Rapid acceleration of radiation belt energetic electrons by Z‐mode waves

Xiao, Fuliang; Zhang, Sai; Su, Zhenpeng; He, Z. Y.; Tang, Lijun

doi:10.1029/2011gl050625

Cited by 29 publications

(25 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To apply quasi‐linear theory to space plasma physics, where the background magnetic field is inhomogeneous, the diffusion equation is generally averaged along the unperturbed bounce‐orbit [ Lyons et al , 1972; Kozyra et al , 1994]. Various codes [ Glauert and Horne , 2005; Albert , 2005; Xiao et al , 2009, 2010a; Shprits and Ni , 2009] have been developed to calculate the bounce‐averaged diffusion coefficients to be used in the numerical modeling of radiation belt dynamics [ Horne et al , 2005a; Varotsou et al , 2008; Tao et al , 2008; Albert et al , 2009; Subbotin et al , 2010; Xiao et al , 2012, 2010b; Su et al , 2010, 2011].…”

Section: Introductionmentioning

confidence: 99%

Comparison of bounce‐averaged quasi‐linear diffusion coefficients for parallel propagating whistler mode waves with test particle simulations

et al. 2012

View full text Add to dashboard Cite

[1] Quasi-linear bounce-averaged diffusion coefficients for interactions between electrons and parallel propagating whistler waves in a dipole field are compared with test particle simulations. We solve equations of motion for a large number of electrons interacting with waves with a Gaussian distribution of wave power. For broadband and small amplitude waves, which are assumed by the quasi-linear analysis, our test particle simulation results agree well with quasi-linear theory predictions. We then demonstrate the effect of the wave amplitude on diffusion coefficients. We show that as the amplitude increases, the bounce-averaged quasi-linear diffusion coefficients become invalid. Critical wave amplitudes for the breakdown of the bounce-averaged diffusion coefficients for a range of energies and pitch angles are calculated for the set of wave parameters we used. Finally, we investigate the effect of wave bandwidth on bounce-averaged diffusion coefficients. Consistent with a previous theoretical prediction, bounce-averaged quasi-linear diffusion coefficients are still valid for narrowband waves, as long as the wave amplitude is small. When the amplitude of the narrowband wavefield increases, nonlinear effects such as phase-bunching and trapping become dominant and correspondingly quasi-linear theory becomes invalid. Our results demonstrate the validity of applying quasi-linear theory to interactions between electrons and small amplitude plasma waves in the radiation belt.Citation: Tao, X., J. Bortnik, J. M. Albert, and R. M. Thorne (2012), Comparison of bounce-averaged quasi-linear diffusion coefficients for parallel propagating whistler mode waves with test particle simulations,

show abstract

Section: Introductionmentioning

confidence: 99%

Comparison of bounce‐averaged quasi‐linear diffusion coefficients for parallel propagating whistler mode waves with test particle simulations

et al. 2012

View full text Add to dashboard Cite

show abstract

“…The ultra low frequency (ULF) waves can drift-resonate with radiation belt electrons [Zong et al, 2007[Zong et al, , 2009, and cause radial diffusion [Elkington et al, 1999[Elkington et al, , 2003] and/or convection [Degeling et al, 2008] violating the third adiabatic invariant. The cyclotron/ Landau resonances with chorus, hiss, electromagnetic ion cyclotron (EMIC), magnetosonic, R-X and Z-mode waves have been suggested to be the important in-situ acceleration and/or loss mechanisms violating the first and second adiabatic invariants [Horne and Thorne, 1998;Summers et al, 1998Summers et al, , 2004Summers et al, , 2007aSummers et al, , 2007bRoth et al, 1999;Summers and Ma, 2000;Albert, 2003Albert, , 2005Horne et al, 2003Horne et al, , 2005aHorne et al, , 2007Xiao et al, 2007Xiao et al, , 2010bXiao et al, , 2012. The bounce-resonance with magnetosonic and EMIC waves violating the second adiabatic invariant may also potentially contribute to the local acceleration and loss of radiation belt electrons [Roberts and Schulz, 1968;Shprits, 2009].…”

Section: Introductionmentioning

confidence: 99%

Bounce‐averaged advection and diffusion coefficients for monochromatic electromagnetic ion cyclotron wave: Comparison between test‐particle and quasi‐linear models

et al. 2012

Self Cite

View full text Add to dashboard Cite

[1] The electromagnetic ion cyclotron (EMIC) wave has long been suggested to be responsible for the rapid loss of radiation belt relativistic electrons. The test-particle simulations are performed to calculate the bounce-averaged pitch angle advection and diffusion coefficients for parallel-propagating monochromatic EMIC waves. The comparison between test-particle (TP) and quasi-linear (QL) transport coefficients is further made to quantify the influence of nonlinear processes. For typical EMIC waves, four nonlinear physical processes, i.e., the boundary reflection effect, finite perturbation effect, phase bunching and phase trapping, are found to occur sequentially from small to large equatorial pitch angles. The pitch angle averaged finite perturbation effect yields slight differences between the transport coefficients of TP and QL models. The boundary reflection effect and phase bunching produce an average reduction of >80% in the diffusion coefficients but a small change in the corresponding average advection coefficients, tending to lower the loss rate predicted by QL theory. In contrast, the phase trapping causes continuous negative advection toward the loss cone and a minor change in the corresponding diffusion coefficients, tending to increase the loss rate predicted by QL theory. For small amplitude EMIC waves, the transport coefficients grow linearly with the square of wave amplitude. As the amplitude increases, the boundary reflection effect, phase bunching and phase trapping start to occur. Consequently, the TP advection coefficients deviate from the linear growth with the square of wave amplitude, and the TP diffusion coefficients become saturated with the amplitude approaching 1 nT or above. The current results suggest that these nonlinear processes can cause significant deviation of transport coefficients from the prediction of QL theory, which should be taken into account in the future simulations of radiation belt dynamics driven by the EMIC waves.Citation: Su, Z., H. Zhu, F. Xiao, H. Zheng, C. Shen, Y. Wang, and S. Wang (2012), Bounce-averaged advection and diffusion coefficients for monochromatic electromagnetic ion cyclotron wave: Comparison between test-particle and quasi-linear models,

show abstract

“…This is further confirmed by the latest studies based on the observation of recently launched Van Allen probes (Thorne et al 2013;Xiao et al 2014). Analogous to the whistler-mode chorus wave, Z-mode waves are found to produce efficient stochastic acceleration of energetic electrons (Horne et al 2003;Summers and Ma 2000;Iles et al 2006;Xiao et al 2012a). Electromagnetic ion cyclotron (EMIC) and hiss waves cause effective pitch angle scattering of radiation belt energetic particles, driving particles into the atmosphere (Summers and Thorne 2003;Xiao et al 2006Xiao et al , 2011b.…”

Section: )mentioning

confidence: 99%

Radiation belt electron acceleration induced by gyroresonant interaction with magnetosonic waves

Yang

Zhang

Yang

et al. 2014

Astrophys Space Sci

View full text Add to dashboard Cite

Using Cluster 4 satellite data, we examine activities of fast magnetosonic (MS) waves in the outer radiation belt near the location L = 4.2 on 28 May 2005. We adopt a Gaussian distribution to fit the observed power spectral density of MS waves and find the fitting wave strength to be 245 pT. We then calculate the bounce-averaged diffusion coefficients and show that these diffusion coefficients are pronounced within a region of pitch angles about 25°-70°. By solving a 2D Fokker-Planck diffusion equation, we simulate the dynamic evolution of the electron phase space density (PSD), and demonstrate that significant increases in electron PSDs at energies of MeVs occur mainly within the aforementioned pitch-angle range over a time scale of several hours. The current results suggest that the interaction between MS waves and electrons could be an important mechanism of electron acceleration in the radiation belt.

show abstract

Rapid acceleration of radiation belt energetic electrons by Z‐mode waves

Cited by 29 publications

References 29 publications

Comparison of bounce‐averaged quasi‐linear diffusion coefficients for parallel propagating whistler mode waves with test particle simulations

Comparison of bounce‐averaged quasi‐linear diffusion coefficients for parallel propagating whistler mode waves with test particle simulations

Bounce‐averaged advection and diffusion coefficients for monochromatic electromagnetic ion cyclotron wave: Comparison between test‐particle and quasi‐linear models

Radiation belt electron acceleration induced by gyroresonant interaction with magnetosonic waves

Contact Info

Product

Resources

About