Excitation of the Alfvén Ion Cyclotron Mode Solely by the Ion Pressure Distribution

1998 ◽  
Vol 37 (Part 1, No. 1) ◽  
pp. 342-343
Author(s):  
Motoyuki Nakamura ◽  
Makoto Ichimura ◽  
Satoru Tanaka ◽  
Seikou Kanazawa ◽  
Eiji Ishikawa ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Ion Cyclotron ◽  
Cyclotron Mode

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.

Low-frequency waves in a high-beta collisionless plasma: polarization, compressibility and helicity

1986 ◽  
Vol 35 (3) ◽  
pp. 431-447 ◽  
Author(s):  
S. Peter Gary
Keyword(s):  
Numerical Solutions ◽  
Collisionless Plasma ◽  
Low Frequency ◽  
Order Unity ◽  
Left Hand ◽  
Long Wavelength ◽  
Oblique Propagation ◽  
Ion Cyclotron ◽  
Cyclotron Mode ◽  
High Beta

This paper considers the linear theory of waves near and below the ion cyclotron frequency in an isothermal electron-ion Vlasov plasma which is isotropic, homogeneous and magnetized. Numerical solutions of the full dispersion equation for the magnetosonic/whistler and Alfvén/ion cyclotron modes at βi = 1·0 are presented, and the polarizations, compressibilities, helicities, ion Alfvén ratios and ion cross-helicities are exhibited and compared. At sufficiently large βi and θ, the angle of propagation with respect to the magnetic field, the real part of the polarization of the Alfvén/ion cyclotron wave changes sign, so that, for such parameters, this mode is no longer left-hand polarized. The Alfvén/ion cyclotron mode becomes more compressive as the wavenumber ulereases, whereas the magnetosonic/whistler becomes more compressive with increasing θ, At oblique propagation, the helicity of both modes approaches zero in the long-wavelength limit; in contrast, the ion cross-helicity is of order unity for the Alfvén/ion cyclotron wave and decreases as θ increases for the magnetosonic/whistler mode.

Nonlinear ion motion in a slow ion cyclotron mode

1976 ◽  
Vol 19 (10) ◽  
pp. 1626 ◽  
Author(s):  
M. C. Vella ◽  
R. E. Aamodt
Keyword(s):  
Ion Motion ◽  
Ion Cyclotron ◽  
Cyclotron Mode

Axial Structures of the Alfvén Ion Cyclotron Mode in the GAMMA10 Tandem Mirror

1997 ◽  
Vol 36 (Part 1, No. 11) ◽  
pp. 6978-6980 ◽  
Author(s):  
Akira Kumagai ◽  
Makoto Ichimura ◽  
Motoyuki Nakamura ◽  
Satoru Tanaka ◽  
Seikou Kanazawa ◽  
...  
Keyword(s):  
Tandem Mirror ◽  
Ion Cyclotron ◽  
Cyclotron Mode

QUASI-LINEAR THEORY OF TRANSVERSE PLASMA INSTABILITIES WITH APPLICATIONS TO HYDROMAGNETIC EMISSIONS FROM THE MAGNETOSPHERE

1966 ◽  
Vol 44 (4) ◽  
pp. 815-835 ◽  
Author(s):  
Tomiya Watanabe
Keyword(s):  
Growth Rate ◽  
Magnetoactive Plasma ◽  
Equatorial Region ◽  
Time Change ◽  
Wave Frequency ◽  
Multiple Time ◽  
Ion Cyclotron ◽  
Transverse Electromagnetic ◽  
Effective Wave ◽  
Cyclotron Mode

Transverse instabilities in two magnetoactive plasma streams are investigated theoretically. The approach taken is to investigate how a small signal transverse electromagnetic wave, which, in a zero temperature background plasma, can be propagated as a circularly polarized sinusoidal wave (with the two possible modes, electron and ion cyclotron) along the external magnetic field, behaves under perturbations arising from the existence of the streaming plasma and the nonlinear terms in the Boltzmann equations describing the plasma particle distribution. The perturbation method originally given by Bogoliuboff et al. and since developed into the so-called multiple time-scale method by Frieman et al. (1963) is employed to solve the problem. The cyclotron instability is rediscovered as the effect of the lowest order (viz., the most effective) among all possible instability processes. The wave amplitude is found to grow gradually with time in the vicinity of the cyclotron resonance frequency because of the instability. The effective wave frequency is also found to change gradually in time. The growth rate of the signal intensity and the rate of the time change in the frequency are calculated for a case of geophysical interest, viz. the instability in the ion cyclotron mode of waves by a proton stream proposed as the generation mechanism for hydromagnetic (hereafter hm) emissions. The location of the occurrence of the instabilities is taken to be the equatorial region in the outer magnetosphere. A model is considered where the instabilities occur in the region with L value equal to about 5.6. The growth rate of the signal strength calculated with reasonable values of the geophysical parameters involved is in agreement with the observations. Calculations of the rate of the time change in the wave frequency show that the frequency is seen to increase with time, and the rate, which is of the order of 0.1 c.p.s./minute, is comparable to that obtained from observations, showing that the process proposed for hm emissions may be correct.

Local stability of anisotropy-driven modes in diffuse high-beta plasmas

1980 ◽  
Vol 23 (3) ◽  
pp. 501-513
Author(s):  
J. Goedert ◽  
J. P. Mondt
Keyword(s):  
Growth Rate ◽  
Local Stability ◽  
Larmor Radius ◽  
Temperature Anisotropy ◽  
Ion Cyclotron ◽  
Mirror Mode ◽  
Cyclotron Mode ◽  
High Beta

Finite ion Larmor radius effects (ε ≡ γLi/LΙ< 1 but finite) are found to cause a branching of the Alfvén ion cyclotron mode, whereas the growth rate of the mirror mode is found to be of the order of for ωci for ε≥ 0.1 and rather moderate values of plasma beta and temperature anisotropy. For this regime its growth rate considerably exceeds that of the Alfvén ion cyclotron mode.

Ion diffusion in a velocity space induced by Alfvén ion cyclotron mode observed in a mirror plasma

2000 ◽  
Vol 7 (6) ◽  
pp. 2485-2493 ◽  
Author(s):  
T. Goto ◽  
K. Ishii ◽  
Y. Goi ◽  
N. Kikuno ◽  
Y. Katsuki ◽  
...  
Keyword(s):  
Velocity Space ◽  
Ion Diffusion ◽  
Ion Cyclotron ◽  
Cyclotron Mode

Decay of the lower-hybrid wave into an ion cyclotron mode and a whistler wave

1982 ◽  
Vol 28 (1) ◽  
pp. 149-157 ◽  
Author(s):  
M. K. Saxena
Keyword(s):  
Short Wavelength ◽  
Whistler Wave ◽  
Lower Hybrid ◽  
Hybrid Wave ◽  
Lower Hybrid Wave ◽  
Parametrically Excited ◽  
Ion Cyclotron ◽  
Cyclotron Mode ◽  
Hybrid Waves ◽  
Lower Hybrid Waves

The electrostatic lower-hybrid wave is shown to decay parametrically into a whistler wave and a resonant ion cyclotron mode or an ion cyclotron quasi-mode or a reactive quasi-mode. The convective threshold powers for these decay instabilities are found to be much larger than presently available pump powers. These decay instabilities, however, are expected to play an important role in the saturation of the parametrically excited short-wavelength lower-hybrid waves having frequency close to ωlh.

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