Mode conversion and electron damping of the fast Alfvén wave in a tokamak at the ion–ion hybrid frequency

AbstractWaves propagating obliquely in a magnetized cold pair plasma experience an approximate resonance in the wavevector component perpendicular to the magnetic field, which is the analogue of the Alfvén resonance in normal electron-ion plasmas. Wave absorption at the resonance can take place via mode conversion to the analogue of the short wavelength inertial Alfvén wave. The Alfvén resonance could play a role in wave propagation in the pulsar magnetosphere leading to pulsar radio emission. Ducting of waves in strong plasma gradients may occur in the pulsar magnetosphere, which leads to the consideration of Alfvén surface waves, whose energy is concentrated in the region of strong gradients.

Download Full-text

Mode conversion and dissipation of the fast Alfvén wave in ion cyclotron heating

Physics of Fluids B Plasma Physics ◽

10.1063/1.859147 ◽

1989 ◽

Vol 1 (2) ◽

pp. 350-357 ◽

Cited By ~ 6

Author(s):

R. A. Cairns ◽

V. Fuchs

Keyword(s):

Mode Conversion ◽

Alfven Wave ◽

Ion Cyclotron

Download Full-text

Evolution of Alfvén wave-driven solar winds to red giants

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308014889 ◽

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.

Download Full-text

Resonant mode conversion of a shear Alfvén wave

Canadian Journal of Physics ◽

10.1139/p87-041 ◽

1987 ◽

Vol 65 (4) ◽

pp. 357-358

Author(s):

Bhimsen K. Shivamoggi

Keyword(s):

Solar Wind ◽

Acoustic Wave ◽

Wave Energy ◽

Mode Conversion ◽

Resonant Absorption ◽

Resonant Mode ◽

Alfven Wave ◽

Ion Acoustic Wave ◽

Ion Acoustic ◽

Kinetic Alfven Wave

A new mechanism for the resonant absorption of a shear Alfvén wave is proposed that involves a direct mode conversion of the latter to an ion-acoustic wave without bringing in the intermediary — the kinetic Alfvén wave. The fraction of the incident Alfvén-wave energy that is mode-converted to an ion-acoustic wave is calculated. This mechanism likely operates in the solar wind, where it might lead to heating of the plasma.

Download Full-text

Collisionless Damping of Fast and Ion?Cyclotron Surface Waves

Australian Journal of Physics ◽

10.1071/ph930271 ◽

1993 ◽

Vol 46 (2) ◽

pp. 271 ◽

Cited By ~ 3

Author(s):

GW Rowe

Keyword(s):

Surface Waves ◽

Short Wavelength ◽

Mode Conversion ◽

Low Frequency ◽

Wave Mode ◽

Alfven Wave ◽

Field Boundary ◽

First Order ◽

Vacuum Interface ◽

Ion Cyclotron

A recently developed general kinetic theory of surface waves is used to calculate the collisionless damping of low frequency fast and ion-cyclotron surface waves on a magnetised plasma-vacuum interface. In particular, the possibility of Cherenkov (Landau and transit-time magnetic) absorption by electrons is accounted for, assuming a bi-Maxwellian distribution of electrons in velocity space. It is shown that in general the surface waves are damped via mode conversion to a short-wavelength mode, such as the kinetic Alfven wave, which is subsequently Landau absorbed within the plasma. For high temperatures this short-wavelength mode can also be radiated into the plasma without being completely absorbed. It is also shown that the related ion-sound surface wave mode and instability identified by Alexandrov et al. (1984) are unphysical, and are the result of neglecting the gas pressure in the first-order magnetic field boundary condition.

Download Full-text

Alfvén Wave Mode Conversion in Pulsar Magnetospheres

The Astrophysical Journal ◽

10.3847/1538-4357/abd405 ◽

2021 ◽

Vol 908 (2) ◽

pp. 176

Author(s):

Yajie Yuan ◽

Yuri Levin ◽

Ashley Bransgrove ◽

Alexander Philippov

Keyword(s):

Mode Conversion ◽

Wave Mode ◽

Alfven Wave

Download Full-text

Source mechanism of Saturn narrowband emission

Annales Geophysicae ◽

10.5194/angeo-28-1013-2010 ◽

2010 ◽

Vol 28 (4) ◽

pp. 1013-1021 ◽

Cited By ~ 11

Author(s):

J. D. Menietti ◽

P. H. Yoon ◽

B. Cecconi ◽

A. M. Rymer ◽

Keyword(s):

Cyclotron Frequency ◽

Mode Conversion ◽

Source Region ◽

Source Mechanism ◽

Inner Magnetosphere ◽

Rate Analysis ◽

Source Regions ◽

Cyclotron Maser ◽

Hybrid Frequency

Abstract. Narrowband emission (NB) is observed at Saturn centered near 5 kHz and 20 kHz and harmonics. This emission appears similar in many ways to Jovian kilometric narrowband emission observed at higher frequencies, and therefore may have a similar source mechanism. Source regions of NB near 20 kHz are believed to be located near density gradients in the inner magnetosphere and the emission appears to be correlated with the occurrence of large neutral plasma clouds observed in the Saturn magnetotail. In this work we present the results of a growth rate analysis of NB emission (~20 kHz) near or within a probable source region. This is made possible by the sampling of in-situ wave and particle data. The results indicate waves are likely to be generated by the mode-conversion of directly generated Z-mode emission to O-mode near a density gradient. When the local hybrid frequency is close n fce (n is an integer and fce is the electron cyclotron frequency) with n=4, 5 or 6 in our case, electromagnetic Z-mode and weak ordinary (O-mode) emission can be directly generated by the cyclotron maser instability.

Download Full-text

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.

Download Full-text