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

2008 ◽  
Vol 26 (6) ◽  
pp. 1605-1615 ◽  
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.

scholarly journals LHR effects in nonducted whistler propagation – new observations and numerical modelling

2001 ◽  
Vol 19 (2) ◽  
pp. 147-157 ◽  
Author(s):  
F. Jiřiček ◽  
D. R. Shklyar ◽  
P. Třiska
Keyword(s):  
Wave Propagation ◽  
Numerical Modelling ◽  
Plasma Frequency ◽  
Cutoff Frequency ◽  
Lower Hybrid ◽  
Noise Band ◽  
Maximum Value ◽  
Lower Hybrid Resonance ◽  
Whistler Propagation ◽  
Lower Cutoff

Abstract. VLF-ELF broadband measurements onboard the MAGION 4 and 5 satellites at heights above 1 Re in plasmasphere provide new data on various known phenomena related to ducted and nonducted whistler wave propagation. Two examples are discussed: magnetospherically reflected (MR) whistlers and lower hybrid resonance (LHR) noise band. We present examples of rather complicated MR whistler spectrograms not reported previously and argue the conditions for their generation. Analytical consideration, together with numerical modelling, yield understanding of the main features of those spectrograms. LHR noise band, as well as MR whistlers, is a phenomenon whose source is the energy propagating in the nonducted way. At the plasmaspheric heights, where hydrogen (H+) is the prevailing ion, and electron plasma frequency is much larger than gyrofrequency, the LHR frequency is close to its maximumvalue in a given magnetic field. This frequency is well followed by the observed noise bands. The lower cutoff frequency of this band is somewhat below that maximum value. The reason for this, as well as the possibility of using the LHR noise bands for locating the plasma through position, are discussed.Key words. Magnetospheric physics (plasmasphere; wave propagation)

scholarly journals Ray tracing of whistler-mode chorus elements: implications for generation mechanisms of rising and falling tone emissions

2013 ◽  
Vol 31 (4) ◽  
pp. 665-673 ◽  
Author(s):  
K. Yamaguchi ◽  
T. Matsumuro ◽  
Y. Omura ◽  
D. Nunn
Keyword(s):  
Ray Tracing ◽  
Low Frequency ◽  
Equatorial Region ◽  
Lower Hybrid ◽  
Wave Pulse ◽  
Generation Region ◽  
Field Lines ◽  
Generation Mechanisms ◽  
Tone Generation ◽  
Lower Hybrid Resonance

Abstract. Using a well-established magnetospheric very-low-frequency (VLF) ray tracing method, in this work we trace the propagation of individual rising- and falling-frequency elements of VLF chorus from their generation point in the equatorial region of the magnetosphere through to at least one reflection at the lower-hybrid resonance point. Unlike recent work by Bortnik and co-workers, whose emphasis was on demonstrating that magnetospheric hiss has its origins in chorus, we here track the motion in the equatorial plane of the whole chorus element, paying particular regard to movement across field lines, rotation, and compression or expansion of the wave pulse. With a generation point for rising chorus at the equator, it was found the element wave pulse remained largely field aligned in the generation region. However, for a falling tone generation point at 4000 km upstream from the equator, by the time the pulse crosses the equator the wavefield had substantial obliquity, displacement, and compression, which has substantial implications for the theory of falling chorus generation.

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

2021 ◽  
Vol 923 (2) ◽  
pp. 216
Author(s):  
S. T. Yao ◽  
Q. Q. Shi ◽  
Q. G. Zong ◽  
A. W. Degeling ◽  
R. L. Guo ◽  
...  
Keyword(s):  
Solar Wind ◽  
Electromagnetic Fields ◽  
Low Frequency ◽  
Space Physics ◽  
Lower Hybrid ◽  
High Temporal Resolution ◽  
Modulation Amplitude ◽  
Whistler Waves ◽  
Direction Parallel ◽  
Background Magnetic Field

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.

Current-driven drift wave instability in a collisional dusty negative ion plasma

2013 ◽  
Vol 79 (6) ◽  
pp. 1113-1116 ◽  
Author(s):  
M. ROSENBERG
Keyword(s):  
Negative Ions ◽  
Negative Ion ◽  
Drift Waves ◽  
Charged Dust ◽  
Wave Instability ◽  
Nonuniform Plasma ◽  
Positive Ions ◽  
Ion Plasma ◽  
The Magnetic Field ◽  
Linear Kinetic Theory

AbstractThe excitation of drift waves by an electron current parallel to the magnetic field is investigated in a nonuniform plasma composed of electrons, positive ions, negative ions, and massive, negatively charged dust. Electrostatic drift waves with frequencies smaller than the ion gyrofrequencies and wavelengths larger than the ion gyroradii are considered. Linear kinetic theory is used, and collisions of charged particles with neutrals are taken into account. The present results may be relevant to laboratory collisional magnetoplasmas containing negative ions and dust.

Low-frequency electrostatic waves in a magnetized, current-free, heavy negative ion plasma

2013 ◽  
Vol 79 (6) ◽  
pp. 1107-1111 ◽  
Author(s):  
S. H. KIM ◽  
R. L. MERLINO ◽  
J. K. MEYER ◽  
M. ROSENBERG
Keyword(s):  
Large Fraction ◽  
Low Frequency ◽  
Negative Ions ◽  
Wave Mode ◽  
Negative Ion ◽  
Electrostatic Wave ◽  
Electrostatic Waves ◽  
Positive Ions ◽  
Ion Plasma ◽  
The Waves

AbstractWe report experimental observations of a low-frequency (≪ ion gyrofrequency) electrostatic wave mode in a magnetized cylindrical (Q machine) plasma containing positive ions, very few electrons and a relatively large fraction (n−/ne > 103) of heavy negative ions (m−/m+ ≈ 10), and no magnetic field-aligned current. The waves propagate nearly perpendicular to B with a multiharmonic spectrum. The maximum wave amplitude coincided spatially with the region of largest density gradient suggesting that the waves were excited by a drift instability in a nearly electron-free positive ion–negative ion plasma

Modified electron whistler dispersion law

2002 ◽  
Vol 67 (2-3) ◽  
pp. 149-161 ◽  
Author(s):  
B. V. LUNDIN ◽  
C. KRAFFT
Keyword(s):  
Cold Plasma ◽  
Wave Dispersion ◽  
Plasma Electron ◽  
Lower Hybrid ◽  
Analytical Treatment ◽  
Dispersion Law ◽  
Wide Range ◽  
Lightning Discharges ◽  
Ray Trajectories ◽  
Dynamical Spectra

A modified electron whistler dispersion law is derived in the cold-plasma approximation for analytical treatment and simplified numerical calculations of wave propagation in a wide range of ratios ωc/ωp of electron gyro- to plasma frequencies if the wave frequency is much less than ωp. The net contribution of ions to the wave dispersion law is expressed through the value of the lower-hybrid resonance frequency ωlhr only. This approximate dispersion law is valid in a wide frequency domain, that is, from the range of ωlhr until the domain where the contribution of ions can be neglected. A comparison of geometrical-optics ray trajectories calculated by the use of modified and total cold-plasma electron whistler dispersion laws is presented for the case of the Earth's plasma environment. Computer simulations of dynamical spectra of whistler waves excited by lightning discharges and registered in remote regions of the Earth's plasmasphere reveal good numerical stability of the developed ray-tracing code.

scholarly journals Electromagnetic waves and bursty electron acceleration: implications from Freja

2002 ◽  
Vol 20 (2) ◽  
pp. 139-150 ◽  
Author(s):  
L. Andersson ◽  
J.-E. Wahlund ◽  
J. Clemmons ◽  
B. Gustavsson ◽  
L. Eliasson
Keyword(s):  
Electromagnetic Waves ◽  
Large Scale ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
Correlation Study ◽  
Auroral Oval ◽  
Alfven Wave ◽  
Lower Hybrid ◽  
Field Aligned Current ◽  
Langmuir Probe Measurements

Abstract. Dispersive Alfvén wave activity is identified in four dayside auroral oval events measured by the Freja satellite. The events are characterized by ion injection, bursty electron precipitation below about 1 keV, transverse ion heating and broadband extremely low frequency (ELF) emissions below the lower hybrid cutoff frequency (a few kHz). Large-scale density depletions/cavities, as determined by the Langmuir probe measurements, and strong electrostatic emissions are often observed simultaneously. A correlation study has been carried out between the E and B field fluctuations below 64 Hz and 10 Hz, respectively, (the DC instruments upper threshold) and the characteristics of the precipitating electrons. This study revealed that the energisation of electrons is indeed related to the broadband ELF emissions and that the electrostatic component plays a predominant role during very active magnetospheric conditions. Furthermore, the effect of the ELF electromagnetic emissions on the larger scale field-aligned current systems has been investigated, and it is found that such an effect cannot be detected. Instead, the Alfvénic activity creates a local region of field-aligned currents. It is suggested that dispersive Alfvén waves set up these local field-aligned current regions and, in turn, trigger more electrostatic emissions during certain conditions. In these regions, ions are transversely heated, and large-scale density depletions/cavities may be created during especially active periods.Key words. Ionosphere (particle acceleraton; wave-particle interactions) Magnetospheric physics (auroral phenomena)

scholarly journals Low-frequency electrostatic wave in a metallic electron-hole-ion plasma with nanoparticles

2009 ◽  
Vol 75 (5) ◽  
pp. 581-585
Author(s):  
P. K. SHUKLA ◽  
G. E. MORFILL
Keyword(s):  
Metallic Nanoparticles ◽  
Low Frequency ◽  
Dispersion Property ◽  
Charged Dust ◽  
Number Density ◽  
Electron Hole ◽  
Electrostatic Wave ◽  
Quantum Hydrodynamic Model ◽  
Ion Plasma ◽  
Density Perturbations

AbstractWe investigate the dispersion property of a low-frequency electrostatic wave in a dense metallic electron-hole-ion plasma with nanoparticles. The latter are charged due to the field emission, and hence the metallic nanoparticles/nanotubes can be regarded as charged dust rods surrounded by degenerate electrons and holes, and non-degenerate ions. By using a quantum hydrodynamic model for the electrons and holes, we obtain the electron and hole number density perturbations, while the ion and dust rod number density perturbations follow the classical expressions. A dispersion relation for the low-frequency electrostatic wave in our multi-species dense metallic plasma is derived and analyzed. The possibility of exciting non-thermal electrostatic waves is also discussed.

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