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Claudepierre SG, Ma Q, Bortnik J. Quantifying Radiation Belt Electron Loss Processes at L < 4. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2022; 127:e2022JA030756. [PMID: 37034821 PMCID: PMC10078220 DOI: 10.1029/2022ja030756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 09/13/2022] [Accepted: 09/28/2022] [Indexed: 06/19/2023]
Abstract
We present a comprehensive analysis of the processes that lead to quasilinear pitch-angle-scattering loss of electrons from the L < 4 region of the Earth's inner magnetosphere during geomagnetically quiet times. We consider scattering via Coulomb collisions, hiss waves, lightning-generated whistler (LGW) waves, waves from ground-based very-low-frequency (VLF) transmitters, and electromagnetic ion cyclotron (EMIC) waves. The amplitude, frequency, and wave normal angle spectra of these waves are parameterized with empirical wave models, which are then used to compute pitch-angle diffusion coefficients. From these coefficients, we estimate the decay timescales, or lifetimes, of 30 keV to 4 MeV electrons and compare the results with timescales obtained from in-situ observations. We demonstrate good quantitative agreement between the two over most of the L and energy range under investigation. Our analysis suggests that the electron decay timescales are very sensitive to the choice of plasmaspheric density model. At L < 2, where our theoretical lifetimes do not agree well with the observations, we show that including Coulomb energy drag (ionization energy loss) in our calculations significantly improves the quantitative agreement with the observed decay timescales. We also use an accurate model of the geomagnetic field to provide an estimate of the effect that the drift-loss cone has on the theoretically calculated electron lifetimes, which are usually obtained using an axisymmetric dipole field.
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Affiliation(s)
| | - Q. Ma
- Department of Atmospheric and Oceanic SciencesUCLALos AngelesCAUSA
- Center for Space PhysicsBoston UniversityBostonMAUSA
| | - J. Bortnik
- Department of Atmospheric and Oceanic SciencesUCLALos AngelesCAUSA
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Discovery and insights from DSX mission's high-power VLF wave transmission experiments in the radiation belts. Sci Rep 2022; 12:14304. [PMID: 35995921 PMCID: PMC9395515 DOI: 10.1038/s41598-022-18542-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 08/16/2022] [Indexed: 11/23/2022] Open
Abstract
Space weather phenomena can threaten space technologies. A hazard among these is the population of relativistic electrons in the Van Allen radiation belts. To reduce the threat, artificial processes can be introduced by transmitting very-low-frequency (VLF) waves into the belts. The resulting wave-particle interactions may deplete these harmful electrons. However, when transmitting VLF waves in space plasma, the antenna, plasma, and waves interact in a manner that is not well-understood. We conducted a series of VLF transmission experiments in the radiation belts and measured the power and radiation impedance under various frequencies and conditions. The results demonstrate the critical role played by the plasma-antenna-wave interaction around high-voltage space antennae and open the possibility to transmit high power in space. The physical insight obtained in this study can provide guidance to future high-power space-borne VLF transmitter developments, laboratory whistler-mode wave injection experiments, and the interpretation of various astrophysical and optical phenomena.
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Artemyev AV, Neishtadt AI, Vasiliev AA, Mourenas D. Transitional regime of electron resonant interaction with whistler-mode waves in inhomogeneous space plasma. Phys Rev E 2021; 104:055203. [PMID: 34942734 DOI: 10.1103/physreve.104.055203] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/21/2021] [Indexed: 11/07/2022]
Abstract
Resonances with electromagnetic whistler-mode waves are the primary driver for the formation and dynamics of energetic electron fluxes in various space plasma systems, including shock waves and planetary radiation belts. The basic and most elaborated theoretical framework for the description of the integral effect of multiple resonant interactions is the quasilinear theory, which operates through electron diffusion in velocity space. The quasilinear diffusion rate scales linearly with the wave intensity, D_{QL}∼B_{w}^{2}, which should be small enough to satisfy the applicability criteria of this theory. Spacecraft measurements, however, often detect whistle-mode waves sufficiently intense to resonate with electrons nonlinearly. Such nonlinear resonant interactions imply effects of phase trapping and phase bunching, which may quickly change the electron fluxes in a nondiffusive manner. Both regimes of electron resonant interactions (diffusive and nonlinear) are well studied, but there is no theory quantifying the transition between these two regimes. In this paper we describe the integral effect of nonlinear electron interactions with whistler-mode waves in terms of the timescale of electron distribution relaxation, ∼1/D_{NL}. We determine the scaling of D_{NL} with wave intensity B_{w}^{2} and other main wave characteristics, such as wave-packet size. The comparison of D_{QL} and D_{NL} provides the range of wave intensity and wave-packet sizes where the electron distribution evolves at the same rates for the diffusive and nonlinear resonant regimes. The obtained results are discussed in the context of energetic electron dynamics in the Earth's radiation belt.
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Affiliation(s)
- A V Artemyev
- Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA.,Space Research Institute RAS, Moscow, Russia
| | - A I Neishtadt
- Space Research Institute RAS, Moscow, Russia.,Department of Mathematical Sciences, Loughborough University, Loughborough LE11 3TU, United Kingdom
| | | | - D Mourenas
- LPC2E, CNRS, 3 Av. de la Recherche Scientifique, Orléans, France
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Claudepierre SG, Blake JB, Boyd AJ, Clemmons JH, Fennell JF, Gabrielse C, Looper MD, Mazur JE, O’Brien TP, Reeves GD, Roeder JL, Spence HE, Turner DL. The Magnetic Electron Ion Spectrometer: A Review of On-Orbit Sensor Performance, Data, Operations, and Science. SPACE SCIENCE REVIEWS 2021; 217:80. [PMID: 34744192 PMCID: PMC8553741 DOI: 10.1007/s11214-021-00855-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/02/2021] [Indexed: 06/13/2023]
Abstract
Measurements from NASA's Van Allen Probes have transformed our understanding of the dynamics of Earth's geomagnetically-trapped, charged particle radiation. The Van Allen Probes were equipped with the Magnetic Electron Ion Spectrometers (MagEIS) that measured energetic and relativistic electrons, along with energetic ions, in the radiation belts. Accurate and routine measurement of these particles was of fundamental importance towards achieving the scientific goals of the mission. We provide a comprehensive review of the MagEIS suite's on-orbit performance, operation, and data products, along with a summary of scientific results. The purpose of this review is to serve as a complement to the MagEIS instrument paper, which was largely completed before flight and thus focused on pre-flight design and performance characteristics. As is the case with all space-borne instrumentation, the anticipated sensor performance was found to be different once on orbit. Our intention is to provide sufficient detail on the MagEIS instruments so that future generations of researchers can understand the subtleties of the sensors, profit from these unique measurements, and continue to unlock the mysteries of the near-Earth space radiation environment. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s11214-021-00855-2.
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Affiliation(s)
- S. G. Claudepierre
- Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA USA
- Department of Atmospheric and Oceanic Sciences, UCLA, Los Angeles, CA USA
| | - J. B. Blake
- Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA USA
| | - A. J. Boyd
- Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA USA
| | - J. H. Clemmons
- Department of Physics and Astronomy, University of New Hampshire, Durham, NH USA
| | - J. F. Fennell
- Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA USA
| | - C. Gabrielse
- Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA USA
| | - M. D. Looper
- Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA USA
| | - J. E. Mazur
- Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA USA
| | - T. P. O’Brien
- Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA USA
| | - G. D. Reeves
- Space and Atmospheric Sciences Group, Los Alamos National Laboratory, Los Alamos, NM USA
| | - J. L. Roeder
- Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA USA
| | - H. E. Spence
- Department of Physics and Astronomy, University of New Hampshire, Durham, NH USA
| | - D. L. Turner
- Space Exploration Sector, The Johns Hopkins University Applied Physics Laboratory, Laurel, MD USA
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Hua M, Li W, Ni B, Ma Q, Green A, Shen X, Claudepierre SG, Bortnik J, Gu X, Fu S, Xiang Z, Reeves GD. Very-Low-Frequency transmitters bifurcate energetic electron belt in near-earth space. Nat Commun 2020; 11:4847. [PMID: 32973130 PMCID: PMC7518438 DOI: 10.1038/s41467-020-18545-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 08/31/2020] [Indexed: 11/17/2022] Open
Abstract
Very-Low-Frequency (VLF) transmitters operate worldwide mostly at frequencies of 10-30 kilohertz for submarine communications. While it has been of intense scientific interest and practical importance to understand whether VLF transmitters can affect the natural environment of charged energetic particles, for decades there remained little direct observational evidence that revealed the effects of these VLF transmitters in geospace. Here we report a radially bifurcated electron belt formation at energies of tens of kiloelectron volts (keV) at altitudes of ~0.8-1.5 Earth radii on timescales over 10 days. Using Fokker-Planck diffusion simulations, we provide quantitative evidence that VLF transmitter emissions that leak from the Earth-ionosphere waveguide are primarily responsible for bifurcating the energetic electron belt, which typically exhibits a single-peak radial structure in near-Earth space. Since energetic electrons pose a potential danger to satellite operations, our findings demonstrate the feasibility of mitigation of natural particle radiation environment.
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Affiliation(s)
- Man Hua
- Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan, Hubei, China
- Center for Space Physics, Boston University, Boston, MA, USA
| | - Wen Li
- Center for Space Physics, Boston University, Boston, MA, USA.
| | - Binbin Ni
- Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan, Hubei, China.
- CAS Center for Excellence in Comparative Planetology, Anhui, Hefei, China.
| | - Qianli Ma
- Center for Space Physics, Boston University, Boston, MA, USA
- Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, USA
| | - Alex Green
- Center for Space Physics, Boston University, Boston, MA, USA
| | - Xiaochen Shen
- Center for Space Physics, Boston University, Boston, MA, USA
| | - Seth G Claudepierre
- Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, USA
- Space Sciences Department, The Aerospace Corporation, EI Segundo, CA, USA
| | - Jacob Bortnik
- Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, USA
| | - Xudong Gu
- Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan, Hubei, China
| | - Song Fu
- Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan, Hubei, China
| | - Zheng Xiang
- Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan, Hubei, China
| | - Geoffrey D Reeves
- Space Science and Applications Group, Los Alamos National Laboratory, Los Alamos, NM, USA
- Space Sciences Division, New Mexico Consortium, Los Alamos, NM, USA
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