Resonant acceleration of alpha particles by ion cyclotron waves in the solar wind

1991 ◽  
Vol 96 (A6) ◽  
pp. 9801 ◽  
Author(s):  
L. Gomberoff ◽  
R. Elgueta
Keyword(s):  
Solar Wind ◽  
Alpha Particles ◽  
Ion Cyclotron Waves ◽  
Ion Cyclotron ◽  
Resonant Acceleration

Feasibility of Ion-cyclotron Resonant Heating in the Solar Wind

2021 ◽  
Author(s):  
Roberto E. Navarro ◽  
Victor Muñoz ◽  
Juan A. Valdivia ◽  
Pablo S. Moya
Keyword(s):  
Solar Wind ◽  
Solar Wind Plasma ◽  
Alpha Particles ◽  
Particle Interactions ◽  
Fermi Acceleration ◽  
Ion Cyclotron Waves ◽  
Proton Temperature ◽  
Propagating Waves ◽  
Ion Cyclotron ◽  
Cold Electrons

<p>Wave-particle interactions are believed to be one of the most important kinetic processes regulating the heating and acceleration of Solar Wind plasma. One possible explanation to the observed preferential heating of alpha (He<sup>+2</sup>) ions relies on a process similar to a second order Fermi acceleration mechanism. In this model, heavy ions are able to resonate with multiple counter-propagating ion-cyclotron waves, while protons can encounter only single resonances, resulting in the subsequent preferential energization of minor ions. In this work, we address and test this idea by calculating the number of plasma particles that are resonating with ion-cyclotron waves propagating parallel and anti-parallel to an ambient magnetic field in a proton/alpha plasma with cold electrons. Resonances are calculated through the proper kinetic multi-species dispersion relation of Alfven waves. We show that 100% of the alpha population can resonate with counter-propagating waves below a threshold ΔU<sub>αp</sub>/v<sub>A</sub><U<sub>0</sub>+a(β+β<sub>0</sub>)<sup>b</sup> in the differential streaming between protons and alpha particles, where U<sub>0</sub>=-0.532, a=1.211, β<sub>0</sub>=0.0275, and b=0.348 for isotropic ions. This threshold seems to match with constraints of the observed ΔU<sub>αp</sub> in the Solar Wind for low values of the proton plasma beta<strong>.</strong> Finally, it is also shown that this process is limited by the growth of plasma kinetic instabilities, a constraint that could explain alpha-to-proton temperature ratio observations in the Solar Wind at 1 AU.</p>

scholarly journals Observations of ion cyclotron waves in the solar wind near 0.3 AU

2010 ◽  
Vol 115 (A12) ◽  
pp. n/a-n/a ◽  
Author(s):  
L. K. Jian ◽  
C. T. Russell ◽  
J. G. Luhmann ◽  
B. J. Anderson ◽  
S. A. Boardsen ◽  
...  
Keyword(s):  
Solar Wind ◽  
Ion Cyclotron Waves ◽  
Ion Cyclotron

scholarly journals Properties of A Supercritical Quasi-Perpendicular Interplanetary Shock Propagating in Super-Alfvénic Solar Wind: from MHD to Kinetic Scales

2021 ◽  
Author(s):  
Mingzhe Liu ◽  
Zhongwei Yang ◽  
Ying D. Liu ◽  
Bertrand Lembege ◽  
Karine Issautier ◽  
...  
Keyword(s):  
Solar Wind ◽  
Energy Dissipation ◽  
Interplanetary Shock ◽  
Particle Interactions ◽  
Temperature Anisotropy ◽  
Ion Cyclotron Waves ◽  
Proton Temperature ◽  
Ion Cyclotron ◽  
Mirror Mode

<p>We investigate the properties of an interplanetary shock (M<sub>A</sub>=3.0, θ<sub>Bn</sub>=80°) propagating in Super-Alfvénic solar wind observed on September 12<sup>th,</sup> 1999 with in situ Wind/MFI and Wind/3DP observations. Key results are obtained concerning the possible energy dissipation mechanisms across the shock and how the shock modifies the ambient solar wind at MHD and kinetic scales:  (1) Waves observed in the far upstream of the shock are incompressional and mostly shear Alfvén waves.  (2) In the downstream, the shocked solar wind shows both Alfvénic and mirror-mode features due to the coupling between the Alfvén waves and ion mirror-mode waves.  (3) Specularly reflected gyrating ions, whistler waves, and ion cyclotron waves are observed around the shock ramp, indicating that the shock may rely on both particle reflection and wave-particle interactions for energy dissipation.  (4) Both ion cyclotron and mirror mode instabilities may be excited in the downstream of the shock since the proton temperature anisotropy touches their thresholds due to the enhanced proton temperature anisotropy.  (5) Whistler heat flux instabilities excited around the shock give free energy for the whistler precursors, which help explain the isotropic electron number and energy flux together with the normal betatron acceleration of electrons across the shock.  (6) The shock may be somehow connected to the electron foreshock region of the Earth’s bow shock, since Bx > 0, By < 0, and the electron flux varies only when the electron pitch angles are less than PA = 90°, which should be further investigated. Furthermore, the interaction between Alfvén waves and the shock and how the shock modifies the properties of the Alfvén waves are also discussed.</p>

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