scholarly journals Memory Efficient Method for Electromagnetic Multi-Region Models Using Scattering Matrices

2018 ◽  
Vol 23 (4) ◽  
pp. 71 ◽  
Author(s):  
C. Custers ◽  
J. Jansen ◽  
E. Lomonova
Keyword(s):  
Electromagnetic Field ◽  
Boundary Conditions ◽  
Efficient Method ◽  
Maximum Size ◽  
Scattering Matrix ◽  
Matrix Approach ◽  
Matrix Formulation ◽  
Scattering Matrices ◽  
Memory Efficient

This paper describes the scattering matrix approach to obtain the solution to electromagnetic field quantities in harmonic multi-layer models. Using this approach, the boundary conditions are solved in such way that the maximum size of any matrix used during the computations is independent of the number of regions defined in the problem. As a result, the method is more memory efficient than classical methods used to solve the boundary conditions. Because electromagnetic sources can be located inside the regions of a configuration, the scattering matrix formulation is developed to incorporate these sources into the solving process. The method is applied to a 3D electromagnetic configuration for verification.

“Preparation of Single Crystalline Gold Films for ED Studies”

1972 ◽  
Vol 30 ◽  
pp. 634-635
Author(s):  
Joseph D. C. Peng
Keyword(s):  
Crystal Morphology ◽  
Diffraction Theory ◽  
Scattering Matrix ◽  
Vacuum Evaporation ◽  
Gold Films ◽  
Matrix Formulation ◽  
Silver Films ◽  
Single Crystalline ◽  
Grating Pattern ◽  
Stacking Disorder

The relative intensities of the ED spots in a cross-grating pattern can be calculated using N-beam electron diffraction theory. The scattering matrix formulation of N-beam ED theory has been previously applied to imperfect microcrystals of gold containing stacking disorder (coherent twinning) in the (111) crystal plane. In the present experiment an effort has been made to grow single-crystalline, defect-free (111) gold films of a uniform and accurately know thickness using vacuum evaporation techniques. These represent stringent conditions to be met experimentally; however, if a meaningful comparison is to be made between theory and experiment, these factors must be carefully controlled. It is well-known that crystal morphology, perfection, and orientation each have pronounced effects on relative intensities in single crystals.The double evaporation method first suggested by Pashley was employed with some modifications. Oriented silver films of a thickness of about 1500Å were first grown by vacuum evaporation on freshly cleaved mica, with the substrate temperature at 285° C during evaporation with the deposition rate at 500-800Å/sec.

Simulations of electric field at the initiation altitudes of sprites and halos generated by the thundercloud charge structure and lightning channels of causative return strokes

2021 ◽  
Author(s):  
Petr Kaspar ◽  
Ivana Kolmasova ◽  
Ondrej Santolik ◽  
Martin Popek ◽  
Pavel Spurny ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Electric Field ◽  
Boundary Conditions ◽  
Free Space ◽  
Nonlinear Effects ◽  
Charge Structure ◽  
Transient Luminous Events ◽  
Lightning Channel ◽  
Free Parameters

<p><span>Sprites and halos are transient luminous events occurring above thunderclouds. They can be observed simultaneously or they can also appear individually. Circumstances leading to initiation of these events are still not completely understood. In order to clarify the role of lightning channels of causative lightning return strokes and the corresponding thundercloud charge structure, we have developed a new model of electric field amplitudes at halo/sprite altitudes. It consists of electrostatic and inductive components of the electromagnetic field generated by the lightning channel in free space at a height of 15 km. Above this altitude we solve Maxwell’s equations self-consistently including the nonlinear effects of heating and ionization/attachment of the electrons. At the same time, we investigate the role of a development of the thundercloud charge structure and related induced charges above the thundercloud. We show how these charges lead to the different distributions of the electric field at the initiation heights of the halos and sprites. We adjust free parameters of the model using observations of halos and sprites at the Nydek TLE observatory and using measurements of luminosity curves of the corresponding return strokes measured by an array of fast photometers. The latter measurements are also used to set the boundary conditions of the model.</span></p>

Scattering-matrix approach to multilayer diffraction

1995 ◽  
Vol 12 (5) ◽  
pp. 1097 ◽  
Author(s):  
N. P. K. Cotter ◽  
T. W. Preist ◽  
J. R. Sambles
Keyword(s):  
Scattering Matrix ◽  
Matrix Approach
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