title: Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave.
abstract: Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA's Magnetospheric Multiscale (MMS) mission, we utilize Earth's magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations.
authors.affiliation: Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA.|NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Gershman
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
authors.forename: Adolfo
authors.initials: A
authors.lastname: F-Viñas
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Dorelli
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.|Goddard Planetary Heliophysics Institute, University of Maryland, Baltimore County, Maryland 21250, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Boardsen
authors.affiliation: Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA.|NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
authors.forename: Levon A
authors.initials: LA
authors.lastname: Avanov
authors.affiliation: Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Bellan
authors.affiliation: Blackett Laboratory, Imperial College London, London SW7 2AZ, UK.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Schwartz
authors.affiliation: Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Toulouse F-31400, France.|Centre National de la Recherche Scientifique, UMR 5277, Toulouse F-31400, France.
authors.forename: Benoit
authors.initials: B
authors.lastname: Lavraud
authors.affiliation: NASA Marshall Space Flight Center, Huntsville, Alabama 35808, USA.
authors.forename: Victoria N
authors.initials: VN
authors.lastname: Coffey
authors.affiliation: NASA Marshall Space Flight Center, Huntsville, Alabama 35808, USA.
authors.forename: Michael O
authors.initials: MO
authors.lastname: Chandler
authors.affiliation: JAXA Institute of Space and Astronautical Science, Sagamihara, Kanagawa 252-5210, Japan.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Saito
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
authors.forename: William R
authors.initials: WR
authors.lastname: Paterson
authors.affiliation: Southwest Research Institute, San Antonio, Texas 78238, USA.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Fuselier
authors.affiliation: Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80305, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Ergun
authors.affiliation: Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California 90095, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Strangeway
authors.affiliation: Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California 90095, USA.
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Russell
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Giles
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Pollock
authors.affiliation: Physics Department, University of New Hampshire, Durham, New Hampshire 03824, USA.|Southwest Research Institute Durham, Durham, New Hampshire 03824, USA.
authors.forename: Roy B
authors.initials: RB
authors.lastname: Torbert
authors.affiliation: Southwest Research Institute, San Antonio, Texas 78238, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Burch