Statistical Study of Pitch Angle Diffusion during Substorm Injections

2020 ◽  
Author(s):  
Reihaneh Ghaffari ◽  
Christopher Cully
Keyword(s):  
Pitch Angle ◽  
Energetic Electron ◽  
Loss Cone ◽  
Linear Diffusion ◽  
Whistler Mode ◽  
Wave Measurements ◽  
Whistler Mode Waves ◽  
Substorm Injection ◽  
Injection Region

<p>Energetic Electron Precipitation (EEP) associated with substorm injections typically occurs when magnetospheric waves, particularly whistler-mode waves, resonantly interact with electrons to affect their equatorial pitch angle. This can be considered as a diffusion process that scatters particles into the loss cone. In this study, we investigate whistler-mode wave generation in conjunction with electron injections using in-situ wave measurements by the Themis mission. We calculate the pitch angle diffusion coefficient exerted by the observed wave activity using the quasi-linear diffusion approximation and estimate scattering efficiency in the substorm injection region to constrain where and how much scattering happens typically during these events.</p>

scholarly journals The generation of Ganymede's diffuse aurora through pitch angle scattering

2017 ◽  
Vol 35 (2) ◽  
pp. 239-252
Author(s):  
Arvind K. Tripathi ◽  
Rajendra P. Singhal ◽  
Onkar N. Singh II
Keyword(s):  
Electron Temperature ◽  
Pitch Angle ◽  
Atomic Oxygen ◽  
Particle Interaction ◽  
Distribution Functions ◽  
Dissociative Excitation ◽  
Kappa Distribution ◽  
Loss Cone ◽  
Whistler Mode ◽  
Whistler Mode Waves

Abstract. Diffuse auroral intensities of neutral atomic oxygen OI λ1356 Å emission on Ganymede due to whistler mode waves are estimated. Pitch angle diffusion of magnetospheric electrons into the loss cone due to resonant wave–particle interaction of whistler mode waves is considered, and the resulting electron precipitation flux is calculated. The analytical yield spectrum approach is used for determining the energy deposition of electrons precipitating into the atmosphere of Ganymede. It is found that the intensities (4–30 R) calculated from the precipitation of magnetospheric electrons observed near Ganymede are inadequate to account for the observational intensities (≤ 100 R). This is in agreement with the conclusions reached in previous works. Some acceleration mechanism is required to energize the magnetospheric electrons. In the present work we consider the heating and acceleration of magnetospheric electrons by electrostatic waves. Two particle distribution functions (Maxwellian and kappa distribution) are used to simulate heating and acceleration of electrons. Precipitation of a Maxwellian distribution of electrons can produce about 70 R intensities of OI λ1356 Å emission for electron temperature of 150 eV. A kappa distribution can also yield a diffuse auroral intensity of similar magnitude for a characteristic energy of about 100 eV. The maximum contribution to the estimated intensity results from the dissociative excitation of O2. Contributions from the direct excitation of atomic oxygen and cascading in atomic oxygen are estimated to be only about 1 and 2 % of the total calculated intensity, respectively. The findings of this work are relevant for the present JUNO and future JUICE missions to Jupiter. These missions will provide new data on electron densities, electron temperature and whistler mode wave amplitudes in the magnetosphere of Jupiter near Ganymede.

scholarly journals Early-Time Non-Equilibrium Pitch Angle Diffusion of Electrons by Whistler-Mode Hiss in a Plasmaspheric Plume Associated with BARREL Precipitation

2021 ◽  
Vol 8 ◽  
Author(s):  
R. M. Millan ◽  
J.-F. Ripoll ◽  
O. Santolík ◽  
W. S. Kurth
Keyword(s):  
Phase Space ◽  
Pitch Angle ◽  
Particle Interaction ◽  
Phase Space Density ◽  
Angle Distribution ◽  
Loss Cone ◽  
Linear Diffusion ◽  
Whistler Mode ◽  
Space Density ◽  
Van Allen Probes

In August 2015, the Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) observed precipitation of energetic (<200 keV) electrons magnetically conjugate to a region of dense cold plasma as measured by the twin Van Allen Probes spacecraft. The two spacecraft passed through the high density region during multiple orbits, showing that the structure was spatial and relatively stable over many hours. The region, identified as a plasmaspheric plume, was filled with intense hiss-like plasma waves. We use a quasi-linear diffusion model to investigate plume whistler-mode hiss waves as the cause of precipitation observed by BARREL. The model input parameters are based on the observed wave, plasma and energetic particle properties obtained from Van Allen Probes. Diffusion coefficients are found to be largest in the same energy range as the precipitation observed by BARREL, indicating that the plume hiss waves were responsible for the precipitation. The event-driven pitch angle diffusion simulation is also used to investigate the evolution of the electron phase space density (PSD) for different energies and assumed initial pitch angle distributions. The results show a complex temporal evolution of the phase space density, with periods of both growth and loss. The earliest dynamics, within the ∼5 first minutes, can be controlled by a growth of the PSD near the loss cone (by a factor up to ∼2, depending on the conditions, pitch angle, and energy), favored by the absence of a gradient at the loss cone and by the gradients of the initial pitch angle distribution. Global loss by 1-3 orders of magnitude (depending on the energy) occurs within the first ∼100 min of wave-particle interaction. The prevalence of plasmaspheric plumes and detached plasma regions suggests whistler-mode hiss waves could be an important driver of electron loss even at high L-value (L ∼6), outside of the main plasmasphere.

Electron Pitch Angle Distributions in the Compressional Pc5 Waves

2021 ◽  
Author(s):  
Xiao Ma ◽  
Anmin Tian ◽  
Quanqi Shi ◽  
Shichen Bai ◽  
Ji Liu ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Interaction Effects ◽  
Plasma Pressure ◽  
Whistler Waves ◽  
Whistler Mode ◽  
Compressional Waves ◽  
The Earth ◽  
Pressure Anisotropy ◽  
Electron Distributions ◽  
Whistler Mode Waves

&lt;p&gt;In the two flanks of the Earth&amp;#8217;s magnetosphere, the compressional Pc5 waves are often observed. Previous study suggests that these waves are usually excited by plasma pressure anisotropy such as drift mirror instability. Interestingly, whistler mode waves are often observed in the magnetic trough regions of the compressional Pc5 waves. In this study, we use 10 years (2007-2016) THEMIS A data to study the electron distributions in the compressional Pc5 waves associated with the whistler mode waves. We find three typical electron pitch angle distributions (PADs) in these compressional waves: cigar-shape, donut-shape and pancake-shape. They predominantly occur at tens to hundreds eV, several keV and &gt;10 keV, respectively. The interaction effects between the electrons and whistler waves inside the magnetic troughs are stressed in understanding the formation of these PADs.&lt;/p&gt;

scholarly journals Quantification of Energetic Electron Precipitation Driven by Plume Whistler Mode Waves, Plasmaspheric Hiss, and Exohiss

2019 ◽  
Vol 46 (7) ◽  
pp. 3615-3624 ◽  
Author(s):  
W. Li ◽  
X.‐C. Shen ◽  
Q. Ma ◽  
L. Capannolo ◽  
R. Shi ◽  
...  
Keyword(s):  
Energetic Electron ◽  
Electron Precipitation ◽  
Whistler Mode ◽  
Whistler Mode Waves

scholarly journals Comparison between CNA and energetic electron precipitation: simultaneous observation by Poker Flat Imaging Riometer and NOAA satellite

2005 ◽  
Vol 23 (5) ◽  
pp. 1555-1563 ◽  
Author(s):  
Y.-M. Tanaka ◽  
M. Ishii ◽  
Y. Murayama ◽  
M. Kubota ◽  
H. Mori ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Electron Flux ◽  
Energetic Electron ◽  
Energetic Particles ◽  
Electron Precipitation ◽  
Angle Distribution ◽  
Pitch Angle Distribution ◽  
Loss Cone ◽  
Isotropic Pitch ◽  
Trapped Electron

Abstract. The cosmic noise absorption (CNA) is compared with the precipitating electron flux for 19 events observed in the morning sector, using the high-resolution data obtained during the conjugate observations with the imaging riometer at Poker Flat Research Range (PFRR; 65.11° N, 147.42° W), Alaska, and the low-altitude satellite, NOAA 12. We estimate the CNA, using the precipitating electron flux measured by NOAA 12, based on a theoretical model assuming an isotropic pitch angle distribution, and quantitatively compare them with the observed CNA. Focusing on the eight events with a range of variation larger than 0.4dB, three events show high correlation between the observed and estimated CNA (correlation coefficient (r0)>0.7) and five events show low correlation (r0<0.5). The estimated CNA is often smaller than the observed CNA (72% of all data for 19 events), which appears to be the main reason for the low-correlation events. We examine the assumption of isotropic pitch angle distribution by using the trapped electron flux measured at 80° zenith angle. It is shown that the CNA estimated from the trapped electron flux, assuming an isotropic pitch angle distribution, is highly correlated with the observed CNA and is often overestimated (87% of all data). The underestimate (overestimate) of CNA derived from the precipitating (trapped) electron flux can be interpreted in terms of the anisotropic pitch angle distribution similar to the loss cone distribution. These results indicate that the CNA observed with the riometer may be quantitatively explained with a model based on energetic electron precipitation, provided that the pitch angle distribution and the loss cone angle of the electrons are taken into account. Keywords. Energetic particles, precipitating – Energetic particles, trapped – Ionosphere-magnetosphere interactions

scholarly journals Evidence of stronger pitch angle scattering loss caused by oblique whistler-mode waves as compared with quasi-parallel waves

2014 ◽  
Vol 41 (17) ◽  
pp. 6063-6070 ◽  
Author(s):  
W. Li ◽  
D. Mourenas ◽  
A. V. Artemyev ◽  
O. V. Agapitov ◽  
J. Bortnik ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Whistler Mode ◽  
Scattering Loss ◽  
Angle Scattering ◽  
Whistler Mode Waves

Global Morphology of Lower-band Chorus Wave Intensity Reconstructed Using multi-year POES Electron Measurements

2020 ◽  
Author(s):  
Yang Zhang ◽  
Binbin Ni ◽  
Xudong Gu ◽  
Yuri Shprits ◽  
Song Fu ◽  
...  
Keyword(s):  
Radiation Belt ◽  
Wave Intensity ◽  
Global Distribution ◽  
Loss Cone ◽  
Wave Measurements ◽  
Lower Band ◽  
Chorus Waves ◽  
Radiation Belt Electrons ◽  
Chorus Wave

&lt;p&gt;&lt;span&gt;Magnetospheric chorus is known to play a significant role in the acceleration and loss of radiation belt electrons. Interactions of chorus waves with radiation belt particles are commonly evaluated using quasi-linear diffusion codes that rely on statistical models, which might not accurately provide the instantaneous global wave distribution from limited in-situ wave measurements. Thus, a novel technique capable of inferring wave amplitudes from POES particle measurements, with an extensive coverage of L-shell and magnetic local time, has been established to obtain event-specific, global dynamic evolutions of chorus waves. This study, using 5 years of POES electron data, further improves the technique, and enables us to subsequently infer the chorus wave amplitudes for all useful data points (removing the electrons which were in the drift loss cone) and to construct the global distribution of lower-band chorus wave intensity. The results obtained from the improved technique reproduce Van Allen Probes in-situ observations of chorus waves reasonably well and reconstruct the major features of the global distribution of chorus waves. We demonstrate that such a data-based, dynamic model can provide near-real-time estimates of chorus wave intensity on a global scale for any time period when POES data are available, which cannot be obtained from in-situ wave measurements by equatorial satellites alone, but is crucial for quantifying the&amp;#160; dynamics of the radiation belt electrons.&lt;/span&gt;&lt;/p&gt;

Instability of whistler-mode waves by a relativistic kappa-loss-cone distribution in space plasmas

2006 ◽  
Vol 48 (9) ◽  
pp. 1437-1445 ◽  
Author(s):  
Fuliang Xiao ◽  
Qinghua Zhou ◽  
Huiyong He ◽  
Lijun Tang
Keyword(s):  
Space Plasmas ◽  
Loss Cone ◽  
Whistler Mode ◽  
Whistler Mode Waves
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