Article
Geosciences, Multidisciplinary
Longzhi Gan, Anton Artemyev, Wen Li, Xiao-Jia Zhang, Qianli Ma, Didier Mourenas, Vassilis Angelopoulos, Ethan Tsai, Colin Wilkins
Summary: Resonant interactions between energetic electrons and whistler-mode waves are important for rapid electron precipitation. This study provides the first direct evidence for high-order resonant scattering driven precipitation, explaining a bursty precipitation event. The results highlight the importance of high-order resonant scattering in both long-term diffusion models and short timescale events.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Astronomy & Astrophysics
Brent Page, Ivan Y. Vasko, Anton Artemyev, Stuart D. Bale
Summary: Observations from the Magnetospheric Multiscale spacecraft have identified a free energy source for high-frequency whistler waves in the Earth's quasi-perpendicular bow shock, with localized pitch angle anisotropy in the electron velocity distribution function playing a key role. Heat flux along - B (0) creates preferential conditions for the high-frequency whistler waves, which can scatter electrons and prolong their time in the shock transition region, promoting electron energization.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
Yi-Kai Hsieh, Yoshiharu Omura, Yuko Kubota
Summary: The study investigates the interaction between electrons and whistler mode chorus waves of different amplitudes and directions in the outer radiation belt. It finds that oblique chorus emissions lead to greater electron precipitation and proposes a two-step precipitation process involving Landau resonance and cyclotron resonance, resulting in higher precipitation rates.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Geosciences, Multidisciplinary
I. Svenningsson, E. Yordanova, G. Cozzani, Yu. V. Khotyaintsev, M. Andre
Summary: This study investigates whistler waves detected in the Earth's magnetosheath and finds that they occur even in regions predicted stable to wave growth. Whistler waves are observed in ion-scale magnetic minima and are associated with electrons having butterfly-shaped pitch-angle distributions. Modeling and analysis demonstrate the instability of the butterfly distribution to the observed whistler waves, indicating local generation of the waves.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
Paul J. Morris, Artem Bohdan, Martin S. Weidl, Michelle Tsirou, Karol Fulat, Martin Pohl
Summary: Thermal electrons need to be pre-accelerated before crossing a shock. A study using particle-in-cell simulation shows that oblique whistler waves in the inner foreshock can scatter and trap reflected electrons, leading to efficient pre-acceleration process.
ASTROPHYSICAL JOURNAL
(2023)
Article
Oncology
Stefano Ursino, Giovanni Gadducci, Noemi Giannini, Alessandra Gonnelli, Taiushia Fuentes, Fabio Di Martino, Fabiola Paiar
Summary: Radiotherapy is commonly used in cancer patients but limited by the tolerance of surrounding normal tissues. Recent advancements in the FLASH Effect show that high-dose radiation treatment delivered in a short time can increase normal tissue tolerance without compromising tumor efficacy. Studies have demonstrated significant protective effects of FLASH RT on neurocognitive function, skin toxicity, lung fibrosis, and bowel injury.
FRONTIERS IN ONCOLOGY
(2023)
Article
Astronomy & Astrophysics
Xinliang Gao, Quanming Lu, Ning Kang, Yangguang Ke, Jiuqi Ma, Bruce Tsurutani, Rui Chen, Huayue Chen
Summary: Oblique whistler-mode waves are as important as quasi-parallel waves in regulating electron dynamics in radiation belts. By analyzing Van Allen Probe-A data, we found that the majority of poleward propagating oblique waves preferentially occur at relatively larger magnetic latitudes and their favored latitudes are strongly dependent on magnetic local time. Combined with ray tracing simulations, we propose that parallel waves generated at the equator propagate toward poles and turn oblique to the ambient magnetic field, leading to oblique waves detected at large magnetic latitudes.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Geosciences, Multidisciplinary
Ning Kang, Jacob Bortnik
Summary: This study uses numerical methods to simulate the electron precipitation induced by a superbolt event and investigates the underlying structure of the precipitation. The simulation results are in good agreement with observations, demonstrating the reliability of the model. This research is crucial for understanding the energy spectrum evolution and different drivers of precipitation.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
B. Bezdekova, F. Nemec, J. Manninen, O. Santolik, G. B. Hospodarsky, W. S. Kurth
Summary: This study analyzes events with significant intensity enhancements in the 1.5-4 kHz frequency range measured by the ground-based Kannuslehto station in Finland. A total of 465 events are identified in the data collected between December 2012 and October 2019. It is found that these events usually last for several hours and preferentially occur on the dawn side during geomagnetically active periods. Simultaneous measurements from the Van Allen Probes spacecraft are used to determine the L-shells and magnetic local times associated with the intensity increase in space.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Physics, Fluids & Plasmas
Vadim Roytershteyn, Gian Luca Delzanno
Summary: Kinetic simulations and theory show that whistler waves can excite oblique, short-wavelength fluctuations through secondary drift instabilities in the presence of a sufficiently cold plasma population. The excited modes lead to heating of the cold populations and damping of the primary whistler waves. The threshold for instability depends on the density and temperature of the cold population, with a relatively small threshold if the cold population's temperature is low enough. This mechanism may play a significant role in controlling the amplitude of whistlers in regions of the Earth's magnetosphere with cold background plasma of sufficient density.
PHYSICS OF PLASMAS
(2021)
Article
Nanoscience & Nanotechnology
Amit Kumar, Ruby Gupta, Jyotsna Sharma
Summary: The study focuses on the effect of dust grain fluctuations on the parametric up conversion of lower hybrid waves into whistler waves in a complex plasma. The results show that the growth rate of lower hybrid waves is influenced by the amplitude of pump waves, density perturbations, dust grain charges, and electron cyclotron frequency. The findings provide insights into the excitation of whistler waves in various plasma environments.
Article
Geosciences, Multidisciplinary
Yangguang Ke, Xinliang Gao, Quanming Lu, Xueyi Wang, Rui Chen, Huayue Chen, Shui Wang
Summary: In this paper, the effects of whistler waves on electron distributions are investigated. It is found that whistler waves cause flux increases and the formation of electron butterfly distributions. Nonlinear Landau trapping is suggested as a potential mechanism for the formation of these distributions.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Wen Li, Q. Ma, X. -C. Shen, X. -J. Zhang, B. H. Mauk, G. Clark, F. Allegrini, W. S. Kurth, G. B. Hospodarsky, V. Hue, G. R. Gladstone, T. K. Greathouse, S. J. Bolton
Summary: This study provides an in-depth analysis of a diffuse auroral electron precipitation event, using coordinated observations from the Juno satellite to quantify energetic electron precipitation driven by whistler mode waves. The modeled electron precipitation features are consistent with measurements from several keV to several hundred keV over M-shells of 8-18, but additional mechanisms are needed to explain electron precipitation at lower energies.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Farhad Izadi, Eugene Arthur-Baidoo, Lisa T. Strover, Li-Juan Yu, Michelle L. Coote, Graeme Moad, Stephan Denifl
Summary: This study demonstrates that specific cleavage of the C-S bond is induced upon low-energy electron attachment, showing a high level of control over the chemical reactions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Analytical
Tymoteusz Piga, Waldemar Wodziak, Jacek Sobczyk, Andrzej Rachalski
Summary: This article introduces an experimental apparatus for generating gas flows with very low velocities. A constant volume air flow was achieved using a Mariotte bottle and water column method. The air-flow velocity was determined by measuring the change in water piston height over time. The results obtained from particle image velocimetry method were compared with those from the water piston method, showing differences within 7%.
Article
Astronomy & Astrophysics
F. S. Mozer, O. V. Agapitov, J. C. Kasper, R. Livi, O. Romeo, I. Y. Vasko
Summary: The aim of this study is to determine the perpendicular and parallel proton heating rates in the solar wind. By removing the speed dependence, the perpendicular and parallel temperatures of protons were compared to the radial dependence. Perpendicular heating of protons was observed between 20 and 160 solar radii, while there was no heating or cooling of parallel protons below 70 solar radii. The heating rates that produced the perpendicular temperatures were estimated at different distances from the Sun.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
C. Froment, O. V. Agapitov, V. Krasnoselskikh, S. Karbashewski, T. Dudok de Wit, A. Larosa, L. Colomban, D. Malaspina, M. Kretzschmar, V. K. Jagarlamudi, S. D. Bale, J. W. Bonnell, F. S. Mozer, M. Pulupa
Summary: The study aims to investigate the parameters of whistler waves in the young solar wind using the Parker Solar Probe (PSP). The results show that most of the detected wave packets in the cross-spectra are quasi-parallel to the background magnetic field, but a significant portion of the waves have oblique wave normal angles. It is concluded that magnetic dips provide favorable conditions for the generation of whistler waves.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
S. Karbashewski, O. V. Agapitov, H. Y. Kim, F. S. Mozer, J. W. Bonnell, C. Froment, T. Dudok de Wit, Stuart D. D. Bale, D. Malaspina, N. E. Raouafi
Summary: Observations by the Parker Solar Probe reveal intense plasma wave bursts in the young solar wind, often accompanied by inhomogeneities in the magnetic field. These waves, identified as electromagnetic whistler waves, propagate in different directions and experience significant Doppler frequency shifts. They have peak amplitudes exceeding 2 nT and represent up to 10% of the background magnetic field. We evaluate their properties, estimate the length of PSP electric field antennas at whistler frequencies, and discuss their generation mechanism.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
O. V. Agapitov, M. Balikhin, A. J. Hull, Y. Hobara, V. Angelopoulos, F. S. Mozer
Summary: This study presents the first results of the effects of the powerful gamma-ray burst GRB 221009A, which occurred on October 9, 2022, and was accidentally recorded by electron and proton detectors on four spacecraft of the NASA THEMIS mission. GRB 221009A is the brightest burst ever observed due to its enormous energy and proximity. The high time resolution of the particle flux measurements allows the resolution of the fine structure of the GRB and determination of its temporal scales.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
O. V. Agapitov, V. Krasnoselskikh, M. Balikhin, J. W. Bonnell, F. S. Mozer, L. Avanov
Summary: The evolution of plasma entropy and the redistribution of plasma energy at the collisionless plasma shock front were evaluated using high temporal resolution data from four Magnetospheric Multiscale spacecraft. Different populations of ions were observed near the shock front, and their moments were determined separately. It was found that the solar wind core population velocity slows down mainly in the ramp region, and the proton temperature peak in the foot region is an effect of relative motion of different ion populations. The ion entropy showed a significant increase across the shock, while the entropy of electrons did not show a significant change. Rating: 8/10.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Immanuel Christopher Jebaraj, Vladimir Krasnoselskikh, Marc Pulupa, Jasmina Magdalenic, Stuart D. Bale
Summary: This research report presents the first detailed observations of type III fundamental-harmonic pairs in hectokilometric wavelengths, observed by the Parker Solar Probe. The report provides a statistical analysis of the spectral characteristics, polarization measurements, and other characteristics of the fundamental-harmonic pairs, drawing conclusions based on the observations.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
Andrii Voshchepynets, Oleksiy V. Agapitov, Lynn Wilson III, Vassilis Angelopoulos, Samer T. Alnussirat, Michael Balikhin, Myroslava Hlebena, Ihor Korol, Davin Larson, David Mitchell, Christopher Owen, Ali Rahmati
Summary: In this study, we present the results of processing the effects of the powerful gamma-ray burst GRB221009A captured by spacecraft at different points in the heliosphere on October 9, 2022. By using data from various missions, we tracked the propagation of GRB221009A and determined its source location.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
L. A. Da Silva, J. Shi, J. P. Marchezi, O. V. Agapitov, D. Sibeck, L. R. Alves, L. E. A. Vieira, V. Deggeroni, L. C. A. Resende, R. Lopez, J. E. R. Costa, C. Wang, J. Moro, H. Li, A. Dal Lago, K. J. C. Ferreira, A. Inostroza, Z. Liu
Summary: The high-energy electron flux enhancement pattern in the outer radiation belt under the influence of Interplanetary Coronal Mass Ejections (ICMEs) is investigated. The analysis suggests that a compressed magnetopause, southward B-z component, and high storm indices are observed at the beginning of the electron flux enhancements. Model parameter simulations indicate that the local acceleration driven by chorus waves plays a crucial role in these enhancements at low L*, while the contribution of ULF waves is insignificant.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Michael A. Balikhin, Michael Gedalin, Simon N. Walker, Oleksiy V. Agapitov, Tielong Zhang
Summary: The aim of this study is to compare the magnetic field structure of observed quasi-parallel collisionless shock fronts with analytic results. An analytical model of the shock front structure was derived, showing an oscillatory magnetic field structure. Observations of the Venusian bow shock validated these theoretical findings, confirming a strong similarity between the observed and analytical structures.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Vladimir Krasnoselskikh, Arnaud Zaslavsky, Anton Artemyev, Clara Froment, Thierry Dudok de Wit, Nour E. Raouafi, Oleksiy V. Agapitov, Stuart D. Bale, Jaye L. Verniero
Summary: The exploration of the inner heliosphere by the Parker Solar Probe has revealed the presence of switchbacks in the highly structured solar wind, which may be generated by interchange reconnection (IR). Although IR does not significantly contribute to the heating and acceleration of the solar wind, it affects the way the solar wind is connected to its sources and can lead to a new energy balance.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
F. S. Mozer, O. Agapitov, S. D. Bale, R. Livi, O. Romeo, K. Sauer, I. Y. Vasko, J. Verniero
Summary: This letter describes a new phenomenon observed on the Parker Solar Probe, which is the recurring plasma density enhancements. These enhancements have a similar Delta n/n of 10% and occur at a repetition rate of about 5 Hz. The steady-state existence of these enhancements suggests a balance between their pressure gradient and the electric field. The measurements of the electric field and density fluctuations provide strong evidence for their accuracy. These plasma density enhancements are accompanied by low-frequency electromagnetic waves and may play an important role in plasma heating, scattering, and acceleration.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Xiao-Jia Zhang, Xing Meng, Anton V. Artemyev, Ying Zou, Didier Mourenas
Summary: Energetic electron precipitation from the equatorial magnetosphere into the atmosphere is crucial for magnetosphere-ionosphere coupling. This study aims to address the mapping uncertainties between ionospheric measurements and measurements of wave and energetic electron properties by projecting low-altitude measurements onto total electron content (TEC) maps. The distinct features of different types of precipitation in TEC horizontal gradients are discussed.
GEOPHYSICAL RESEARCH LETTERS
(2023)
