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2 Nukleonika

2 2011

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On the study of ion cyclotron waves in a cylindrical magnetized plasma

Zaki N. G.

Nukleonika

2011

Vol. 56, No. 2

179-184

In this work, a general dispersion relation of waves in the region of ion cyclotron frequency in the cylindrical magnetized plasma is derived. The waves are assumed to be cylindrically symmetric oscillations of small amplitude. Analytical calculations are performed to find the plasma dielectric tensor for the plasma consisting of hot electron and multi-component cold ions fluid. The special case of a three component plasma with hot electrons in a strong magnetic field may be interesting, e.g., in the context of fusion plasma containing D+, T+ and He2+. The general dispersion relation is simplified in two solutions. Firstly, E1 wave (E2 = 0) which has an electrostatic character, and secondly E2 wave (E1 = 0) which has an electromagnetic character. The dispersion relations for both waves are described and identified as the ion acoustic and electrostatic ion cyclotron (EIC) waves for E1 wave and the torsional Alfvén, i.e. ion cyclotron (IC) waves and the compressional Alfvén wave for E2 wave. These waves are studied due to their importance in the heating of plasmas.

Effects of warmness and spatial nonuniformity of plasma waveguide on periodic absolute parametric instability

Zaki N. G., Bekheit A. H.

Nukleonika

2011

Vol. 56, No. 4

305-309

The periodic absolute parametric instability (API) of the low-frequency oscillations excited by a monochromatic pumping field of an arbitrary amplitude in a warm 1-D (one-dimensional) nonuniform magnetoactive plasma is investigated. The separation method can be used for solving the two-fluid plasma equations describing the system. By applying this method we were able to determine the frequencies and growth rates of unstable modes and the self-consistent electric field. Plasma electrons are considered to have a thermal velocity. Different solutions for the spatial equation can be obtained the following cases: A) API in a uniform plasma, B) API in a nonuniform plasma. The latter has been studied here for two cases: B.1) the exact harmonic oscillator and B.2) the bounded harmonic oscillator (a bounded plasma). An increment has been found in the build-up of the oscillations, and it has been shown that the spatial nonuniformity of the plasma exerts the stabilizing effect on the parametric instability. A reduced growth rate of API in the warm plasma, in comparison to the cold plasma, is reported. It has also been found that the warmness of the plasma has no effect on the solution of the space part of the problem (only through the separation constant).