697 results on '"Fuselier, S. A."'
Search Results
2. Global-Scale Processes and Effects of Magnetic Reconnection on the Geospace Environment
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Fuselier, S. A., Petrinec, S. M., Reiff, P. H., Birn, J., Baker, D. N., Cohen, I. J., Nakamura, R., Sitnov, M. I., Stephens, G. K., Hwang, J., Lavraud, B., Moore, T. E., Trattner, K. J., Giles, B. L., Gershman, D. J., Toledo-Redondo, S., and Eastwood, J. P.
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- 2024
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3. Cross-Scale Processes of Magnetic Reconnection
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Hwang, K.-J., Nakamura, R., Eastwood, J. P., Fuselier, S. A., Hasegawa, H., Nakamura, T., Lavraud, B., Dokgo, K., Turner, D. L., Ergun, R. E., and Reiff, P. H.
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- 2023
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4. Simultaneous macroscale and microscale wave–ion interaction in near-earth space plasmas
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Liu, Z.-Y., Zong, Q.-G., Rankin, R., Zhang, H., Wang, Y. F., Zhou, X.-Z., Fu, S.-Y., Yue, C., Zhu, X.-Y., Pollock, C. J., Fuselier, S. A., and Le, G.
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- 2022
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5. Identification and characterization of a new ensemble of cometary organic molecules
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Hänni, N., Altwegg, K., Combi, M., Fuselier, S. A., De Keyser, J., Rubin, M., and Wampfler, S. F.
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- 2022
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6. Investigating Boundary Layer Properties at Jupiter's Dawn Magnetopause.
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Montgomery, Jake, Ebert, R. W., Allegrini, F., Fuselier, S. A., Bagenal, F., Bolton, S. J., Szalay, J., and Wilson, R. J.
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SOLAR magnetic fields ,MAGNETIC reconnection ,PLASMA boundary layers ,MAGNETOPAUSE ,BOUNDARY layer (Aerodynamics) ,SOLAR wind - Abstract
We survey crossings of Jupiter's dawn magnetopause during the Juno prime mission to identify and characterize Jupiter's magnetopause boundary layer. Using plasma and magnetic field observations from Jovian Auroral Distributions Experiment and Juno Magnetic Field investigation, we identify 53 boundary layer events from the 62 magnetopause crossings studied here. We find that the boundary layer generally exhibits mixed properties of magnetosheath and magnetosphere electron distributions, including lower characteristic electron energies and denser ion populations than in the magnetosphere, but higher characteristic electron energies and less dense ion populations than in the magnetosheath. Boundary layer proton speeds are on average slower than both the magnetosheath and magnetosphere. Other proton parameters in the boundary layer have intermediate values between the magnetosheath and magnetosphere. Through ion composition analysis in regions adjacent to the magnetopause, we find evidence of solar wind and magnetospheric plasma in the boundary layer that suggests plasma is transported across the magnetopause in both directions. This mass and energy transport may be the result of solar wind interactions such as magnetic reconnection and Kelvin‐Helmholtz instabilities. However, many boundary layer events do not exhibit local signatures of these solar wind interactions and plasma may be transported by a non‐local process or diffusively transported. Plain Language Summary: Jupiter has the strongest planetary magnetic field in the solar system and over one metric ton per second of sulfur and oxygen is ejected via volcanic activity on the moon, Io. These two factors inflate Jupiter's magnetosphere as material from Io slowly travels outward from Jupiter to near the magnetopause, the boundary between the magnetosphere and magnetosheath. Jupiter's magnetopause boundary layer is located between its outer magnetosphere and surrounding magnetosheath. The magnetosheath is a region of primarily solar wind plasma between the bow shock and the magnetopause and is draped over the magnetosphere. We find that the dawnside boundary layer that separates the magnetosphere and the magnetosheath is comprised of plasma from both regions and travels across this region due to a variety of physical processes. Additionally, we find solar wind plasma in the magnetosphere and plasma from Io in the magnetosheath. This result implies that plasma travels across the boundary layer in both directions. Lastly, our survey shows the plasma in the dawnside boundary layer moves in the opposite direction of Jupiter's rotation, contrary to the plasma located closer to Jupiter. Key Points: The primary characteristic of Jupiter's magnetopause boundary layer is a dual distribution of magnetosphere and magnetosheath electronsIon composition in the boundary layer and adjacent regions show that plasma is transported across the magnetopause in both directionsIon flow speeds in Jupiter's dawn flank magnetopause boundary layer are hundreds of km/s tailward, opposite to corotation on the dawnside [ABSTRACT FROM AUTHOR]
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- 2024
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7. Assessing the Sources of the O+ in the Plasma Sheet.
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Liao, J., Kistler, L. M., Mouikis, C. G., Fuselier, S. A., and Hedlund, M.
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PLASMA boundary layers ,ION sources ,HIGH temperature plasmas ,AURORAS ,PLASMA sources - Abstract
To study the average contributions of the cusp outflow through the lobes and of the nightside auroral outflow to the O+ in the plasma sheet (PS), we performed a statistical study of tailward streaming O+ in the lobes, plasma sheet boundary layer|the plasma sheet boundary layer (PSBL) and the PS, using MMS/Hot Plasma Composition Analyzer (HPCA) data from 2017 to 2020. Similar spatial patterns illustrate the entry of cusp‐origin O+ from the lobes to the PS through the PSBL. There is an YGSM‐dependent energy pattern for the lobe O+, with low‐energy O+ streaming closer to the tail center and high energy (1–3 keV) O+ streaming near the flanks. Low energy (1–100 eV) O+ from the nightside auroral oval is identified in the near‐Earth PSBL/PS with high‐density (>0.02 cm−3), and energetic (>3 keV) streaming O+ with similar density (∼0.013 cm−3) is observed further out on the duskside of the PSBL/PS. The rest of the nightside auroral O+ in the PSBL is mixed with O+ coming in from the lobe, making it difficult to distinguish the source. We estimated the contributions of the different sources of H+ and O+ ions through the PS between 7 and 17 RE, using estimates from this work and data extracted from previous studies. We conclude that, during quiet times, the majority of the near‐Earth PS H+ are from the cusps, the polar wind and Earthward convection from the distant tail. Similarly, while the O+ in the same region has a mixed source, cusp origin outflow provides the highest contribution. Plain Language Summary: We studied the sources of the plasma sheet (PS), using MMS/HPCA data. We observed and mapped the location of the oxygen ions streaming from the dayside cusp region entering the PS through the plasma sheet boundary layer (PSBL). The observations of the oxygen ions from the nightside auroral oval streaming inside PSBL show that this population has higher density than the dayside cusp origin oxygen ions. We estimated the number of the proton and oxygen ions per second entering and leaving the PS and conclude that during quiet times, the solar wind protons are the major source for PS population and ionospheric oxygen ions from dayside cusp is the major source for oxygen ions in the PS. Key Points: Cusp‐source O+ is observed entering the plasma sheet (PS) from the lobe throughout the <25 RE magnetotailThe nightside auroral‐source O+ is identified at <100 eV inside 10 RE, with a more energetic component further out on the dusksideWe estimate that during quiet times, the dayside cusp contributes the most to the near‐earth PS O+ [ABSTRACT FROM AUTHOR]
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- 2024
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8. Shocks in the Very Local Interstellar Medium
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Mostafavi, P., Burlaga, L. F., Cairns, I. H., Fuselier, S. A., Fraternale, F., Gurnett, D. A., Kim, T. K., Kurth, W. S., Pogorelov, N. V., Provornikova, E., Richardson, J. D., Turner, D. L., and Zank, G. P.
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- 2022
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9. TRICE‐2/SuperDARN Observations and Comparison With the Associated MMS Magnetopause Crossing.
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Trattner, K. J., Fuselier, S. A., Kletzing, C. A., Bonnell, J. W., Bounds, S. R., Petrinec, S. M., Sawyer, R. P., Yeoman, T. K., Ergun, R. E., and Burch, J. L.
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MAGNETOPAUSE ,SOLAR cycle ,ROCKETS (Aeronautics) ,BOUNDARY layer (Aerodynamics) ,ION beams ,ION energy ,ION bombardment - Abstract
Two sounding rockets, designated TRICE‐2, were launched on 8 December 2018 into the northern cusp region. The two rockets were designated the high‐ and low‐flyers, respectively, and launched 2 min apart to investigate cusp structures, specifically their spatial or temporal nature. 2 hr prior to the cusp encounter by the TRICE‐2 rockets, the MMS satellites, located in the magnetopause boundary layer, observed switching ion beams under very similar IMF conditions as later observed by TRICE‐2. The observed ion beam switch in the boundary layer defined the location of the primary dayside X‐line. Both, TRICE‐2 and MMS, also observed the signatures of multiple X‐lines at the magnetopause, overlapping ion‐energy dispersions in the cusp and counterstreaming ion beams in the magnetopause boundary layer, respectively. In addition to the TRICE‐2 cusp observations, ionospheric convection patterns from the SuperDARN radar are used to explain the vastly different cusp ion signatures observed by the TRICE‐2 rockets. While the high‐flyer rocket progressed north through the center of the cusp, the low‐flyer rocket drifted off to the east and crossed into the dusk convection cell, traveling perpendicular to the ionospheric convection direction before reaching the poleward oriented section of the convection cell also observed by the high‐flyer counterpart. Key Points: TRICE‐2 cusp ion dispersions are explained using the different magnetic foot points of the rockets through the ionospheric convection cellsTRICE‐2 cusp crossing occurred 2 hr after an MMS magnetopause crossing during similar IMF conditionsOverlapping cusp ion energy dispersions result from multiple magnetopause reconnection locations in agreement with MMS observations [ABSTRACT FROM AUTHOR]
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- 2024
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10. Statistical Observations of Proton‐Band Electromagnetic Ion Cyclotron Waves in the Outer Magnetosphere: Full Wavevector Determination.
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Toledo‐Redondo, S., Lee, J. H., Vines, S. K., Albert, I. F., André, M., Castilla, A., Dargent, J. P., Fu, H. S., Fuselier, S. A., Genot, V., Graham, D. B., Kitamura, N., Khotyaintsev, Yu. V., Lavraud, B., Montagud‐Camps, V., Navarro, E. A., Norgren, C., Perrone, D., Phan, T. D., and Portí, J.
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ION acoustic waves ,MAGNETOSPHERE ,RELATIVISTIC electrons ,SOLAR wind ,DECOMPOSITION method ,CYCLOTRONS - Abstract
Electromagnetic Ion Cyclotron (EMIC) waves mediate energy transfer from the solar wind to the magnetosphere, relativistic electron precipitation, or thermalization of the ring current population, to name a few. How these processes take place depends on the wave properties, such as the wavevector and polarization. However, inferring the wavevector from in‐situ measurements is problematic since one needs to disentangle spatial and time variations. Using 8 years of Magnetospheric Multiscale (MMS) mission observations in the dayside magnetosphere, we present an algorithm to detect proton‐band EMIC waves in the Earth's dayside magnetosphere, and find that they are present roughly 15% of the time. Their normalized frequency presents a dawn‐dusk asymmetry, with waves in the dawn flank magnetosphere having larger frequency than in the dusk, subsolar, and dawn near subsolar region. It is shown that the observations are unstable to the ion cyclotron instability. We obtain the wave polarization and wavevector by comparing Single Value Decomposition and Ampere methods. We observe that for most waves the perpendicular wavenumber (k⊥) is larger than the inverse of the proton gyroradius (ρi), that is, k⊥ρi > 1, while the parallel wavenumber is smaller than the inverse of the ion gyroradius, that is, k‖ρi < 1. Left‐hand polarized waves are associated with small wave normal angles (θBk < 30°), while linearly polarized waves are associated with large wave normal angles (θBk > 30°). This work constitutes, to our knowledge, the first attempt to statistically infer the full wavevector of proton‐band EMIC waves observed in the outer magnetosphere. Key Points: We conduct a statistical analysis of proton‐band Electromagnetic Ion Cyclotron (EMIC) waves in dayside magnetosphere using 8 years of Magnetospheric Multiscale data and measure full wavevectorsThe normalized frequency of EMIC waves presents a dawn‐dusk asymmetryThe perpendicular wavevector is, for most of the waves, larger than the inverse of proton gyroradius and ion inertial lengths [ABSTRACT FROM AUTHOR]
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- 2024
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11. Temporal Evolution of O+ Population in the Near‐Earth Plasma Sheet During Geomagnetic Storms as Observed by the Magnetospheric Multiscale Mission.
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Regoli, L. H., Gkioulidou, M., Ohtani, S., Raptis, S., Mouikis, C. G., Kistler, L. M., Cohen, I. J., and Fuselier, S. A.
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AURORAS ,PLASMA density ,MAGNETOSPHERE ,STORMS ,GEOMAGNETISM ,IONOSPHERE ,MAGNETIC storms - Abstract
During geomagnetic storms, the increase in energy input into the ionosphere in the form of Poynting flux and electron precipitation leads to an enhanced ionospheric outflow that results in an increase of the O+ content in the magnetosphere. Using different missions and instrumentation, two main ionospheric sources have been identified for the oxygen ions reaching the inner magnetosphere during geomagnetic storms: the dayside cusp, and the night side auroral region. Evidence of both pathways have been presented in the literature. However, the relative contribution of each of these pathways to the enhancement of O+ observed in near‐Earth plasma sheet, as well as the dynamics involved during the development of geomagnetic storms remains an open question. Here, we present the first statistical study to date to address this question, in the form of a superposed epoch analysis of O+ and H+ moments obtained by the Magnetospheric Multiscale (MMS) mission throughout the main phase of 90 geomagnetic storms with a minimum SYM‐H of at least −50 nT. The results show a clear increase in the oxygen density in the near‐Earth plasma sheet, with values further from Earth remaining low. Temperature values for both species show an increase with the progress of the storms. These results combined suggest that, during the main phase of geomagnetic storms, most of the oxygen ions observed in the near‐Earth plasma sheet are traveling directly from the nightside auroral region. Key Points: Superposed epoch analysis shows dynamic evolution of O+ ions during geomagnetic stormsSignificant enhancement of the O+‐to‐H+ number density ratio observed at radial distances less than 12 REScalar temperature for both species show the arrival of heated ions far from Earth throughout the analyzed period [ABSTRACT FROM AUTHOR]
- Published
- 2024
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12. Electron-scale dynamics of the diffusion region during symmetric magnetic reconnection in space
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Torbert, R. B., Burch, J. L., Phan, T. D., Hesse, M., Argall, M. R., Shuster, J., Ergun, R. E., Alm, L., Nakamura, R., Genestreti, K. J., Gershman, D. J., Paterson, W. R., Turner, D. L., Cohen, I., Giles, B. L., Pollock, C. J., Wang, S., Chen, L.-J., Stawarz, J. E., Eastwood, J. P., Hwang, K. J., Farrugia, C., Dors, I., Vaith, H., Mouikis, C., Ardakani, A., Mauk, B. H., Fuselier, S. A., Russell, C. T., Strangeway, R. J., Moore, T. E., Drake, J. F., Shay, M. A., Khotyaintsev, Yuri V., Lindqvist, P.-A., Baumjohann, W., Wilder, F. D., Ahmadi, N., Dorelli, J. C., Avanov, L. A., Oka, M., Baker, D. N., Fennell, J. F., Blake, J. B., Jaynes, A. N., Le Contel, O., Petrinec, S. M., Lavraud, B., and Saito, Y.
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- 2018
13. Ion Dynamics Across a Low Mach Number Bow Shock.
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Graham, D. B., Khotyaintsev, Yu. V., Dimmock, A. P., Lalti, A., Boldú, J. J., Tigik, S. F., and Fuselier, S. A.
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MACH number ,CORONAL mass ejections ,PARTICLE detectors ,HELIUM ions ,ALPHA rays ,SOLAR wind ,HEAVY ions ,PARTICLE acceleration ,CYCLOTRON resonance - Abstract
A thorough understanding of collisionless shocks requires knowledge of how different ion species are accelerated across the shock. We investigate a bow shock crossing using the Magnetospheric Multiscale spacecraft after a coronal mass ejection crossed Earth, which led to solar wind consisting of protons, alpha particles, and singly charged helium ions. The three species are resolved upstream of the shock. The low Mach number of the bow shock enabled the ions to be partly distinguished downstream of the shock due to the relatively low ion heating. Some of the protons are specularly reflected and produce quasi-periodic fine structures in the velocity distribution functions downstream of the shock. Heavier ions are shown to transit the shock without reflection. However, the gyromotion of the heavier ions partially obscures the fine structure of proton distributions. Additionally, the calculated proton moments are unreliable when the different ion species are not distinguished by the particle detector. The need for high time-resolution mass-resolving ion detectors when investigating collisionless shocks is discussed. [ABSTRACT FROM AUTHOR]
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- 2024
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14. Direct measurements of two-way wave-particle energy transfer in a collisionless space plasma
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Kitamura, N., Kitahara, M., Shoji, M., Miyoshi, Y., Hasegawa, H., Nakamura, S., Katoh, Y., Saito, Y., Yokota, S., Gershman, D. J., Vinas, A. F., Giles, B. L., Moore, T. E., Paterson, W. R., Pollock, C. J., Russell, C. T., Strangeway, R. J., Fuselier, S. A., and Burch, J. L.
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- 2018
15. Flux Ropes at the Reconnection-Suppressed Magnetopause of Saturn: Cassini Observations
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Jasinski, Jamie M, Akhavan-Tafti, M, Sun, W, Slavin, J. A, Coates, A. J, Fuselier, S. A, Sergis, N, and Murphy, N
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- 2021
16. Flux Ropes at the Reconnection-Suppressed Magnetopause of Saturn: Cassini Observations
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Murphy, N, Sergis, N, Fuselier, S. A, Coates, A. J, Slavin, J. A, Sun, W, Akhavan-Tafti, M, and Jasinski, Jamie M
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- 2021
17. The Location of Magnetic Reconnection at Earth’s Magnetopause
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Trattner, K. J., Petrinec, S. M., and Fuselier, S. A.
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- 2021
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18. D₂O and HDS in the coma of 67P/Churyumov—Gerasimenko
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Altwegg, K., Balsiger, H., Berthelier, J. J., Bieler, A., Calmonte, U., De Keyser, J., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Owen, T., Le Roy, L., Rubin, M., Sémon, T., and Tzou, C.-Y.
- Published
- 2017
19. Xenon isotopes in 67P/Churyumov-Gerasimenko show that comets contributed to Earth's atmosphere
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Marty, B., Altwegg, K., Balsiger, H., Bar-Nun, A., Bekaert, D. V., Berthelier, J.-J., Bieler, A., Briois, C., Calmonte, U., Combi, M., De Keyser, J., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Hansen, K. C., Hässig, M., Jäckel, A., Kopp, E., Korth, A., Le Roy, L., Mall, U., Mousis, O., Owen, T., Rème, H., Rubin, M., Sémon, T., Tzou, C.-Y., Waite, J. H., and Wurz, P.
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- 2017
20. Views of Earth's Magnetosphere with the IMAGE Satellite
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Burch, J. L., Mende, S. B., Mitchell, D. G., Moore, T. E., Pollock, C. J., Reinisch, B. W., Sandel, B. R., Fuselier, S. A., Gallagher, D. L., Green, J. L., Perez, J. D., and Reiff, P. H.
- Published
- 2001
21. Statistical analysis of overlapping double ion energy dispersion events in the northern cusp.
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da Silva, D. E., Chen, L. J., Fuselier, S. A., Petrinec, S. M., Trattner, K. J., Cucho-Padin, G., Connor, H. K., Burkholder, B. L., Huntenburg, A. J., Forsyth, Colin, and Ivchenko, Nickolay
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ION energy ,INTERPLANETARY magnetic fields ,SOLAR wind ,MAGNETIC reconnection ,STATISTICS ,METEOROLOGICAL satellites ,ORBITS of artificial satellites - Abstract
This article presents a statistical analysis of overlapping double ion-energy dispersion events in the northern cusp ("double dispersion"). Double dispersion in either cusp is a phenomenon associated with multiple reconnections occurring on the dayside magnetosphere as a result of its constant interaction with the variable solar wind. Using observations from a low Earth orbiting (LEO) Defense Meteorological Satellite Program (DMSP) satellite, we analyze 138 dayside events selected by the automatic algorithm extended from our previous work. We conducted a correlation study between the number of detected double dispersion events and 1) the month of the year to analyze the seasonal response of the cusp, and 2) solar wind interplanetary magnetic field (IMF) components and clock/cone angles to investigate its relationship with magnetic reconnection. We found that dispersion events occur more frequently during the northern summer months (i.e., when the dipole is tilted Sunward) and when the B
y component of IMF is positive. In addition, we provide a machine-readable list of the events and the code used to automatically detect the events. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
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22. MMS Observations of Warm‐Ion (E < 100 eV) Heating Inside Plasmaspheric Plumes.
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Kim, M. J., Goldstein, J., Fuselier, S. A., Vines, S. K., Usanova, M. E., Gonzalez, C. A., Mukherjee, J., and Burch, J. L.
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ELECTROMAGNETIC interactions ,MAGNETIC reconnection ,CYCLOTRONS ,HEATING - Abstract
Near‐Earth plasma surges sunward during enhanced magnetospheric convection (driven by dayside magnetic reconnection) to form a pathway feature called a plasmaspheric plume. This study uses Magnetospheric Multiscale (MMS) observations to investigate the heating of warm ions (H+ and He+) inside plumes. We identify 287 plume events using targeted in‐situ‐observational criteria and plasmapause test particle simulations. One plume‐crossing event by MMS shows that the scalar temperatures of warm He+ increase from ∼10 to ∼40 eV during simultaneous observations of helium‐band electromagnetic ion cyclotron (EMIC) waves, while H+ temperature is almost constant. Next, we analyze all individual observations to investigate warm‐ion heating and its possible association with EMIC waves. The statistical results show that EMIC waves associated with the plume have left‐hand polarizations and small normal angles and the temperatures of warm He+ are always higher than those of warm H+. Also, the minimum resonant energies for H+ are mostly above 100 eV, whereas 17% of warm He+ observations show that they can interact with the H+‐band EMIC waves via cyclotron resonance. These observations suggest that while EMIC waves play a role, there is an unknown mechanism for warm‐ion heating inside the plume that requires more investigation. Key Points: Warm He+ heating inside the plasmaspheric plume results from the interaction with electromagnetic ion cyclotron (EMIC) wavesCoincident with plumes and EMIC waves, warm He+ is more heated than warm H+Statistical results indicate that resonant interactions with EMIC waves are insufficient to account for all the observed warm ion heating [ABSTRACT FROM AUTHOR]
- Published
- 2023
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23. Tracking Magnetopause Motion Using Cold Plasmaspheric Ions.
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LLera, K., Fuselier, S. A., Petrinec, S. M., Rice, R. C., Burch, J. L., Giles, B., Trattner, K. J., and Strangeway, R. J.
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MAGNETOPAUSE ,ION migration & velocity ,MOTION capture (Human mechanics) ,SPACE environment ,PARTICLE tracks (Nuclear physics) - Abstract
We demonstrate that any plasmaspheric/cold ions accelerated in the vicinity of the magnetopause boundary, can proxy the local magnetopause motion over many minutes. The timeseries of this motion capture local structures such as waves on the boundary. We determine cold ion velocities normal to full magnetopause boundary crossings for three events with varying distances to the predicted reconnection X‐line, thus, providing a proof‐of‐concept study demonstrating the potential for using cold ion velocities to track magnetopause motion over a long period of time. Obtaining the time history of the (local) motion of the magnetopause relative to the spacecraft is determined by integrating the bulk (<100 eV for H+) ion velocities normal to the boundary. Timeseries of these tracked cold ion accelerations may be used to investigate boundary layer thicknesses, potential wave structures on the magnetopause, and their evolution beyond the boundary crossing. This method generally tracks magnetopause motion out to distances of ∼1–2RE away from the spacecraft during quasi‐steady space weather conditions. Key Points: Energized plasmaspheric cold ions effectively track the magnetopause motion continuously over many minutesThe magnetopause location and velocity are tracked reliably out to distances of ∼1–2 RE from the spacecraft given fairly consistent cold ion detectabilityOne of the 3 events shows quasi‐periodic magnetopause motion suggesting that this technique reveals wave propagation along the boundary [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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24. Interstellar Conditions Deduced from Interstellar Neutral Helium Observed by IBEX and Global Heliosphere Modeling
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Swaczyna, P., Bzowski, M., Heerikhuisen, J., Kubiak, M. A., Rahmanifard, F., Zirnstein, E. J., Fuselier, S. A., Galli, A., McComas, D. J., Möbius, E., and Schwadron, N. A.
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Astrophysics - Solar and Stellar Astrophysics ,Physics - Space Physics ,Astrophysics of Galaxies (astro-ph.GA) ,FOS: Physical sciences ,Astrophysics - Astrophysics of Galaxies ,Solar and Stellar Astrophysics (astro-ph.SR) ,Space Physics (physics.space-ph) - Abstract
In situ observations of interstellar neutral (ISN) helium atoms by the IBEX-Lo instrument onboard the Interstellar Boundary Explorer (IBEX) mission are used to determine the velocity and temperature of the pristine very local interstellar medium (VLISM). Most ISN helium atoms penetrating the heliosphere, known as the primary population, originate in the pristine VLISM. As the primary atoms travel through the outer heliosheath, they charge exchange with He$^+$ ions in slowed and compressed plasma creating the secondary population. With more than 2.4 million ISN helium atoms sampled by IBEX during ISN seasons 2009-2020, we compare the observations with predictions of a parametrized model of ISN helium transport in the heliosphere. We account for the filtration of ISN helium atoms at the heliospheric boundaries by charge exchange and elastic collisions. We examine the sensitivity of the ISN helium fluxes to the interstellar conditions described by the pristine VLISM velocity, temperature, magnetic field, and composition. We show that comprehensive modeling of the filtration processes is critical for interpreting ISN helium observations, as the change in the derived VLISM conditions exceeds the statistical uncertainties when accounting for these effects. The pristine VLISM parameters found by this analysis are the flow speed (26.6 km s$^{-1}$), inflow direction in ecliptic coordinates (255.7$^\circ$, 5.04$^\circ$), temperature (7350 K), and B-V plane inclination to the ecliptic plane (53.7$^\circ$). The derived pristine VLISM He$^+$ density is $9.7\times10^3$ cm$^{-3}$. Additionally, we show a strong correlation between the interstellar plasma density and magnetic field strength deduced from these observations., 13 pages, 3 figures, 2 tables, accepted for publication in ApJ
- Published
- 2023
25. The Effect of Angular Scattering Imposed by Charge Exchange and Elastic Collisions on Interstellar Neutral Hydrogen Atoms
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Rahmanifard, F., Swaczyna, P., Zirnstein, E. J., Heerikhuisen, J., Galli, A., Sokół, J. M., Schwadron, N. A., Möbius, E., McComas, D. J., and Fuselier, S. A.
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Physics - Space Physics ,FOS: Physical sciences ,Space Physics (physics.space-ph) - Abstract
Angular scattering in charge exchange and elastic collisions between interstellar ions and neutral (ISN) atoms has been assumed to be negligible in previous studies. Here, we investigated the momentum transfer associated with the angular scattering of H atoms using Monte Carlo calculations to simulate their transport through the outer heliosheath. We considered two cases where charge exchange and elastic collisions between ISN H atoms and protons occur with and without momentum transfer in the outer heliosheath. We then simulated the transport of ISN H atoms inside the heliosphere to simulate count rates observed in the lowest energy bin of IBEX-Lo. We studied the effect of radiation pressure on the ISN H measurements for the cases with and without momentum transfer and compared them with our previous findings. We found an effective radiation parameter ($\mu_{\scriptsize\textrm{eff}}$, which represents for force associated with radiation pressure relative to gravity) for the years 2009-2018 based on the longitudinal shift of the ISN H signal. The two cases with and without momentum transfer reproduce the longitudinal shift in accordance with variations in solar activity, in agreement with our previous results, and they result in similar values for the $\mu_{\scriptsize\textrm{eff}}$, which is $\sim21-22 \%$ larger than the value found based on Ly$\alpha$ observations.
- Published
- 2023
26. Autogenous and efficient acceleration of energetic ions upstream of Earth’s bow shock
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Turner, D. L., Wilson, III, L. B., Liu, T. Z., Cohen, I. J., Schwartz, S. J., Osmane, A., Fennell, J. F., Clemmons, J. H., Blake, J. B., Westlake, J., Mauk, B. H., Jaynes, A. N., Leonard, T., Baker, D. N., Strangeway, R. J., Russell, C. T., Gershman, D. J., Avanov, L., Giles, B. L., Torbert, R. B., Broll, J., Gomez, R. G., Fuselier, S. A., and Burch, J. L.
- Published
- 2018
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27. Electron-scale measurements of magnetic reconnection in space
- Author
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Burch, J. L., Torbert, R. B., Phan, T. D., Chen, L.-J., Moore, T. E., Ergun, R. E., Eastwood, J. P., Gershman, D. J., Cassak, P. A., Argall, M. R., Wang, S., Hesse, M., Pollock, C. J., Giles, B. L., Nakamura, R., Mauk, B. H., Fuselier, S. A., Russell, C. T., Strangeway, R. J., Drake, J. F., Shay, M. A., Khotyaintsev, Yu. V., Lindqvist, P.-A., Marklund, G., Wilder, F. D., Young, D. T., Torkar, K., Goldstein, J., Dorelli, J. C., Avanov, L. A., Oka, M., Baker, D. N., Jaynes, A. N., Goodrich, K. A., Cohen, I. J., Turner, D. L., Fennell, J. F., Blake, J. B., Clemmons, J., Goldman, M., Newman, D., Petrinec, S. M., Trattner, K. J., Lavraud, B., Reiff, P. H., Baumjohann, W., Magnes, W., Steller, M., Lewis, W., Saito, Y., Coffey, V., and Chandler, M.
- Published
- 2016
28. Plasma Properties in the Earth's Magnetosheath Near the Subsolar Magnetopause: Implications for Geocoronal Density Estimates.
- Author
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Fuselier, S. A., Petrinec, S. M., Trattner, K. J., LLera, K., Burch, J. L., Gershman, D. J., Dayeh, M. A., Schwadron, N., Funsten, H. O., and McComas, D. J.
- Subjects
- *
MAGNETOPAUSE , *SOLAR wind , *GAS dynamics , *ION bombardment , *WIND pressure , *DENSITY - Abstract
Combined in situ ion measurements and remote sensing of energetic neutral atoms are used to determine the geocoronal Hydrogen density at large (∼10 RE) distances from the Earth. This method for determining the geocoronal density requires global magnetospheric modeling. Observations in the Earth's subsolar magnetosheath from the Magnetospheric Multiscale mission are used to determine the accuracy of using global models to predict the geocoronal density. On average, gas dynamic and magnetohydrodynamic (MHD) models and observations are in reasonable agreement, with differences <25%. In addition, the MHD model subsolar magnetopause is about 0.5 RE sunward of the observed location. However, variations around averages are large (up to a factor of 2), indicating that global models introduce relatively large uncertainties in geocoronal density estimates. Finally, the critical ion flux in the Interstellar Boundary Explorer IBEX‐Hi energy range is often minimally affected by fluctuations of a factor of 2 in the density. Plain Language Summary: Scientists use a combination of in situ measurements and remote sensing of energetic neutral atoms to determine the density of hydrogen in the geocorona, which a very tenuous neutral atmosphere surrounding the Earth. This method relies on global models of the magnetosphere to determine the geocoronal density accurately. To validate these models, they are compared with measurements taken by the Magnetospheric Multiscale mission in the Earth's subsolar magnetosheath. The magnetosheath is the sheath that encompasses the Earth's magnetosphere. On average, the models and observations match reasonably well, with differences of less than 25%. However, there are significant variations around these averages, sometimes reaching twice the average value, indicating that the global models have relatively large uncertainties in the ultimate estimate of the geocoronal density. Interestingly, fluctuations in density by a factor of 2 have minimal impact on the critical ion flux in the Interstellar Boundary Explorer IBEX‐Hi energy range. Key Points: Magnetohydrodynamic modeling tends to overestimate the subsolar magnetopause standoff distance and underestimate the magnetosheath densityThe subsolar magnetopause moves constantly, even under quasi‐steady solar wind pressure, with displacements at least as large as ∼1 REModels for magnetosheath line‐of‐sight ion fluxes introduce uncertainties of up to a factor of 2 in the geocoronal density estimate at 10 RE [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
29. Ion Acceleration by Foreshock Bubbles: Magnetospheric Multiscale Observations.
- Author
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Lee, S. H., Sibeck, D. G., Omidi, N., Silveira, M. V. D., Vu, A., Vines, S. K., Cohen, I. J., Fuselier, S. A., Wei, H., Russell, C. T., and Burch, J. L.
- Subjects
INTERPLANETARY magnetic fields ,SOLAR wind ,MAGNETIC flux density ,MACH number ,PLASMA flow ,HYBRID computer simulation - Abstract
Foreshock bubbles (FBs) occur when interplanetary magnetic field discontinuities encounter the Earth's foreshock. These transient (∼1 to 5 min) features exhibit depressed densities and magnetic field strengths, enhanced temperatures, and deflected plasma flows trailed by a region of enhanced plasma density and magnetic field strength. Ions can be accelerated inside the FBs through the Fermi acceleration process. Hybrid simulations and test particle calculations predict that the maximum energies of ions accelerated by FBs reach 5.6 times the solar wind ram energy (Esw). We identify 23 FBs from September 2015 to January 2020 Magnetospheric Multiscale spacecraft observations. Most FBs (17 of 23) occurred upstream of the dusk‐side bow shock and above the ecliptic. The FBs occurred for Alfvé $\acute{e}$n Mach numbers ranging from 5 to 15, with 11 FBs having an Alfvé $\acute{e}$n Mach number near 10. To investigate ion energization inside the cores of the FBs we compare the proton spectra observed by the Hot Plasma Composition Analyzer and Energetic Ion Spectrometer before (upstream), during (core), and after (downstream) the FBs. The proton intensities at energies from Esw (the solar wind ram energy, 0.5×m×Vsw2 $0.5\times m\times {V}_{sw}^{2}$) up to about 5.6Esw are greater inside than outside 19 of 23 FBs, confirming that FBs can accelerate particles to these energies. The proton flux intensities at energies between Esw and 5.6Esw in the core of the FBs are consistent with results from global hybrid simulations for ion energization from FBs through second‐order Fermi acceleration. Key Points: Hybrid simulations and test particle calculations predict that foreshock bubbles (FBs) can accelerate ions up to 5.6 times solar wind ram energyWe identified 23 FBs during 5 Magnetospheric Multiscale dayside seasons from September 2015 to January 2020Proton intensities at energies between Esw and 5.6Esw during the FB events exceed those before and after for 19 out of 23 FB events [ABSTRACT FROM AUTHOR]
- Published
- 2023
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30. Two Classes of Equatorial Magnetotail Dipolarization Fronts Observed by Magnetospheric Multiscale Mission: A Statistical Overview.
- Author
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Alqeeq, S. W., Le Contel, O., Canu, P., Retinò, A., Chust, T., Mirioni, L., Chuvatin, A., Nakamura, R., Ahmadi, N., Wilder, F. D., Gershman, D. J., Khotyaintsev, Yu. V., Lindqvist, P.‐A., Ergun, R. E., Burch, J. L., Torbert, R. B., Fuselier, S. A., Russell, C. T., Wei, H. Y., and Strangeway, R. J.
- Subjects
ENERGY conversion ,ELECTRIC fields ,MAGNETIC fields ,ELECTRONS - Abstract
We carried out a statistical study of equatorial dipolarization fronts (DFs) detected by the Magnetospheric Multiscale mission during the full 2017 Earth's magnetotail season. We found that two DF classes are distinguished: class I (74.4%) corresponds to the standard DF properties and energy dissipation and a new class II (25.6%). This new class includes the six DF discussed in Alqeeq et al. (2022, https://doi.org/10.1063/5.0069432) and corresponds to a bump of the magnetic field associated with a minimum in the ion and electron pressures and a reversal of the energy conversion process. The possible origin of this second class is discussed. Both DF classes show that the energy conversion process in the spacecraft frame is driven by the diamagnetic current dominated by the ion pressure gradient. In the fluid frame, it is driven by the electron pressure gradient. In addition, we have shown that the energy conversion processes are not homogeneous at the electron scale mostly due to the variations of the electric fields for both DF classes. Key Points: We reveal a new class of dipolarization front related to a bump of the magnetic field associated with a minimum in the ion and electron pressuresThe energy conversion process in the S/C frame is driven by the diamagnetic current dominated by the ion pressure gradientThe energy conversion processes are not homogeneous at the electron scale due to the variations of the electric fields [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
31. Scaling of Magnetic Reconnection Electron Bulk Heating in the High-Alfvén-speed and Low- β Regime of Earth's Magnetotail.
- Author
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Øieroset, M., Phan, T. D., Oka, M., Drake, J. F., Fuselier, S. A., Gershman, D. J., Maheshwari, K., Giles, B. L., Zhang, Q., Guo, F., Burch, J. L., Torbert, R. B., and Strangeway, R. J.
- Subjects
MAGNETIC reconnection ,SOLAR corona ,ELECTRONS ,ELECTRON temperature ,PLASMA density - Abstract
We have surveyed 21 reconnection exhaust events observed by Magnetospheric MultiScale in the low-plasma- β and high-Alfvén-speed regime of the Earth's magnetotail to investigate the scaling of electron bulk heating produced by reconnection. The ranges of inflow Alfvén speed and inflow electron β
e covered by this study are 800–4000 km s−1 and 0.001–0.1, respectively, and the observed heating ranges from a few hundred electronvolts to several kiloelectronvolts. We find that the temperature change in the reconnection exhaust relative to the inflow, Δ Te , is correlated with the inflow Alfvén speed, VAx,in , based on the reconnecting magnetic field and the inflow plasma density. Furthermore, Δ Te is linearly proportional to the inflowing magnetic energy per particle, m i V Ax , in 2 , and the best fit to the data produces the empirical relation Δ Te = 0.020 m i V Ax , in 2 , i.e., the electron temperature increase is on average ∼2% of the inflowing magnetic energy per particle. This magnetotail study extends a previous magnetopause reconnection study by two orders of magnitude in both magnetic energy and electron β, to a regime that is comparable to the solar corona. The validity of the empirical relation over such a large combined magnetopause–magnetotail plasma parameter range of VA ∼ 10–4000 km s−1 and βe ∼ 0.001–10 suggests that one can predict the magnitude of the bulk electron heating by reconnection in a variety of contexts from the simple knowledge of a single parameter: the Alfvén speed of the ambient plasma. [ABSTRACT FROM AUTHOR]- Published
- 2023
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- View/download PDF
32. Reconnection Rates at the Earth's Magnetopause and in the Magnetosheath.
- Author
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Pritchard, K. R., Burch, J. L., Fuselier, S. A., Genestreti, K. J., Denton, R. E., Webster, J. M., and Broll, J. M.
- Subjects
SOLAR wind ,MAGNETOPAUSE ,ELECTRIC field strength ,MAGNETIC reconnection ,ELECTRON diffusion ,ELECTRIC fields - Abstract
Reconnection electric fields and normalized reconnection rates (RRs) were determined with the four Magnetospheric Multiscale (MMS) spacecraft for 14 reconnection events on the dayside of the Earth's magnetosphere. Half of the events occurred at the magnetopause (MP) and the other half in the magnetosheath (MS). The RRs were determined by measurements of the reconnection electric field within electron diffusion regions. Since the reconnection electric field component is much smaller than the other components, special care had to be taken to eliminate contamination by the larger components. Normalized RRs between 0.02 and 0.48 were determined with average values in the range of theoretical predictions for steady‐state reconnection (0.1–0.2). Using measurements from individual MMS spacecraft, 20 normalized RRs were determined for the seven MP events with a mean of 0.14 and a standard deviation of 0.09. For the 27 RRs that were determined for the seven MS events, the normalized RRs had a mean of 0.16 and a standard deviation of 0.12. These results show variations of over an order of magnitude between the fastest and slowest RRs. However, when summed over all spacecraft, calculations suggest that the RR per event is relatively constant, as predicted theoretically. Searches for dependence of the normalized RR on local or solar‐wind parameters were inconclusive. However, we do find that for the MS events, the reconnection electric field showed a direct dependence on solar‐wind dynamic pressure. Plain Language Summary: Magnetic reconnection (MR) is a fundamental process that occurs naturally throughout the universe in magnetized plasmas in which energy is transformed and redistributed throughout a small region known as the diffusion region where plasma is decoupled from the magnetic field. This process is the main driver of energy and momentum from the solar wind into the magnetosphere. The reconnection rate (RR) is one of the most important properties of MR and can be defined as the rate at which magnetic flux is transferred from the inflow to the outflow of the diffusion region and is determined by the electric field component that is perpendicular to both the inflowing and outflowing plasma velocities. This component is called the reconnection electric field. In this study, we measure the reconnection electric field within the diffusion region to determine the RR and compare it to measured magnetic and plasma parameters in the solar wind. Key Points: The average reconnection rate (RR) for 14 events is 0.15 with significant variability within relatively small spatial and temporal rangesBy analyzing 47 individual normalized RRs, we find no correlation with external parametersWe find that the reconnection electric field is positively correlated with solar‐wind dynamic pressure in the magnetosheath [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
33. Variation of Hydrogen Energetic Neutral Atom Flux in the Subsolar Magnetosheath as a Function of Solar Cycle.
- Author
-
Sokół, J. M., Starkey, M. J., Dayeh, M. A., Fuselier, S. A., Petrinec, S. M., McComas, D. J., Schwadron, N. A., Szalay, J., and Ogasawara, K.
- Subjects
SOLAR cycle ,SOLAR wind ,SOLAR oscillations ,SOLAR activity ,WIND pressure ,DYNAMIC pressure - Abstract
We analyzed observations of energetic neutral atoms (ENAs) of hydrogen collected from the subsolar magnetosheath by the Interstellar Boundary Explorer (IBEX) in Solar Cycle 24. We looked for long‐term solar activity‐related variation and correlation between the H ENA flux and the solar wind parameters. The H ENA flux in the energy range from 0.5 to 6 keV increased during the maximum and declining phases of the solar cycle. This H ENA flux increase happened during a period of enhanced solar wind dynamic pressure observed at 1 au. We study the relation between the ENA flux and solar wind pressure in the subsolar magnetosheath and conclude that the increase in the ENA flux is a consequence of enhanced ENA production. It is because of the increased solar wind pressure during the declining phase of the solar activity that moved the subsolar magnetosheath earthward into a region of denser hydrogen geocorona, thus increasing the H ENA production. Furthermore, we report a positive correlation between the H ENA flux in the subsolar magnetosheath and the solar wind pressure for the first four energy steps observed by IBEX‐Hi and a decrease for the highest energy acquired, which indicates the presence of a different parent ion population for those ENAs from that of the core solar wind. Our study also shows that the ENA flux correlates differently with the solar wind density and speed as a function of increasing energy of ENAs. Key Points: The H energetic neutral atom (ENA) flux in the subsolar magnetosheath measured by Interstellar Boundary Explorer increased during the declining phase of the Solar Cycle 24The H ENA flux variations in the subsolar magnetosheath are positively correlated with the solar wind dynamic pressure variations in time [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
34. Interstellar Mapping and Acceleration Probe (IMAP): A New NASA Mission
- Author
-
McComas, D. J., Christian, E. R., Schwadron, N. A., Fox, N., Westlake, J., Allegrini, F., Baker, D. N., Biesecker, D., Bzowski, M., Clark, G., Cohen, C. M. S., Cohen, I., Dayeh, M. A., Decker, R., de Nolfo, G. A., Desai, M. I., Ebert, R. W., Elliott, H. A., Fahr, H., Frisch, P. C., Funsten, H. O., Fuselier, S. A., Galli, A., Galvin, A. B., Giacalone, J., Gkioulidou, M., Guo, F., Horanyi, M., Isenberg, P., Janzen, P., Kistler, L. M., Korreck, K., Kubiak, M. A., Kucharek, H., Larsen, B. A., Leske, R. A., Lugaz, N., Luhmann, J., Matthaeus, W., Mitchell, D., Moebius, E., Ogasawara, K., Reisenfeld, D. B., Richardson, J. D., Russell, C. T., Sokół, J. M., Spence, H. E., Skoug, R., Sternovsky, Z., Swaczyna, P., Szalay, J. R., Tokumaru, M., Wiedenbeck, M. E., Wurz, P., Zank, G. P., and Zirnstein, E. J.
- Published
- 2018
- Full Text
- View/download PDF
35. Molecular nitrogen in comet 67P/Churyumov-Gerasimenko indicates a low formation temperature
- Author
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Rubin, M., Altwegg, K., Balsiger, H., Bar-Nun, A., Berthelier, J.-J., Bieler, A., Bochsler, P., Briois, C., Calmonte, U., Combi, M., De Keyser, J., Dhooghe, F., Eberhardt, P., Fiethe, B., Fuselier, S. A., Gasc, S., Gombosi, T. I., Hansen, K. C., Hässig, M., Jäckel, A., Kopp, E., Korth, A., Le Roy, L., Mall, U., Marty, B., Mousis, O., Owen, T., Réme, H., Sémon, T., Tzou, C.-Y., Waite, J. H., and Wurz, P.
- Published
- 2015
36. Time variability and heterogeneity in the coma of 67P/Churyumov-Gerasimenko
- Author
-
Hässig, M., Altwegg, K., Balsiger, H., Bar-Nun, A., Berthelier, J. J., Bieler, A., Bochsler, P., Briois, C., Calmonte, U., Combi, M., De Keyser, J., Eberhardt, P., Fiethe, B., Fuselier, S. A., Galand, M., Gasc, S., Gombosi, T. I., Hansen, K. C., Jäckel, A., Keller, H. U., Kopp, E., Korth, A., Kührt, E., Le Roy, L., Mall, U., Marty, B., Mousis, O., Neefs, E., Owen, T., Rème, H., Rubin, M., Sémon, T., Tornow, C., Tzou, C.-Y., Waite, J. H., and Wurz, P.
- Published
- 2015
37. 67P/Churyumov-Gerasimenko, a Jupiter family comet with a high D/H ratio
- Author
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Altwegg, K., Balsiger, H., Bar-Nun, A., Berthelier, J. J., Bieler, A., Bochsler, P., Briois, C., Calmonte, U., Combi, M., De Keyser, J., Eberhardt, P., Fiethe, B., Fuselier, S., Gasc, S., Gombosi, T. I., Hansen, K.C., Hässig, M., Jäckel, A., Kopp, E., Korth, A., LeRoy, L., Mall, U., Marty, B., Mousis, O., Neefs, E., Owen, T., Rème, H., Rubin, M., Sémon, T., Tzou, C.-Y., Waite, H., and Wurz, P.
- Published
- 2015
38. Abundant ammonium hydrosulphide embedded in cometary dust grains
- Author
-
Altwegg, K, Combi, M, Fuselier, S A, Hänni, N, De Keyser, J, Mahjoub, A, Müller, D R, Pestoni, B, Rubin, M, and Wampfler, S
- Subjects
Earth and Planetary Astrophysics (astro-ph.EP) ,Space and Planetary Science ,530 Physics ,520 Astronomy ,FOS: Physical sciences ,Astronomy and Astrophysics ,620 Engineering ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Ammonium hydrosulphide has long since been postulated to exist at least in certain layers of the giant planets. Its radiation products may be the reason for the red colour seen on Jupiter. Several ammonium salts, the products of NH3 and an acid, have previously been detected at comet 67P/Churyumov-Gerasimenko. The acid H2S is the fifth most abundant molecule in the coma of 67P followed by NH3. In order to look for the salt NH4+SH-, we analysed in situ measurements from the Rosetta/ROSINA Double Focusing Mass Spectrometer during the Rosetta mission. NH3 and H2S appear to be independent of each other when sublimating directly from the nucleus. However, we observe a strong correlation between the two species during dust impacts, clearly pointing to the salt. We find that NH4+SH- is by far the most abundant salt, more abundant in the dust impacts than even water. We also find all previously detected ammonium salts and for the first time ammonium fluoride. The amount of ammonia and acids balance each other, confirming that ammonia is mostly in the form of salt embedded into dust grains. Allotropes S2 and S3 are strongly enhanced in the impacts, while H2S2 and its fragment HS2 are not detected, which is most probably the result of radiolysis of NH4+SH-. This makes a prestellar origin of the salt likely. Our findings may explain the apparent depletion of nitrogen in comets and maybe help to solve the riddle of the missing sulphur in star forming regions., accepted by MNRAS
- Published
- 2022
39. Investigating the Occurrence of Kelvin‐Helmholtz Instabilities at Jupiter's Dawn Magnetopause.
- Author
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Montgomery, J., Ebert, R. W., Allegrini, F., Bagenal, F., Bolton, S. J., DiBraccio, G. A., Fuselier, S. A., Wilson, R. J., and Masters, Adam
- Subjects
KELVIN-Helmholtz instability ,MAGNETOPAUSE ,SOLAR wind ,MAGNETIC reconnection ,JUPITER (Planet) ,JUNO (Space probe) - Abstract
We use the Kelvin‐Helmholtz instability (KHI) condition with particle and magnetic field observations from Jovian Auroral Distributions Experiment and MAG on Juno along the dawn flank of Jupiter's magnetosphere. We identify the occurrence of magnetopause crossings that show evidence of being KH (Kelvin‐Helmholtz) unstable. When estimating the k vector to be parallel to the velocity shear, we find that 25 of 62 (40%) magnetopause crossings satisfy the KHI condition. When considering the k vector of the maximum growth rate through a solid angle approach, we find that 60 of 62 (97%) events are KH unstable. This study shows evidence of KH waves at Jupiter's dawn flank, including primary drivers such as high velocity shears and changes in plasma pressure. Signatures of magnetic reconnection were also observed in ∼25% of the KH unstable crossings. We discuss these results and their implication for the prevalence of KHI at Juno's dawn magnetopause as measured by Juno. Plain Language Summary: The Kelvin‐Helmholtz instability occurs when a boundary separating two fluids of different densities is perturbed and these fluids are moving at different speeds, directions, or both. The difference in speeds across the perturbed boundary that separates the fluids creates wave structures as these fluids diffuse into each other. The Kelvin‐Helmholtz instability may be observed at the boundary that separates a planetary magnetic field (magnetosphere) from the stream of charged particles emitted by the Sun (solar wind); this boundary is known as the magnetopause. This instability is confirmed to occur at Earth and Saturn, but is not confirmed at Jupiter. This study analyzes the properties of the plasma and magnetic field in Jupiter's magnetosphere and the surrounding solar wind to identify signatures of the Kelvin‐Helmholtz instability. We find that out of 62 occurrences where the Juno spacecraft crosses the magnetopause, 25 events signify that the Kelvin‐Helmholtz instability is possible—primarily due to large differences in velocities—and 37 events do not. Key Points: There is evidence of Kelvin‐Helmholtz instability (KHI)‐driven waves along Jupiter's dawn flank magnetopause during the Juno prime mission24 (38.7%) crossings satisfied the KHI condition and 38 (61.3%) crossings did not satisfy the KHI conditionMagnetopause crossings that satisfied the KHI condition had, in general, larger velocity shears than those that did not [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
40. Wave analysis during energetic electron microinjections: A case study.
- Author
-
Nykyri, K., Liou, Y., Ma, X., Kavosi, S., Egedal, J., Fuselier, S. A., and Gomez, R. G
- Subjects
WAVE analysis ,MICROINJECTIONS ,ELECTROMAGNETIC waves ,MAGNETIC declination ,ELECTRON scattering - Abstract
The Magnetospheric Multi-scale Mission has frequently observed periodic bursts of counterstreaming electrons with energies ranging from ≈ 30 to 500 keV at the Earth's magnetospheric boundary layers, termed "microinjections." Recently, a source region for microinjections was discovered at the high-latitude magnetosphere where microinjections showed up simultaneously at all energy channels and were organized by magnetic field variation associated with ultra low frequency mirror mode waves (MMWs) with ≈ 5 min periodicity. These MMWs were associated with strong higher frequency electromagnetic wave activity. Here, we have identified some of these waves as electromagnetic ion cyclotron (EMIC) waves. EMIC waves and parallel electric fields often lead to the radiation belt electron losses due to pitch-angle scattering. We show that, for the present event, the EMIC waves are not responsible for scattering electrons into a loss cone, and thus, they are unlikely to be responsible for the observed microinjection signature. We also find that the parallel electric field potentials within the waves are not adequate to explain the observed electrons with >90 keV energies. While whistler waves may contribute to the electron scattering and may exist during this event, there was no burst mode data available to verify this. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
41. Relative In-flight Response of IBEX-Lo to Interstellar Neutral Helium Atoms.
- Author
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Swaczyna, P., Bzowski, M., Fuselier, S. A., Galli, A., Heerikhuisen, J., Kubiak, M. A., McComas, D. J., Möbius, E., Rahmanifard, F., and Schwadron, N. A.
- Published
- 2023
- Full Text
- View/download PDF
42. Intense Electric Fields and Electron-Scale Substructure Within Magnetotail Flux Ropes as Revealed by the Magnetospheric Multiscale Mission
- Author
-
Stawarz, J. E, Eastwood, J. P, Genestreti, K. J, Nakamura, R, Ergun, R. E, Burgess, D, Burch, J. L, Fuselier, S. A, Gershman, D. J, Giles, Barbara L, Contel, O. Le, Lindqvist, P.-A, Russell, C. T, and Torbert, R. B
- Subjects
Plasma Physics - Abstract
Three flux ropes associated with near-Earth magnetotail reconnection are analyzed using Magnetospheric Multiscale observations. The flux ropes are Earthward propagating with sizes from ∼3 to 11 ion inertial lengths. Significantly different axial orientations are observed, suggesting spatiotemporal variability in the reconnection and/or flux rope dynamics. An electron-scale vortex, associated with one of the most intense electric fields (E) in the event, is observed within one of the flux ropes. This E is predominantly perpendicular to the magnetic field (B); the electron vortex is frozen-in with E × B drifting electrons carrying perpendicular current and causing a small-scale magnetic enhancement. The vortex is ∼16 electron gyroradii in size perpendicular to B and potentially elongated parallel to B. The need to decouple the frozen-in vortical motion from the surrounding plasma implies a parallel E at the structure's ends. The formation of frozen-in electron vortices within reconnection-generated flux ropes may have implications for particle acceleration.
- Published
- 2018
- Full Text
- View/download PDF
43. Identification and characterization of a new ensemble of cometary organic molecules
- Author
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Hänni, N, Altwegg, K, Combi, M, Fuselier, S A, De Keyser, J, Rubin, M, and Wampfler, S F
- Subjects
Science & Technology ,MASS-SPECTRA ,ORIGIN ,520 Astronomy ,DUST ,EXTENDED SOURCES ,620 Engineering ,SATURNS RINGS ,Multidisciplinary Sciences ,POLYCYCLIC AROMATIC-HYDROCARBONS ,Science & Technology - Other Topics ,PARTICLES ,SPECTROMETER ,SOLAR ,MATTER - Abstract
In-situ study of comet 1P/Halley during its 1986 apparition revealed a surprising abundance of organic coma species. It remained unclear, whether or not these species originated from polymeric matter. Now, high-resolution mass-spectrometric data collected at comet 67P/Churyumov-Gerasimenko by ESA's Rosetta mission unveil the chemical structure of complex cometary organics. Here, we identify an ensemble of individual molecules with masses up to 140 Da while demonstrating inconsistency of the data with relevant amounts of polymeric matter. The ensemble has an average composition of C1H1.56O0.134N0.046S0.017, identical to meteoritic soluble organic matter, and includes a plethora of chain-based, cyclic, and aromatic hydrocarbons at an approximate ratio of 6:3:1. Its compositional and structural properties, except for the H/C ratio, resemble those of other Solar System reservoirs of organics-from organic material in the Saturnian ring rain to meteoritic soluble and insoluble organic matter -, which is compatible with a shared prestellar history. ispartof: NATURE COMMUNICATIONS vol:13 issue:1 ispartof: location:England status: published
- Published
- 2022
44. Magnetospheric Multiscale Science Mission Profile and Operations
- Author
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Fuselier, S. A., Lewis, W. S., Schiff, C., Ergun, R., Burch, J. L., Petrinec, S. M., and Trattner, K. J.
- Published
- 2016
- Full Text
- View/download PDF
45. Hot Plasma Composition Analyzer for the Magnetospheric Multiscale Mission
- Author
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Young, D. T., Burch, J. L., Gomez, R. G., De Los Santos, A., Miller, G. P., Wilson, IV, P., Paschalidis, N., Fuselier, S. A., Pickens, K., Hertzberg, E., Pollock, C. J., Scherrer, J., Wood, P. B., Donald, E. T., Aaron, D., Furman, J., George, D., Gurnee, R. S., Hourani, R. S., Jacques, A., Johnson, T., Orr, T., Pan, K. S., Persyn, S., Pope, S., Roberts, J., Stokes, M. R., Trattner, K. J., and Webster, J. M.
- Published
- 2016
- Full Text
- View/download PDF
46. Ion Acceleration at Magnetotail Plasma Jets
- Author
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Richard, L., Khotyaintsev, Yu. V., Graham, D. B, Vaivads, A., Nikoukar, R., Cohen, I. J., Turner, D. L., Fuselier, S. A., and Russell, C. T.
- Subjects
Physics - Space Physics ,Physics::Space Physics ,FOS: Physical sciences ,Space Physics (physics.space-ph) - Abstract
We investigate a series of Earthward bursty bulk flows (BBFs) observed by the Magnetospheric Multiscale (MMS) spacecraft in Earth's magnetotail at (-24, 7, 4) RE in Geocentric Solar Magnetospheric (GSM) coordinates. At the leading edges of the BBFs, we observe complex magnetic field structures. In particular, we focus on one which presents a chain of small scale (~0.5 RE) dipolarizations, and another with a large scale (~3.5 RE) dipolarization. Although the two structures have different scales, both of these structures are associated with flux increases of supra-thermal ions with energies > 100 keV. We investigate the ion acceleration mechanism and its dependence on the mass and charge state. We show that the ions with gyroradii smaller than the scale of the structure are accelerated by the ion bulk flow. We show that whereas in the small scale structure, ions with gyroradii comparable with the scale of the structure undergo resonance acceleration, and the acceleration in the larger scale structure is more likely due to a spatially limited electric field., Submitted to JGR: Space Physics
- Published
- 2022
47. A Multi‐Satellite Case Study of Low‐Energy H+ Asymmetric Field‐Aligned Distributions Observed by MMS in the Earth's Magnetosphere.
- Author
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Kim, M. J., Goldstein, J., Fuselier, S. A., Glocer, A., and Burch, J. L.
- Subjects
MAGNETOSPHERE ,PHASE space ,HIGH temperature plasmas ,IONOSPHERE ,ELECTRONS - Abstract
Field‐aligned distributions of H+ with energy less than 100 eV in the magnetosphere originate from the ionosphere through ionospheric outflow. Recently, a statistical interhemispheric asymmetry in this ion outflow was reported. In this study, we investigate a case study of asymmetric field‐aligned distributions (E < 100 eV) resulting from asymmetric outflow observed on 13 August 2019 by the Hot Plasma Composition Analyzer onboard the Magnetospheric Multiscale mission. During the reported event, the average phase space density in the parallel direction (pitch angle < 45°) is about 4.7 times higher than in the anti‐parallel direction (pitch angle > 135°), indicating greater outflow from the southern hemisphere. In this event, electron precipitation fluxes are also asymmetric between hemispheres, with more electrons traveling to the southern hemisphere than to the northern hemisphere. Global MHD simulation results (SWMF/BAT‐S‐RUS available from the CCMC) confirm that several ionospheric parameters (joule heating, convection velocities, and energy fluxes of precipitating electrons) are more enhanced in the southern hemisphere. We suggest that these interhemispheric asymmetries might cause a stronger outflow from the southern hemisphere than from the northern hemisphere, to produce the observed asymmetric field‐aligned distributions for the low‐energy H+. Key Points: Low‐energy (E < 100 eV) H+ field‐aligned distributions are asymmetric in the outer magnetosphereConditions in the southern hemisphere ionosphere are favorable and result in asymmetric outflowThe observed low‐energy H+ pitch‐angle distributions are consistent with asymmetric outflow as the cause [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
48. MMS Observations of Dayside Warm (Several eV to 100 eV) Ions in the Middle and Outer Magnetosphere.
- Author
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Goldstein, J., Burch, J. L., Fuselier, S. A., Gomez, R., Gonzalez, C. A., Kim, M. J., Mukherjee, J., Turner, N. E., and Wilson, M. E.
- Subjects
MAGNETOSPHERE ,EARTH (Planet) ,ION traps ,TOROIDAL plasma ,ION analysis ,ION temperature - Abstract
Warm (several eV to 100 eV) ions are an important, and still poorly understood, component of the magnetospheric plasma environment. We present the first comprehensive statistical analysis of several distinct populations of warm ions in the dayside middle and outer magnetosphere. We analyze 7 months (1 September 2015–31 March 2016) of Magnetospheric Multiscale Hot Plasma Composition Analyzer data comprising 734,200 moments (density, temperature) and energy‐dependent pitch angle distributions (PADs) of three major ion species (H+, He+, and O+) with energy ≤100 eV. PADs are represented by an energy‐averaged index that characterizes the shape of the PAD as field‐aligned (FA), pancake, or isotropic. We use filtering by temperature, pitch angle, and concentration to distinguish different populations, and obtain new and more complete information about average density, temperature, PADs, and composition. Our analysis explores two known populations of warm ions: the warm plasmasphere (WPS) and the warm cloak/trough (C/T). The WPS is a higher‐temperature, higher‐L extension of the duskside plasmaspheric bulge, containing mostly trapped (pancake/isotropic) ions with an H+:He+:O+ order of ion dominance. The C/T contains mostly FA warm ions with a dawnward (duskward) temperature gradient for H+ (He+ and O+), lower densities, and an H+:O+:He+ order of ion dominance. The WPS‐C/T overlap contains a mixture of the two populations (e.g., FA He+ in WPS, trapped O+ in C/T). Pancake (FA) PADs are correlated with higher (lower) density/temperature. Our analysis also identifies warm ions in the low‐energy plasma sheet. Our work consolidates and systematically extends the characterizations of warm ions reported in previous studies. Plain Language Summary: The plasmasphere is often defined as the cold and dense innermost region of the magnetosphere. The ring current may be defined as the torus of hot ions encircling the planet at several Earth radii of geocentric distance. Warm plasma (several eV to 100 eV) is an intermediate‐energy population. In this paper, we present the first comprehensive statistical analysis of several distinct populations of warm ions in the dayside middle and outer magnetosphere. We analyze 7 months (1 September 2015–31 March 2016) of data from the Magnetospheric Multiscale mission. Several‐eV to 100‐eV ions constitute a large reservoir of mass and momentum that can influence numerous basic, system‐level aspects of the magnetosphere. Warm ions are also a "bridge population" whose intermediate‐energy dynamics reveal heating and energization processes that trap ions to enable plasmaspheric refilling and transform very cold, ionospheric‐origin plasma into an integral component of the stormtime plasma sheet and ring current. Key Points: Statistical analysis of dayside warm (≤100 eV) ions uses 734,200‐point database of density, temperature, and pitch angle (PA) distributionsFiltering by temperature, PA, and concentration helps distinguish and separate different warm ion populationsThis analysis consolidates and systematically extends the characterizations of the warm plasmasphere and the warm cloak/trough (C/T) [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
49. TRICE‐2 Rocket Observations in the Low‐Altitude Cusp: Boundaries and Comparisons With Models.
- Author
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Petrinec, S. M., Kletzing, C. A., Bounds, S. R., Fuselier, S. A., Trattner, K. J., and Sawyer, R. P.
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ELECTROSTATIC analyzers ,BOUNDARY layer (Aerodynamics) ,ROCKET launching ,MAGNETIC reconnection ,ELECTRODYNAMICS - Abstract
The launch of the Twin Rockets to Investigate Cusp Electrodynamics‐2 (TRICE‐2) took place on the morning of 08 December 2018. The two rockets of this campaign each sampled the low‐altitude Northern Hemisphere cusp region at approximately the apex of each rocket's trajectory (1,042 and 757 km for the High flyer and Low flyer, respectively). Ion and electron electrostatic analyzers (ESAs) on board each rocket measured in situ particle populations throughout the flights. Energy‐flux spectrograms of ions and electrons from each ESA clearly show the passage of each rocket through the cusp region. This work examines the locations of these entrance/exit points in relation to cusp models as provided in and compiled from the published literature, along with a discussion of model variables that have been optimized to best fit the cusp region boundary sampling locations by TRICE‐2. The results of this study set the stage for understanding the upcoming NASA Small Explorer Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites orbital plane intersections with (i.e., "trajectory cuts" through) the cusp region. Key Points: The low‐altitude cusp region was directly sampled by instruments onboard the two Twin Rockets to Investigate Cusp Electrodynamics‐2 rocketsCusp models have been compiled from published studies, with free parameters representing the low‐latitude boundary layer and mantleCusp model free parameters have been optimized to best match the observed cusp region location [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
50. Ion Acceleration at the Quasi‐Parallel Shock: The Source Distributions of the Diffuse Ions.
- Author
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Trattner, K. J., Fuselier, S. A., Schwartz, S. J., Kucharek, H., Burch, J. L., Ergun, R. E., Petrinec, S. M., and Madanian, H.
- Subjects
SOLAR wind ,SOLAR thermal energy ,PARTICLE acceleration ,ALPHA rays ,COLLISIONLESS plasmas ,ION sources - Abstract
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. Key Points: Two ion sources for the bow shock accelerated diffuse ion population are identified: Shock drift accelerated and specularly reflected ionsShock drift accelerated ions are directly accelerated out of the solar wind without an intermediate step to a suprathermal distributionThe bow shock magnetic field steepens enough to cause reflected solar wind ions that contribute to the source distribution [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
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