Details

Autor(en) / Beteiligte

• Chen, X.‐R.
• Zong, Q.‐G.
• Zhou, X.‐Z.
• Blake, J. Bernard
• Wygant, J. R.
• Kletzing, C. A.

Titel

Van Allen Probes observation of a 360° phase shift in the flux modulation of injected electrons by ULF waves

Ist Teil von

• Geophysical research letters, 2017-02, Vol.44 (4), p.1614-1624

Ort / Verlag

Washington: John Wiley & Sons, Inc

Erscheinungsjahr

2017

Quelle

Wiley Online Library E-Journals

Beschreibungen/Notizen

• We present Van Allen Probe observation of drift‐resonance interaction between energetic electrons and ultralow frequency (ULF) waves on 29 October 2013. Oscillations in electron flux were observed at the period of ∼450 s, which is also the dominant period of the observed ULF magnetic pulsations. The phase shift of the electron fluxes (∼50 to 150 keV) across the estimated resonant energy (∼104 keV) is ∼360°. This phase relationship is different from the characteristic 180° phase shift as expected from the drift‐resonance theory. We speculate that the additional 180° phase difference arises from the inversion of electron phase space density (PSD) gradient, which in turn is caused by the drift motion of the substorm injected electrons. This PSD gradient adjusts the characteristic particle signatures in the drift‐resonance theory, which indicates a coupling effect between the magnetotail and the radiation belt and helps to better understand the wave‐particle interaction in the magnetosphere. Key Points Both electron flux oscillations in response to ULF waves and drift echoes of injected electrons are observed A 360° phase shift in the electron fluxes modulated by ULF waves via drift‐resonance interaction is observed for the first time The unusual phase relationship is associated with the inversion of PSD gradient caused by the drift motion of the injected electrons