Observation and Fully Thermal Simulation of Quasi‐Electrostatic Magnetosonic Waves

Fast magnetosonic (MS) waves have also been known as "equatorial noise" (Russell et al., 1969) as they are mostly observed near the geomagnetic equator. MS waves can interact with radiation belt electrons in various ways. They can not only accelerate radiation belt electrons through Landau resonance (Horne et al., 2007), but also interact with electrons through bounce resonance (Fu et al., 2019;Shprits et al., 2013). In addition, there is transit time scattering when electrons bounce through the limited range of MS wave occurrence in latitude (Bortnik & Thorne, 2010;J. Li et al., 2014;X. Yu et al., 2020). The evaluation of electron scattering by MS waves, either based on quasi-linear theory or through test particle simulations, has traditionally involved the assumption that MS waves follow the MS/whistler branch of the cold plasma dispersion relation (CPDR)

Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Wave Dispersion Relationsmentioning

confidence: 93%

See 1 more Smart Citation

Scattering of Radiation Belt Electrons by Fast Magnetosonic Waves: Considering the Kinetic Effects

Yao

Liu

et al. 2023

“…The fully thermal simulation is conducted by adopting the fitted electron distribution (Gao et al., 2021; Gary & Saito, 2003; Horne, 1989, 2015; Long et al., 2023; Tao et al., 2010; Zhou et al., 2017). The total electron density is 2.0 cm −3 and the equatorial magnetic field is 85.0 nT, which are the averaged values from EMFISIS data.…”

Section: Calculationmentioning

confidence: 99%

Efficient Scattering Loss of Energetic Electrons by Enhanced Higher‐Band ECH Waves Observed by Van Allen Probes

Yang

Liu

Yang

et al. 2023

Self Cite

Electron cyclotron harmonic (ECH) waves, which are responsible for the diffuse aurora, are usually observed with the strongest intensity in the first band. Here, we present observations of enhanced higher‐band ECH with wave intensities above 10−3 mV2m−2 Hz−1 by Van Allen Probes. Fully thermal simulation results indicate that these waves can be locally excited by the observed electron distributions, and higher plasma density and lower magnetic strength are favorable for generating the enhanced higher‐band ECH. The pitch angle diffusion coefficient 〈〉Dαα $\left\langle {D}_{\alpha \alpha }\right\rangle $ of the higher‐band ECH can exceed 10−5 s−1 inside the loss cone for energetic electrons (300 eV–∼15 keV), greater than the momentum diffusion coefficient 〈〉Dpp $\left\langle {D}_{pp}\right\rangle $ by ∼100 times. It is suggested that the enhanced higher‐band ECH can also efficiently scatter these electrons into the loss cone and contribute to the diffuse aurora.

“…It is well accepted that MS waves develop from the ion Bernstein mode instability driven by the positive gradient in proton perpendicular velocity distributions (∂ f ⊥ /∂ v ⊥ > 0), called also as ring‐like distributions (Gao et al., 2021; Min et al., 2016; Sun et al., 2016; X. Yu et al., 2016; Yuan et al., 2017). In fact, when fresh plasmas are injected from the plasma sheet into the inner magnetosphere, they would suffer different drifts.…”

Section: Introductionmentioning

confidence: 99%

Fast Magnetosonic Waves in a Dipolarizing Flux Bundle Inside the Geosynchronous Orbit

Yuan

Huang

et al. 2022

Although commonly observed in the inner magnetosphere, fast magnetosonic (MS) waves are often owe to be excited by those proton rings resulting from the so‐called energy‐dependent drift path of ring current protons. In this letter, we report an interesting MS wave event in a dipolarizing flux bundle (DFB) observed by the Van Allen Probe A. In the DFB, perpendicular proton fluxes are found depleted at low and intermediate energies, while enhanced at high energies, which should be attributed to proton accelerations by DFB. As a result, proton ring could be locally formed. Using the observed plasma environment parameters and the modeled proton distributions, we have calculated the linear growth rates for MS waves and found that these MS waves might be locally excited. Our results provide insight into the generation of MS waves in a DFB, and provide a new channel to excite MS waves in the inner magnetosphere.