Lag-correlated rising tones of electron cyclotron harmonic and whistler-mode upper-band chorus waves

2021 ◽  
Author(s):  
Zhonglei Gao
Keyword(s):  
Electron Cyclotron ◽  
Hot Electrons ◽  
Time Lags ◽  
Discrete Elements ◽  
Loss Cone ◽  
Whistler Mode ◽  
Chorus Waves ◽  
Van Allen Probes ◽  
Gain Energy ◽  
Cyclotron Harmonic

<p>Electron cyclotron harmonic (ECH) and whistler-mode chorus waves can contribute significantly to the magnetospheric dynamics. In the frequency-time spectrogram, ECH usually appears as a series of harmonic structureless bands, while chorus often exhibits successive discrete elements. Here, we present surprising observations by Van Allen Probes of lag-correlated rising tones of ECH and upper-band chorus waves. The time lags of ECH elements with respect to chorus elements range from 0.05 to 0.28 s, negatively correlated with the chorus peak amplitudes. The ECH elements seemingly emerge only when the chorus elements are sufficiently intense (peak amplitude >3 mV/m), and their peak amplitudes are positively correlated. Our data and modeling suggest that upper-band chorus may promote the generation of ECH through rapidly precipitating the ~keV electrons near the loss cone. This phenomenon implies that ECH and chorus may not grow independently but competitively or collaboratively gain energy from hot electrons.</p>

Lag-correlated rising tones of electron cyclotron harmonic and whistler-mode upper-band chorus waves

2020 ◽  
Vol 27 (6) ◽  
pp. 062903
Author(s):  
Zhonglei Gao ◽  
Xiongjun Shang ◽  
Pingbing Zuo ◽  
Zhengyang Zou ◽  
Geng Wang ◽  
...  
Keyword(s):  
Electron Cyclotron ◽  
Whistler Mode ◽  
Chorus Waves ◽  
Cyclotron Harmonic

scholarly journals Nonlinear Coupling Between Whistler‐Mode Chorus and Electron Cyclotron Harmonic Waves in the Magnetosphere

2018 ◽  
Vol 45 (23) ◽  
Author(s):  
Zhonglei Gao ◽  
Zhenpeng Su ◽  
Fuliang Xiao ◽  
Danny Summers ◽  
Nigang Liu ◽  
...  
Keyword(s):  
Electron Cyclotron ◽  
Harmonic Waves ◽  
Nonlinear Coupling ◽  
Whistler Mode ◽  
Cyclotron Harmonic

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-cyclotron maser theory for extraordinary Bernstein waves

1997 ◽  
Vol 58 (1) ◽  
pp. 171-191 ◽  
Author(s):  
A. J. WILLES ◽  
P. A. ROBINSON
Keyword(s):  
Electron Distribution ◽  
Electron Cyclotron ◽  
Loss Cone ◽  
Wave Growth ◽  
Electron Cyclotron Maser ◽  
Cyclotron Maser ◽  
Hybrid Frequency ◽  
Bernstein Waves ◽  
Bernstein Wave ◽  
Cyclotron Harmonic

Electron-cyclotron maser emission is investigated in the regime where wave growth in the electrostatic Bernstein modes dominates (ωp/Ωe>1.5). A semirelativistic growth rate is derived assuming that the wave dispersion is dominated by a cool background electron distribution and the instability is driven by a low-density hot loss-cone-like electron distribution. The properties of Bernstein wave growth are most strongly dependent on the relative temperatures of the hot and cool electron distributions. For Thot/Tcool[gsim ]10, the fastest growing Bernstein waves are produced at frequencies just below each cyclotron harmonic in Bernstein modes lying below the upper-hybrid frequency. For Thot/Tcool[lsim ]10, additional Bernstein modes above the upper-hybrid frequency are excited, with wave frequencies in each excited mode lying significantly above the corresponding cyclotron harmonic. The dependence of Bernstein wave growth on the relative hot and cool electron number densities and emission angle is also discussed.

scholarly journals Electron Cyclotron Harmonic Wave Instability by Loss Cone Distribution

2018 ◽  
Vol 123 (11) ◽  
pp. 9035-9044 ◽  
Author(s):  
Xu Liu ◽  
Lunjin Chen ◽  
Wenyao Gu ◽  
Xiao‐Jia Zhang
Keyword(s):  
Harmonic Wave ◽  
Electron Cyclotron ◽  
Wave Instability ◽  
Loss Cone ◽  
Cyclotron Harmonic

scholarly journals Particle‐in‐Cell Simulation of Electron Cyclotron Harmonic Waves Driven by a Loss Cone Distribution

2020 ◽  
Vol 47 (9) ◽  
Author(s):  
Yifan Wu ◽  
Xin Tao ◽  
Xu Liu ◽  
Lunjin Chen ◽  
Huasheng Xie ◽  
...  
Keyword(s):  
Electron Cyclotron ◽  
Harmonic Waves ◽  
Loss Cone ◽  
Particle In Cell ◽  
Cell Simulation ◽  
Cyclotron Harmonic

scholarly journals Penetration of MeV electrons into the mesosphere accompanying pulsating aurorae

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Y. Miyoshi ◽  
K. Hosokawa ◽  
S. Kurita ◽  
S.-I. Oyama ◽  
Y. Ogawa ◽  
...  
Keyword(s):  
High Energy ◽  
Daily Basis ◽  
Maximum Energy ◽  
Energy Electron ◽  
High Energy Electron ◽  
Whistler Mode ◽  
Chorus Waves ◽  
Mesospheric Ozone ◽  
Field Lines ◽  
Eiscat Radar

AbstractPulsating aurorae (PsA) are caused by the intermittent precipitations of magnetospheric electrons (energies of a few keV to a few tens of keV) through wave-particle interactions, thereby depositing most of their energy at altitudes ~ 100 km. However, the maximum energy of precipitated electrons and its impacts on the atmosphere are unknown. Herein, we report unique observations by the European Incoherent Scatter (EISCAT) radar showing electron precipitations ranging from a few hundred keV to a few MeV during a PsA associated with a weak geomagnetic storm. Simultaneously, the Arase spacecraft has observed intense whistler-mode chorus waves at the conjugate location along magnetic field lines. A computer simulation based on the EISCAT observations shows immediate catalytic ozone depletion at the mesospheric altitudes. Since PsA occurs frequently, often in daily basis, and extends its impact over large MLT areas, we anticipate that the PsA possesses a significant forcing to the mesospheric ozone chemistry in high latitudes through high energy electron precipitations. Therefore, the generation of PsA results in the depletion of mesospheric ozone through high-energy electron precipitations caused by whistler-mode chorus waves, which are similar to the well-known effect due to solar energetic protons triggered by solar flares.

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