S. D. Bale
A5068531833- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Earthquake Detection and Analysis
- Stellar, planetary, and galactic studies
- Solar Radiation and Photovoltaics
- Planetary Science and Exploration
- Geophysics and Gravity Measurements
- Spacecraft Design and Technology
- Magnetic confinement fusion research
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Space Science and Extraterrestrial Life
- High-pressure geophysics and materials
- Magnetic Field Sensors Techniques
- Photovoltaic System Optimization Techniques
- Space exploration and regulation
- Seismic Waves and Analysis
- solar cell performance optimization
- Atmospheric Ozone and Climate
- Spacecraft and Cryogenic Technologies
- Ocean Waves and Remote Sensing
- Laser-induced spectroscopy and plasma
University of California, Berkeley
2016-2025
Imperial College London
2011-2024
Queen Mary University of London
1995-2024
Berkeley College
2008-2024
Space Science Institute
2012-2024
University of Iowa
2023
Nagoya University
2023
Los Alamos National Laboratory
2023
Memorial University of Newfoundland
2023
Planetary Science Institute
2023
Solar Probe Plus (SPP) will be the first spacecraft to fly into low solar corona. SPP’s main science goal is determine structure and dynamics of Sun’s coronal magnetic field, understand how corona wind are heated accelerated, what processes accelerate energetic particles. Understanding these fundamental phenomena has been a top-priority for over five decades, dating back 1958 Simpson Committee Report. The scale concept such mission revised at intervals since that time, yet core always close...
The Solar Wind Electrons Alphas and Protons (SWEAP) Investigation on Probe Plus is a four sensor instrument suite that provides complete measurements of the electrons ionized helium hydrogen constitute bulk solar wind coronal plasma. SWEAP consists Cup (SPC) Analyzers (SPAN). SPC Faraday looks directly at Sun measures ion electron fluxes flow angles as function energy. SPAN an electrostatic analyzer (ESA) ram side SPP (SPAN-A) ESA anti-ram (SPAN-B). SPAN-A has time flight section enables it...
Magnetohydrodynamic (MHD) turbulence in the solar wind is observed to show spectral behavior of classical Kolmogorov fluid over an inertial subrange and departures from this at short wavelengths, where energy should be dissipated. Here we present first measurements electric field fluctuation spectrum dissipative wave number ranges a Beta > or approximately = 1 plasma. The k(-5/3) agrees strikingly with magnetic spectrum; phase speed regime shown consistent Alfvén speed. At smaller...
The Electric Fields and Waves (EFW) Instruments on the two Radiation Belt Storm Probe (RBSP) spacecraft (recently renamed Van Allen Probes) are designed to measure three dimensional quasi-static low frequency electric fields waves associated with major mechanisms responsible for acceleration of energetic charged particles in inner magnetosphere Earth. For this measurement, instrument uses pairs spherical double probe sensors at ends orthogonal centripetally deployed booms spin plane...
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...
Solar wind is probably the best laboratory to study turbulence in astrophysical plasmas. In addition presence of magnetic field, differences with neutral fluid isotropic are: weakness collisional dissipation and several characteristic space time scales. this paper we discuss observational properties solar a large range from MHD electron At scales, within inertial range, cascade fluctuations develops mostly plane perpendicular mean field. compressible nature. The spectrum velocity do not...
The first two orbits of the Parker Solar Probe (PSP) spacecraft have enabled in situ measurements solar wind down to a heliocentric distance 0.17 au (or 36 Rs). Here, we present an analysis this data study turbulence at and its evolution out 1 au. While many features remain similar, key differences include: increased energy levels by more than order magnitude, magnetic field spectral index -3/2 matching that velocity both Elsasser fields, lower compressibility consistent with smaller...
The magnetometer instrument on the Solar Orbiter mission is designed to measure magnetic field local spacecraft continuously for entire duration. need characterise not only background but also its variations scales from far above well below proton gyroscale result in challenging requirements stability, precision, and noise, as operational limitations both other instruments. vibration thermal environment has led significant development of mechanical sensor design. overall design, performance,...
One of the most striking observations made by Parker Solar Probe during its first solar encounter is omnipresence rapid polarity reversals in a magnetic field that otherwise mostly radial. These so-called switchbacks strongly affect dynamics field. We concentrate here on their macroscopic properties. First, we find these structures are self-similar, and have neither characteristic magnitude, nor duration. Their waiting time statistics shows evidence for aggregation. The associated long...
Abstract Launched on 12 Aug. 2018, NASA’s Parker Solar Probe had completed 13 of its scheduled 24 orbits around the Sun by Nov. 2022. The mission’s primary science goal is to determine structure and dynamics Sun’s coronal magnetic field, understand how solar corona wind are heated accelerated, what processes accelerate energetic particles. returned a treasure trove data that far exceeded quality, significance, quantity expectations, leading significant number discoveries reported in nearly...
We present EUV solar observations showing evidence for omnipresent jetting activity driven by small-scale magnetic reconnection at the base of corona. argue that physical mechanism heats and drives wind its source is ubiquitous in form (i.e., a.k.a. jetlets). This activity, like heating coronal plasma, are regardless cycle phase. Each event arises from opposite polarity fields producing a short-lived jet hot plasma Alfv\'en waves into The discrete nature these jetlet events leads to...
The fast solar wind that fills the heliosphere originates from deep within regions of open magnetic field on Sun called 'coronal holes'. energy source responsible for accelerating plasma is widely debated; however, there evidence it ultimately in nature, with candidate mechanisms including wave heating1,2 and interchange reconnection3-5. coronal near surface structured scales associated 'supergranulation' convection cells, whereby descending flows create intense fields. density these...
Abstract The dissipation of turbulence in astrophysical systems is fundamental to energy transfer and heating environments ranging from the solar wind corona accretion disks intracluster medium. Although turbulent relatively well understood fluid dynamics, plasmas often exhibit exotic behaviour, arising lack interparticle collisions, which complicates these systems. Recent observations by NASA’s Parker Solar Probe mission inner heliosphere have shed new light on role ion cyclotron resonance...
On 1 April 2001, the Polar satellite crossed a subsolar magnetopause associated with antiparallel magnetic fields. Over width approximately 6 magnetosheath ion skin depths (approximately 3 magnetospheric depths), perpendicular flows different from E x B/B(2) as well Hall and electric field signatures were observed. At smaller scale, electron flow decoupled near deep minimum in strength. Separatrices identified boundaries of low frequency turbulence density minima parallel The reconnection...
We report direct measurements of high-energy particles in a rare crossing the diffusion region Earth's magnetotail by Wind spacecraft. The fluxes energetic electrons up to approximately 300 keV peak near center and decrease monotonically away from this region. electron flux spectrum obeys power law with an index -3.8 above 2 keV, angular distribution displays strong field-aligned bidirectional anisotropy at energies below becoming isotropic 6 keV. These observations indicate significant...
We present observations of intense, bipolar, electrostatic structures in the transition region terrestrial bow shock from Wind spacecraft. The electric field signatures are on order a tenth millisecond duration and greater than 100 mV/m amplitude. measured is generally larger smaller dipole antenna, indicating small spatial size. compare potential two antennas with model antenna response to Gaussian profile. This result agrees scale determined by convection gives characteristic size 2–7 λ d...
The IMPACT (In situ Measurements of Particles And CME Transients) investigation on the STEREO mission was designed and developed to provide multipoint solar wind suprathermal electron, interplanetary magnetic field, energetic particle information required unravel nature coronal mass ejections their heliospheric consequences. consists seven individual sensors which are packaged into a boom suite, SEP suite. This review summarizes science objectives IMPACT, instruments that comprise...
During a passage through the Earth's dawn‐side outer radiation belt, whistler‐mode waves with amplitudes up to more than ∼240 mV/m were observed by STEREO S/WAVES instrument. These are an order of magnitude larger previously for whistlers in belt. Although peak frequency is similar whistler chorus, there distinct differences from addition amplitudes, including lack drift and oblique propagation large longitudinal electric field component. Simulations show that these amplitude can energize...