Low-frequency Whistler Waves Modulate Electrons and Generate Higher-frequency Whistler Waves in the Solar Wind

Abstract The role of whistler-mode waves in the solar wind and the relationship between their electromagnetic fields and charged particles is a fundamental question in space physics. Using high-temporal-resolution electromagnetic field and plasma data from the Magnetospheric MultiScale spacecraft, we report observations of low-frequency whistler waves and associated electromagnetic fields and particle behavior in the Earth’s foreshock. The frequency of these whistler waves is close to half the lower-hybrid frequency (∼2 Hz), with their wavelength close to the ion gyroradius. The electron bulk flows are strongly modulated by these waves, with a modulation amplitude comparable to the solar wind velocity. At such a spatial scale, the electron flows are forcibly separated from the ion flows by the waves, resulting in strong electric currents and anisotropic ion distributions. Furthermore, we find that the low-frequency whistler wave propagates obliquely to the background magnetic field ( B 0), and results in spatially periodic magnetic gradients in the direction parallel to B 0. Under such conditions, large pitch-angle electrons are trapped in wave magnetic valleys by the magnetic mirror force, and may provide free perpendicular electron energy to excite higher-frequency whistler waves. This study offers important clues and new insights into wave–particle interactions, wave generation, and microscale energy conversion processes in the solar wind.

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Hybrid Vlasov simulations for alpha particles heating in the solar wind

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311006843 ◽

2010 ◽

Vol 6 (S274) ◽

pp. 168-171

Author(s):

Denise Perrone ◽

Francesco Valentini ◽

Pierluigi Veltri

Keyword(s):

Solar Wind ◽

Physical Space ◽

Low Noise ◽

Space Physics ◽

Distribution Functions ◽

Alpha Particles ◽

Theoretical Problem ◽

Direction Parallel ◽

Background Magnetic Field ◽

Kinetic Effects

AbstractHeating and acceleration of heavy ions in the solar wind and corona represent a long-standing theoretical problem in space physics and are distinct experimental signatures of kinetic processes occurring in collisionless plasmas. To address this problem, we propose the use of a low-noise hybrid-Vlasov code in four dimensional phase space (1D in physical space and 3D in velocity space) configuration. We trigger a turbulent cascade injecting the energy at large wavelengths and analyze the role of kinetic effects along the development of the energy spectra. Following the evolution of both proton and α distribution functions shows that both the ion species significantly depart from the maxwellian equilibrium, with the appearance of beams of accelerated particles in the direction parallel to the background magnetic field.

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Collisionless energy transfer in kinetic turbulence: field–particle correlations in Fourier space

Journal of Plasma Physics ◽

10.1017/s0022377819000515 ◽

2019 ◽

Vol 85 (4) ◽

Author(s):

Tak Chu Li ◽

Gregory G. Howes ◽

Kristopher G. Klein ◽

Yi-Hsin Liu ◽

Jason M. TenBarge

Keyword(s):

Solar Wind ◽

Energy Transfer ◽

Low Frequency ◽

Particle Energy ◽

Distribution Functions ◽

Velocity Space ◽

Correlation Technique ◽

Direction Parallel ◽

Particle Correlation ◽

Particle Correlations

Turbulence is commonly observed in nearly collisionless heliospheric plasmas, including the solar wind and corona and the Earth’s magnetosphere. Understanding the collisionless mechanisms responsible for the energy transfer from the turbulent fluctuations to the particles is a frontier in kinetic turbulence research. Collisionless energy transfer from the turbulence to the particles can take place reversibly, resulting in non-thermal energy in the particle velocity distribution functions (VDFs) before eventual collisional thermalization is realized. Exploiting the information contained in the fluctuations in the VDFs is valuable. Here we apply a recently developed method based on VDFs, the field–particle correlation technique, to a $\unicode[STIX]{x1D6FD}=1$ , solar-wind-like, low-frequency Alfvénic turbulence simulation with well-resolved phase space to identify the field–particle energy transfer in velocity space. The field–particle correlations reveal that the energy transfer, mediated by the parallel electric field, results in significant structuring of the VDF in the direction parallel to the magnetic field. Fourier modes representing the length scales between the ion and electron gyroradii show that energy transfer is resonant in nature, localized in velocity space to the Landau resonances for each Fourier mode. The energy transfer closely follows the Landau resonant velocities with varying perpendicular wavenumber $k_{\bot }$ and plasma $\unicode[STIX]{x1D6FD}$ . This resonant signature, consistent with Landau damping, is observed in all diagnosed Fourier modes that cover the dissipation range of the simulation.

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On the dispersion law of low-frequency electron whistler waves in a multi-ion plasma

Annales Geophysicae ◽

10.5194/angeo-26-1605-2008 ◽

2008 ◽

Vol 26 (6) ◽

pp. 1605-1615 ◽

Cited By ~ 3

Author(s):

B. V. Lundin ◽

C. Krafft

Keyword(s):

Cutoff Frequency ◽

Low Frequency ◽

Negative Ions ◽

Plasma Electron ◽

Lower Hybrid ◽

Charged Dust ◽

Whistler Waves ◽

Dispersion Law ◽

Ion Plasma ◽

Lower Hybrid Resonance

Abstract. A new and simple dispersion law for extra-low-frequency electron whistler waves in a multi-ion plasma is derived. It is valid in a plasma with finite ratio ωc/ωpe of electron gyro-to-plasma frequency and is suitable for wave frequencies much less than ωpe but well above the gyrofrequencies of most heavy ions. The resultant contribution of the ions to the dispersion law is expressed by means of the lower hybrid resonance frequency, the highest ion cutoff frequency and the relative content of the lightest ion. In a frequency domain well above the ions' gyrofrequencies, this new dispersion law merges with the "modified electron whistler dispersion law" determined in previous works by the authors. It is shown that it fits well to the total cold plasma electron whistler dispersion law, for different orientations of the wave vectors and different ion constituents, including negative ions or negatively charged dust grains.

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Role of Whistler Waves in Regulation of the Heat Flux in the Solar Wind

10.5194/egusphere-egu2020-1175 ◽

2020 ◽

Author(s):

Ilya Kuzichev ◽

Ivan Vasko ◽

Angel Rualdo Soto-Chavez ◽

Anton Artemyev

Keyword(s):

Magnetic Field ◽

Heat Flux ◽

Solar Wind ◽

Particle Interaction ◽

Solar Wind Plasma ◽

Whistler Waves ◽

Particle In Cell ◽

Electron Heat ◽

Background Magnetic Field ◽

Institute Of Technology

The electron heat flux is one of the leading terms in energy flow processes in the collisionless or weakly-collisional solar wind plasma. The very first observations demonstrated that the collisional Spitzer-H&#211;&#147;rm law could not describe the heat flux in the solar wind well. In particular, in-situ observations at 1AU showed that the heat flux was suppressed below the collisional value. Different mechanisms of the heat flux regulation in the solar wind were proposed. One of these possible mechanisms is the wave-particle interaction with whistler-mode waves produced by the so-called whistler heat flux instability (WHFI). This instability operates in plasmas with at least two counter-streaming electron populations. Recent observations indicated that the WHFI operates in the solar wind producing predominantly quasi-parallel whistler waves with the amplitudes up to several percent of the background magnetic field. But whether such whistler waves can regulate the heat flux still remained an open question.We present the results of simulation of the whistler generation and nonlinear evolution using the 1D full Particle-in-Cell code TRISTAN-MP. This code models self-consistent dynamics of ions and two counter-streaming electron populations:&#160; warm (core) electrons and hot (halo) electrons. We performed two sets of simulations. In the first set, we studied the wave generation for the classical WHFI, so both core and halo electron distributions were taken to be isotropic. We found a positive correlation between the plasma beta and the saturated wave amplitude. For the heat flux, the correlation changes from positive to a negative one at some value of the heat flux. The observed wave amplitudes and correlations are consistent with the observations. Our calculations show that the electron heat flux does not change substantially in the course of the WHFI development; hence such waves are unlikely to contribute significantly to the heat flux regulation in the solar wind.The classical WHFI drives only those whistler waves that propagate along the halo electron drift direction (consequently, parallel with respect to background magnetic field). Such waves interact resonantly with electrons that move in the opposite direction; hence, only a relatively small fraction of hot halo electrons is affected by these waves. On the contrary, anti-parallel whistler waves would interact with a substantial fraction of halo electrons. Thus, they could influence the heat flux more significantly. To test this hypothesis, we performed the second set of simulations with anisotropic halo electrons. Anisotropic distribution drives both parallel and anti-parallel waves. Our calculations demonstrate that anti-parallel whistler waves can decrease the heat flux. This indicates that the waves generated via combined whistler anisotropy and heat flux instabilities might contribute to regulation of the heat flux in the solar wind.The work was supported by NSF grant 1502923. I. Kuzichev would also like to acknowledge the support of the RBSPICE Instrument project by JHU/APL sub-contract 937836 to the New Jersey Institute of Technology under NASA Prime contract NAS5-01072. Computational facility: Cheyenne supercomputer (doi:10.5065/D6RX99HX) provided by NCAR&#8217;s Computational and Information Systems Laboratory, sponsored by NSF

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Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

Annales Geophysicae ◽

10.5194/angeo-21-1393-2003 ◽

2003 ◽

Vol 21 (7) ◽

pp. 1393-1403 ◽

Cited By ~ 16

Author(s):

C. Krafft ◽

A. Volokitin

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Energetic Electron ◽

High Energy ◽

Electron Velocity ◽

Lower Hybrid ◽

Whistler Waves ◽

Electron Velocity Distribution ◽

Radio Science ◽

Ambient Magnetic Field

Abstract. Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field), the fan instability can excite VLF waves (whistlers and lower hybrid waves) with characteristics close to those observed in space experiments.Key words. Space plasma physics (waves and instabilities) – Radio Science (waves in plasma) – Solar physics, astrophysics and astronomy (radio emissions)

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High Bandwidth Measurements of Auroral Langmuir Waves with Multiple Antennas

10.5194/angeo-2021-68 ◽

2021 ◽

Author(s):

Chrystal Moser ◽

James LaBelle ◽

Iver H. Cairns

Keyword(s):

Magnetic Field ◽

Multiple Antennas ◽

Low Frequency ◽

Langmuir Wave ◽

Wave Interaction ◽

Lower Hybrid ◽

Background Magnetic Field ◽

Auroral Hiss ◽

Plasma Line ◽

High Bandwidth

Abstract. The High-Bandwidth Auroral Rocket (HIBAR) was launched from Poker Flat, Alaska on January 28, 2003 at 07:50 UT towards an apogee of 382 km in the night-side aurora. The flight was unique in having three high-frequency (HF) receivers using multiple antennas parallel and perpendicular to the ambient magnetic field, as well as very low frequency (VLF) receivers using antennas perpendicular to the magnetic field. These receivers observed five short-lived Langmuir wave bursts lasting from 0.1–0.2 s, consisting of a thin plasma line with frequencies in the range of 2470–2610 kHz that had an associated diffuse feature occurring 5–10 kHz above the plasma line. Both of these waves occurred slightly above the local plasma frequency with amplitudes between 1–100 μV/m. The ratio of the parallel to perpendicular components of the plasma line and diffuse feature were used to determine the angle of propagation of these waves with respect to the background magnetic field. These angles were found to be comparable to the theoretical Z-infinity angle that these waves would resonate at. The VLF receiver detected auroral hiss throughout the flight at 5–10 kHz, a frequency matching the difference between the plasma line and the diffuse feature. A dispersion solver, partially informed with measured electron distributions, and associated frequency- and wavevector-matching conditions were employed to determine if the diffuse features could be generated by a nonlinear wave-wave interaction of the plasma line with the lower frequency auroral hiss waves/lower-hybrid waves. The results show that this interpretation is plausible.

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Electrostatic Waves with Rapid Frequency Shifts in the Solar Wind Sunward of 1/3 AU

10.5194/egusphere-egu21-16103 ◽

2021 ◽

Author(s):

Lily Kromyda ◽

David M. Malaspina ◽

Robert E. Ergun ◽

Jasper Halekas ◽

Michael L. Stevens ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Plasma Wave ◽

Detection Algorithm ◽

Space Physics ◽

University Of California ◽

Magnetic Fluctuations ◽

Plasma Parameters ◽

University Of Colorado ◽

Background Magnetic Field

During its first five orbits, the FIELDS plasma wave investigation on board Parker Solar Probe (PSP)&#160; has observed a multitude of plasma waves, including electrostatic whistler and electron Bernstein waves (Malaspina et al. 2020), sunward propagating whistlers (Agapitov et al. 2020), ion-scale electromagnetic waves (Verniero et al. 2020, Bowen et al. 2020) and Alfven, slow and fast mode waves (Chaston et al. 2020).The importance of these waves lies in their potential to redistribute the energy of the solar wind among different particles species (wave-particle interactions) or different types of waves (wave-wave interactions). The abundance of waves and instabilities observed with PSP points to their central role in the regulation of this energy exchange.Here we present first observations of an intermittent, electrostatic and broadband plasma wave that is ubiquitous in the range of distances that PSP has probed so far. A unique feature of these waves (FDWs) is a frequency shift that occurs on millisecond timescales. In the frame of the spacecraft, FDWs usually appear between the electron cyclotron and electron plasma frequencies.We develop a detection algorithm that identifies the FDWs in low cadence spectra. We analyze them using various statistical techniques. We establish their phenomenology and compare the magnetic fluctuations of the background magnetic field at times of FDWs and at times without FDWs. We establish their polarization with respect to the background magnetic field and search for correlations with various plasma parameters and features in the electron, proton and alpha particle distribution moments. We also investigate possible plasma wave modes that could be responsible for the growth of FDWs and the instability mechanisms that could be generating them.&#160;Lily Kromyda*(1), David M. Malaspina (1,2), Robert E. Ergun(1,2) , Jasper Halekas(3), Michael L. Stevens(4) , Jennifer Verniero(5), Alexandros Chasapis(2) , Daniel Vech(2) , Stuart D. Bale(5,6) , John W. Bonnell(5) , Thierry Dudok de Wit(7) , Keith Goetz(8) , Katherine Goodrich(5) , Peter R. Harvey(5) , Robert J. MacDowall(9) , Marc Pulupa(5) , Anthony W. Case(4) , Justin C. Kasper(10) , Kelly E. Korreck(4) , Davin Larson(5) , Roberto Livi(5) , Phyllis Whittlesey(5)(1) Astrophysical and Planetary Sciences Department, University of Colorado, Boulder, CO, USA(2) Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA(3) &#160;University of Iowa, Iowa City, IA, USA(4) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA(5) &#160;Space Sciences Laboratory, University of California, Berkeley, CA, USA(6) Physics Department, University of California, Berkeley, CA, USA(7) &#160;LPC2E, CNRS, and University of Orleans, Orleans, France(8) &#160;School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA(9) &#160;NASA Goddard Space Flight Center, Greenbelt, MD, USA(10) University of Michigan, Ann Arbor, MI, USA

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Nongyrotropy in magnetoplasmas: simulation of wave excitation and phase-space diffusion

Annales Geophysicae ◽

10.1007/s00585-997-0603-3 ◽

1997 ◽

Vol 15 (6) ◽

pp. 603-613 ◽

Cited By ~ 17

Author(s):

U. Motschmann ◽

H. Kafemann ◽

M. Scholer

Keyword(s):

Phase Space ◽

Diffusion Processes ◽

Low Frequency ◽

Particle Energy ◽

Direction Parallel ◽

Longitudinal Modes ◽

Ion Distributions ◽

Left Handed ◽

Background Magnetic Field ◽

Hybrid Code

Abstract. Nongyrotropic (gyrophase bunched) ion distributions in a magnetoplasma are studied by analytical methods and by two-dimensional hybrid code simulations. Nongyrotropy may not occur in a plasma being simultaneously homogeneous, stationary, and solenoidal in phase space. A detailed study is performed for a homogeneous and stationary plasma with sources and sinks in phase space. The analytical investigation cast in the framework of linearized Maxwell-Vlasov theory yields a coupling of low-frequency left-handed, right-handed, and longitudinal modes. Nongyrotropic ion distributions are unstable; they excite left-handed waves. The growth rate is comparable to that of the ion ring instability. The hybrid code simulation study confirms the expected propagation direction parallel to the background magnetic field. Three diffusion processes are studied: arc lengthening, arc broadening, and arc radius decreasing corresponding to particle energy diffusion. The characteristic diffusion time-scales are found to be of the order of 101 wave cycles.

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