摘要:

The purpose of this report is to outline a possible method of removing high‐energy particles from natural or artificially produced radiation belts. This method is based on the idea of the geocyclotron [Helliwell and Bell, 1960] and in essence is the time reversal of the geocyclotron mechanism.In this inverse geocyclotron interaction the object is to de‐energize high‐energy electrons by means of gyroresonance, a phenomenon in which electrons in the earth's outer ionosphere are decelerated by frequency‐modulated, circularly polarized electromagnetic waves generated on the ground. These waves would be guided approximately along the earth's magnetic field lines in the whistler mode until they reach a region suitable for interaction. In the interaction region, electrons in the proper relativistic energy band will see a wave whose frequency is equal to the electron's natural relativistic frequency of rotation about the field lines (i.e., the electron's relativistic gyrofrequency). If the wave frequency increases slowly with time, it is possible to trap a number of these relativistic particles for a time in the potential well of the wave; during this period the particles can be continuously dece

ISSN:0148-0227    

DOI:10.1029/JZ069i001p00177

年代:1964

数据来源: WILEY

摘要:

The notation and classification of geomagnetic micropulsations have been discussed in two recent letters in this Journal [Matsushita, 1963;Jacobs et al., 1963]. At the 13th General Assembly of the International Union of Geodesy and Geophysics (IUGG) in Berkeley, California, August 1963, the question was considered in some detail by Committee 10 of the International Association of Geomagnetism and Aeronomy (IAGA). A small subcommittee, consisting of the four authors of this note, was set up to submit the recommendations which are presented below.From experimental knowledge, particularly that obtained since the IGY, it has been recognized that micropulsations can be divided into two main classes: those of a regular and mainly continuous character, and those with an irregular pattern. The first class covers the whole range of micropulsations with periods from about 0.2 to 600 sec. They can be divided into subgroups depending on their period, but it is extremely difficult to decide where the boundaries should be drawn. A purely mathematical division can be made, based perhaps on a logarithmic scale, or a division can be based on their physical and morphological properties. The second approach was adopted, and Table 1 gives the proposed classification and notation.

ISSN:0148-0227    

DOI:10.1029/JZ069i001p00180

年代:1964

数据来源: WILEY

摘要:

Instruments carried on earth satellites continue to reveal the distribution and time behavior of the earth's trapped radiation environment in increasing detail, yet remarkably little is known of the sources of the energetic particles that make up this environment. The vast majority of the particles probably derive their energy from dynamic processes (i.e., electric fields, time‐varying magnetic fields, hydromagnetic waves, etc.) in the magnetosphere, but there is, at present, practically no firm knowledge about the nature of these processes. It is likely that the acceleration processes are associated in some way with gross motions of the low‐energy (cold) plasma, such as those induced by the flow of the solar wind around the boundary of the magnetosphere cavity [Axford and Hines, 1961] or by the rotation of the earth [Hones, 1963a]. Therefore the inability, in measurements of the natural trapped radiation, to identify specific particles or groups of particles, to follow them as they move through the magnetosphere, or to measure the changes in their energy is a serious handicap in the effort to develop an understanding of magnetosphere dynam

ISSN:0148-0227    

DOI:10.1029/JZ069i001p00182

年代:1964

数据来源: WILEY

摘要:

In view of the vast amount of data accumulating from Alouette, the Canadian topside sounder satellite [Chapman, 1963], it is highly desirable to establish the accuracy of this technique by comparing the electron density profiles obtained by Alouette with similar data obtained independently. This accuracy affects the geophysical interpretation of the data as well as the possibility of using the topside sounder to calibrate ground‐based techniques such as the incoherent backscatter radar. There are two possible sources of errors in the electron density profiles derived from topside sounders. The first one is associated with the method of converting the observed ionograms to true‐height profi

ISSN:0148-0227    

DOI:10.1029/JZ069i001p00186

年代:1964

数据来源: WILEY

摘要:

Introduction. Valuable information about the behavior of the ionized layers in the upper atmosphere may be acquired during periods of solar eclipse, when ionizing radiation from the sun is varied gradually and smoothly over a 2‐hour period. If, as most recent studies indicate, the ionized layers in the upper atmosphere result primarily from various ionization reactions due to solar X rays in the wavelength region between 10 and 600 A [Friedman, 1960], removal by eclipse of the source of these radiations should have detectable effects upon the extent of ionization in the regions of the ionosphere. Modern radio techniques permit the study of ionospheric behavior in considerable detail, and experiments have been performed during past eclipses with the aid of ionosondes, riometers, and high‐frequency (HF) oblique‐sounding equi

ISSN:0148-0227    

DOI:10.1029/JZ069i001p00190

年代:1964

数据来源: WILEY

摘要:

During the evening of September 24, 1963, strong auroral echoes were received on theS‐band research radar at Cornell Aeronautical Laboratory near Buffalo, New York. The radar, which operates at 2850 Mc/s, has an unobstructed northern horizon. Between 2015, when observations commenced, and 2200 EDT, many echoes were observed. The strongest was 18 db above noise, which corresponds to a peak radar cross section of 10−

ISSN:0148-0227    

DOI:10.1029/JZ069i001p00194

年代:1964

数据来源: WILEY

摘要:

In this note the effect of Coulomb collisions on incoherent scattering and, in particular, on the gyroresonance phenomenon is investigated, though in a rather approximate way. It is shown that in many situations ion‐ion interactions can completely destroy the resonance at the iongyrofrequency, even though the ion‐ion ‘collision frequency,’ as it is usually defined, is much less than the ion gyrofrequency. The electron gyroresonance is also affected by the Coulomb collisions involving the electrons, but this effect is apt to be much less severe.A number of authors [Farley et al., 1961;Fejer, 1961;Hagfors, 1961;Salpeter, 1961] have demonstrated that the incoherent scattering of radio waves from a collisionless plasma in a magnetic field should, under certain conditions, exhibit gyroresonance effects. The radio wavelength used for incoherent scattering experiments is often small compared to the Debye length and the ion gyroradius. If this is the case, and if the radio beam is sufficiently narrow and directed approximately normal to the magnetic field, the power spectrum of the backscattered wave will have peaks corresponding to Doppler shifts which are approximate multiples of the ion gyrofrequency. If more than one species of ion is present, each gyrofrequency will appear in the spectrum. The autocorrelation function of the scattered signal (the Fourier transform of the power spectrum) will have peaks at time delays approximately equal to the different iongyroperiods. A qualitative understanding of this result can be obtained by supposing, as a crude model, that the plasma is composed of ions that move independently of each other and are surrounded by a neutralizing cloud of electrons. If a radar is directed perpendicular to the magnetic field, the helical motion of the ions and the associated electron clouds will appear to be completely periodic, since the radar will not be affected by the random motion along the lines o

ISSN:0148-0227    

DOI:10.1029/JZ069i001p00197

年代:1964

数据来源: WILEY