disturbed eccentric anomaly. The present development, in terms of the orbital true longitude, is a substantial improvement over the earlier work in that it leads to the faster convergence for large eccentricities and to a smaller number of terms in the series representing the perturbations. Moreover, each approximation of the radius vector and of the parameters determining the position of the orbit plane is obtained not in the form of a truncated infinite series but in the form of trigonometric polynomials in two arguments. These arguments are the mean true anomaly and the mean argument of the latitude. The present theory, like the previous one, permits the computation of perturbations of any desired order. Thus, any future information about earth's gravitational field can easily be included.

ISSN:0148-0227    

DOI:10.1029/JZ066i002p00403

年代:1961

数据来源: WILEY

摘要:

This paper deals with the geometry of radio rays originating at an arbitrary point in a force‐free dipole magnetic field. The echo surface, defined by the points where the rays intersect the field at right angles, is calculated. The distance from the source point to the echo surface is computed and plotted for various configurations. Assuming an opaque sphere in the field, the solid angle subtended at the source by the echo surface as well as the height of the echo surface above the sphere is computed and plotted. This is done also for the derivative of the angle between the ray and the magnetic field, evaluated at the echo surface. Graphs are drawn only for rays lying in the magnetic meridian plan

ISSN:0148-0227    

DOI:10.1029/JZ066i002p00411

年代:1961

数据来源: WILEY