Stellar winds with non-WKB Alfven waves 1: Wind models for solar coronal conditions

1994 ◽  
Vol 430 ◽  
pp. 387 ◽  
Author(s):  
K. B. MacGregor ◽  
P. Charbonneau
Keyword(s):  
Alfven Waves ◽  
Alfvén Waves ◽  
Stellar Winds ◽  
Solar Coronal

Concerning the Dynamics of Energetic Protons in Coronal Magnetic Loops: Dispersion Effects of Alfven Waves

1985 ◽  
Vol 107 ◽  
pp. 559-559
Author(s):  
V. A. Mazur ◽  
A. V. Stepanov
Keyword(s):  
Magnetic Field ◽  
Wave Dispersion ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Wave Number ◽  
Alfvén Waves ◽  
Coronal Loops ◽  
Coronal Magnetic Loops ◽  
The Magnetic Field ◽  
Solar Coronal

It is shown that the existence of plasma density inhomogeneities (ducts) elongated along the magnetic field in coronal loops, and of Alfven wave dispersion, associated with the taking into account of gyrotropy U ≡ ω/ωi ≪ 1 (Leonovich et al., 1983), leads to the possibility of a quasi-longitudinal k⊥ < √U k‖ propagation (wave guiding) of Alfven waves. Here ω is the frequency of Alfven waves, ωi is the proton gyrofrequency, and k is the wave number. It is found that with the parameter ξ = ω2 R/ωi A > 1, where R is the inhomogeneity scale of a loop across the magnetic field, and A is the Alfven wave velocity, refraction of Alfven waves does not lead, as contrasted to Wentzel's inference (1976), to the waves going out of the regime of quasi-longitudinal propagation. As the result, the amplification of Alfven waves in solar coronal loops can be important. A study is made of the cyclotron instability of Alfven waves under solar coronal conditions.

scholarly journals Concerning the Dynamics of Energetic Protons in Coronal Magnetic Loops: Dispersion Effects of Alfven Waves

1985 ◽  
Vol 107 ◽  
pp. 559-559
Author(s):  
V. A. Mazur ◽  
A. V. Stepanov
Keyword(s):  
Magnetic Field ◽  
Wave Dispersion ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Wave Number ◽  
Alfvén Waves ◽  
Coronal Loops ◽  
Coronal Magnetic Loops ◽  
The Magnetic Field ◽  
Solar Coronal

It is shown that the existence of plasma density inhomogeneities (ducts) elongated along the magnetic field in coronal loops, and of Alfven wave dispersion, associated with the taking into account of gyrotropy U ≡ ω/ωi ≪ 1 (Leonovich et al., 1983), leads to the possibility of a quasi-longitudinal k⊥ < √U k‖ propagation (wave guiding) of Alfven waves. Here ω is the frequency of Alfven waves, ωi is the proton gyrofrequency, and k is the wave number. It is found that with the parameter ξ = ω2 R/ωi A > 1, where R is the inhomogeneity scale of a loop across the magnetic field, and A is the Alfven wave velocity, refraction of Alfven waves does not lead, as contrasted to Wentzel's inference (1976), to the waves going out of the regime of quasi-longitudinal propagation. As the result, the amplification of Alfven waves in solar coronal loops can be important. A study is made of the cyclotron instability of Alfven waves under solar coronal conditions.

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.

PROTON HEATING BY NONLINEAR FIELD-ALIGNED ALFVÉN WAVES IN SOLAR CORONAL HOLES

2009 ◽  
Vol 695 (2) ◽  
pp. 1413-1420 ◽  
Author(s):  
S. A. Markovskii ◽  
Bernard J. Vasquez ◽  
Joseph V. Hollweg
Keyword(s):  
Coronal Holes ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Nonlinear Field ◽  
Solar Coronal

scholarly journals Evolution of stellar winds from the Sun to red giants

2008 ◽  
Vol 4 (S257) ◽  
pp. 589-599
Author(s):  
Takeru K. Suzuki
Keyword(s):  
Ad Hoc ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Radiative Cooling ◽  
Stellar Winds ◽  
Red Giants ◽  
The Sun ◽  
Compressive Wave ◽  
Stellar Radius ◽  
Red Giant

AbstractBy performing global 1D MHD simulations, we investigate the heating and acceleration of solar and stellar winds in open magnetic field regions. Our simulation covers from photosphere to 20-60 stellar radii, and takes into account radiative cooling and thermal conduction. We do not adopt ad hoc heating function; heating is automatically calculated from the solutions of Riemann problem at the cell boundaries. In the solar wind case we impose transverse photospheric motions with velocity ~1 km/s and period between 20 seconds and 30 minutes, which generate outgoing Alfvén waves. We have found that the dissipation of Alfvén waves through compressive wave generation by decay instability is quite effective owing to the density stratification, which leads to the sufficient heating and acceleration of the coronal plasma. Next, we study the evolution of stellar winds from main sequence to red giant phases. When the stellar radius becomes ~10 times of the Sun, the steady hot corona with temperature 106K, suddenly disappears. Instead, many hot and warm (105– 106K) bubbles are formed in cool (T< 2 × 104K) chromospheric winds because of the thermal instability of the radiative cooling function; the red giant wind is not a steady stream but structured outflow.

Non-inductive current driven by Alfvén waves in solar coronal loops

Solar Physics ◽  
1996 ◽  
Vol 167 (1-2) ◽  
pp. 203-216 ◽  
Author(s):  
A. G. Elfimov ◽  
C. A. De Azevedo ◽  
A. S. De Assis
Keyword(s):  
Alfven Waves ◽  
Alfvén Waves ◽  
Coronal Loops ◽  
Solar Coronal

Solar coronal heating by plasma waves

2009 ◽  
Vol 76 (2) ◽  
pp. 135-158 ◽  
Author(s):  
R. BINGHAM ◽  
P. K. SHUKLA ◽  
B. ELIASSON ◽  
L. STENFLO
Keyword(s):  
Collisionless Plasma ◽  
Alfven Waves ◽  
Coronal Plasma ◽  
Alfvén Waves ◽  
Lower Hybrid ◽  
Particle Interactions ◽  
Wave Particle Interactions ◽  
Turbulent Wave ◽  
Kinetic Alfvén Waves ◽  
Solar Coronal

AbstractThe solar coronal plasma is maintained at temperatures of millions of degrees, much hotter than the photosphere, which is at a temperature of just 6000 K. In this paper, the plasma particle heating based on the kinetic theory of wave–particle interactions involving kinetic Alfvén waves and lower-hybrid drift modes is presented. The solar coronal plasma is collisionless and therefore the heating must rely on turbulent wave heating models, such as lower-hybrid drift models at reconnection sites or the kinetic Alfvén waves. These turbulent wave modes are created by a variety of instabilities driven from below. The transition region at altitudes of about 2000 km is an important boundary chromosphere, since it separates the collision-dominated photosphere/chromosphere and the collisionless corona. The collisionless plasma of the corona is ideal for supporting kinetic wave–plasma interactions. Wave–particle interactions lead to anisotropic non-Maxwellian plasma distribution functions, which may be investigated by using spectral analysis procedures being developed at the present time.

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