A5057521105- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Planetary Science and Exploration
- Geomagnetism and Paleomagnetism Studies
- Space Science and Extraterrestrial Life
- Solar Radiation and Photovoltaics
- Earthquake Detection and Analysis
- Geophysics and Gravity Measurements
- Stellar, planetary, and galactic studies
- Spaceflight effects on biology
- Magnetic confinement fusion research
- Spacecraft Design and Technology
- Space exploration and regulation
- Advanced MRI Techniques and Applications
- Photovoltaic System Optimization Techniques
- Electrostatic Discharge in Electronics
- Radiation Effects in Electronics
- Fluid Dynamics and Turbulent Flows
- Scientific Research and Discoveries
- Gamma-ray bursts and supernovae
University of Colorado Boulder
2020-2022
Laboratory for Atmospheric and Space Physics
2020-2022
University of Colorado System
2021
University of Michigan
2016-2020
Imperial College London
2016
Swedish Institute of Space Physics
2016
HUN-REN Wigner Research Centre for Physics
2015
Luleå University of Technology
2015
We present a technique for deriving the temperature anisotropy of solar wind protons observed by Parker Solar Probe (PSP) mission in near-Sun wind. The radial proton measured Wind Electrons, Alphas, and Protons (SWEAP) Cup is compared with orientation local magnetic field FIELDS fluxgate magnetometer, temperatures parallel perpendicular to are extracted. This procedure applied different data products, results optimum timescales selection trends uncertainty method identified. find that...
We perform a statistical assessment of solar wind stability at 1 AU against ion sources free energy using Nyquist's instability criterion. In contrast to typically employed threshold models which consider single free-energy source, this method includes the effects proton and ${\mathrm{He}}^{2+}$ temperature anisotropy with respect background magnetic field as well relative drifts between core, beam, components on stability. Of 309 randomly selected spectra from Wind spacecraft, 53.7% are...
The solar wind shows periods of highly Alfvénic activity, where velocity fluctuations and magnetic are aligned or antialigned with each other. It is generally agreed that plasma field observed by the Parker Solar Probe (PSP) during first encounter mostly Alfvénic. However, quantitative measures Alfvénicity needed to understand how characterization these compares standard from prior missions in inner outer heliosphere, fast slow wind, at high low latitudes. To investigate this issue, we...
Abstract The power spectral density of magnetic fluctuations in the solar wind exhibits several power-law-like frequency ranges with a well-defined break between approximately 0.1 and 1 Hz spacecraft frame. exact dependence this scale on parameters has been extensively studied but is not yet fully understood. Recent studies have suggested that reconnection may induce spectrum at “disruption scale” , which be larger than fundamental ion kinetic scales, producing an unusually steep just below...
Magnetic field fluctuations in the solar wind are commonly observed to follow a power-law spectrum. Near proton-kinetic scales, spectral break occurs that is interpreted as transition kinetic turbulence. However, this not yet entirely understood. By studying scaling of with various plasma properties, it may be possible constrain processes leading onset Using data from Parker Solar Probe, we measure proton-scale over range heliocentric distances, enabling measurement inertial kinetic-scale...
Field and plasma variations during the first perihelion pass of Parker Solar Probe (PSP) from 53 into 35 solar radii (RS) Sun over a frequency range in spacecraft frame (fSC) 0.0002 to 0.2 Hz are decomposed constituent magnetohydrodynamic (MHD) modes. The analysis operates on measurements MHD variables recorded between impulsive, large amplitude rotations magnetic field reveal dominance broad spectrum shear Alfvén waves propagating antiparallel (backward) background (B0) with significant...
Abstract The solar wind undergoes significant heating as it propagates away from the Sun; exact mechanisms responsible for this are not yet fully understood. We present first time a statistical test one of proposed mechanisms: stochastic ion heating. use amplitude magnetic field fluctuations near proton gyroscale proxy ratio velocity to perpendicular (with respect field) thermal speed, defined . Enhanced temperatures observed when is larger than critical value (∼0.019–0.025). This...
Abstract We present a statistical study on the interaction between interplanetary coronal mass ejections (ICMEs) and induced magnetosphere of Venus when peak magnetic field barrier was anomalously large (>65 nT). Based entire available Express data set from April 2006 to October 2014, we selected 42 events analyzed solar wind parameters, position bow shock, size plasma properties barrier, ion composition boundary (ICB). It found that investigated ICMEs can be characterized with shocks...
Abstract In this study we present the first statistical analysis on effects of heliospheric current sheet crossings induced magnetosphere Venus. These events are particular interest because they lead to reconfiguration with opposite polarity. We use a approach based 117 orbit pairs, and spatial distribution heavy ion flux measurements in plasma environment The average median compared before after polarity reversal events. results show that fluxes magnetotail reduced by factors 0.75 ± 0.09...
In this Paper, we present the first results from Flux Angle operation mode of Faraday Cup instrument onboard Parker Solar Probe. The allows rapid measurements phase space density fluctuations close to peak proton velocity distribution function with a cadence 293 Hz. This approach provides an invaluable tool for understanding kinetic scale turbulence in solar wind and corona. We describe technique convert into vector components compute several parameters such as spectral index, residual...
ABSTRACT We present a multi-spacecraft approach to test the predictions of recent studies on effect solar wind expansion radial spectral, variance, and local 3D anisotropies turbulence. found that small scales (5000–10,000 km) power levels B-trace structure functions do not depend sampling direction with respect suggesting this scale is possibly due fast turbulent timescales. On larger (110–135 R E ), fluctuations magnetic field component are reduced by ∼20% compared transverse...
The available magnetic field data from the terrestrial magnetosphere, solar wind and planetary magnetospheres exceeds over $10^6$ hours. Identifying plasma waves in these large sets is a time consuming tedious process. In this Paper, we propose solution to problem. We demonstrate how Self-Organizing Maps can be used for rapid reduction identification of sets. use 72,000 fluxgate 110,000 search coil power spectra Magnetospheric Multiscale Mission (MMS$_1$) show Map sorts into groups based on...
Abstract In this paper we study electrostatic waves with time‐dependent frequency features in the terrestrial foreshock. These short (0.1–0.3 s) duration are characterized by a significant drift where peak wave power shifts from few hundred Hz to 2–4,000 milliseconds. Based on electric field data Magnetospheric Multiscale Mission (MMS) have identified 46 of these packets. Using four spacecraft timing approach find that propagation direction pointing upstream. However, their plasma frame...
In this Letter we study the connection between large-scale dynamics of turbulence cascade and particle heating on kinetic scales. We find that inertial range amplitude ($\delta B_i$; measured in 0.01-0.1 Hz) is a simple effective proxy to identify onset significant ion when it combined with $\beta_{||p}$, characterizes energy partitioning protons electrons ($T_p/T_e$), proton temperature anisotropy ($T_{\perp}/T_{||}$) scalar ($T_p$) way consistent previous predictions. For fixed $\delta...
Context. The first studies with Parker Solar Probe (PSP) data have made significant progress toward the understanding of fundamental properties ion cyclotron waves in inner heliosphere. survey mode particle measurements PSP, however, did not make it possible to measure coupling between electromagnetic fields and particles on time scale wave periods. Aims. We present a novel approach study wave-particle energy exchange PSP. Methods. use Flux Angle operation Cup conjunction electric field case...
The slow solar wind is typically characterized as having low Alfv\'enicity. However, Parker Solar Probe (PSP) observed predominately Alfv\'enic during several of its initial encounters. From first encounter observations, about 55.3\% the inside 0.25 au highly ($|\sigma_C| > 0.7$) at current minimum, which much higher than fraction quiet-Sun-associated maximum 1 au. Intervals with different Alfv\'enicities seem to show similar plasma characteristics and temperature anisotropy distributions....
Context: The analysis of the thermal part velocity distribution functions (VDF) is fundamentally important for understanding kinetic physics that governs evolution and dynamics space plasmas. However, calculating proton core, beam alpha-particle parameters large data sets VDFs a time consuming computationally demanding process always requires supervision by human expert. Aims: We developed machine learning tool can extract using images (2-D grid consisting pixel values) VDFs. Methods: A...
Previous statistical studies of plasmaspheric hiss investigated the averaged shape magnetic field power spectra at various points in magnetosphere. However, this approach does not consider fact that very diverse spectral shapes exist a given L-shell and local time. Averaging data together means important features are lost. In paper, we use an unsupervised machine learning technique to categorize hiss. contrast previous studies, allows us identify have "similar" study their spatial...