Alfvén waves in the foreshock propagating upstream in the plasma rest frame: statistics from Cluster observations

Abstract. We statistically study various properties of low-frequency waves such as frequencies, wave numbers, phase velocities, and polarization in the plasma rest frame in the terrestrial foreshock. Using Cluster observations the wave telescope or k-filtering is applied to investigate wave numbers and rest frame frequencies. We find that most of the foreshock waves propagate upstream along the magnetic field at phase velocity close to the Alfvén velocity. We identify that frequencies are around 0.1xΩcp and wave numbers are around 0.1xΩcp/VA, where Ωcp is the proton cyclotron frequency and VA is the Alfvén velocity. Our results confirm the conclusions drawn from ISEE observations and strongly support the existence of Alfvén waves in the foreshock.

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Association of Alfvén waves and proton cyclotron waves with electrostatic bipolar pulses: magnetic hole events observed by Polar

Nonlinear Processes in Geophysics ◽

10.5194/npg-11-205-2004 ◽

2004 ◽

Vol 11 (2) ◽

pp. 205-213 ◽

Cited By ~ 6

Author(s):

G. S. Lakhina ◽

B. T. Tsurutani ◽

J. Pickett

Keyword(s):

Boundary Layer ◽

Free Energy ◽

High Frequency ◽

Low Frequency ◽

Alfven Waves ◽

Alfvén Waves ◽

Polar Cap ◽

Electron Holes ◽

Proton Cyclotron ◽

Low Frequency Waves

Abstract. Two magnetic hole events observed by Polar on 20 May 1996 when it was in the polar cap/polar cusp boundary layer are studied. Low-frequency waves, consisting of nonlinear Alfvén waves and large amplitude (±14nT peak-to-peak) obliquely propagating proton cyclotron waves (with frequency f~0.6 to 0.7 fcp), accompanied by electric bipolar pulses (electron holes) and electron heating have been observed located within magnetic holes. It is shown that low-frequency waves can provide free energy to drive some high frequency instabilities which saturate by trapping electrons, thus, leading to the generation of electron holes.

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Controlling the type and intensity of low-frequency waves generated by laser plasma clots in a force tube of magnetized plasma

Journal of Physics Conference Series ◽

10.1088/1742-6596/2067/1/012019 ◽

2021 ◽

Vol 2067 (1) ◽

pp. 012019

Author(s):

A G Berezutsky ◽

V N Tishchenko ◽

A A Chibranov ◽

I B Miroshnichenko ◽

Yu P Zakharov ◽

...

Keyword(s):

Magnetic Field ◽

Laser Plasma ◽

Low Frequency ◽

Alfven Waves ◽

Magnetized Plasma ◽

Background Plasma ◽

Alfvén Waves ◽

Whistler Waves ◽

Low Frequency Waves

Abstract In this work, we study the influence of the parameters of a magnetized background plasma on the intensity of whistler waves generated by periodic laser plasma bunches in a magnetic field tube. It is shown that at 0.3 < Lpi > 0.4 Alfvén waves and whistlers are generated. In the region Lpi> 0.5, intense whistlers with an amplitude of δBmax / B0 ∼ 0.24 are generated.

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The parametric excitation of kinetic Alfvén waves by a magnetic pump

Journal of Plasma Physics ◽

10.1017/s0022377800010667 ◽

1981 ◽

Vol 26 (2) ◽

pp. 253-266 ◽

Cited By ~ 3

Author(s):

N. F. Cramer ◽

I. J. Donnelly

Keyword(s):

Finite Temperature ◽

Acoustic Waves ◽

Temperature Effects ◽

Mode Conversion ◽

Low Frequency ◽

Alfven Waves ◽

Alfven Wave ◽

Alfvén Waves ◽

Ion Acoustic Wave ◽

Low Frequency Waves

The parametric decay of a magneto-acoustic pump wave into low-frequency waves modified by finite temperature effects is considered. The excited waves are the kinetic Alfvén wave and the ion-acoustic wave. The former wave plays an important role in linear heating schemes employing the mode conversion of magneto-acoustic waves at the Alfvén resonance. Here we calculate the parametric growth rates and pump thresholds for excitation of these waves. The main result is that finite temperature effects tend to reduce the growth rate of Alfvén waves.

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Penetration to the Earth's surface of standing Alfvén waves excited by external currents in the ionosphere

Annales Geophysicae ◽

10.1007/s00585-996-0545-1 ◽

1996 ◽

Vol 14 (5) ◽

pp. 545-556 ◽

Cited By ~ 13

Author(s):

A. S. Leonovich ◽

V. A. Mazur

Keyword(s):

Spatial Structure ◽

Boundary Conditions ◽

Geomagnetic Field ◽

Alfven Waves ◽

Conductivity Tensor ◽

Alfvén Waves ◽

Wave Numbers ◽

Electromagnetic Oscillations ◽

Field Lines ◽

Alfven Velocity

Abstract. The problem of boundary conditions for monochromatic Alfvén waves, excited in the magnetosphere by external currents in the ionospheric E-layer, is solved analytically. Waves with large azimuthal wave numbers m»1 are considered. In our calculations, we used a model for the horizontally homogeneous ionosphere with an arbitrary inclination of geomagnetic field lines and a realistic height disribution of Alfvén velocity and conductivity tensor components. A relationship between such Alfvén waves on the upper ionospheric boundary with electromagnetic oscillations on the ground was detected, and the spatial structure of these oscillations determined.

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Low-frequency waves in inhomogeneous magnetic fields

Journal of Plasma Physics ◽

10.1017/s002237780002184x ◽

1979 ◽

Vol 21 (2) ◽

pp. 279-286 ◽

Cited By ~ 2

Author(s):

A. Hruška

Keyword(s):

Low Frequency ◽

Sound Waves ◽

Isotropic Plasma ◽

Phase Velocities ◽

Magnetic Field Topology ◽

Hot Plasma ◽

Propagation Of Waves ◽

The Magnetic Field ◽

Low Frequency Waves ◽

Scale Length

Propagation of waves in inhomogeneous, hot, isotropic plasma is described, assuming that the wavelength is much smaller than the scale-length of the plasma. The effect of the magnetic field topology on properties of waves is discussed in some detail. Coupling between the modes of oscillations is always present in an inhomogeneous ‘hot’ plasma. It is particularly strong for magneto- dynamic and sound waves propagating essentially along the fleidlines in the vicinity of a point where the phase velocities of the two modes are equal.

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Analysis of The Phase Velocities of (Pure, Slow And Fast ) Alfvèn Waves In The E Region of The Ionosphere For Low Latitudes

10.21203/rs.3.rs-1213915/v1 ◽

2022 ◽

Author(s):

kadri kurt

Keyword(s):

Magnetic Field ◽

Field Vector ◽

Alfven Waves ◽

Alfvén Waves ◽

Phase Velocities ◽

Propagation Vector ◽

Low Latitudes ◽

E Region ◽

Dip Angle ◽

The Magnetic Field

Abstract In this paper, (pure, slow, and fast) Alfvèn waves for the accepted conditions in Northern-hemisphere at E-region of ionospheric plasma were calculated with low latitudes by using Eq. (20,25-26) and the real geometry of Earth’s magnetic field, at hours 12.00 LT for the 1990 year which sunspot is maximum. One of the most important results of this study is to show analytically that the “MHD modes= (pure, slow and fast) Alfvèn waves” depend not only on the angle between the wave propagation vector (k) and the magnetic field (B) but also on the declination (D=It is the angle value between the direction of the sun's rays and the equatorial plane) and magnetic dip angle (I=It is the angle between real north and magnetic north). From the results obtained, the behavior of the magnitudes of the squares of the phase velocities of all MHD modes is consistent with the behavior of the distribution of electron density with low geographic latitude, even if the magnetic field vector is both perpendicular and parallel to the propagation vector of the wave. In parallel, the phase velocities of the waves are greater in summer than in winter. It has been determined that the propagation velocities of the fast and slow MHD mode in the magnetic equatorial trough region at (q = I) are very small, the energy is almost non-existent, but if q = 90 + I, the energy increases with latitude and is approximately maximum at the low latitude limit. It can be said that the minimum points are between 0-10 oN latitudes where the wave energies are the smallest, and the maximum points are between 20-30 oN latitudes the wave energies are the biggest.

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PEMANFAATAN RADIASI ENERGI TEGANGAN 150 KV UNTUK LAMPU LED PENERANGAN JALAN

Jurnal Teknik ◽

10.31000/jt.v7i1.936 ◽

2018 ◽

Vol 7 (1) ◽

Author(s):

Mauludi Manfaluthy

Keyword(s):

Magnetic Field ◽

Electric Field ◽

High Voltage ◽

Low Frequency ◽

Energy Utilization ◽

World Health ◽

Electromagnetic Signals ◽

Health Organization ◽

The Magnetic Field ◽

Low Frequency Waves

WHO (World Health Organization) concludes that not much effect is caused by electric field up to 20 kV / m in humans. WHO standard also mentions that humans will not be affected by the magnetic field under 100 micro tesla and that the electric field will affect the human body with a maximum standard of 5,000 volts per meter. In this study did not discuss about the effect of high voltage radiation SUTT (High Voltage Air Channel) with human health. The research will focus on energy utilization of SUTT radiation. The combination of electric field and magnetic field on SUTT (70-150KV) can generate electromagnetic (EM) and radiation waves, which are expected to be converted to turn on street lights around the location of high voltage areas or into other forms. The design of this prototype works like an antenna in general that captures electromagnetic signals and converts them into AC waves. With a capacitor that can store the potential energy of AC and Schottky diode waves created specifically for low frequency waves, make the current into one direction (DC). From the research results obtained the current generated from the radiation is very small even though the voltage is big enough.Keywords : Radiance Energy, Joule Thief, and LED Module.

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Integral Equations for Problems on Wave Propagation in Near-Earth Plasma

Symmetry ◽

10.3390/sym13081395 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1395

Author(s):

Danila Kostarev ◽

Dmitri Klimushkin ◽

Pavel Mager

Keyword(s):

Magnetic Field ◽

Integral Equations ◽

Field Potential ◽

Low Frequency ◽

Fredholm Equation ◽

Compression Waves ◽

Parallel Component ◽

Electric Field Potential ◽

The Magnetic Field ◽

Low Frequency Waves

We consider the solutions of two integrodifferential equations in this work. These equations describe the ultra-low frequency waves in the dipol-like model of the magnetosphere in the gyrokinetic framework. The first one is reduced to the homogeneous, second kind Fredholm equation. This equation describes the structure of the parallel component of the magnetic field of drift-compression waves along the Earth’s magnetic field. The second equation is reduced to the inhomogeneous, second kind Fredholm equation. This equation describes the field-aligned structure of the parallel electric field potential of Alfvén waves. Both integral equations are solved numerically.

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Ion flow driven by low frequency Alfvén waves in a low-beta plasma

Physics of Plasmas ◽

10.1063/5.0021310 ◽

2021 ◽

Vol 28 (2) ◽

pp. 022903

Author(s):

X. Q. Lu ◽

L. M. Yu ◽

W. Guo ◽

K. H. Li

Keyword(s):

Low Frequency ◽

Alfven Waves ◽

Alfvén Waves ◽

Ion Flow

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Nonlinear Alfvén waves, discontinuities, proton perpendicular acceleration, and magnetic holes/decreases in interplanetary space and the magnetosphere: intermediate shocks?

Nonlinear Processes in Geophysics ◽

10.5194/npg-12-321-2005 ◽

2005 ◽

Vol 12 (3) ◽

pp. 321-336 ◽

Cited By ~ 64

Author(s):

B. T. Tsurutani ◽

G. S. Lakhina ◽

J. S. Pickett ◽

F. L. Guarnieri ◽

N. Lin ◽

...

Keyword(s):

Interplanetary Space ◽

Alfven Waves ◽

Alfven Wave ◽

Alfvén Waves ◽

Reverse Shock ◽

Propagating Waves ◽

Mirror Mode ◽

Interaction Regions ◽

Electron Holes ◽

Proton Cyclotron

Abstract. Alfvén waves, discontinuities, proton perpendicular acceleration and magnetic decreases (MDs) in interplanetary space are shown to be interrelated. Discontinuities are the phase-steepened edges of Alfvén waves. Magnetic decreases are caused by a diamagnetic effect from perpendicularly accelerated (to the magnetic field) protons. The ion acceleration is associated with the dissipation of phase-steepened Alfvén waves, presumably through the Ponderomotive Force. Proton perpendicular heating, through instabilities, lead to the generation of both proton cyclotron waves and mirror mode structures. Electromagnetic and electrostatic electron waves are detected as well. The Alfvén waves are thus found to be both dispersive and dissipative, conditions indicting that they may be intermediate shocks. The resultant "turbulence" created by the Alfvén wave dissipation is quite complex. There are both propagating (waves) and nonpropagating (mirror mode structures and MDs) byproducts. Arguments are presented to indicate that similar processes associated with Alfvén waves are occurring in the magnetosphere. In the magnetosphere, the "turbulence" is even further complicated by the damping of obliquely propagating proton cyclotron waves and the formation of electron holes, a form of solitary waves. Interplanetary Alfvén waves are shown to rapidly phase-steepen at a distance of 1AU from the Sun. A steepening rate of ~35 times per wavelength is indicated by Cluster-ACE measurements. Interplanetary (reverse) shock compression of Alfvén waves is noted to cause the rapid formation of MDs on the sunward side of corotating interaction regions (CIRs). Although much has been learned about the Alfvén wave phase-steepening processfrom space plasma observations, many facets are still not understood. Several of these topics are discussed for the interested researcher. Computer simulations and theoretical developments will be particularly useful in making further progress in this exciting new area.

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