The parametric excitation of kinetic Alfvén waves by a magnetic pump

1981 ◽  
Vol 26 (2) ◽  
pp. 253-266 ◽  
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.

Resonant four-wave mixing of finite-amplitude Alfvén waves

1996 ◽  
Vol 55 (2) ◽  
pp. 173-180 ◽  
Author(s):  
S. Rauf ◽  
J. A. Tataronis
Keyword(s):  
Evolution Equations ◽  
Low Frequency ◽  
Four Wave Mixing ◽  
Finite Amplitude ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Wave Mixing ◽  
Derivative Nonlinear Schrödinger Equation ◽  
Pump Waves

Using the derivative nonlinear SchrÖdinger equation, resonant four-wave mixing of finite-amplitude Alfvén waves is explored in this paper. The evolution equations governing the amplitudes of the interacting waves and the conservation relations ale derived from the basic equation. These evolution equations are used to study parametric amplification and oscillation of two small-amplitude Alfvén waves due to two large-amplitude pump (Alfvén) waves. It is also shown that three pump waves can mix together to generate a low-frequency Alfven wave in a dissipative plasma.

scholarly journals Evolution of Alfvén wave-driven solar winds to red giants

2007 ◽  
Vol 3 (S247) ◽  
pp. 201-207
Author(s):  
Takeru K. Suzuki
Keyword(s):  
Solar Wind ◽  
Mode Conversion ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Stellar Winds ◽  
Red Giants ◽  
Giant Stars ◽  
Solar Winds ◽  
Red Giant

AbstractIn this talk we introduce our recent results of global 1D MHD simulations for the acceleration of solar and stellar winds. We impose transverse photospheric motions corresponding to the granulations, which generate outgoing Alfvén waves. The Alfvén waves effectively dissipate by 3-wave coupling and direct mode conversion to compressive waves in density-stratified atmosphere. We show that the coronal heating and the solar wind acceleration in the open magnetic field regions are natural consequence of the footpoint fluctuations of the magnetic fields at the surface (photosphere). We also discuss winds from red giant stars driven by Alfvén waves, focusing on different aspects from the solar wind. We show that red giants wind are highly structured with intermittent magnetized hot bubbles embedded in cool chromospheric material.

Stabilization of collisional drift waves by kinetic Alfvén waves

1992 ◽  
Vol 47 (2) ◽  
pp. 249-260
Author(s):  
C. Kar ◽  
S. K. Majumdar ◽  
A. N. Sekar Iyengar
Keyword(s):  
Mode Coupling ◽  
Ponderomotive Force ◽  
Low Frequency ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Drift Waves ◽  
Coupling Mechanism ◽  
Plasma Parameters ◽  
Kinetic Alfvén Waves

We have investigated a mode-coupling mechanism between kinetic Alfvén waves and a collisional drift wave in an inhomogeneous cylindrical plasma. Drift waves satisfying the condition k⊥D > 1/r0 (where r0 is the radius of the plasma cylinder) are stabilized by the low-frequency ponderomotive force generated by the kinetic Alfvén waves. For typical plasma parameters and a moderate level of Alfven-wave intensity the stabilization factor is comparable to the destabilization mechanism due to collisions.

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

2004 ◽  
Vol 22 (7) ◽  
pp. 2315-2323 ◽  
Author(s):  
Y. Narita ◽  
K.-H. Glassmeier ◽  
S. Schäfer ◽  
U. Motschmann ◽  
M. Fränz ◽  
...  
Keyword(s):  
Rest Frame ◽  
Low Frequency ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Phase Velocities ◽  
Wave Numbers ◽  
The Magnetic Field ◽  
Proton Cyclotron ◽  
Low Frequency Waves ◽  
Alfven Velocity

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.

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

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.

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

2004 ◽  
Vol 11 (2) ◽  
pp. 205-213 ◽  
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.

scholarly journals Generation of resonant Alfvén waves in the auroral oval

2016 ◽  
Vol 34 (2) ◽  
pp. 241-248 ◽  
Author(s):  
V. A. Pilipenko ◽  
D. Yu. Klimushkin ◽  
P. N. Mager ◽  
M. J. Engebretson ◽  
O. V. Kozyreva
Keyword(s):  
Field Line ◽  
Low Frequency ◽  
Auroral Oval ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Simple Explanation ◽  
Independent Observations ◽  
External Sources ◽  
Magnetic Shell

Abstract. Many independent observations have shown that resonant field line Pc5 pulsations (typical periods of about several minutes) are preferably excited inside the auroral oval. Consideration of the most evident interpretation schemes shows that there is no simple explanation of this effect. Here we consider theoretically the generation of toroidal Pc5 Alfvén waves by fluctuating magnetospheric field-aligned currents. It is shown that the Alfvén wave latitudinal structure has the same features as in the case of the classical field line resonance driven by external sources: a peak localized in latitude and a 180° phase shift across the resonant magnetic shell. This model suggests an additional mechanism of ultra-low-frequency (ULF) wave excitation which can operate at auroral latitudes.

scholarly journals Observational study of generation conditions of substorm-associated low-frequency AKR emissions

2004 ◽  
Vol 22 (10) ◽  
pp. 3571-3582 ◽  
Author(s):  
A. Olsson ◽  
P. Janhunen ◽  
J. Hanasz ◽  
M. Mogilevsky ◽  
S. Perraut ◽  
...  
Keyword(s):  
Extrasolar Planets ◽  
Source Region ◽  
Low Frequency ◽  
Radial Distance ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Frequency Wave ◽  
Inertial Alfvén Waves ◽  
Generation Mechanisms

Abstract. It has lately been shown that low-frequency bursts of auroral kilometric radiation (AKR) are nearly exclusively associated with substorm expansion phases. Here we study low-frequency AKR using Polar PWI and Interball POLRAD instruments to constrain its possible generation mechanisms. We find that there are more low-frequency AKR emission events during wintertime and equinoxes than during summertime. The dot-AKR emission radial distance range coincides well with the region where the deepest density cavities are seen statistically during Kp>2. We suggest that the dot-AKR emissions originate in the deepest density cavities during substorm onsets. The mechanism for generating dot-AKR is possibly strong Alfvén waves entering the cavity from the magnetosphere and changing their character to more inertial, which causes the Alfvén wave associated parallel electric field to increase. This field may locally accelerate electrons inside the cavity enough to produce low-frequency AKR emission. We use Interball IESP low-frequency wave data to verify that in about half of the cases the dot-AKR is accompanied by low-frequency wave activity containing a magnetic component, i.e. probably inertial Alfvén waves. Because of the observational geometry, this result is consistent with the idea that inertial Alfvén waves might always be present in the source region when dot-AKR is generated. The paper illustrates once more the importance of radio emissions as a powerful remote diagnostic tool of auroral processes, which is not only relevant for the Earth's magnetosphere but may be relevant in the future in studying extrasolar planets.

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