References

ANGEO

Annales Geophysicae

ANGEO

Ann. Geophys.

1432-0576

Copernicus Publications

Göttingen, Germany

10.5194/angeo-32-507-2014

Resonant scattering of energetic electrons in the plasmasphere by monotonic whistler-mode waves artificially generated by ionospheric modification

Chang

S. S.

¹ ² Ni

B. B.

¹ ² Bortnik

² Zhou

https://orcid.org/0000-0003-2692-9451

¹ Zhao

Z. Y.

¹ Li

J. X.

³ Gu

X. D.

Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan, Hubei 430072, China

Department of Atmospheric and Oceanic Sciecnes, University of California, Los Angeles, Los Angeles, California 90095-1565, USA

Institute of Space Physics and Applied Technology, Peking University, Beijing 100871, China

21 05 2014

32 5 507 518

2014

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://angeo.copernicus.org/articles/32/507/2014/angeo-32-507-2014.html

The full text article is available as a PDF file from https://angeo.copernicus.org/articles/32/507/2014/angeo-32-507-2014.pdf

Modulated high-frequency (HF) heating of the ionosphere provides a feasible means of artificially generating extremely low-frequency (ELF)/very low-frequency (VLF) whistler waves, which can leak into the inner magnetosphere and contribute to resonant interactions with high-energy electrons in the plasmasphere. By ray tracing the magnetospheric propagation of ELF/VLF emissions artificially generated at low-invariant latitudes, we evaluate the relativistic electron resonant energies along the ray paths and show that propagating artificial ELF/VLF waves can resonate with electrons from ~ 100 keV to ~ 10 MeV. We further implement test particle simulations to investigate the effects of resonant scattering of energetic electrons due to triggered monotonic/single-frequency ELF/VLF waves. The results indicate that within the period of a resonance timescale, changes in electron pitch angle and kinetic energy are stochastic, and the overall effect is cumulative, that is, the changes averaged over all test electrons increase monotonically with time. The localized rates of wave-induced pitch-angle scattering and momentum diffusion in the plasmasphere are analyzed in detail for artificially generated ELF/VLF whistlers with an observable in situ amplitude of ~ 10 pT. While the local momentum diffusion of relativistic electrons is small, with a rate of < 10−7 s−1, the local pitch-angle scattering can be intense near the loss cone with a rate of ~ 10−4 s−1. Our investigation further supports the feasibility of artificial triggering of ELF/VLF whistler waves for removal of high-energy electrons at lower L shells within the plasmasphere. Moreover, our test particle simulation results show quantitatively good agreement with quasi-linear diffusion coefficients, confirming the applicability of both methods to evaluate the resonant diffusion effect of artificial generated ELF/VLF whistlers.

References 1

Abel, B. and Thorne, R. M.: Electron scattering loss in Earth's inner magnetosphere: 1. Dominant physical processes, J. Geophys. Res., 103, A22385, <a href="http://dx.doi.org/10.1029/97JA02919">https://doi.org/10.1029/97JA02919</a>, 1998a.

Abel, B. and Thorne, R. M.: Electron scattering loss in Earth's inner magnetosphere: 2. Sensitivity to model parameters, J. Geophys. Res., 103, A22397, <a href="http://dx.doi.org/10.1029/97JA02920">https://doi.org/10.1029/97JA02920</a>, 1998b.

Albert, J. M.: Analysis of quasi-linear diffusion coefficients, J. Geophys. Res., 104, A22429, <a href="http://dx.doi.org/10.1029/1998JA900113">https://doi.org/10.1029/1998JA900113</a>, 1999.

Artemyev, A. V., Krasnoselskikh, V. V., Agapitov, O. V., Mourenas, D., and Rolland, G.: Non-diffusive resonant acceleration of electron in the radiation belts, Phys. Plasmas, 19, 122901, <a href="http://dx.doi.org/10.1063/1.4769726">https://doi.org/10.1063/1.4769726</a>, 2012.

Artemyev, A. V., Vasiliev, A. A., Mourenas, D., Agapitov, O. V., and Krasnoselskikh, V. V.: Nonlinear electron acceleration by oblique whistler waves: Landau resonance vs. cyclotron resonance, Phys. Plasmas, 20, 122901, <a href="http://dx.doi.org/10.1063/1.4836595">https://doi.org/10.1063/1.4836595</a>, 2013.

Barr, R. and Stubbe, P.: ELF radiation from the Tromsø "Super Heater" facility, Geophys. Res. Lett., 18, 1035–1038, 1991a.

Bell, T. F.: The nonlinear gyroresonance interaction between energetic electrons and coherent VLF waves propagating at an arbitrary angle with respect to the Earth's magnetic field, J. Geophys. Res., 89, 905–918, <a href="http://dx.doi.org/10.1029/JA089iA02p00905">https://doi.org/10.1029/JA089iA02p00905</a>, 1984.

Bell, T. F., Inan, U. S., Platino, M., Pickett, J. S., Kossey, P. A., and Kennedy, E. J.: CLUSTER observations of lower hybrid waves excited at high altitudes by electromagnetic whistler mode signals from the HAARP facility, Geophys. Res. Lett., 31, L06811, <a href="http://dx.doi.org/10.1029/2003GL018855">https://doi.org/10.1029/2003GL018855</a>, 2004.

Bortnik, J.: Precipitation of Radiation Belt Electrons by Lightning-Generated Magnetospherically Reflecting Whistler Waves, Ph.D.'s thesis, Stanford University, California, 2005.

Bortnik, J. and Thorne, R. M.: Transit time scattering of energetic electrons due to equatorially confined magnetosonic waves, J. Geophys. Res., 115, A07213, <a href="http://dx.doi.org/10.1029/2010JA015283">https://doi.org/10.1029/2010JA015283</a>, 2010.

Bortnik, J., Inan, U. S., and Bell, T. F.: Energy distribution and lifetime of magnetospherically reflecting whistlers in the plasmasphere, J. Geophys. Res., 108, 1199, <a href="http://dx.doi.org/10.1029/2002JA009316">https://doi.org/10.1029/2002JA009316</a>, 2003.

Bortnik, J., Inan, U. S., and Bell, T. F.: Temporal signatures of radiation belt electron precipitation induced by lightning-generated MR whistler waves: 1. Methodology, J. Geophys. Res., 111, A02204, <a href="http://dx.doi.org/10.1029/2005JA011182">https://doi.org/10.1029/2005JA011182</a>, 2006a.

Bortnik, J., Inan, U. S., and Bell, T. F.: Temporal signatures of radiation belt electron precipitation induced by lightning generated MR whistler waves. 2: Global signatures, J. Geophys. Res., 111, A02205, <a href="http://dx.doi.org/10.1029/2005JA011398">https://doi.org/10.1029/2005JA011398</a>, 2006b.

Dysthe, K. B.: Some studies of triggered whistler emissions, J. Geophys. Res., 76, 6915–6931, <a href="http://dx.doi.org/10.1029/JA076i028p06915">https://doi.org/10.1029/JA076i028p06915</a>, 1971.

Ferraro, A. J., Lee, H. S., Allshouse, R., Carroll, K., Tomko, A. A., Kelly, F. J., and Joiner, R. G.: VLF/ELF radiation from the ionospheric dynamo current system modulated by powerful HF signals, J. Atmos. Terr. Phys., 44, 1113–1122, <a href="http://dx.doi.org/10.1016/0021-9169(82)90022-8">https://doi.org/10.1016/0021-9169(82)90022-8</a>, 1982.

Helliwell, R. A.: A theory of discrete VLF emissions from the magnetosphere, J. Geophys. Res., 72, 4773–4790, <a href="http://dx.doi.org/10.1029/JZ072i019p04773">https://doi.org/10.1029/JZ072i019p04773</a>, 1967.

Inan, U. S. and Bell, T. F.: The plasmapause as a VLF wave guide, J. Geophys. Res., 19, 2819–2827, <a href="http://dx.doi.org/10.1029/JA082i019p02819">https://doi.org/10.1029/JA082i019p02819</a>, 1977.

Inan, U. S., Chang, H. C., and Hellwell, R. A.: Electron precipitation zones around major ground-based VLF signal Sources J. Geophys. Res., 89, 2891–2906, <a href="http://dx.doi.org/10.1029/JA089iA05p02891">https://doi.org/10.1029/JA089iA05p02891</a>, 1984.

Inan, U. S., Bell, T. F., Bortnik, J., and Albert, J. M.: Controlled precipitation of radiation belt electrons, J. Geophys. Res., 108, 1186, <a href="http://dx.doi.org/10.1029/2002JA009580">https://doi.org/10.1029/2002JA009580</a>, 2003.

Inan, U. S., Golkowski, M., Carpenter, D. L., Reddell, N., Moore, R. C., Bell, T. F., Paschal, E., Kossey, P., Kennedy, E., and Meth, S. Z.: Multihop whistler-mode ELF/VLF signals and triggered emissions excited by the HAARP HF heater, Geophys. Res. Lett., 31, L24805, <a href="http://dx.doi.org/10.1029/2004GL021647">https://doi.org/10.1029/2004GL021647</a>, 2004.

James, H. G., Dowden, R. L., Rietveld, P., Stubbe, P., and Kopka, H.: Simultaneous observations of ELF waves from an artificially modulated auroral electrojet in space and on the ground, J. Geophys. Res., 89, 1655–1666, 1984.

Kulkarni, P., Inan, U. S., Bell, T. F., and Bortnik, J.: Precipitation signatures of ground-based VLF transmitters, J. Geophys. Res., 113, A07214, <a href="http://dx.doi.org/10.1029/2007JA012569">https://doi.org/10.1029/2007JA012569</a>, 2010.

Lyons, L. R: Electron diffusion driven by magnetospheric electrostatic waves, J. Geophys. Res., 79, A4575, <a href="http://dx.doi.org/10.1029/JA079i004p00575">https://doi.org/10.1029/JA079i004p00575</a>, 1974.

Mourenas, D., Artemyev, A. V., Agapitov, O. V., and Krasnoselskikh, V.: Analytical estimates of electron quasi-linear diffusion by fast magnetosonic waves, J. Geophys. Res. Space Phys., 118, 3096–3112, <a href="http://dx.doi.org/10.1002/jgra.50349">https://doi.org/10.1002/jgra.50349</a>, 2013.

Ni, B., Thorne, R. M., Shprits, Y. Y., and Bortnik, J.: Resonant scattering of plasma sheet electrons by whistlermode chorus: Contribution to diffuse auroral precipitation, Geophys. Res. Lett., 35, L11106, <a href="http://dx.doi.org/10.1029/2008GL034032">https://doi.org/10.1029/2008GL034032</a>, 2008.

Ni, B., Bortnik, J., Thorne, R. M., Ma, Q., and Chen, L.: Resonant scattering and resultant pitch angle evolution of relativistic electrons by plasmaspheric hiss, J. Geophys. Res. Space Phys., 118, 7740–7751, <a href="http://dx.doi.org/10.1002/2013JA019260">https://doi.org/10.1002/2013JA019260</a>, 2013.

Platino, M., Inan, U. S., Bell, T. F., Parrot, M., and Kennedy, E. J.: DEMETER observations of ELF waves injected with the HAARP HF transmitter, Geophys. Res. Lett., 33, L16101, <a href="http://dx.doi.org/10.1029/2006GL026462">https://doi.org/10.1029/2006GL026462</a>, 2006.

Piddyachiy, D., Inan, U. S., Bell, T. F., Lehtinen, N. G., and Parrot, M.: DEMETER observations of an intense upgoing column of ELF/VLF radiation excited by the HAARP HF heater, J. Geophys. Res., 113, A10308, <a href="http://dx.doi.org/10.1029/2008JA013208">https://doi.org/10.1029/2008JA013208</a>, 2008.

Shprits, Y. Y. and Ni, B.: Dependence of the quasi-linear scattering rates on the wave normal distribution of chorus waves, J. Geophys. Res., 114, A11205, <a href="http://dx.doi.org/10.1029/2009JA014223">https://doi.org/10.1029/2009JA014223</a>, 2009.

Shprits, Y. Y., Runov, A., and Ni, B.: Gyro-resonant Scattering of Radiation Belt Electrons during the Solar Minimum by Fast Magnetosonic Waves, J. Geophys. Res., 118, 648–652, <a href="http://dx.doi.org/10.1002/jgra.50108">https://doi.org/10.1002/jgra.50108</a>, 2013.

Shklayr, D. and Matsumoto, H.: Oblique whistler-mode waves in the inhomogeneous magnetospheric plasma: resonant interactions with energetic charged particles, Surv. Geophys., 30, 55–104, 2009.

Summers, D. and Ni, B.: Effects of latitudinal distributions of particle density and wave power on cyclotron resonant diffusion rates of radiation belt electrons, Earth Planet. Space, 60, 763–771, 2008.

Summers, D., Ni, B., and Meredith, N. P.: Timescales for radiation belt electron acceleration and loss due to resonant wave-particle interactions: 1. Theory, J. Geophys. Res., 112, A04206, <a href="http://dx.doi.org/10.1029/2006JA011801">https://doi.org/10.1029/2006JA011801</a>, 2007a.

Summers, D., Ni, B., and Meredith, N. P.: Timescales for radiation belt electron acceleration and loss due to resonant wave-particle interactions: 2. Evaluation for VLF chorus, ELF hiss, and electromagnetic ion cyclotron waves, J. Geophys. Res., 112, A04207, <a href="http://dx.doi.org/10.1029/2006JA011993">https://doi.org/10.1029/2006JA011993</a>, 2007b.

Tao, X. and Bortnik, J.: Nonlinear interactions between relativistic radiation belt electrons and oblique whistler mode waves, Nonlin. Processes Geophys., 17, 599–604, <a href="http://dx.doi.org/10.5194/npg-17-599-2010">https://doi.org/10.5194/npg-17-599-2010</a>, 2010.

Tao, X., Bortnik, J., Albert, J. M., Liu, K., and Thorne, R. M.: Comparison of quasilinear diffusion coefficients for parallel propagating whistler mode waves with test particle simulations, Geophys. Res. Lett., 38, L06105, <a href="http://dx.doi.org/10.1029/2011GL046787">https://doi.org/10.1029/2011GL046787</a>, 2011.

Thorne, R. M.: Radiation belt dynamics: The importance of wave-particle interactionse importance of wave-particle interactions, Geophys. Res. Lett., 37, L22107, <a href="http://dx.doi.org/10.1029/2010GL044990">https://doi.org/10.1029/2010GL044990</a>, 2010.

Zheng, Q., Zheng, Y., Fok, M.-C., and Lui, A.: Electron energy diffusion and advection due to non-linear electron-chorus wave interactions, J. Atmos. Sol.-Terr. Phys., 80, 152–160, 2012.

Zheng, Q., Fok, M.-C., Zheng, Y., and Lui, A.: Non-linear whistler mode wave effects on magnetospheric energetic electrons, J. Atmos. Sol.-Terr. Phys., 102, 8–16, 2013.