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RBSP observations: Poloidal ULF waves and drift-resonance wave particle interaction

RBSP observations: Poloidal ULF waves and drift-resonance wave particle interaction. Lei Dai, Kazue Takahashi, John Wygant, EFW team. EMFISIS and ECT( MagEIS ) team. EFW/BARREL Science team meeting, June, 2014 Minnesota. Poloidal ULF waves with intense azimuthal electric fields near equator.

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RBSP observations: Poloidal ULF waves and drift-resonance wave particle interaction

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  1. RBSP observations: Poloidal ULF waves and drift-resonance wave particle interaction Lei Dai, Kazue Takahashi, John Wygant, EFW team. EMFISIS and ECT(MagEIS) team. EFW/BARREL Science team meeting, June, 2014 Minnesota

  2. Poloidal ULF waves with intense azimuthal electric fields near equator Large azimuthal electric fields near equator: symmetric poloidal mode/fundamental mode

  3. RBSP observations: Excitations of poloidal ULF waves through drift-resonance wave-particle interaction Dai et al., 2013 GRL, selected by AGU as a ‘Research spotlight’.

  4. RBSP Data Azimuthal electric field ~10mv/m. Radial magnetic field ~3-4nT Oscillations of ion fluxes. Phase is energy dependent. 88keV ions is in-phase and has a high coherence with the azimuthal electric fields, direct evidence of drift-resonance At 88keV.

  5. Drift-resonance N=0, drift-resonance with a symmetric (fundamental) mode Existence of the fundamental mode are hinted from ground observations of Giant Pulsations before. [Green, 1979; Thompson and Kivelson, 2001] Only recently have observations started to identify the fundamental (symmetric) mode of poloidal waves in space [Takahashi et al., 2011;Takahashi et al., 2013] and reveal their correspondence to Giant Pulsations on the ground [Glassmeier et al., 1999;Takahashi et al., 2011]

  6. Identification of the fundamental mode poloidal waves Model results of the fundamental mode poloidal mode [Cummings et al., 1969] with realistic ionosphere boundary condition. Fundamental poloidal mode courtesy of Kazue Takahashi

  7. Free energy source for the wave generation Resonant ions~ 11-12 meV/G Particles lose energy to waves when drifting outward. Free energy for waves= more ions “closer” than “farther out”.

  8. What’s next • Fundamental mode Poloidal waves as the source of Giant Pulsations on the ground. • The occurrence rate and location dependence of Poloidal waves produced by drift/drift-bounce resonance in the inner magnetosphere. • Drift-bounce resonance instability may accelerate relativistic-energy electrons.

  9. END

  10. Intense poloidal ULF waves when the dst index increased at rate faster than normal.

  11. Resonance interaction with ~ 100-200keV ions. However, This is not the core population Of ring current.

  12. END

  13. Intense azimuthal wave electric field and radial wave magnetic fields, with some mixture of compression magnetic field component .

  14. Resonance interaction with ~ 100-200keV ions

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