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First observations of low latitude whistlers using WHU ELF/VLF receiver system

Science China(Technological Sciences) 2017年第1期60卷 166-174页

作者： CHEN YanPing NI BinBin GU XuDong ZHAO ZhengYu YANG GuoBin ZHOU Chen ZHANG YuanNong Department of Space Physics School of Electronic Information Wuhan University Wuhan 430072 China

The recently developed high-quality WHU ELF/VLF receiver system has been deployed in Suizhou, China （geomagnetic lati- tude 21.81°N, longitude 174.44°E, L=1.16） to detect low latitude extremely-low-frequency （ELF： 0.3-3 kHz） and very-low-frequency （VLF： 3-30 kHz） emissions originating from either natural or artificial sources since February 2016. Dur- ing the first-month operation of the receiver system, a total of 3039 clear whistlers have been recorded at this low latitude sta- tion with the majority （97.0%） occurring on 28 February and 1 March 2016. Observed whistlers manifest various types includ- ing single one-hop, echo train, multi-flash, and multi-path. They tend to intensify after local midnight, reach the peak around 04435 LT, and then weaken quickly. Both features of lower cutoff frequencies of most whistlers below -1.6 kHz and almost uniform dispersion for many successive multi-flash whistlers suggest that these whistlers propagate along the geomagnetic field lines in the duct mode. The computed dispersion varies between -15 s1/2 and 23 s1/2 for observed one-hop whistlers and is greater than 50 sm for three-hop echo train whistlers, indicating that the whistlers observed at the Suizhou station are low lati- tude whistlers.

关键词： WHU ELF/VLF receiver whistlers dispersion duct mode

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Bounce-Averaged Acceleration of Energetic Electrons by Whistler Mode Chorus in the Magnetosphere

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Chinese Physics Letters 2007年第1期24卷 294-297页

作者：肖伏良陈良旭周庆华贺慧勇文勇军 School of Physics and Electronic Sciences Changsha University of Science and Technology Changsha 410076 State Key Laboratory of Space Weather Chinese Academy of Sciences Beijing 100080

We construct the bounce-averaged diffusion coefficients and study the bounce-averaged acceleration for energetic electrons in gyroresonance with whistler mode chorus. Numerical calculations have been performed for a band of chorus frequency distributed over a standard Gaussian spectrum specifically in the region near L = 4.5, where peaks of the electron phase space density occur. It is found that whistler mode chorus can efficiently accelerate electrons and can increase the phase space density at energies of about 1 MeV by more than one order of magnitude about one day, in agreement with the satellite observations during the recovery phase of magnetic storms.

关键词： Chorus whistlers Diffusion coefficient Magnetosphere Satellite data Geomagnetic storms

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Frequency Bands and Gaps of Magnetospheric Chorus Waves Generated by Resonant Beam/Plateau Electrons

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Journal of Modern Physics 2022年第6期13卷 864-891页

作者： Konrad Sauer Huayue Chen Eduard Dubinin Quanming Lu CAS Key Laboratory of Geoscience Environment School of Earth and Space Sciences University of Science and Technology of China Hefei China CAS Center of Excellence in Comparative Planetology Hefei China Max-Plnack Institute for Solar System Research G&ouml ttingen Germany

In this paper, the modifications of the whistler dispersion characteristics are investigated which arise if resonant electrons are taken into account. The following chain of processes is emphasized: Generation of whistler waves propagating at different angles to the magnetic field and their nonlinear interaction with resonant electrons result in the appearance of modulated electron beams in the background plasma. As a result, the dispersion characteristics of waves in this new plasma might be significantly changed. By analysing the modified dispersion characteristics these changes are discussed. Supported by particle simulations and space observations, it is assumed that in the electron distribution function at the resonance velocity a plateau-like beam is formed. Because of the weakness of the beam, the term “beam/plateau population (b/p)” is used. By solving the kinetic dispersion relation of whistler waves in electron plasmas with b/p populations, the associated modifications of the whistler dispersion characteristics are presented in diagrams showing, in particular, the frequency versus propagation angle dependence of the excited waves. It is important to point out the two functions of the b/p populations. Because of the bi-directional excitation of whistler waves by temperature anisotropy, one has to distinguish between up- and downstream populations and accordingly between two b/p modes. The interaction of the beam-shifted cyclotron mode ω= Ωe + k⋅Vb (V bVb is the b/p velocity, Ωe: electron cyclotron frequency) with the whistler mode leads to enhanced damping at the ω-k point where they intersect. This is the origin of the frequency gap at half the electron cyclotron frequency (ω~Ωe/2) for quasi-parallel waves which are driven by temperature anisotropy. Furthermore, it is shown that the upstream b/p electrons alone (in the absence of temperature anisotropy) can

关键词： Radiation Belts Waves whistlers Chorus

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Study of Duct Characteristics Deduced from Low Latitude Ground Observations of Day-Time Whistler at Jammu

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International Journal of Astronomy and Astrophysics 2013年第3期3卷 274-277页

作者： M. Altaf M. M. Ahmad Department of Physics National Institute of Technology Srinagar India

Propagation characteristics of low latitude whistler duct characteristics have been investigated based on day-time measurements at Jammu. The morphogical characteristics of low latitude whistlers are discussed and compared with characteristics of middle and high latitude whistlers. The Max. electron density (Nm) at the height of the ionosphere obtained from whistler dispersion comes out to be higher than that of the background which is in accordance with the characteristics of whistler duct. The equivalent width is found to be close to the satellite observations and the characteristics of whistler duct in low latitude ionosphere are similar to those in middle and high latitude ionosphere. The width of ducts estimated from the diffuseness of the whistler track observed during magnetic storm is found to lie in the range of 50 - 200 Km.

关键词： Electron Density Dispersion Duct whistlers Ionosphere

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