Scalar equation for wave beams in a magnetized plasma

Ray-tracing code TRAVIS for ECR heating, EC current drive and ECE diagnostic

“…However, this approach fails near focal points where the width of the RF beam, d, becomes comparable with the wave length. Beam-tracing techniques, complex eikonal and quasi-optic approaches [5][6][7][8][9], below all referred as beam-tracing, include higher order effects and are necessary for scenarios with highly focused beams, where d cL/ω and such effects as diffraction and aberration become significant. In the more typical case, when the RF beam is not perfectly focused or even diverges, the raytracing technique is well applicable and even preferable, especially if the width of divergent beam is comparable to the characteristic scale of the plasma (in this case, the beam-tracing technique based on the paraxial approach fails).…”

Quasi-optical theory of microwave plasma heating in open magnetic trap

“…typical for radiation belts in Earth ionosphere or Solar flares, in a straightforward manner just by introducing new coordinates with a curvilinear axis z and taking into account the curvature when calculating a conjugated momenta operator. The similar approach was previously used for toroidal magnetic traps in which the axis z was chosen along the reference geometric optics ray representing the center of the quasi-optical wave beam [15][16][17] . However, using geometric optics rays as a reference for the quasi-optical equation in open traps is not optimal because such rays may be strongly curved and even divergent inside the plasma column in most interesting cases 9,11 .…”

“…Straightforward simulation of these effects for large devices within a complete set of Maxwell's equations is very complicated, in particular, because of the smallness of a wavelength. A good alternative is the consistent quasi-optical approach based on an asymptotic expansion of Maxwell's equations in the paraxial approximation in the vicinity of the selected Wentzel-Kramers-Brillouin (WKB) mode 14,15 . In this paper, the quasi-optical approximation is adopted to describe the propagation of wave beams in a high-temperature plasma in an open magnetic trap.…”

Quasi-optical approach for inhomogeneous dissipative media with high-order spatial dispersion

“…Its generalization to the case of anisotropic and gyrotropic media with spatial dispersion and dissipation [3] was used to simulate the propagation of quasi-optical wave beams in tokamaks and showed much higher accuracy for resonance absorption in comparison to the previously used approaches [4]. In this paper, we discuss the further generalization of the quasi-optical approach [5] and the features of its application in media of a special kind.A quasi-optical equation [3] is the equation for the scalar complex amplitude U of the wave beam corresponding to selected electromagnetic mode in smoothly inhomogeneous mediaHere the momentum operatoris defined as the differentiation operator in the coordinate space normalized on the vacuum wave number k 0 = Ȧ/c. The simplification of this equation is possible for paraxial wave beams (broad in the wavelength scale) with parameters varying slowly along some curve r 0 (the reference ray).…”

“…Such a description allows one to consistently take into account the media anisotropy, spatial inhomogeneity, dispersion, and resonance dissipation within the framework of a unified approach [2]. Its generalization to the case of anisotropic and gyrotropic media with spatial dispersion and dissipation [3] was used to simulate the propagation of quasi-optical wave beams in tokamaks and showed much higher accuracy for resonance absorption in comparison to the previously used approaches [4]. In this paper, we discuss the further generalization of the quasi-optical approach [5] and the features of its application in media of a special kind.…”