Publications
271 results found
Trattner KJ, Fuselier SA, Schwartz SJ, et al., 2023, Ion Acceleration at the Quasi-Parallel Shock: The Source Distributions of the Diffuse Ions, Journal of Geophysical Research: Space Physics, Vol: 128, ISSN: 2169-9380
The terrestrial bow shock is the boundary that slows and diverts the supermagnetosonic solar wind around the terrestrial magnetosphere by converting the kinetic energy of the solar wind into thermal and magnetic energy. Shock fronts are an important acceleration site for ions and electrons in collisionless plasmas, and are responsible for much of the particle acceleration in solar, planetary, and astrophysical regions. One of the fundamental outstanding questions of ion acceleration at shocks for which the upstream magnetic field is nearly aligned with the shock normal (i.e., quasi-parallel shocks) is which portion of the incoming solar wind ion distribution ultimately becomes the seed population that is subsequently accelerated to high energies. This study discusses distribution functions of protons and alpha particles observed by the HPCA and FPI instruments onboard the MMS satellites during a crossing of the quasi-parallel bow shock. The bow shock transition from the downstream region into the upstream solar wind shows the occasional presence of reflected ions and a population of 90° pitch angle ions in the shock ramp consistent with shock drift accelerated ions. Both populations contribute to the seed population of the shock accelerated ions known as the diffuse ion population.
Gingell I, Schwartz SJ, Kucharek H, et al., 2023, Hybrid simulations of the decay of reconnected structures downstream of the bow shock, PHYSICS OF PLASMAS, Vol: 30, ISSN: 1070-664X
Pathak N, Ergun RE, Qi Y, et al., 2022, Evidence of a Nonorthogonal X-line in Guide-field Magnetic Reconnection, ASTROPHYSICAL JOURNAL LETTERS, Vol: 941, ISSN: 2041-8205
Fowler CM, Hanley KG, McFadden J, et al., 2022, A MAVEN Case Study of Radial IMF at Mars: Impacts on the Dayside Ionosphere, Journal of Geophysical Research: Space Physics, Vol: 127, ISSN: 2169-9380
The solar wind interaction with Mars controls the transfer of energy and momentum from the solar wind into the magnetosphere, ionosphere and atmosphere, driving structure, and dynamics within each. This interaction is highly dependent on the upstream Interplanetary Magnetic Field (IMF) orientation. We use in-situ plasma measurements made by the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission to identify several prominent features that arise when the IMF is aligned approximately parallel or antiparallel to solar wind flow (conditions known as “radial IMF”). In particular, solar wind protons and alphas are observed to directly penetrate down to periapsis altitudes, while the magnetic barrier forms deep within the dayside ionosphere. The MAVEN observations are consistent with either an ionopause-like boundary or diamagnetic cavity forming beneath the barrier, as a consequence of the dense cold ionosphere and the absence of significant crustal magnetic fields at this periapsis location. The planetary ions above the magnetic barrier are exposed to solar wind flow and subsequent mass-loading. The (Formula presented.) (convective electric field or “ion pickup”) force is weak and highly variable during radial IMF. While wave particle interactions and subsequent wave heating contribute to incorporating the heavy planetary ions into the solar wind flow, the solar wind momentum is not fully deflected around the obstacle and is delivered into the collisional atmosphere. Significant ion heating is observed deep within the dayside ionosphere, and observed ionospheric density and temperature profiles demonstrate that these ion energization mechanisms drive significant erosion and likely escape to space.
Wilson LB, Goodrich KA, Turner DL, et al., 2022, The need for accurate measurements of thermal velocity distribution functions in the solar wind, FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, Vol: 9, ISSN: 2296-987X
Pollock CJ, Chen L-J, Schwartz SJ, et al., 2022, Dynamics of Earth's bow shock under near-radial interplanetary magnetic field conditions, PHYSICS OF PLASMAS, Vol: 29, ISSN: 1070-664X
Schwartz SJ, Goodrich KA, Wilson LB, et al., 2022, Energy Partition at Collisionless Supercritical Quasi-Perpendicular Shocks, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 127, ISSN: 2169-9380
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- Citations: 2
Ergun RE, Pathak N, Usanova ME, et al., 2022, Observation of Magnetic Reconnection in a Region of Strong Turbulence, ASTROPHYSICAL JOURNAL LETTERS, Vol: 935, ISSN: 2041-8205
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- Citations: 1
Schwartz SJ, Goodrich KA, Wilson III LB, et al., 2022, Energy partition at collisionless supercritical quasiperpendicular shocks
Thaller SA, Andersson L, Schwartz SJ, et al., 2022, Bipolar Electric Field Pulses in the Martian Magnetosheath and Solar Wind; Their Implication and Impact Accessed by System Scale Size, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 127, ISSN: 2169-9380
Schwartz SJ, Goodrich KA, Wilson III LB, et al., 2022, Energy partition at collisionless supercritical quasiperpendicular shocks
Akbari H, Newman D, Fowler C, et al., 2022, Micro-Scale Plasma Instabilities in the Interaction Region of the Solar Wind and the Martian Upper Atmosphere, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 127, ISSN: 2169-9380
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- Citations: 1
Ukhorskiy AY, Sorathia KA, Merkin VG, et al., 2022, Cross-scale energy cascade powered by magnetospheric convection, SCIENTIFIC REPORTS, Vol: 12, ISSN: 2045-2322
Chen L-J, Halekas J, Wang S, et al., 2022, Solitary Magnetic Structures Developed From Gyro-Resonance With Solar Wind Ions at Mars and Earth, GEOPHYSICAL RESEARCH LETTERS, Vol: 49, ISSN: 0094-8276
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- Citations: 1
Schwartz S, Kucharek H, Farrugia C, et al., 2021, Characteristics of Intense Current-carrying Structures in the Terrestrial Magnetosheath
Vech D, Malaspina DM, Cattell C, et al., 2021, Experimental Determination of Ion Acoustic Wave Dispersion Relation With Interferometric Analysis, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380
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- Citations: 1
Gingell I, Schwartz SJ, Kucharek H, et al., 2021, Observing the prevalence of thin current sheets downstream of Earth's bow shock, PHYSICS OF PLASMAS, Vol: 28, ISSN: 1070-664X
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- Citations: 4
Fowler CM, Hanley KG, McFadden JP, et al., 2021, MAVEN Observations of Low Frequency Steepened Magnetosonic Waves and Associated Heating of the Martian Nightside Ionosphere, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380
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- Citations: 5
Schwartz SJ, Ergun R, Kucharek H, et al., 2021, Evaluating the deHoffmann-Teller Cross-Shock Potential at Real Collisionless Shocks, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380
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- Citations: 3
Shuster JR, Gershman DJ, Dorelli JC, et al., 2021, Structures in the terms of the Vlasov equation observed at Earth's magnetopause, NATURE PHYSICS, Vol: 17, Pages: 1056-+, ISSN: 1745-2473
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- Citations: 7
Madanian H, Schwartz SJ, Fuselier SA, et al., 2021, Direct Evidence for Magnetic Reflection of Heavy Ions from High Mach Number Collisionless Shocks, ASTROPHYSICAL JOURNAL LETTERS, Vol: 915, ISSN: 2041-8205
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- Citations: 4
Starkey MJ, Fuselier SA, Desai MI, et al., 2021, MMS Observations of Energized He+ Pickup Ions at Quasiperpendicular Shocks, ASTROPHYSICAL JOURNAL, Vol: 913, ISSN: 0004-637X
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- Citations: 2
Johlander A, Battarbee M, Vaivads A, et al., 2021, Ion Acceleration Efficiency at the Earth's Bow Shock: Observations and Simulation Results, ASTROPHYSICAL JOURNAL, Vol: 914, ISSN: 0004-637X
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- Citations: 1
Hoilijoki S, Pucci F, Ergun RE, et al., 2021, Origin of Electron-Scale Magnetic Fluctuations Close to an Electron Diffusion Region, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380
Horaites K, Andersson L, Schwartz SJ, et al., 2021, Observations of Energized Electrons in the Martian Magnetosheath, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380
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- Citations: 3
Turner DL, Wilson LB, Goodrich KA, et al., 2021, Direct multipoint observations capturing the reformation of a supercritical fast magnetosonic shock, The Astrophysical Journal Letters, Vol: 911, Pages: 1-11, ISSN: 2041-8205
Using multipoint Magnetospheric Multiscale (MMS) observations in an unusual string-of-pearls configuration, we examine in detail observations of the reformation of a fast magnetosonic shock observed on the upstream edge of a foreshock transient structure upstream of Earth's bow shock. The four MMS spacecraft were separated by several hundred kilometers, comparable to suprathermal ion gyroradius scales or several ion inertial lengths. At least half of the shock reformation cycle was observed, with a new shock ramp rising up out of the "foot" region of the original shock ramp. Using the multipoint observations, we convert the observed time-series data into distance along the shock normal in the shock's rest frame. That conversion allows for a unique study of the relative spatial scales of the shock's various features, including the shock's growth rate, and how they evolve during the reformation cycle. Analysis indicates that the growth rate increases during reformation, electron-scale physics play an important role in the shock reformation, and energy conversion processes also undergo the same cyclical periodicity as reformation. Strong, thin electron-kinetic-scale current sheets and large-amplitude electrostatic and electromagnetic waves are reported. Results highlight the critical cross-scale coupling between electron-kinetic- and ion-kinetic-scale processes and details of the nature of nonstationarity, shock-front reformation at collisionless, fast magnetosonic shocks.
Xu S, Schwartz SJ, Mitchell DL, et al., 2021, Cross-Shock Electrostatic Potentials at Mars Inferred From MAVEN Measurements, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380
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- Citations: 5
Schwartz SJ, Kucharek H, Farrugia CJ, et al., 2021, Energy Conversion Within Current Sheets in the Earth's Quasi-Parallel Magnetosheath, GEOPHYSICAL RESEARCH LETTERS, Vol: 48, ISSN: 0094-8276
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- Citations: 4
Madanian H, Desai M, Schwartz SJ, et al., 2021, The Dynamics of a High Mach Number Quasi-perpendicular Shock: MMS Observations, ASTROPHYSICAL JOURNAL, Vol: 908, ISSN: 0004-637X
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- Citations: 14
Chandler MO, Schwartz SJ, Avanov LA, et al., 2021, Observations of Mirror Mode Structures in the Dawn-Side Magnetosphere, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380
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- Citations: 2
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