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Journal ArticleDOI

Čerenkov radiation within the Earth's upper atmosphere

Syam Sundar De1, B. Ghosh1, Bimal Kumar Sarkar1, M. De1, S. K. Adhikari1 
01 May 1993-Earth Moon and Planets (Kluwer Academic Publishers)-Vol. 61, Iss: 2, pp 169-173
TL;DR: A brief review of Cerenkov radiation within the upper atmospheric plasma has been presented in this article, where the results of analysis about the nature and characteristics of VLF hisses in terms of incoherent Cererkov radiation are given in a concise manner.
Abstract: A brief review of Cerenkov radiation within the upper atmospheric plasma has been presented. Different attempts in this context are systematically discussed. The results of analysis about the nature and characteristics of VLF hisses in terms of incoherent Cerenkov radiation are given in a concise manner. The occurrence of resonance cone has also been reported.
Citations
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26 Dec 1962
TL;DR: In this article, the authors investigated the radiation from a point charge moving uniformly in a plasma, when the charge is moving in the direction of an external magnetic field, and obtained two sets of values of these parameters, the frequency and the angular spectrum of the emitted radiation.
Abstract: The radiation from a point charge moving uniformly in a plasma is investigated when the charge is moving in the direction of an external magnetic field. In general, there are two modes, for each of which all the components of the electric and magnetic field are present. The two parameters of interest in this problem are the ratio of the velocity of the charges to the free-space velocity of electromagnetic waves, and the ratio of the gyromagnetic frequency to the plasma frequency of the electrons. For two sets of values of these parameters, the frequency and the angular spectrum of the emitted radiation are obtained. In certain cases, as many as three Cherenkov rays are found to propagate in the same direction; these multiple-rays, however, correspond to different frequency components and to different modes of propagation. The motivation for this investigation is indicated briefly. (auth)

13 citations

References
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Journal ArticleDOI
TL;DR: In this article, the average rate of energy loss suffered by a charged particle moving in a helical orbit in a homogeneous medium is derived for the Cerenkov excitation of the whistler and ion cyclotron waves.
Abstract: A formula is derived for the average rate of energy loss suffered by a charged particle moving in a helical orbit in a homogeneous medium. In a cold, magnetized plasma it is shown that the Cerenkov excitation of the whistler and ion cyclotron waves depends critically on certain characteristic wave speeds relative to the component of the particle's velocity parallel to the magnetic field. The power spectrum of Cerenkov radiation exhibits sharp peaks not only at the frequencies of the lower and upper hybrid resonances but also at those frequencies at which the ray phase velocity equals the particle's velocity, v∥, parallel to the magnetic field. An intriguing feature of this radiation is that the more slowly the particle moves along the magnetic field, the greater is the emitted radiation; the power emitted in the whistler mode also becomes large when v∥ equals the group speed of those waves that are beamed along the magnetic field. By using a simple graphical construction one can readily locate those direc...

38 citations

Journal ArticleDOI
TL;DR: In this paper, a short dipole antenna in a hot uniaxially anisotropic plasma (B_0→∞) has been studied and the appearance of the cone and the characteristic interference structure in the field is useful from the viewpoint of laboratory diagnostics.
Abstract: The fields excited by a short dipole antenna in a hot uniaxially anisotropic plasma (B_0→∞) have been studied. When ω<ω_p, the dipole effectively excites two propagating waves, a slow wave and a fast wave, inside a cone of half‐cone angle sin^(−1)(ω/ω_p). Inside the cone a characteristic interference structure in the angular distribution of the fields is noted. Outside the cone fields fall off exponentially. The appearance of the cone and the characteristic interference structure in the field is useful from the viewpoint of laboratory diagnostics.

34 citations

Journal ArticleDOI
TL;DR: In this article, two types of emission events are discussed: polar emissions close to the auroral zone occurring only at night-time, and low-latitude emissions having a different character and occurring at daytime.

29 citations