Joseph E. Borovsky
Misa M. Cowee
Richard B. Horne
Yuri Y. Shprits
Charles W. Smith- 1Space Science Institute, Boulder, CO, United States
- 2Los Alamos National Laboratory, Los Alamose, NM, United States
- 3British Antarctic Survey, Cambridge, United Kingdom
- 4Department of Earth and Space Sciences, University of California, Los Angeles, Los Angeles, CA, United States
- 5Space Science Center, University of New Hampshire, Durham, NH, United States
Editorial on the Research Topic
Plasma waves in space physics: Carrying on the research legacies of Peter Gary and Richard Thorne
The importance of plasma waves to the evolution of the solar wind and to the evolutions and interactions of the multiple particle populations of the Earth’s magnetosphere is overwhelming. Two giants in the field of plasma-wave physics recently passed -- Peter Gary and Richard Thorne (cf. Figure 1). Peter and Richard largely established the complexities of plasma waves, plasma instabilities, wave-particle interactions, and the dissipation of turbulence. They opened the eyes of the space-research community to the impact of plasma waves in the solar wind and in the Earth’s magnetosphere. Seminal publications are (Thorne et al., 1973; Thorne, 2010; Thorne et al., 2013; Gary et al., 1984; Gary 1991; Gary and Smith, 2009) and the textbook Gary (1993). They both collaborated widely both nationally and internationally, a key factor that made them world leaders. The Frontiers Research Topic “Plasma Waves in Space Physics: Carrying On the Research Legacies of Peter Gary and Richard Thorne” was designed to honor their hard work, their accomplishments, and their leadership and to extend their research legacies into the future.
FIGURE 1. Photographs of Peter Gary (top) and Richard Thorne (bottom).
The goals of the Research Topic were 1) to celebrate the scientific achievements of Richard Thorne, Peter Gary, and the entire space-plasma-physics research community, 2) to showcase state-of-the-art research findings, and 3) to take an assessment (a) of the present state of knowledge and (b) of where the research community goes in the future.
From this Frontiers Research Topic 14 papers on plasma waves, wave-particle interactions, plasma-wave instabilities, and plasma turbulence are contained in this electronic book. Synopses of the 14 papers are as follows, ordered by papers that focus on 1) plasma waves, 2) wave-particle interactions, 3) plasma-wave instabilities, and 4) plasma turbulence.
Hartinger et al. (2022) review the progress made by the “ULF Wave Modeling, Effects, and Applications” GEM focus group. This review article makes the connection of modern UL F wave research to the ULF wave research of Peter Gary and Richard Thorne.
Albert et al. (2022) examine the equations of motion for test particles encountering field-aligned whistler-mode waves. The investigation focuses on which approximations in the equations of motion capture phase trapping and phase bunching as functions of particle pitch angle.
Haas et al. (2022) examine the pitch-angle distribution of ∼10 keV electrons in the ring-current region of the Earth’s magnetosphere finding that wave-particle interactions are a minor contributor for moderate storms but an important contributor for strong (Kp > 6) storms. They investigate the use of the Kp index as a proxy (predictor) of the flux of electrons in the ring current region of the Earth’s magnetosphere.
Lejosne et al. (2022) review different physical processes that lead to the energization of radiation-belt electrons. They specifically compare radial-diffusion acceleration versus chorus-wave energization, pointing out the insightful contributions of Richard Thorne in focusing on whistler-mode-chorus wave-particle interactions. The Lejosne et al. review highlights the existing challenges in discerning the relative importance of the two processes (radial diffusion versus whistler-mode wave-particle energization) for radiation-belt electron acceleration.
Smirnov et al. (2002) extensively examine the evolution of outer-radiation-belt electron pitch-angle distributions during 129 geomagnetic storms, versus the energy range of the electrons and verses dayside/nightside. They find that the pitch-angle distributions of lower-energy electrons show little evolution through a storm but that higher-energy electrons show distinct evolution through the various phases of a storm.
Borovsky (2021) discusses a system-science view of diverse ion and electron populations interacting via wave-particle interactions, both in the solar wind and in the Earth’s magnetosphere. An important point is that the diverse ions and electrons are co-located because of their confinement by the magnetic field.
Verscharen et al. (2022) review multiple electron plasma-wave instabilities in the solar wind driven by non-equilibrium electron distributions as a function of distance from the sun. The review importantly discusses unsolved questions about electron-driven instabilities in the solar wind.
Zenteno-Quinteros and Moya (2022) examine the whistler-heat-flux instability in the solar wind driven by the high-energy tails of the solar-wind electron distribution functions. They use a “core-strahlo” description of the electron distribution with a skewed kappa distribution of the strahl population.
Winske and Wilson (2002) focus on Peter Gary’s contributions to the understanding of electromagnetic ion-beam instabilities driving ULF waves in the Earths foreshock. The discussion focuses on theory, ISEE-spacecraft observations, and subsequent unsolved Research Topic.
Le et al. (2003) examine the resonant right-hand ion-beam instability in the Earth’s foreshock driven in the solar-wind plasma by ions reflected from the Earth’s bow shock. Using hybrid computer simulations and spacecraft observations they find that plasma-wave modes with a variety of propagation angles are excited.
Birn et al. (2022) examine the statistics of test electrons in MHD simulations of magnetotail dipolarization events to examine expected electron anisotropy distributions which could drive plasma waves via micro-instabilities. They confirm that the dynamics of the electrons are chiefly governed by betatron and first-order Fermi acceleration.
Narita et al. (2002) overview the legacy of Peter Gary, who made large contributions to the picture of short-wavelength plasma turbulence. In the kinetic range of turbulence two pathways for energy cascade are discussed, one involving Alfven waves and the other involving magnetosonic waves.
Cui et al. (2022) use particle-in-cell simulations to explore the various roles that the whistler-anisotropy instability play in whistler turbulence. They find that the whistler-anisotropy instability may act as a regulation mechanism for turbulence in the kinetic range via wave-particle interactions.
Allanson et al. (2022) use a Markovian approach to examine charged-particle dynamics for electromagnetic waves propagating parallel to or antiparallel to a uniform magnetic field. They derive quasilinear diffusion coefficients are derived using this physically intuitive approach.
Author contributions
All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.
Funding
JB was supported at the Space Science Institute by the NSF GEM Program via grant AGS-2027569 and by the NASA HERMES Interdisciplinary Science Program via grant 80NSSC21K1406.
Acknowledgments
The authors of this editorial were honored to be able to oversee this Research Topic focused on the legacy of Peter Gary and Richard Thorne. The authors thank Xochitl Blanco-Cano and Olga Khabarov for their help with editorial duties and the authors thank the many reviewers of these articles Laxman Adhikari, Jay Albert, Anton Artemyev, Fraz Bashir, Xochitl Blanco-Cano, Mourad Djebi, Alexei Dmitriev, Phil Erickson, Stephen Fuselier, Nickolay Ivchenko, Amy Keesee, Kris Klein, Arnaud Masson, Thom Moore, Agnit Mukhopadhyay, Yasuhito Narita, Yoshiharu Omura, Kristoff Paulson, Victor Sergeev, Danny Summers, Xin Tao, Daniel Verscharen, Dan Winske, Peter Yoon, and Qiugang Zong.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher’s note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
References
Gary, S. P. (1991). Electromagnetic ion/ion instabilities and their consequences in space plasmas: A review. Space Sci. Rev. 56, 373. doi:10.1007/bf00196632
Gary, S. P., Smith, C. W., Lee, M. A., Goldstein, M. L., and Forslund, D. W. (1984). Electromagnetic ion beam instabilities. Phys. Fluids 27, 1852. doi:10.1063/1.864797
Gary, S. P., and Smith, C. W. (2009). Short-wavelength turbulence in the solar wind: Linear theory of whistler and kinetic Alfven fluctuations. J. Geophys. Res. 114, A12105. doi:10.1029/2009ja014525
Gary, S. P. (1993). Theory of space plasma instabilities. Cambridge, UK: Cambridge University Press.
Thorne, R. M., Li, W., Ma, Q., Bortnik, J., Chen, L., Baker, D. N., et al. (2013). Rapid local acceleration of relativistic radiation-belt electrons by magnetospheric chorus. Nature 504, 411–414. doi:10.1038/nature12889
Thorne, R. M. (2010). Radiation belt dynamics: The importance of wave-particle interactions. Geophys. Res. Lett. 37, L22107. doi:10.1029/2010gl044990
Keywords: plasma waves, plasma instabilities, plasma turbulence, wave-particle interactions, radiation belt, solar wind
Citation: Borovsky JE, Cowee MM, Horne RB, Shprits YY and Smith CW (2023) Editorial: Plasma waves in space physics: Carrying on the research legacies of Peter Gary and Richard Thorne. Front. Astron. Space Sci. 10:1149649. doi: 10.3389/fspas.2023.1149649
Received: 22 January 2023; Accepted: 03 February 2023;
Published: 22 February 2023.
Edited and reviewed by:
John C. Dorelli, Goddard Space Flight Center, National Aeronautics and Space Administration, United StatesCopyright © 2023 Borovsky, Cowee, Horne, Shprits and Smith. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Joseph E. Borovsky, jborovsky@spacescience.org