Some parametric instabilities of an ordinary electromagnetic wave in magnetized plasmas

Abstract

Some of the parametric instabilities of an ordinary electromagnetic wave decaying into (i) a highfrequency upper hybrid wave and a low-frequency mixed-mode kinetic Alfven wave and (ii) an obliquely propagating ordinary scattered electromagnetic wave and a low-frequency electrostatic-ion Bernstein wave (stimulated Brillouin scattering) have been investigated. In channel (i), the partially electrostatic nature of the kinetic Alfven wave and the component of the low-frequency ponderomotive force along the direction of the external magnetic field lead to the dominant coupling. Explicit expressions for the growth rate and threshold power are given. It is found that, in the case of channel (ii), the homogeneous threshold power is lowest at the first harmonic of the low-frequency electrostatic-ion Bernstein wave. The relevance of the present investigation to fusion, ionospheric modification experiments, and space plasmas has been pointed out. For example, for fusion plasmas the convective threshold power for channel (i) is found to be approximately 20 kW/cm .

On nonlinear decay of kinetic Alfvén waves and application to some processes in space plasmas

“…Recently, the works further point out that the KAWs can parametrically excite the convective cell [ Pokhotelov et al , 2003; Onishchenko et al , 2004]. On the other hand, the KAWs can also be excited by other modes, such as by the whistler wave [ Chen , 1977; Sharma et al , 1986], the lower hybrid wave [ Shukla and Mamedow , 1978], the high‐frequency radio wave [ Papadopoulos et al , 1982], the ion cyclotron wave [ Yu et al , 1984; Patel et al , 1985], the ion Bernstein wave [ Sharma and Tripathi , 1988], the ordinary electromagnetic wave [ Triphthi and Sharma , 1988], the higher hybrid wave [ Yukhimuk et al , 1998], the Langmuir wave [ Voitenko et al , 2003], and MHD waves [ Voitenko and Goossens , 2002, 2005a, 2005b; Fedun et al , 2004].…”

Parametric decay of a whistler wave at the difference frequency of two electromagnetic waves in a plasma

“…In this paper ion heating in connection with parametric decay at the beat frequency has been discussed and explained analytically as heating by parametrically excited low-frequency ion-Bernstein waves (Tripathi & Sharma 1988) in a multi-ion-species plasma (Dash, Sharma & Buti 1984;Sharma, Yashvir & Bhatnagar 1986;Milic & Krstic 1987). It has been found that the growth rate can be controlled by several parameters, such as the mass, density and temperature of two ion species.…”

“…a high-frequency lower-hybrid wave and a low-frequency ion-Bernstein wave in a multi-ion-species plasma. Parametric decays are among the most promising heating mechanisms for plasmas (Porkolab & Chang 1977;Tripathi & Sharma 1988). The idea of heating by parametric decay is to pump power into modes at technically available frequencies; the pump modes themselves are not effectively absorbed by the plasmas, but one or both of the decay modes are (Krause, Luthen & Schluter 1980).…”