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Author(s):
K. Nishimura, R. Horiuchi and T. Sato
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Title:
Drift-kink Instability Induced by Beam Ions in Field-reversed Configurations
Date of publication:
Apr. 1999
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Key words:
FRC plasmas, drift-kink instability, tilt instability, particle simulation
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Abstract:
The drift-kink instability in field-reversed configurations with a beam component is investigated by means of a three-dimensional particle simulation. The unstable mode with the toroidal mode number n = 4 grows with the rate gamma ~ 0.1 - 1.0 omega_ci for a strong beam current and deforms the plasma profile along the beam orbit in the vicinity of the field-null line. This mode is nonlinearly saturated as a result of the relaxation of current profile. Both the saturation leve1 and the growth rate tend to increase as the ratio of the beam current to the plasma current I_b/I_p increases. It is also found that there is a threshold value of the beam velocity upsilon_b ~ upsilon_Ti (ion thermal velocity) for the excitation of the instability.
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