Electrostatic ion-cyclotron waves in a nonuniform magnetic field

1985 ◽  
Vol 28 (10) ◽  
pp. 3066 ◽  
Author(s):  
S. L. Cartier ◽  
N. D’Angelo ◽  
R. L. Merlino
Keyword(s):  
Magnetic Field ◽  
Nonuniform Magnetic Field ◽  
Ion Cyclotron Waves ◽  
Ion Cyclotron

scholarly journals Multi-spacecraft determination of wave characteristics near the proton gyrofrequency in high-altitude cusp

2005 ◽  
Vol 23 (3) ◽  
pp. 983-995 ◽  
Author(s):  
D. Sundkvist ◽  
A. Vaivads ◽  
M. André ◽  
J.-E. Wahlund ◽  
Y. Hobara ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Altitude ◽  
Nonlinear Effects ◽  
Linear Wave ◽  
Wave Growth ◽  
Ion Cyclotron Waves ◽  
Background Magnetic Field ◽  
Ion Cyclotron ◽  
The Waves ◽  
Proton Gyrofrequency

Abstract. We present a detailed study of waves with frequencies near the proton gyrofrequency in the high-altitude cusp for northward IMF as observed by the Cluster spacecraft. Waves in this regime can be important for energization of ions and electrons and for energy transfer between different plasma populations. These waves are present in the entire cusp with the highest amplitudes being associated with localized regions of downward precipitating ions, most probably originating from the reconnection site at the magnetopause. The Poynting flux carried by these waves is downward/upward at frequencies below/above the proton gyrofrequency, which is consistent with the waves being generated near the local proton gyrofrequency in an extended region along the flux tube. We suggest that the waves can be generated by the precipitating ions that show shell-like distributions. There is no clear polarization of the perpendicular wave components with respect to the background magnetic field, while the waves are polarized in a parallel-perpendicular plane. The coherence length is of the order of one ion-gyroradius in the direction perpendicular to the ambient magnetic field and a few times larger or more in the parallel direction. The perpendicular phase velocity was found to be of the order of 100km/s, an order of magnitude lower than the local Alfvén speed. The perpendicular wavelength is of the order of a few proton gyroradius or less. Based on our multi-spacecraft observations we conclude that the waves cannot be ion-whistlers, while we suggest that the waves can belong to the kinetic Alfvén branch below the proton gyrofrequency fcp and be described as non-potential ion-cyclotron waves (electromagnetic ion-Bernstein waves) above. Linear wave growth calculations using kinetic code show considerable wave growth of non-potential ion cyclotron waves at wavelengths agreeing with observations. Inhomogeneities in the plasma on the order of the ion-gyroradius suggests that inhomogeneous (drift) or nonlinear effects or both of these should be taken into account.

Ion beam excitation of ion-cyclotron waves and ion heating in plasmas with drifting ions

1978 ◽  
Vol 19 (2) ◽  
pp. 237-252 ◽  
Author(s):  
J. P. Hauck ◽  
H. Böhmer ◽  
N. Rynn ◽  
Gregory Benford
Keyword(s):  
Magnetic Field ◽  
Ion Beam ◽  
Ion Beams ◽  
Ion Heating ◽  
Ion Cyclotron Waves ◽  
Diffusion Effects ◽  
Ion Cyclotron ◽  
Cyclotron Mode ◽  
The Magnetic Field ◽  
Beam Excitation

Ion-cyclotron waves are excited by cesium and potassium ion beams in cesium and potassium Q-machine plasmas. The ion beams are injected along the magnetic field with care to avoid beam transverse velocities. The observed ion-cyclotron mode frequencies are below those driven by electron currents. These resonant instabilities are convective in character with small spatial growth rates ki/kr ≃ 0.05. Plasma ion heating is observed and is consistent with a model in which mode amplitudes are saturated by diffusion effects.

Amplification of electrostatic ion-cyclotron waves in a plasma with magnetic-field-aligned ion flow shear and no electron current

2004 ◽  
Vol 11 (9) ◽  
pp. 4501-4505 ◽  
Author(s):  
Su-Hyun Kim ◽  
Erick Agrimson ◽  
Michael J. Miller ◽  
Nicola D’Angelo ◽  
Robert L. Merlino ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Current ◽  
Flow Shear ◽  
Ion Flow ◽  
Ion Cyclotron Waves ◽  
Ion Cyclotron

Ion beam expansion due to ion cyclotron wave interactions

1979 ◽  
Vol 21 (1) ◽  
pp. 19-25 ◽  
Author(s):  
J. P. Hauck ◽  
Gregory Benford
Keyword(s):  
Magnetic Field ◽  
Diffusion Process ◽  
Ion Beam ◽  
Radial Expansion ◽  
Wave Interactions ◽  
Beam Spreading ◽  
Ion Cyclotron Waves ◽  
Ion Cyclotron ◽  
Guide Magnetic Field

We observe radial expansion of an ion beam propagating along a homogeneous guide magnetic field. The beam spreading appears to arise from interactions with beam-excited resonant ion cyclotron waves. Magnitude and scaling of the expansion agree with a theory based on a resonant diffusion process.

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