Parametric excitation of surface electron cyclotron O-modes by an external alternating electric field

Abstract

Using the model of uniform semi-bounded plasma, it is shown that the influence of an external alternating electric field in the range of electron cyclotron frequencies leads to excitation of eigen ordinary polarized waves at the first harmonic of electron cyclotron frequency. The external electric field was assumed to be uniform and monochromatic; electro-dynamical properties of the plasma were described by the kinetic Vlasov–Boltzmann equation in the approach of a weak spatial dispersion of plasma. Two components of these modes’ wave vector oriented across an external magnetic field are taken into consideration. Fields of these electron cyclotron O-modes are described by the Maxwell equations; their phase velocity is assumed to be less than the velocity of light. Nonlinear boundary condition-described discontinuity of the modes’ tangential magnetic field is formulated using the concept of a nonlinear surface electric current. The infinite set of equations for harmonics of these O-modes’ tangential electric field has been derived with the aid of this nonlinear boundary condition. It is solved using a wave packet consisting of the basic harmonic and two nearest satellite harmonics. A simple analytical expression for growth rates of these surface waves’ parametric instability is obtained; the influence of plasma parameters on their excitation is numerically analyzed.

Parametric Instability of Surface Electron Cyclotron Tm-Modes

“…Decreasing Z value increases growth rate values Im(γ/|ω e |). This result coincides with analogous result obtained for surface electron cyclotron O-modes [10]. Increasing electron cyclotron harmonics number shifts curves Im(γ/|ω e |) as a whole to the side of higher values of parameter x.…”

“…Application of these boundary conditions allows one to derive the infinite set of equations for nth harmonics of SECTM-modes tangential electric field on the plasma interface in the form, which is analogous to those obtained in [9,10]. Let us write it below:…”

“…A utilization of restricted plasma volumes for different practical purposes makes it possible to excite both bulk and surface types of waves [8]. In our previous articles [9,10], we have studied the cases of surface electron cyclotron waves with extraordinary and ordinary polarization, correspondingly, and also their propagation under conditions, when an external magnetic field was assumed to be oriented parallel to a plasma-dielectric interface. Unlike these cases, here we study the case of perpendicular orientation of an external steady magnetic field and do not restrict our consideration by the wavelength range located near a limit of long wavelengths compared with Larmor radius of electron, as it has been done in [9,10].…”

“…In our previous articles [9,10], we have studied the cases of surface electron cyclotron waves with extraordinary and ordinary polarization, correspondingly, and also their propagation under conditions, when an external magnetic field was assumed to be oriented parallel to a plasma-dielectric interface. Unlike these cases, here we study the case of perpendicular orientation of an external steady magnetic field and do not restrict our consideration by the wavelength range located near a limit of long wavelengths compared with Larmor radius of electron, as it has been done in [9,10]. To derive a set of equations describing parametric excitation of surface electron cyclotron TM-modes (SECTMmodes) the non-linear boundary condition, which determines discontinuity of tangential magnetic field of studied modes, is formulated as done in papers [9,10].…”

“…Unlike these cases, here we study the case of perpendicular orientation of an external steady magnetic field and do not restrict our consideration by the wavelength range located near a limit of long wavelengths compared with Larmor radius of electron, as it has been done in [9,10]. To derive a set of equations describing parametric excitation of surface electron cyclotron TM-modes (SECTMmodes) the non-linear boundary condition, which determines discontinuity of tangential magnetic field of studied modes, is formulated as done in papers [9,10]. This discontinuity is determined by surface electric current, which is induced by external alternating electric field on the plasma interface.…”