scholarly journals PROPAGATION OF SYMMETRIC HYBRID ELECTROMAGNETIC WAVES IN A PLANAR INHOMOGENEOUS NONLINEAR WAVEGUIDE: A NUMERICAL STUDY

2017 ◽  
Author(s):  
V. Yu. Kurseeva ◽  
Keyword(s):  
Electromagnetic Waves ◽  
Numerical Study ◽  
Nonlinear Waveguide

Numerical study of soliton emission from a nonlinear waveguide

1987 ◽  
Vol 4 (11) ◽  
pp. 1837 ◽  
Author(s):  
M. A. Gubbels ◽  
J. V. Moloney ◽  
E. M. Wright ◽  
G. I. Stegeman ◽  
C. T. Seaton
Keyword(s):  
Numerical Study ◽  
Nonlinear Waveguide

Re-examination of the one-dimensional theory of a Raman free-electron laser

2001 ◽  
Vol 66 (5) ◽  
pp. 301-313 ◽  
Author(s):  
J. E. WILLETT ◽  
B. BOLON ◽  
U.-H. HWANG ◽  
Y. AKTAS
Keyword(s):  
Dispersion Relation ◽  
Space Charge ◽  
Free Electron ◽  
Free Electron Laser ◽  
Electromagnetic Waves ◽  
Numerical Study ◽  
Polynomial Equation ◽  
Algebraic Equations ◽  
Degree Polynomial ◽  
One Dimensional

A new one-dimensional analysis of the collective interaction in a free-electron laser with combined helical wiggler and uniform axial magnetic fields is presented. Maxwell's curl relations and the cold-fluid equations are employed, with the appropriate form of solution for right and left circularly polarized electromagnetic waves and space-charge waves. A set of three linear homogeneous algebraic equations for the electric field amplitudes of the three propagating waves is derived. This set may be employed to obtain the general dispersion relation in the form of a tenth-degree polynomial equation. With the left circular wave assumed to be nonresonant, the dispersion relation reduces to a seventh-degree polynomial equation corresponding to four space-charge modes and three right circular modes. The results of a numerical study of the spatial growth rate and radiation frequency are presented.

scholarly journals Investigation of electromagnetic fields in the arctic zone with uneven ice cover

2021 ◽  
Vol 254 ◽  
pp. 02008
Author(s):  
Vladimir Korochentsev ◽  
Vey Syue ◽  
Sergey Gorovoy ◽  
Vasily Chernenko ◽  
Artem Em ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Numerical Study ◽  
Ice Cover ◽  
The Arctic ◽  
Experimental Investigations ◽  
Arctic Zone ◽  
Wave Source ◽  
Half Wave ◽  
Transmitted Signal ◽  
Good Agreement

Numerical investigation of electromagnetic waves propagating near an ice cover with hummocks of different height has been carried out. Half-wave vibrators, melted into ice at the depth of about 20 sm, were used as an antenna. Transmitted signal frequencies were from 10 to 30 MHz. A mathematical model for amplitude spatial distribution of electromagnetic wave source, placed inside an ice cover with hummocks, was developed. The results of numerical study show that, when antenna is inside hummocks, the signal is amplified. Experimental investigations show good agreement with the theoretical model.

A comparison between electron orbits for both an axial magnetic field and an ion-channel guiding in a FEL with an electromagnetic wave wiggler

2008 ◽  
Vol 74 (2) ◽  
pp. 187-196 ◽  
Author(s):  
H. MEHDIAN ◽  
S. JAFARI
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Wave ◽  
Ion Channel ◽  
Free Electron ◽  
Free Electron Laser ◽  
Large Amplitude ◽  
Electromagnetic Waves ◽  
Axial Magnetic Field ◽  
Numerical Study ◽  
Guide Magnetic Field

AbstractThe operation of a free-electron laser (FEL) with electromagnetic wave wiggler in the presence of an ion-channel guiding as well as an axial guide magnetic field is considered and compared. Theoretical studies of electron trajectories and dispersion relations in a combined ion electrostatic field as well as large-amplitude backward-propagating electromagnetic waves are analyzed. The large-amplitude wave acts like a magnetostatic wiggler in a FEL. The results of a numerical study are presented and discussed. It is shown that in the wiggler pumped ion-channel free-electron laser (WPIC-FEL), electron orbits and dispersion relation are time-dependent, and over time, electron orbits while oscillating bear a periodic motion.

Guided electromagnetic waves for damage detection and localization in metallic plates: numerical and experimental results

2020 ◽  
Vol 12 (6) ◽  
pp. 455-460
Author(s):  
Jochen Moll
Keyword(s):  
Damage Detection ◽  
Electromagnetic Waves ◽  
Numerical Study ◽  
Ultra Wideband ◽  
Destructive Testing ◽  
Material Defects ◽  
Wideband Signals ◽  
Rectangular Waveguides ◽  
Different Diameters ◽  
Detection And Localization

AbstractElectromagnetic waves in the microwave and millimeter-wave frequency range are used in non-destructive testing and structural health monitoring applications to detect material defects such as delaminations, cracks, or inclusions. This work presents a sensing concept based on guided electromagnetic waves (GEW), in which the waveguide forms a union with the structure to be inspected. Exploiting ultra-wideband signals a surface defect in the area under the waveguide can be detected and accurately localized. This paper presents numerical and experimental GEW results for a straight waveguide focusing on the detection of through holes and cracks with different orientation. It was found that the numerical model qualitatively replicates the experimental S-parameter measurements for holes of different diameters. A parametric numerical study indicates that the crack parameters such as its orientation and width has a significant influence on the interaction of the incident wave with the structural defect. On top, a numerical study is performed for complex-shaped rectangular waveguides including several waveguide bends. Besides a successful damage detection, the damage position can also be precisely determined with a maximum localization error of less than 3%.

Numerical Study of Plasma Flow Around a Reentry Vehicle During Atmospheric Reentry With an Unstructured Grid Solver

2015 ◽  
Author(s):  
Reo Nakasato ◽  
Yusuke Takahashi ◽  
Nobuyuki Oshima
Keyword(s):  
Shock Wave ◽  
Plasma Flow ◽  
Shock Layer ◽  
Electromagnetic Waves ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Aerodynamic Heating ◽  
Accurate Evaluation ◽  
Reentry Vehicle ◽  
Atmospheric Reentry

When a reentry vehicle enters the planetary atmosphere, a strong shock wave is generated and the strong aerodynamic heating appears. Gas temperature in front of the vehicle exceeds 10,000K and chemical reactions (ionizations and dissociations) occur behind the shock wave. Because the reentry vehicle is damaged by the aerodynamic heating, accurate evaluation of the aerodynamic heating in the high-enthalpy flow is necessary for the design and the development of the vehicle. The communication blackout phenomenon which prevents the propagation of the electromagnetic waves can occur by the characteristics of electrons in the shock layer to absorb and reflect the electromagnetic waves. To estimate the communicationable time and understand the behavior of the electromagnetic waves around the vehicle, the accurate evaluation of the plasma flow around the vehicle is also necessary. In this study, the three-dimensional numerical analysis was conducted to consider an angle of attack by using the analysis software for compressible fluid, RG-FaSTAR which has been developed by JAXA. Moreover, unstructured grids were used to make it easier to generate computational grid around the vehicle with complicated shape. Note that RG-FaSTAR is a version of FaSTAR (FaST Aerodynamic Routine) installing the real gas effect. We reproduced the actual flow field around the Atmospheric Reentry Demonstrator (ARD) which was launched by the European Space Agency (ESA) in 1998 and revealed the aerodynamic heating and plasma flow properties during atmospheric reentry. The computational result showed good agreement with measured pressure coefficient at the stagnation point. In addition, the features of the shock layer and the rear region around ARD were revealed.

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