| The physics mechanics of radiation belt electrons’ acceleration and precipitation are hot topic in space physic research.The interaction between plasma waves and energetic electrons mostly contributes to electrons’ acceleration and precipitation.Based on DEMETER satellite data from 2005 to 2009 year detected by the Instrument for the Detection of Particles (IDP) and the Instrument for the Champ Electrique (ICE), it is the first time that we have studied the space distribution characteristics of two components of electromagnetic waves with different frequency widths emitted by ground-based NTS transmitter. The electromagnetic signal has the central frequency 18.6 kHz and frequency bandwidths 80Hz and 200Hz respectively. According to the features of NTS transmitter ON and OFF of two electromagnetic components, there are three states:ON, HALF, OFF. By the ON-OFF methods for removing the complex background, we study precisely the power spectrum of electromagnetic wave. In this paper, we also study for the first time the precipitation electrons induced by two components of wide and narrow NTS electromagnetic wave (NTS electrons) and show the significance distribution of NTS electrons. It found that there is about 5-10 times enhancement for the NTS electrons induced by NTS transmitter which is investigated in a range of the Mcllwain parameter L(1.8-2.2) and the affected electron energy ranges in 100-400keV.On the one hand,we study the wave-particle resonance interaction between plasma and radiation belts electron from the quasi-linear theory and test particle theory respectively.Based on quasi-linear theory,we found that the pitch angle,mixed and momentum diffusion rates for wave-particle resonance interaction are not only based on the resonance frequency, bandwidth and the amplitude of wave,but also the equatorial pitch angle, energy,magnetic shell and the latitude of electrons.The size of center frequency determines the energy of resonance electrons in a giving L-shell,the wider bandwidth of electromagnetic wave,the greater scope of resonance energy of electrons,but the pitch angle diffusion rate decreases.Additionally,the diffusion rate is proportional to the square of the amplitude,and the electron loss timescale is inversely proportional to the energy of magnetic wave, so we can adjust the amplitude of VLF wave to improve the electron precipitation efficiency in radiation belts.On the other hand, we present the correlation among the energy of NTS electrons, L-shell and electromagnetic frequency. For the test particle theory,taking L=2, the chorus wave spectrum by a center frequency wm=18.6kHz, semi-bandwidth δw=80Hz, we can get a range of 140～150keV of electrons’coupling energy,which is close to the coupling energy 131.5keV calculate by quasi-linear theory.Finally, we compared the image of electronic energy along with L-shell with a diagram of NTS electronic signal-to-noise ratio spectrum, the theoretical analysis results show a good agreement with the satellite observations.In this paper, we can provides beneficial evidences and theoretic support for future observation of radiation belt electrons precipitation induce by ground base VLF wave. |
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