scholarly journals A parametric ray tracing study of superluminous auroral kilometric radiation wave modes

2007 ◽  
Vol 112 (A10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Fuliang Xiao ◽  
Lunjin Chen ◽  
Huinan Zheng ◽  
Shui Wang
Keyword(s):  
Ray Tracing ◽  
Auroral Kilometric Radiation ◽  
Radiation Wave ◽  
Wave Modes

Calculation of slowness vectors from ray directions for qP-, qSV-, and qSH-waves in tilted transversely isotropic media

Geophysics ◽  
2018 ◽  
Vol 83 (4) ◽  
pp. C153-C160 ◽  
Author(s):  
Lijiao Zhang ◽  
Bing Zhou
Keyword(s):  
Ray Tracing ◽  
Transversely Isotropic ◽  
Anisotropic Media ◽  
Seismic Wave Propagation ◽  
Previous Method ◽  
New Methods ◽  
Slowness Vector ◽  
Isotropic Media ◽  
Tti Media ◽  
Wave Modes

Kinematic ray tracing is an effective way to simulate the seismic wave propagation in isotropic and anisotropic media. It is essential to know the ray velocity when tracing seismic rays. But in anisotropic media, the ray velocity is a function of the direction of the slowness vector instead of the ray direction and it often deviates from the phase velocity. In this case, it causes a critical problem for ray tracing, which is how to calculate the ray velocity from a known ray direction. If we could calculate the phase slowness vector from ray directions, the ray velocity could be computed. We have evaluated a previous method in the first place. Then, we developed two new methods to solve two existing problems of the previous method: (1) It leads to complex and multiple solutions of the slowness vector and (2) it mixes up the qP- and qSV-wave modes. Our first method solves the two problems by applying eigenvalues to separate the wave modes and decrease the two unknowns ([Formula: see text] and [Formula: see text]) to only one unknown in two equations. Our second method is based on the general relationship between the slowness and ray-velocity vectors and shows that only one unknown is involved in one equation for tilted transversely isotropic (TTI) media. After obtaining the slowness vector, the ray velocity can be computed easily. A 2D model is designed to test the feasibility of the new methods. Using the results for the model, we found that the presented approaches were applicable for ray tracing in TTI media.

scholarly journals Finite Larmor Radius Modifications to the Magnetoionic Wave Modes and Their Effects on Electron Cyclotron Maser Emission

1986 ◽  
Vol 39 (3) ◽  
pp. 407
Author(s):  
LT Ball ◽  
RG Hewitt
Keyword(s):  
Maximum Growth ◽  
Electron Cyclotron ◽  
Larmor Radius ◽  
Maser Emission ◽  
Finite Larmor Radius ◽  
Electron Cyclotron Maser ◽  
Cyclotron Maser ◽  
Auroral Kilometric Radiation ◽  
Solar Microwave ◽  
Wave Modes

Auroral kilometric radiation, Jupiter's decametric and Saturn's kilometric radio emissions, solar microwave spike bursts and microwave emissions from some flare stars have all been attributed to the electron cyclotron maser instability. The maser instability is usually assumed to involve the generation of magnetoionic waves. We investigate the modifications to the magneto ionic wave modes due to finite Larmor radius (FLR) corrections arising from a 'warm' background electron plasma with a Maxwellian distribution. We then consider the effects of these modifications on maser emission at frequencies near the fundamental of the electron cyclotron frequency fl e. The FLR effects are found to be small; the maximum temporal growth rate generally differs by ~ 10% from that for emission occurring in the magnetoionic modes. Small shifts occur in the frequencies and propagation angles corresponding to the maximum growth rates.

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