Nonlinear evolution of dispersive Alfvén waves and the effect of magnetic islands in the solar wind plasmas

2020 ◽  
Vol 27 (7) ◽  
pp. 072903
Author(s):  
Swati Sharma ◽  
R. P. Sharma ◽  
M. K. Mishra ◽  
R. Uma
Keyword(s):  
Solar Wind ◽  
Nonlinear Evolution ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Magnetic Islands

scholarly journals Parametric instability, inverse cascade and the  range of solar-wind turbulence

2018 ◽  
Vol 84 (1) ◽  
Author(s):  
Benjamin D. G. Chandran
Keyword(s):  
Solar Wind ◽  
Nonlinear Evolution ◽  
Parametric Instability ◽  
Alfven Waves ◽  
Turbulence Theory ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Fast Solar Wind ◽  
Parametric Decay ◽  
Inverse Cascade

In this paper, weak-turbulence theory is used to investigate the nonlinear evolution of the parametric instability in three-dimensional low-$\unicode[STIX]{x1D6FD}$ plasmas at wavelengths much greater than the ion inertial length under the assumption that slow magnetosonic waves are strongly damped. It is shown analytically that the parametric instability leads to an inverse cascade of Alfvén wave quanta, and several exact solutions to the wave kinetic equations are presented. The main results of the paper concern the parametric decay of Alfvén waves that initially satisfy $e^{+}\gg e^{-}$, where $e^{+}$ and $e^{-}$ are the frequency ($f$) spectra of Alfvén waves propagating in opposite directions along the magnetic field lines. If $e^{+}$ initially has a peak frequency $f_{0}$ (at which $fe^{+}$ is maximized) and an ‘infrared’ scaling $f^{p}$ at smaller $f$ with $-1<p<1$, then $e^{+}$ acquires an $f^{-1}$ scaling throughout a range of frequencies that spreads out in both directions from $f_{0}$. At the same time, $e^{-}$ acquires an $f^{-2}$ scaling within this same frequency range. If the plasma parameters and infrared $e^{+}$ spectrum are chosen to match conditions in the fast solar wind at a heliocentric distance of 0.3 astronomical units (AU), then the nonlinear evolution of the parametric instability leads to an $e^{+}$ spectrum that matches fast-wind measurements from the Helios spacecraft at 0.3 AU, including the observed $f^{-1}$ scaling at $f\gtrsim 3\times 10^{-4}~\text{Hz}$. The results of this paper suggest that the $f^{-1}$ spectrum seen by Helios in the fast solar wind at $f\gtrsim 3\times 10^{-4}~\text{Hz}$ is produced in situ by parametric decay and that the $f^{-1}$ range of $e^{+}$ extends over an increasingly narrow range of frequencies as $r$ decreases below 0.3 AU. This prediction will be tested by measurements from the Parker Solar Probe.

scholarly journals On the origin of solar wind. Alfvén waves induced jump of coronal temperature

2007 ◽  
Vol 44 (3) ◽  
pp. 533-536 ◽  
Author(s):  
T. M. Mishonov ◽  
M. V. Stoev ◽  
Y. G. Maneva
Keyword(s):  
Solar Wind ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Coronal Temperature

scholarly journals Observations of polar patches generated by solar wind Alfvén wave coupling to the dayside magnetosphere

1999 ◽  
Vol 17 (4) ◽  
pp. 463-489 ◽  
Author(s):  
P. Prikryl ◽  
J. W. MacDougall ◽  
I. F. Grant ◽  
D. P. Steele ◽  
G. J. Sofko ◽  
...  
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Convection Cell ◽  
Convection Flow ◽  
Vhf Radar ◽  
Sky Imager ◽  
The Imf

Abstract. A long series of polar patches was observed by ionosondes and an all-sky imager during a disturbed period (Kp = 7- and IMF Bz < 0). The ionosondes measured electron densities of up to 9 × 1011 m-3 in the patch center, an increase above the density minimum between patches by a factor of \\sim4.5. Bands of F-region irregularities generated at the equatorward edge of the patches were tracked by HF radars. The backscatter bands were swept northward and eastward across the polar cap in a fan-like formation as the afternoon convection cell expanded due to the IMF By > 0. Near the north magnetic pole, an all-sky imager observed the 630-nm emission patches of a distinctly band-like shape drifting northeastward to eastward. The 630-nm emission patches were associated with the density patches and backscatter bands. The patches originated in, or near, the cusp footprint where they were formed by convection bursts (flow channel events, FCEs) structuring the solar EUV-produced photoionization and the particle-produced auroral/cusp ionization by segmenting it into elongated patches. Just equatorward of the cusp footprint Pc5 field line resonances (FLRs) were observed by magnetometers, riometers and VHF/HF radars. The AC electric field associated with the FLRs resulted in a poleward-progressing zonal flow pattern and backscatter bands. The VHF radar Doppler spectra indicated the presence of steep electron density gradients which, through the gradient drift instability, can lead to the generation of the ionospheric irregularities found in patches. The FLRs and FCEs were associated with poleward-progressing DPY currents (Hall currents modulated by the IMF By) and riometer absorption enhancements. The temporal and spatial characteristics of the VHF backscatter and associated riometer absorptions closely resembled those of poleward moving auroral forms (PMAFs). In the solar wind, IMP 8 observed large amplitude Alfvén waves that were correlated with Pc5 pulsations observed by the ground magnetometers, riometers and radars. It is concluded that the FLRs and FCEs that produced patches were driven by solar wind Alfvén waves coupling to the dayside magnetosphere. During a period of southward IMF the dawn-dusk electric field associated with the Alfvén waves modulated the subsolar magnetic reconnection into pulses that resulted in convection flow bursts mapping to the ionospheric footprint of the cusp.Key words. Ionosphere (polar ionosphere). Magneto- spheric physics (magnetosphere-ionosphere interactions; polar wind-magnetosphere interactions).

scholarly journals Propagation of Alfvén Waves in the Expanding Solar Wind with the Fast–Slow Stream Interaction

2020 ◽  
Vol 888 (2) ◽  
pp. 68 ◽  
Author(s):  
Chen Shi ◽  
Marco Velli ◽  
Anna Tenerani ◽  
Franco Rappazzo ◽  
Victor Réville
Keyword(s):  
Solar Wind ◽  
Alfven Waves ◽  
Alfvén Waves
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