Blar i Bergen Open Research Archive på forfatter "Norgren, Astrid Elisabet Cecilia"
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Asymmetrically Varying Guide Field During Magnetic Reconnection: Particle-In-Cell Simulations
Spinnangr, Susanne Flø; Tenfjord, Paul Arne Riksheim; Hesse, Michael; Norgren, Astrid Elisabet Cecilia; Kolstø, Håkon Midthun; Kwagala, Norah Kaggwa; Jørgensen, Therese; Jimenez, Judit Perez-Coll (Journal article; Peer reviewed, 2022)Using fully kinetic particle-in-cell modeling, we investigate how magnetic reconnection responds to a varying guide field in one of the inflow regions. We find that the reconnection rate varies significantly when the ... -
Bifurcated Current Sheet Observed on the Boundary of Kelvin-Helmholtz Vortices
Hwang, K.-J.; Dokgo, K.; Choi, E.; Burch, J.L.; Sibeck, D.G.; Giles, B.L.; Norgren, Astrid Elisabet Cecilia; Nakamura, T.K.M.; Graham, D.B.; Khotyaintsev, Y.; Shi, Q.Q.; Gershman, D.J.; Pollock, C.J.; Ergun, R.E.; Torbert, R.B.; Russell, C.T.; Strangeway, R.J. (Journal article; Peer reviewed, 2021)On May 5, 2017 MMS observed a bifurcated current sheet at the boundary of Kelvin-Helmholtz vortices (KHVs) developed on the dawnside tailward magnetopause. We use the event to enhance our understanding of the formation and ... -
Characteristics of the Flank Magnetopause: MMS Results
Haaland, Stein; Paschmann, Götz; Oieroset, M; Phan, Tai D.; Hasegawa, Hiroshi; Fuselier, Stephen; COnstantinescu, Vlad; Eriksson, Stefan; Trattner, Karlheinz J.; Fadanelli, Sid; Tenfjord, Paul; Lavraud, Benoit; Norgren, Astrid Elisabet Cecilia; Eastwood, Jonathan P.; Hietala, Heli; Burch, J (Journal article; Peer reviewed, 2020)We have used a large number of magnetopause crossings by the Magnetospheric Multiscale (MMS) mission to investigate macroscopic properties of this current sheet, with emphasis on the flanks of the magnetopause. Macroscopic ... -
Collisionless Magnetic Reconnection in an Asymmetric Oxygen Density Configuration
Kolstø, Håkon Midthun; Hesse, Michael; Norgren, Astrid Elisabet Cecilia; Tenfjord, Paul; Spinnangr, Susanne Flø; Kwagala, Norah Kaggwa (Journal article; Peer reviewed, 2020)Combined with the magnetic field, the distribution of charged particles in the inflow region is expected to control the rate of magnetic reconnection. This paper investigates how the reconnection process is altered by a ... -
Direct observations of anomalous resistivity and diffusion in collisionless plasma
Graham, D.B.; Khotyaintsev, Yu. V.; André, M.; Vaivads, A.; Divin, A.; Drake, J.F.; Norgren, Astrid Elisabet Cecilia; Le Contel, Contel; Lindqvist, P.-A.; Rager, A.C.; Gershman, D.J.; Russell, C.T.; Burch, J.L.; Hwang, K.-J.; Dokgo, K. (Journal article; Peer reviewed, 2022)Coulomb collisions provide plasma resistivity and diffusion but in many low-density astrophysical plasmas such collisions between particles are extremely rare. Scattering of particles by electromagnetic waves can lower the ... -
Electron Acceleration and Thermalization at Magnetotail Separatrices
Norgren, Astrid Elisabet Cecilia; Hesse, Michael; Graham, Daniel B.; Khotyaintsev, Yuri V.; Tenfjord, Paul; Vaivads, Andris; Steinvall, Konrad; Xu, Yin; Gershman, Daniel J; Lindqvist, Per-Arne; Plaschke, Ferdinand; Burch, James L (Journal article; Peer reviewed, 2020)In this study we use the Magnetospheric Multiscale mission to investigate the electron acceleration and thermalization occurring along the magnetic reconnection separatrices in the magnetotail. We find that initially cold ... -
Electron Bernstein waves driven by electron crescents near the electron diffusion region
Li, Wenya; Graham, D. B.; Khotyaintsev, Yuri V.; Vaivads, Andris; André, Mats; Min, K.; Liu, K.; Tang, B.B.; Wang, C.; Fujimoto, K.; Norgren, Astrid Elisabet Cecilia; Toledo-Redondo, Sergio; Lindqvist, Per-Arne; Ergun, R.E.; Torbert, Roy B.; Rager, A.C.; Dorelli, J.C.; Gershman, D.J.; Giles, B. L.; Lavraud, B.; Plaschke, F.; Magnes, W.; Le Contel, Olivier; Russell, Christopher T.; Burch, J. L. (Journal article; Peer reviewed, 2020)The Magnetospheric Multiscale (MMS) spacecraft encounter an electron diffusion region (EDR) of asymmetric magnetic reconnection at Earth’s magnetopause. The EDR is characterized by agyrotropic electron velocity distributions ... -
Electron Heating by Debye-Scale Turbulence in Guide-Field Reconnection
Khotyaintsev, Yuri V.; Graham, Daniel B.; Steinvall, Konrad; Alm, Love; Vaivads, Andris; Johlander, Andreas; Norgren, Astrid Elisabet Cecilia; Li, Wenya; Divin, Andrey; Fu, Huishan; Hwang, Kyoung-Joo; Burch, James L; Ahmadi, Narges; Le Contel, Olivier; Gershman, Daniel J; Russell, Christopher T.; Torbert, R. B. (Journal article; Peer reviewed, 2020)We report electrostatic Debye-scale turbulence developing within the diffusion region of asymmetric magnetopause reconnection with a moderate guide field using observations by the Magnetospheric Multiscale mission. We show ... -
The Impact of Oxygen on the Reconnection Rate
Tenfjord, Paul; Hesse, Michael; Norgren, Astrid Elisabet Cecilia; Spinnangr, Susanne Flø; Kolstø, Håkon Midthun (Peer reviewed; Journal article, 2019-05-29)We investigate the role of a background oxygen population in magnetic reconnection, using particle‐in‐cell simulations. We run several simulations, with different initial oxygen temperatures and densities, to understand ... -
Interaction of Cold Streaming Protons with the Reconnection Process
Tenfjord, Paul; Hesse, Michael; Norgren, Astrid Elisabet Cecilia; Spinnangr, Susanne Flø; Kolstø, Håkon Midthun; Kwagala, Norah Kaggwa (Journal article; Peer reviewed, 2020)We employ a 2.5D particle-in-cell simulation to study a scenario where the reconnection process captures cold streaming protons. As soon as the tailward streaming protons become involved, they contribute to the overall ... -
Magnetospheric Multiscale Observations of an Expanding Oxygen Wave in Magnetic Reconnection
Kolstø, Håkon Midthun; Norgren, Astrid Elisabet Cecilia; Hesse, Michael; Chen, Li-Jen; Tenfjord, Paul; Spinnangr, Susanne Flø; Kwagala, Norah Kaggwa (Journal article; Peer reviewed, 2021)Heavier plasma species such as oxygen ions can have a large impact on the magnetic reconnection process. It has been hypothesized that the acceleration of demagnetized oxygen ions by the Hall electric field will lead to ... -
The Micro-Macro Coupling of Mass-Loading in Symmetric Magnetic Reconnection With Cold Ions
Spinnangr, Susanne Flø; Hesse, Michael; Tenfjord, Paul Arne Riksheim; Norgren, Astrid Elisabet Cecilia; Kolstø, Håkon Midthun; Kwagala, Norah Kaggwa; Jørgensen, Therese Moretto (Journal article; Peer reviewed, 2021)We investigate how magnetic reconnection is influenced by an inflow of a dense cold ion population. We compare two 2.5D Particle-In-Cell simulations, one containing the cold population and one without. We find that the ... -
Millisecond observations of nonlinear wave–electron interaction in electron phase space holes
Norgren, Astrid Elisabet Cecilia; Graham, Daniel B.; Argall, Matthew; Steinvall, Konrad; Hesse, Michael; Khotyaintsev, Yuri V.; Vaivads, Andris; Tenfjord, Paul Arne Riksheim; Gershman, Daniel J; Lindqvist, Per-Arne; Burch, James L; Plaschke, Ferdinand (Journal article; Peer reviewed, 2022)Electron phase space holes (EHs) associated with electron trapping are commonly observed as bipolar electric field signatures in both space and laboratory plasma. Until recently, it has not been possible to resolve EHs in ... -
MMS Measurements of the Vlasov Equation: Probing the Electron Pressure Divergence Within Thin Current Sheets
Shuster, JR; Gershman, Daniel J; Chen, LJ; Wang, S; Bessho, Naoki; Dorelli, John C; da Silva, DE; Giles, Barbara L; Paterson, William R.; Denton, Richard E; Schwartz, S. J.; Norgren, Astrid Elisabet Cecilia; Wilder, F.D.; Cassak, P.A.; Swisdak, M; Uritsky, Vadim; Schiff, C.; Rager, AC; Smith, S; Avanov, LA; Vinas, AF (Journal article; Peer reviewed, 2019)We investigate the kinetic structure of electron‐scale current sheets found in the vicinity of the magnetopause and embedded in the magnetosheath within the reconnection exhaust. A new technique for computing terms of the ... -
A new Look at the Electron Diffusion Region in Asymmetric Magnetic Reconnection
Hesse, Michael; Norgren, Astrid Elisabet Cecilia; Tenfjord, Paul; James L., Burch; Liu, Yi‐Hsin; Bessho, Naoki; Wang, Shan; Kolstø, Håkon Midthun; Spinnangr, Susanne Flø; Ergun, Robert E; Moretto, Therese; Kwagala, Norah Kaggwa (Journal article; Peer reviewed, 2021)A new look at the structure of the electron diffusion region in collision less magnetic reconnection is presented. The research is based on a particle-in-cell simulation of asymmetric magnetic reconnection, which includes ... -
On the Impact of a Streaming Oxygen Population on Collisionless Magnetic Reconnection
Kolstø, Håkon Midthun; Hesse, Michael; Norgren, Astrid Elisabet Cecilia; Tenfjord, Paul; Spinnangr, Susanne Flø; Kwagala, Norah Kaggwa (Journal article; Peer reviewed, 2020)Using 2.5-D Particle-In-Cell (PIC) simulations, we investigate how magnetotail reconnection is affected by a cold, streaming, oxygen plasma population, attributed to an ionospheric source, in the inflow region. As the ... -
On the Presence and Thermalization of Cold Ions in the Exhaust of Antiparallel Symmetric Reconnection
Norgren, Astrid Elisabet Cecilia; Tenfjord, Paul Arne Riksheim; Hesse, Michael; Toledo-Redondo, Sergio; Li, Wenya; Xu, Yin; Kwagala, Norah Kaggwa; Spinnangr, Susanne Flø; Kolstø, Håkon Midthun; Moretto, Therese (Journal article; Peer reviewed, 2021)Using fully kinetic 2.5 dimensional particle-in-cell simulations of anti-parallel symmetric magnetic reconnection, we investigate how initially cold ions are captured by the reconnection process, and how they evolve and ... -
The Role of Resistivity on the Efficiency of Magnetic Reconnection in MHD
Jimenez, Judit Perez-Coll; Tenfjord, Paul Arne Riksheim; Hesse, Michael; Norgren, Astrid Elisabet Cecilia; Kwagala, Norah Kaggwa; Kolstø, Håkon Midthun; Spinnangr, Susanne Flø (Journal article; Peer reviewed, 2022)Using a resistive MagnetoHydroDynamic (MHD) simulation, we study how the magnitude and shape of diffusion influence magnetic reconnection. Specifically, we investigate how and why the reconnection rate is influenced by ... -
Solar Wind—Magnetosphere Coupling During Radial Interplanetary Magnetic Field Conditions: Simultaneous Multi-Point Observations
Toledo-Redondo, Sergio; Hwang, Kyoung-Joo; Escoubet, C. P.; Lavraud, Benoit; Fornieles, J.; Aunai, N.; Fear, R.C.; Dargent, J.; Fu, Huishan; Fuselier, Stephen A.; Genestreti, K.J.; Khotyaintsev, Yuri V.; Li, Wenya; Norgren, Astrid Elisabet Cecilia; Phan, Tai D. (Journal article; Peer reviewed, 2021)In-situ spacecraft missions are powerful assets to study processes that occur in space plasmas. One of their main limitations, however, is extrapolating such local measurements to the global scales of the system. To overcome ... -
Universality of Lower Hybrid Waves at Earth's Magnetopause
Graham, D. B.; Khotyaintsev, Yu V; Norgren, Astrid Elisabet Cecilia; Vaivads, Andris; Andre, M.; Drake, J. F.; Egedal, J.; Zhou, M.; Le Contel, O; Webster, J.M.; Lavraud, B.; Kacem, Imed; Génot, V.; Jacquey, C.; Rager, AC; Gershman, Daniel J; Burch, J. L.; Ergun, Robert E (Journal article; Peer reviewed, 2019)Waves around the lower hybrid frequency are frequently observed at Earth's magnetopause and readily reach very large amplitudes. Determining the properties of lower hybrid waves is crucial because they are thought to ...