A5064882711- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Magnetic confinement fusion research
- Astro and Planetary Science
- Earthquake Detection and Analysis
- Radio Astronomy Observations and Technology
- Meteorological Phenomena and Simulations
- Ocean Waves and Remote Sensing
- Laser-Plasma Interactions and Diagnostics
- Planetary Science and Exploration
- Laser-induced spectroscopy and plasma
- Astrophysics and Cosmic Phenomena
- Aerospace Engineering and Energy Systems
- Dust and Plasma Wave Phenomena
- Cold Atom Physics and Bose-Einstein Condensates
- Geophysics and Gravity Measurements
- Fluid Dynamics and Turbulent Flows
- Spacecraft Design and Technology
- Quantum and Classical Electrodynamics
- Methane Hydrates and Related Phenomena
- Advanced X-ray and CT Imaging
- Atmospheric Ozone and Climate
- Magnetic Field Sensors Techniques
- Radiomics and Machine Learning in Medical Imaging
University of California, Berkeley
2008-2025
Centre National de la Recherche Scientifique
2005-2006
Swedish Institute of Space Physics
2001-2006
Université d'Orléans
2005-2006
Uppsala University
2005
The proton temperature anisotropy in the solar wind is known to be constrained by theoretical thresholds for pressure anisotropy-driven instabilities. Here we use approximately 1 million independent measurements of gyroscale magnetic fluctuations show first time that these are enhanced along mirror, oblique firehose, and ion cyclotron In addition, measured compressibility at high plasma beta ($\beta_\parallel \gtrsim 1$) mirror instability threshold but small elsewhere, consistent with...
The nature of small-scale turbulent fluctuations in the solar wind is investigated using a comparison Cluster magnetic and electric field measurements to predictions arising from models consisting either kinetic Alfvén waves or whistler waves. properties these linear theory are used construct spacecraft-frame frequency spectra (|δE|/|δB|)s/c (|δB∥|/|δB|)s/c, allowing for direct spacecraft data. measured fluctuations, found be inconsistent with wave model, agree well prediction spectrum...
We present in situ measurements a space plasma showing that thin current sheets the size of an ion inertial length exist and are abundant strong intermittent turbulence. Many these exhibit microphysical signatures reconnection. The spatial scale where intermittency occurs corresponds to observed structures. reconnecting represent type dissipation mechanism, with rates comparable or even dominating over collisionless damping waves at scales (x100), can have far reaching implications for...
Intermittent structures, such as thin current sheets, are abundant in turbulent plasmas. Numerical simulations indicate that sheets important sites of energy dissipation and particle heating occurring at kinetic scales. However, direct evidence associated within is scarce. Here, we show a new statistical study local electron proton-scale by using high-resolution spacecraft data. Current detected the Partial Variance Increments (PVI) method which identifies regions strong intermittency. We...
The Radio Frequency Spectrometer (RFS) is a two‐channel digital receiver and spectrometer, which will make remote sensing observations of radio waves in situ measurements electrostatic electromagnetic fluctuations the solar wind. A part FIELDS suite for Solar Probe Plus (SPP), RFS optimized inner heliosphere, where bursts are more intense plasma frequency higher compared to previous at distances 1 AU or greater. inputs four electric antennas mounted near front SPP spacecraft single axis...
Comparisons of asymmetric magnetic field reconnection at the subsolar magnetopause are made between satellite data and computer simulations for ratio antiparallel components fields boundaries being about three density 10 to 30. The bipolar electric quadrupolar symmetric not found in either or experimental because Hall term generalized Ohm's Law (the leading on its right side ion scale) is a factor up 100 smaller magnetosheath current layer than magnetospheric side. Average plasma densities...
Whistler wave trains are observed in the foot region of high Mach number quasiperpendicular shocks. The waves oblique with respect to ambient magnetic field as well shock normal. Poynting flux is directed upstream normal frame starting from ramp shock. This suggests that an integral part structure dispersive source waves. These observations lead conclusion supercritical shocks formed a balance dispersion and nonlinearity.
Unlike the vast majority of astrophysical plasmas, solar wind is accessible to spacecraft, which for decades have carried in-situ instruments directly measuring its particles and fields. Though such measurements provide precise detailed information, a single spacecraft on own cannot disentangle spatial temporal fluctuations. Even modest constellation though capable characterizing fluctuations at one or more scales, fully determine plasma’s 3-D structure. We describe here concept new mission,...
Abstract We have performed a detailed analysis of plasma and wave observations in magnetic flux rope encountered by the THEMIS‐D spacecraft at subsolar magnetopause. The extent was ∼270 ion skin depths outflow direction, it flanked two active X lines producing colliding jets core where heating suprathermal electrons were observed. jet region highly dynamic characterized enhanced power broad frequency range. High‐frequency waves, including acoustic‐like electron holes, whistler mode observed...
Abstract. We present a detailed study of waves with frequencies near the proton gyrofrequency in high-altitude cusp for northward IMF as observed by Cluster spacecraft. Waves this regime can be important energization ions and electrons energy transfer between different plasma populations. These are entire highest amplitudes being associated localized regions downward precipitating ions, most probably originating from reconnection site at magnetopause. The Poynting flux carried these is...
Field and plasma measurements made during a quasi‐perpendicular terrestrial bow shock crossing by the Time History of Events Macroscale Interactions Substorms (THEMIS) E spacecraft on 21 August 2010 show that measured electric field, being as great 300 mV/m in ramp, produced potential fluctuations over an electron gyrodiameter, which were much 15 times greater than temperature. This fact requires electrons unmagnetized ramp result scattered many single gyroperiod fluctuating field....
The Lunar Surface Electromagnetics Explorer 'LuSEE Night' is a low frequency radio astronomy experiment that will be delivered to the farside of Moon by NASA Commercial Payload Services (CLPS) program in late 2025 or early 2026. payload system being developed jointly and US Department Energy (DOE) consists 4 channel, 50 MHz Nyquist baseband receiver 2 orthogonal $\sim$6m tip-to-tip electric dipole antennas. LuSEE Night enjoy standalone operations through lunar night, without electromagnetic...
Abstract. Broadband waves around the lower hybrid frequency (around 10 Hz) near magnetopause are studied, using four Cluster satellites. These common at Earthward edge of boundary layer, consistent with earlier observations, and can have amplitudes least up to 5 mV/m. similar on all satellites, i.e. they likely be distributed over large areas boundary. The strongest electric fields occur during a few seconds, distances hundred km in frame moving magnetopause, scale length comparable ion...
[1] Satellite observations near the X line are required to understand electromagnetic energy conversion and particle acceleration resulting from magnetic field reconnection. More than 900 orbits of Time History Events Macroscale Interactions during Substorms (THEMIS) spacecraft across low-latitude dayside magnetopause, involving more 4000 magnetopause crossings 5000 h data, were searched for examples reconnection within a few electron skin depths line. Evidence that was crossed in best these...
We present the results of a study based on several events broadband ULF/ELF emissions observed in auroral region by CLUSTER multi‐spacecraft at distances around 4–5 R E . These emissions, below ion plasma frequency, are similar to lower altitudes (800–4000 km) rockets (e.g. AMICIST) and satellites FREJA FAST). As successive passages four through nearly same regions show, intensity depend thermal properties gradients thereof. The total Poynting flux is downward comparable energy fluxes...
The main characteristics of the long‐boom electric antennas installed on board Cluster satellites are derived from finite element modeling in a kinetic and isotropic space plasma, frequency range about 1–100 kHz. model is based surface charge distribution method quasi‐static conditions. impedances both types antenna, i.e., double‐wire double‐probe, computed versus normalized with respect to local plasma for several different Debye lengths. Most code outputs checked using analytic estimations...
Direct measurements of current density perturbations associated with non-linear phenomena in magnetized plasmas can be carried out using situ magnetic measurements. In this paper we report such for three different kinds phenomena. Current fluctuations the edge gradient region a fusion plasma confined reversed field pinch configuration and Earth magnetosphere are measured compared, showing that both environments they attributed to drift-Alfvén vortices. structures reconnection events...
We present detailed measurements of ion scale vortices drift type coupled to Alfvén waves in an inhomogeneous and collisionless space magnetoplasma. The two free parameters a dipolar vortex, intensity spatial radius, are measured. driven by strong density gradient on boundary layer with size the same order as vortex diameter. Observations off show that symmetry-breaking conditions real plasma can lead not only cross-field but also cross-boundary anomalous transport particles energy.
The energy transport from the exterior cusp into ionosphere is investigated using coordinated ground‐based (EISCAT and MIRACLE) satellite (Cluster) observations. EISCAT MIRACLE data are used to estimate plasma heating in F ‐region Joule E ‐region. Cluster measurements derive electromagnetic particle fluxes at high altitudes. These then compared with deposition ionospheric during a 30 minutes long time interval which nearly conjugated. It shown that particles seen about 9 R e carry an...
Abstract. Though the presence of intermittent turbulence in stratosphere has been well established, much remains unknown about it. In situ observations this phenomenon, which have provided greatest details it, mostly achieved via sounding balloons (i.e., small burst at peak altitude) carrying constant-temperature hot-wire anemometers (CTAs). The Turbulence and Intermittency Long-Duration Atmospheric Experiment (TILDAE) was developed to test a new paradigm for stratospheric observations....