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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Location

 

6M58Huxley BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

271 results found

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

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

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

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

Turner DL, Wilson LB, Goodrich KA, Madanian H, Schwartz SJ, Liu TZ, Johlander A, Caprioli D, Cohen IJ, Gershman D, Hietala H, Westlake JH, Lavraud B, Le Contel O, Burch JLet 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.

Journal article

Xu S, Schwartz SJ, Mitchell DL, Horaites K, Andersson L, Halekas J, Mazelle C, Gruesbeck JRet al., 2021, Cross-Shock Electrostatic Potentials at Mars Inferred From MAVEN Measurements, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380

Journal article

Schwartz SJ, Kucharek H, Farrugia CJ, Trattner K, Gingell I, Ergun RE, Strangeway R, Gershman Det al., 2021, Energy Conversion Within Current Sheets in the Earth's Quasi-Parallel Magnetosheath, GEOPHYSICAL RESEARCH LETTERS, Vol: 48, ISSN: 0094-8276

Journal article

Madanian H, Desai M, Schwartz SJ, Wilson LB, Fuselier SA, Burch JL, Le Contel O, Turner DL, Ogasawara K, Brosius AL, Russell CT, Ergun RE, Ahmadi N, Gershman DJ, Lindqvist P-Aet al., 2021, The Dynamics of a High Mach Number Quasi-perpendicular Shock: MMS Observations, ASTROPHYSICAL JOURNAL, Vol: 908, ISSN: 0004-637X

Journal article

Chandler MO, Schwartz SJ, Avanov LA, Coffey VN, Giles BL, Moore TE, Pollock CJ, Burch JL, Russell CT, Torbert RBet al., 2021, Observations of Mirror Mode Structures in the Dawn-Side Magnetosphere, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380

Journal article

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