scholarly journals Nonlinear mechanisms for cyclotron-resonance accelerations by an Alfvén-wave pulse

2008 ◽  
Vol 112 (4) ◽  
pp. 042039
Author(s):  
K Akimoto ◽  
H Hojo
Keyword(s):  
Cyclotron Resonance ◽  
Alfven Wave ◽  
Wave Pulse

Doppler-Shifted Cyclotron Resonance and Alfvén Wave Damping in Bismuth

1962 ◽  
Vol 9 (10) ◽  
pp. 421-423 ◽  
Author(s):  
Jordan Kirsch ◽  
P. B. Miller
Keyword(s):  
Cyclotron Resonance ◽  
Alfven Wave ◽  
Wave Damping

scholarly journals Solar off-limb line widths with SUMER: revised value of the non-thermal velocity and new results

2009 ◽  
Vol 27 (9) ◽  
pp. 3551-3558 ◽  
Author(s):  
L. Dolla ◽  
J. Solomon
Keyword(s):  
Solar Wind ◽  
Cyclotron Resonance ◽  
Alfven Waves ◽  
Stray Light ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Thermal Velocity ◽  
Line Profiles ◽  
Lower Corona ◽  
Ion Cyclotron

Abstract. Alfvén waves and ion-cyclotron absorption of high-frequency waves are frequently brought into models devoted to coronal heating and fast solar-wind acceleration. Signatures of ion-cyclotron resonance have already been observed in situ in the solar wind and in the upper corona. In the lower corona, one can use the line profiles to infer the ion temperatures. But the value of the so-called "non-thermal" (or "unresolved") velocity, potentially related to the amplitude of Alfvén waves propagating in the corona, is critical in firmly identifying ion-cyclotron preferential heating. In a previous paper, we proposed a method to constrain both the Alfvén wave amplitude and the preferential heating, above a polar coronal hole observed with the SUMER/SOHO spectrometer. Taking into account the effect of instrumental stray light before analysing the line profiles, we ruled out any direct evidence of damping of the Alfvén waves and showed that ions with the lowest charge-to-mass ratios were preferentially heated. We re-analyse these data here to correct the derived non-thermal velocity, and we discuss the consequences on the main results. We also include a measure of the Fe VIII 1442.56 Å line width (second order), thus extending the charge-to-mass ratio domain towards ions more likely to experience cyclotron resonance.

scholarly journals Compressional Alfvén Wave Propagation Below Ion Cyclotron Frequency

1968 ◽  
Vol 21 (2) ◽  
pp. 129 ◽  
Author(s):  
RC Cross ◽  
JA Lehane
Keyword(s):  
Wave Propagation ◽  
Cyclotron Resonance ◽  
Cyclotron Frequency ◽  
Cutoff Frequency ◽  
Compressional Wave ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Ion Cyclotron Resonance ◽  
Wave Measurements ◽  
Ion Cyclotron

When the compressional wave cutoff frequency is below ion cyclotron frequency both compressional and torsional Alfven waves may be present simultaneously. Oompressional wave measurements in this regime are particularly important because of their relevance to certain ion cyclotron resonance heating experiments. This paper extends the work of others in this important regime.

Re-ionization of a partially ionized plasma by an Alfvén wave of moderate amplitude

1980 ◽  
Vol 24 (1) ◽  
pp. 65-74
Author(s):  
M. H. Brennan ◽  
M. L. Sawley
Keyword(s):  
Plasma Temperature ◽  
Torsional Wave ◽  
Alfven Wave ◽  
Helium Plasma ◽  
Acoustic Oscillations ◽  
Radial Density ◽  
Helium Ions ◽  
Wave Pulse ◽  
Partially Ionized ◽  
Doubly Charged

This paper reports on the use of forced magneto-acoustic oscillations to investigate the effect of a torsional hydromagnetic (Alfvén) wave pulse of moderate amplitude on the properties of a partially ionized afterglow helium plasma. Observations of the magnetic flux associated with the oscillations, measured at a number of frequencies, are used to determine radial density proffles and to provide estimates of plasma temperature. The torsional wave is shown to cause significant re-ionization of the plasma with no corresponding increase in the plasma temperature. The torsional wave is shown to cause significant re-ionization of the plasma with no corresponding increase in the plasma temperature. However, the presence of a number of energetic particles is evidenced by the production of a significant number of doubly charged helium ions.

scholarly journals Alfven wave cyclotron resonance heating

1981 ◽  
Author(s):  
R.B. White ◽  
S. Yosikawa ◽  
C. Oberman
Keyword(s):  
Cyclotron Resonance ◽  
Alfven Wave

Numerical simulation of wave propagation and plasma response excited in field-reversed configuration plasma

2021 ◽  
Author(s):  
Urano Takahiro ◽  
Toshiki Takahashi ◽  
Tomohiko Asai ◽  
Shigefumi Okada
Keyword(s):  
Magnetic Field ◽  
Propagation Velocity ◽  
Cyclotron Resonance ◽  
Magnetic Energy ◽  
Axial Direction ◽  
Alfven Wave ◽  
Ion Cyclotron Resonance ◽  
Field Reversed Configuration ◽  
Resonance Point ◽  
Plasma Response

Abstract A hybrid simulation (a model that treats ions as particles and electrons as fluid) is performed to analyse the propagation of waves excited in the field-reversed configuration plasma and the resulting plasma response. The current of the wave excitation antenna changes in a sine wave, and its frequency is set so that it has an ion cyclotron resonance point inside the separatrix. When the antenna current is maximum, a magnetic field with a magnitude of 40% of the external magnetic field is created on the separatrix. A toroidal magnetic field is excited in the plasma by applying waves. The observed propagation velocity of the toroidal magnetic field is comparable with the shear Alfvén wave outside the separatrix, and is on the same order within the separatrix. This result has a tendency similar to the propagation velocity outside the separatrix reported in the wave experiment in the past FIX machine. The simulation results also show that when the excited magnetic field propagates in the axial direction, the separatrix are compressed or expanded, and the high-density region of the ions formed thereby moves in the axial direction. In addition, the excited magnetic energy is rapidly decreased near the position where the velocities of the shear Alfvén wave and the ion sound wave are equal (local beta value is 0.88). It is found that the decay of the excited magnetic energy occurred at a point outside the ion cyclotron resonance point. This suggests that the compression and expansion of the plasma is caused while maintaining the quasi-equilibrium state according to the change in the external magnetic pressure.

scholarly journals The Alfvén edge in asymmetric reconnection

2010 ◽  
Vol 28 (6) ◽  
pp. 1327-1331 ◽  
Author(s):  
A. Vaivads ◽  
A. Retinò ◽  
Yu. V. Khotyaintsev ◽  
M. André
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Plasma Density ◽  
The Other ◽  
Alfven Wave ◽  
Wave Pulse ◽  
Parallel Current ◽  
Alfven Velocity

Abstract. We show that in the case of magnetic reconnection where the Alfvén velocity is much higher in the plasma on one side of the current sheet than the other, an Alfvén edge is formed. This edge is located between the electron and ion edges on the high Alfvén velocity side of the current sheet. The Alfvén edge forms because the Alfvén wave generated near the X-line will propagate faster than the accelerated ions forming the ion edge. We discuss possible generation mechanism and the polarization of the Alfvén wave in the case when higher Alfvén speed is due to larger magnetic field and smaller plasma density, as in the case of magnetopause reconnection. The Alfvén wave can be generated due to Hall dynamics near the X-line. The Alfvén wave pulse has a unipolar electric field and the parallel current will be such that the outer current on the high magnetic field side is flowing away from the X-line. Understanding Alfvén edges is important for understanding the separatrix regions at the boundaries of reconnection jets. We present an example of Alfvén edge observed by the Cluster spacecraft at the magnetopause.

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