Imperial College London

Emeritus ProfessorStevenSchwartz

Faculty of Natural SciencesDepartment of Physics

Distinguished Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 7660s.schwartz Website

 
 
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Assistant

 

Mr Luke Kratzmann +44 (0)20 7594 7770

 
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Location

 

6M58Huxley BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

275 results found

Goodrich K, Schwartz S, III LW, Cohen I, Caspi A, Smith K, Rose R, Whittlesey P, Plaschke F, Halekas J, Hospodarsky G, Burch J, Gingell I, Chen L-J, Retino A, Khotyaintev Yet al., 2023, The Persistent Mystery of Collisionless Shocks, Vol. 55, Issue 3 (Heliophysics 2024 Decadal Whitepapers)

Journal article

Wilson L, Goodrich K, Turner D, Cohen I, Whittlesey P, Schwartz Set al., 2023, The necessity of accurate measurements of thermal velocity distribution functions in the solar wind, Vol. 55, Issue 3 (Heliophysics 2024 Decadal Whitepapers)

Journal article

Madanian H, Omidi N, Sibeck DG, Andersson L, Ramstad R, Xu S, Gruesbeck JR, Schwartz SJ, Frahm RA, Brain DA, Kajdic P, Eparvier FG, Mitchell DL, Curry SMet al., 2023, Transient Foreshock Structures Upstream of Mars: Implications of the Small Martian Bow Shock, Geophysical Research Letters, Vol: 50, ISSN: 0094-8276

The typical subsolar stand-off distance of Mars' bow shock is of the order of a solar wind ion convective gyroradius, making it highly non-planar to incident ions. Using spacecraft observations and a test particle model, we illustrate the impact of the bow shock curvature on transient structures which form near the upstream edge of moving foreshocks caused by slow rotations in the interplanetary magnetic field (IMF). The structures exhibit noticeable decrease in the solar wind plasma density and the IMF strength within their core, are accompanied by a compressional shock layer, and are consistent with foreshock bubbles (FBs). Ion populations responsible for these structures include backstreaming ions that only appear within the moving foreshock and reflected ions with hybrid trajectories that straddle between the quasi-perpendicular and quasi-parallel bow shocks during slow IMF rotations. Both ion populations accumulate near the upstream edge of the moving foreshock which facilitates FB formation.

Journal article

Shuster JR, Gershman DJ, Giles BL, Bessho N, Sharma AS, Dorelli JC, Uritsky V, Schwartz SJ, Cassak PA, Denton RE, Chen LJ, Gurram H, Ng J, Burch J, Webster J, Torbert R, Paterson WR, Schiff C, ViƱas AF, Avanov LA, Stawarz J, Li TC, Liu YH, Argall MR, Afshari A, Payne DS, Farrugia CJ, Verniero J, Wilder F, Genestreti K, da Silva DEet al., 2023, Temporal, Spatial, and Velocity-Space Variations of Electron Phase Space Density Measurements at the Magnetopause, Journal of Geophysical Research: Space Physics, Vol: 128, ISSN: 2169-9380

Temporal, spatial, and velocity-space variations of electron phase space density are measured observationally and compared for the first time using the four magnetospheric multiscale (MMS) spacecraft at Earth's magnetopause. Equipped with these unprecedented spatiotemporal measurements offered by the MMS tetrahedron, we compute each term of the electron Vlasov equation that governs the evolution of collisionless plasmas found throughout the universe. We demonstrate how to use single spacecraft measurements to improve the resolution of the electron pressure gradient that supports nonideal parallel electric fields, and we develop a model to intuit the types of kinetic velocity-space signatures that are observed in the Vlasov equation terms. Furthermore, we discuss how the gradient in velocity-space sheds light on plasma energy conversion mechanisms and wave-particle interactions that occur in fundamental physical processes such as magnetic reconnection and turbulence.

Journal article

Trattner KJ, Fuselier SA, Schwartz SJ, Kucharek H, Burch JL, Ergun RE, Petrinec SM, Madanian Het 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.

Journal article

Gingell I, Schwartz SJ, Kucharek H, Farrugia CJ, Fryer LJ, Plank J, Trattner KJet al., 2023, Hybrid simulations of the decay of reconnected structures downstream of the bow shock, PHYSICS OF PLASMAS, Vol: 30, ISSN: 1070-664X

Journal article

Pathak N, Ergun RE, Qi Y, Schwartz SJ, Vo T, Usanova ME, Hesse M, Phan TD, Drake JF, Eriksson S, Ahmadi N, Chasapis A, Wilder FD, Stawarz JE, Burch JL, Genestreti KJ, Torbert RB, Nakamura Ret al., 2022, Evidence of a Nonorthogonal X-line in Guide-field Magnetic Reconnection, ASTROPHYSICAL JOURNAL LETTERS, Vol: 941, ISSN: 2041-8205

Journal article

Fowler CM, Hanley KG, McFadden J, Halekas J, Schwartz SJ, Mazelle C, Chaffin M, Mitchell D, Espley J, Ramstad R, Dong Y, Curry Set 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.

Journal article

Wilson LB, Goodrich KA, Turner DL, Cohen IJ, Whittlesey PL, Schwartz SJet 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

Journal article

Pollock CJ, Chen L-J, Schwartz SJ, Wang S, Avanov L, Burch JL, Gershman DJ, Giles BL, Raptis S, Russell CTet al., 2022, Dynamics of Earth's bow shock under near-radial interplanetary magnetic field conditions, PHYSICS OF PLASMAS, Vol: 29, ISSN: 1070-664X

Journal article

Schwartz SJ, Goodrich KA, Wilson LB, Turner DL, Trattner KJ, Kucharek H, Gingell I, Fuselier SA, Cohen IJ, Madanian H, Ergun RE, Gershman DJ, Strangeway RJet al., 2022, Energy Partition at Collisionless Supercritical Quasi-Perpendicular Shocks, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 127, ISSN: 2169-9380

Journal article

Ergun RE, Pathak N, Usanova ME, Qi Y, Vo T, Burch JL, Schwartz SJ, Torbert RB, Ahmadi N, Wilder FD, Chasipis A, Newman DL, Stawarz JE, Hesse M, Turner DL, Gershman Det al., 2022, Observation of Magnetic Reconnection in a Region of Strong Turbulence, ASTROPHYSICAL JOURNAL LETTERS, Vol: 935, ISSN: 2041-8205

Journal article

Schwartz SJ, Goodrich KA, Wilson III LB, Turner DL, Trattner K, Kucharek H, Gingell I, Fuselier SA, Cohen IJ, Madanian H, Ergun RE, Gershman DJ, Strangeway RJet al., 2022, Energy partition at collisionless supercritical quasiperpendicular shocks

Journal article

Thaller SA, Andersson L, Schwartz SJ, Mazelle C, Fowler C, Goodrich K, Newman D, Halekas J, Pilinski MD, Pollard Met 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

Journal article

Schwartz SJ, Goodrich KA, Wilson III LB, Turner DL, Trattner K, Kucharek H, Gingell I, Fuselier SA, Cohen IJ, Madanian H, Ergun RE, Gershman DJ, Strangeway RJet al., 2022, Energy partition at collisionless supercritical quasiperpendicular shocks

Journal article

Akbari H, Newman D, Fowler C, Pfaff R, Andersson L, Malaspina D, Schwartz S, Ergun R, McFadden J, Mitchell D, Halekas J, Rowland Det 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

Journal article

Ukhorskiy AY, Sorathia KA, Merkin VG, Crabtree C, Fletcher AC, Malaspina DM, Schwartz SJet al., 2022, Cross-scale energy cascade powered by magnetospheric convection, SCIENTIFIC REPORTS, Vol: 12, ISSN: 2045-2322

Journal article

Chen L-J, Halekas J, Wang S, DiBraccio GA, Romanelli N, Ng J, Russell CT, Schwartz SJ, Sibeck DG, Farrell W, Pollock C, Gershman D, Giles B, Collado-Vega YMet 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

Journal article

Schwartz S, Kucharek H, Farrugia C, Trattner K, Gingell I, Chasapis A, Gershman D, Strangeway Ret al., 2021, Characteristics of Intense Current-carrying Structures in the Terrestrial Magnetosheath

Journal article

Vech D, Malaspina DM, Cattell C, Schwartz SJ, Ergun RE, Klein KG, Kromyda L, Chasapis Aet al., 2021, Experimental Determination of Ion Acoustic Wave Dispersion Relation With Interferometric Analysis, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380

Journal article

Gingell I, Schwartz SJ, Kucharek H, Farrugia CJ, Trattner KJet al., 2021, Observing the prevalence of thin current sheets downstream of Earth's bow shock, PHYSICS OF PLASMAS, Vol: 28, ISSN: 1070-664X

Journal article

Fowler CM, Hanley KG, McFadden JP, Chaston CC, Bonnell JW, Halekas JS, Espley JR, DiBraccio GA, Schwartz SJ, Mazelle C, Mitchell DL, Xu S, Lillis RJet 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

Journal article

Schwartz SJ, Ergun R, Kucharek H, Wilson L, Chen L-J, Goodrich K, Turner D, Gingell I, Madanian H, Gershman D, Strangeway Ret al., 2021, Evaluating the deHoffmann-Teller Cross-Shock Potential at Real Collisionless Shocks, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380

Journal article

Shuster JR, Gershman DJ, Dorelli JC, Giles BL, Wang S, Bessho N, Chen L-J, Cassak PA, Schwartz SJ, Denton RE, Uritsky VM, Paterson WR, Schiff C, Vinas AF, Ng J, Avanov LA, da Silva DE, Torbert RBet al., 2021, Structures in the terms of the Vlasov equation observed at Earth's magnetopause, NATURE PHYSICS, Vol: 17, Pages: 1056-+, ISSN: 1745-2473

Journal article

Madanian H, Schwartz SJ, Fuselier SA, Burgess D, Turner DL, Chen L-J, Desai MI, Starkey MJet al., 2021, Direct Evidence for Magnetic Reflection of Heavy Ions from High Mach Number Collisionless Shocks, ASTROPHYSICAL JOURNAL LETTERS, Vol: 915, ISSN: 2041-8205

Journal article

Johlander A, Battarbee M, Vaivads A, Turc L, Pfau-Kempf Y, Ganse U, Grandin M, Dubart M, Khotyaintsev YV, Caprioli D, Haggerty C, Schwartz SJ, Giles BL, Palmroth Met al., 2021, Ion Acceleration Efficiency at the Earth's Bow Shock: Observations and Simulation Results, ASTROPHYSICAL JOURNAL, Vol: 914, ISSN: 0004-637X

Journal article

Starkey MJ, Fuselier SA, Desai MI, Schwartz SJ, Russell CT, Wei H, Madanian H, Mukherjee J, Wilson LBet al., 2021, MMS Observations of Energized He+ Pickup Ions at Quasiperpendicular Shocks, ASTROPHYSICAL JOURNAL, Vol: 913, ISSN: 0004-637X

Journal article

Schwartz SJ, Ergun RE, Harald K, Wilson LB, Chen L-J, Goodrich KA, Turner DL, Gingell I, Madanian H, Gershman DJ, Strangeway RJet al., 2021, Evaluating the de Hoffmann-Teller cross-shock potential at real collisionless shocks

Journal article

Hoilijoki S, Pucci F, Ergun RE, Schwartz SJ, Wilder FD, Eriksson S, Chasapis A, Ahmadi N, Webster JM, Burch JL, Torbert RB, Strangeway RJ, Giles BLet 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

Journal article

Horaites K, Andersson L, Schwartz SJ, Xu S, Mitchell DL, Mazelle C, Halekas J, Gruesbeck Jet al., 2021, Observations of Energized Electrons in the Martian Magnetosheath, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380

Journal article

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