Localized heating of the Martian topside ionosphere through the combined effects of magnetic pumping by large scale magnetosonic waves and pitch angle diffusion by whistler waves

2020 ◽  
Author(s):  
Christopher Fowler ◽  
Oleksiy Agapitov ◽  
Shaosui Xu ◽  
David Mitchell ◽  
Laila Andersson ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Large Scale ◽  
Local Heating ◽  
Electron Distribution Function ◽  
Topside Ionosphere ◽  
Particle Interactions ◽  
Whistler Waves ◽  
Compressive Wave ◽  
Superthermal Electron ◽  
Wave Particle Interactions

<p>We present Mars Atmosphere and Volatile EvolutioN (MAVEN) observations of periodic (~ 25 s) large scale (100s km) magnetosonic waves propagating into the Martian dayside upper ionosphere. These waves adiabatically modulate the superthermal electron distribution function, and the induced electron temperature anisotropies drive the generation of observed electromagnetic whistler waves. The localized (in altitude) minimum in the ratio f<sub>pe</sub> / f<sub>ce</sub> provides conditions favorable for the local enhancement of efficient wave-particle interactions, so that the induced whistlers act back on the superthermal electron population to isotropize the plasma through pitch angle scattering. These wave-particle interactions break the adiabaticity of the large scale magnetosonic wave compressions, leading to local heating of the superthermal electrons during compressive wave `troughs'. Further evidence of this heating is observed as the subsequent phase shift between the observed perpendicular-to-parallel superthermal electron temperatures and compressive wave fronts. Such a heating mechanism may be important at other unmagnetized bodies such as Venus and comets.</p>

scholarly journals A generation mechanism for chorus emission

1999 ◽  
Vol 17 (1) ◽  
pp. 95-100 ◽  
Author(s):  
V. Y. Trakhtengerts
Keyword(s):  
Electron Distribution Function ◽  
Energetic Electron ◽  
Generation Mechanism ◽  
Phase Correlation ◽  
Particle Interactions ◽  
Backward Wave Oscillator ◽  
Cyclotron Instability ◽  
Wave Oscillator ◽  
Discrete Signals ◽  
Wave Particle Interactions

Abstract. A chorus generation mechanism is discussed, which is based on interrelation of ELF/VLF noise-like and discrete emissions under the cyclotron wave-particle interactions. A natural ELF/VLF noise radiation is excited by the cyclotron instability mechanism in ducts with enhanced cold plasma density or at the plasmapause. This process is accompanied by a step-like deformation of the energetic electron distribution function in the velocity space, which is situated at the boundary between resonant and nonresonant particles. The step leads to the strong phase correlation of interacting particles and waves and to a new backward wave oscillator (BWO) regime of wave generation, when an absolute cyclotron instability arises at the central cross section of the geomagnetic trap, in the form of a succession of discrete signals with growing frequency inside each element. The dynamical spectrum of a separate element is formed similar to triggered ELF/VLF emission, when the strong wavelet starts from the equatorial plane. The comparison is given of the model developed using some satellite and ground-based data. In particular, the appearance of separate groups of chorus signals with a duration 2-10 s can be connected with the preliminary stage of the step formation. BWO regime gives a succession period smaller than the bounce period of energetic electrons between the magnetic mirrors and can explain the observed intervals between chorus elements.Key words. Magnetospheric physics (Energetic particles · trapped). Space plasma physics (wave-particle interactions; waves and instabilities)

scholarly journals Ring Current Proton Dynamics Driven by Wave-Particle Interactions During a Nonstorm Period

2021 ◽  
pp. 98-104
Author(s):  
Sergei V. Smolin
Keyword(s):  
Pitch Angle ◽  
Ring Current ◽  
Activity Index ◽  
Proton Flux ◽  
Angle Distribution ◽  
Particle Interactions ◽  
Pitch Angle Distribution ◽  
Ion Cyclotron ◽  
Wave Particle Interactions ◽  
Emic Waves

Modeling of pitch angle scattering of ring current protons at interaction with electromagnetic ion cyclotron waves during a nonstorm period was considered very seldom. Therefore it is used correlated observation of enhanced electromagnetic ion cyclotron (EMIC) waves and dynamic evolution of ring current proton flux collected by Cluster satellite near the location L = 4.5 during March 26–27, 2003, a nonstorm period (Dst > –10 nT). Energetic (5–30 keV) proton fluxes are found to drop rapidly (e.g., a half hour) at lower pitch angles, corresponding to intensified EMIC wave activities. As mathematical model is used the non-stationary one-dimensional pitch angle diffusion equation which allows to compute numerically density of phase space or pitch angle distribution of the charged particles in the Earth’s magnetosphere. The model depends on time t, a local pitch angle and several parameters (the mass of a particle, the energy, the McIlwain parameter, the magnetic local time or geomagnetic eastern longitude, the geomagnetic activity index, parameter of the charged particle pitch angle distribution taken for the 90 degrees pitch angle at t = 0, the lifetime due to wave–particle interactions). This model allows numerically to estimate also for different geophysical conditions a lifetime due to wave–particle interactions. It is shown, that EMIC waves can yield decrements in proton flux within 30 minutes, consistent with the observational data. The good consent is received. Comparison of results on full model for the pitch angle range from 0 up to 180 degrees and on the model for the 90 degrees pitch angle is lead. For a perpendicular differential flux of the Earth’s ring current protons very good consent with the maximal relative error approximately 3.23 % is received

scholarly journals ULF waves with drift resonance and drift-bounce resonance energy sources as observed in artificially-induced HF radar backscatter

2001 ◽  
Vol 19 (2) ◽  
pp. 159-170 ◽  
Author(s):  
T. K. Yeoman ◽  
D. M. Wright
Keyword(s):  
Large Scale ◽  
Phase Evolution ◽  
Hf Radar ◽  
Mhd Waves ◽  
Energy Sources ◽  
Small Scale ◽  
Particle Interactions ◽  
Radar Backscatter ◽  
Short Period ◽  
Wave Particle Interactions

Abstract. HF radar backscatter which has been artificially-induced by a high power RF facility such as the EISCAT heater at Tromsø has been demonstrated to provide ionospheric electric field data of unprecedented temporal resolution and accuracy. Here such data are used to investigate ULF wave processes observed by the CUTLASS HF radars. Within a short period of time during a single four hour experiment three distinct wave types are observed with differing periods, and latitudinal and longitudinal phase evolution. Combining information from the three waves allows them to be divided into those with a large-scale nature, driven externally to the magnetosphere, and those with small azimuthal scale lengths, driven by wave-particle interactions. Furthermore, the nature of the wave-particle interactions for two distinct small-scale waves is revealed, with one wave interpreted as being driven by a drift resonance process and the other by a drift-bounce resonance interaction. Both of these mechanisms with m ≈ -35 and proton energies of 35–45 keV appear to be viable wave energy sources in the postnoon sector.Key words. Ionosphere (active experiments; wave-particle interactions) – Magnetospheric physics (MHD waves and in-stabilities).

Banded structures in electron pitch angle diffusion coefficients from resonant wave-particle interactions

2016 ◽  
Vol 23 (4) ◽  
pp. 042101 ◽  
Author(s):  
A. K. Tripathi ◽  
R. P. Singhal ◽  
G. V. Khazanov ◽  
L. A. Avanov
Keyword(s):  
Diffusion Coefficients ◽  
Pitch Angle ◽  
Particle Interactions ◽  
Resonant Wave ◽  
Wave Particle Interactions

scholarly journals Particle transport in <sup>3</Sup>He-rich events: wave-particle interactions and particle anisotropy measurements

2002 ◽  
Vol 20 (4) ◽  
pp. 427-444 ◽  
Author(s):  
B. T. Tsurutani ◽  
L. D. Zhang ◽  
G. L. Mason ◽  
G. S. Lakhina ◽  
T. Hada ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Solar Proton ◽  
Energetic Particles ◽  
Proton Event ◽  
Mhd Waves ◽  
Particle Interactions ◽  
Angle Scattering ◽  
Solar Proton Events ◽  
Wave Particle Interactions ◽  
Scattering Rates

Abstract. Energetic particles and MHD waves are studied using simultaneous ISEE-3 data to investigate particle propagation and scattering between the source near the Sun and 1 AU. 3 He-rich events are of particular interest because they are typically low intensity "scatter-free" events. The largest solar proton events are of interest because they have been postulated to generate their own waves through beam instabilities. For 3 He-rich events, simultaneous interplanetary magnetic spectra are measured. The intensity of the interplanetary "fossil" turbulence through which the particles have traversed is found to be at the "quiet" to "intermediate" level of IMF activity. Pitch angle scattering rates and the corresponding particle mean free paths lW - P are calculated using the measured wave intensities, polarizations, and k directions. The values of lW - P are found to be ~ 5 times less than the value of lHe , the latter derived from He intensity and anisotropy time profiles. It is demonstrated by computer simulation that scattering rates through a 90° pitch angle are lower than that of other pitch angles, and that this is a possible explanation for the discrepancy between the lW - P and lHe values. At this time the scattering mechanism(s) is unknown. We suggest a means where a direct comparison between the two l values could be made. Computer simulations indicate that although scattering through 90° is lower, it still occurs. Possibilities are either large pitch angle scattering through resonant interactions, or particle mirroring off of field compression regions. The largest solar proton events are analyzed to investigate the possibilities of local wave generation at 1 AU. In accordance with the results of a previous calculation (Gary et al., 1985) of beam stability, proton beams at 1 AU are found to be marginally stable. No evidence for substantial wave amplitude was found. Locally generated waves, if present, were less than 10-3 nT 2 Hz-1 at the leading proton event edge, where dispersion effects (beaming) are the greatest, and at the point of peak proton flux, where the particle energy flux is the greatest.Key words. Interplanetary physics (energetic particles; MHD waves and turbulence) – Space plasma physics (charged particle motion and acceleration; wave-particle interactions)

Stochastic pitch angle diffusion due to electron-whistler wave–particle interactions

2001 ◽  
Vol 8 (6) ◽  
pp. 2953-2962 ◽  
Author(s):  
W. J. Wykes ◽  
S. C. Chapman ◽  
G. Rowlands
Keyword(s):  
Pitch Angle ◽  
Whistler Wave ◽  
Particle Interactions ◽  
Wave Particle Interactions

scholarly journals Storm-time electron flux precipitation in the inner radiation belt caused by wave-particle interactions

2009 ◽  
Vol 27 (4) ◽  
pp. 1669-1677 ◽  
Author(s):  
H. Tadokoro ◽  
F. Tsuchiya ◽  
Y. Miyoshi ◽  
Y. Katoh ◽  
A. Morioka ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Magnetic Storms ◽  
Transport Processes ◽  
Angle Distribution ◽  
Particle Interactions ◽  
Angle Scattering ◽  
Whistler Mode Waves ◽  
Low Altitude ◽  
Wave Particle Interactions ◽  
The Waves

Abstract. It has been believed that electrons in the inner belt do not show the dynamical variation during magnetic storms except for great magnetic storms. However, Tadokoro et al. (2007) recently disclosed that low-altitude electrons in the inner belt frequently show flux variations during storms (Storm Time inner belt Electron Enhancement at the Low altitude (STEEL)). This paper investigates a possible mechanism explaining STEEL during small and moderate storms, and shows that it is caused not by radial transport processes but by pitch angle scattering through wave-particle interactions. The waves related to wave-particle interactions are attributed to be banded whistler mode waves around 30 kHz observed in the inner magnetosphere by the Akebono satellite. The estimated pitch angle distribution based on a numerical calculation is roughly consistent with the observed results.

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