scholarly journals ON GENERATION OF A WAVE PACKAGE IN A WAVEGUIDE, FILLED ACTIVE MEDIUM

2020 ◽  
pp. 105-109
Author(s):  
V.V. Kostenko ◽  
V.M. Kuklin ◽  
E.V. Poklonskiy
Keyword(s):  
Electromagnetic Waves ◽  
Oscillatory Behavior ◽  
Classical Electrodynamics ◽  
Field Energy ◽  
Level System ◽  
Spatially Inhomogeneous ◽  
Excited Wave ◽  
Wave Package ◽  
Field Energy Density ◽  
The Relationship

Excitation of electromagnetic waves in a waveguide with a medium, which is a two-level system, is considered. To describe the processes, both classical electrodynamics methods and quantum mechanics methods are used. The nature of the processes under study turns out to depend on the relationship between the Rabi frequency and the line width of the excited wave packet. It is shown that if the field energy density is high, then spatially inhomogeneous Rabi frequencies arise, which leads to oscillatory behavior of the wave field amplitudes. If the levels of the excited field are small, then the dynamics of the two-level quantum system becomes monotonic and the population inversion tends to zero.

scholarly journals Finite size scaling in the solar wind magnetic field energy density as seen by WIND

2002 ◽  
Vol 29 (10) ◽  
pp. 86-1-86-4 ◽  
Author(s):  
B. Hnat ◽  
S. C. Chapman ◽  
G. Rowlands ◽  
N. W. Watkins ◽  
W. M. Farrell
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Energy Density ◽  
Finite Size ◽  
Field Energy ◽  
Finite Size Scaling ◽  
Size Scaling ◽  
Magnetic Field Energy ◽  
Solar Wind Magnetic Field ◽  
Field Energy Density

scholarly journals Quantum speedup, non-Markovianity and formation of bound state

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Bahram Ahansaz ◽  
Abbas Ektesabi
Keyword(s):  
Bound States ◽  
Decisive Role ◽  
Bound State ◽  
Negative Energy ◽  
Quantum Evolution ◽  
Level System ◽  
System Environment ◽  
Speed Up ◽  
The Relationship ◽  
Quantum Speedup

Abstract In this paper, we investigate the relationship between the quantum speedup, non-Markovianity and formation of a system-environment bound state. Previous results show a monotonic relation between these three such that providing bound states with more negative energy can lead to a higher degree of non-Markovianity, and hence to a greater speed of quantum evolution. By studying dynamics of a dissipative two-level system or a V-type three-level system, when similar and additional systems are present, we reveal that the quantum speedup is exclusively related to the formation of the system-environment bound state, while the non-Markovian effect of the system dynamics is neither necessary nor sufficient to speed up the quantum evolution. On the other hand, it is shown that only the formation of the system-environment bound state plays a decisive role in the acceleration of the quantum evolution.

Multi-block electret-based mechanical antenna model for low frequency communication

2019 ◽  
Vol 10 (05) ◽  
pp. 1950036
Author(s):  
Bowen Liang ◽  
Yong Cui ◽  
Xiao Song ◽  
Liangya Li ◽  
Chen Wang
Keyword(s):  
Electromagnetic Waves ◽  
Rotation Speed ◽  
Model Simulation ◽  
Low Frequency ◽  
Signal Frequency ◽  
Entire System ◽  
Antenna Structure ◽  
Distribution Mode ◽  
The Relationship ◽  
Mechanical Movement

In an LF/VLF transmission system, the performance of the antenna is of great importance to the entire system. Currently, the electret-based mechanical LF/VLF antenna uses mechanical movement to accelerate electret charges to produce LF/VLF electromagnetic waves, and the frequency of these electromagnetic waves is limited by the rotation speed of the actuating motor. Based on research that addressed the relationship between antenna structure and electromagnetic wave frequency, this paper — in order to increase the frequency of electromagnetic waves — alters the charge distribution mode of the mechanical antenna while keeping the motor’s rotational speed constant to realize an increase of transmission signal frequency. The effectiveness of this method was verified by model simulation.

scholarly journals AXION-ELECTROMAGNETIC WAVES

2013 ◽  
Vol 28 (35) ◽  
pp. 1350162 ◽  
Author(s):  
LUCA VISINELLI
Keyword(s):  
Gauge Symmetry ◽  
Electromagnetic Waves ◽  
Maxwell Equations ◽  
Internal Symmetry ◽  
Classical Electrodynamics ◽  
Gauge Potential ◽  
Explicit Solutions ◽  
Duality Symmetry ◽  
Axion Field ◽  
External Sources

We extend the duality symmetry between the electric and the magnetic fields to the case in which an additional axion-like term is present, and we derive the set of Maxwell equations that preserves this symmetry. This new set of equations allows for a gauge symmetry extending the ordinary symmetry in the classical electrodynamics. We obtain explicit solutions for the new set of equations in the absence of external sources, and we discuss the implications of a new internal symmetry between the axion field and the electromagnetic gauge potential.

scholarly journals COSMOLOGICAL CONSTANT AND THE SPEED OF LIGHT

2001 ◽  
Vol 10 (01) ◽  
pp. 41-48 ◽  
Author(s):  
W. R. ESPÓSITO MIGUEL ◽  
J. G. PEREIRA
Keyword(s):  
Gravitational Field ◽  
Cosmological Constant ◽  
Electromagnetic Waves ◽  
Light Propagation ◽  
Wave Optics ◽  
Speed Of Light ◽  
Positive Cosmological Constant ◽  
Velocity Of Light ◽  
Refractive Medium ◽  
The Relationship

By exploring the relationship between the propagation of electromagnetic waves in a gravitational field and the light propagation in a refractive medium, it is shown that, in the presence of a positive cosmological constant, the velocity of light will be smaller than its special relativity value. Then, restricting again to the domain of validity of geometrical optics, the same result is obtained in the context of wave optics. It is argued that this phenomenon and the anisotropy in the velocity of light in a gravitational field are produced by the same mechanism.

scholarly journals OPTIMAL FOCUSING FOR MONOCHROMATIC SCALAR AND ELECTROMAGNETIC WAVES

2011 ◽  
Vol 23 (08) ◽  
pp. 839-863
Author(s):  
JEFFREY RAUCH
Keyword(s):  
Wave Equation ◽  
Electric Field ◽  
Electromagnetic Waves ◽  
Field Energy ◽  
Scalar Case ◽  
Far Field ◽  
Maxwell’S Equation ◽  
Maximum Field ◽  
Optimal Focusing ◽  
Maxwell's Equation

For monochromatic solutions of D'Alembert's wave equation and Maxwell's equations, we obtain sharp bounds on the sup norm as a function of the far field energy. The extremizer in the scalar case is radial. In the case of Maxwell's equation, the electric field maximizing the value at the origin follows longitude lines on the sphere at infinity. In dimension d = 3, the highest electric field for Maxwell's equation is smaller by a factor 2/3 than the highest corresponding scalar waves. The highest electric field densities on the balls BR(0) occur as R → 0. The density dips to half max at R approximately equal to one third the wavelength. For these small R, the extremizing fields are identical to those that attain the maximum field intensity at the origin.

Analysis of the conductivity property of live working shielding clothing

2017 ◽  
Vol 48 (3) ◽  
pp. 643-659 ◽  
Author(s):  
Ying Su ◽  
Xiuchen Wang ◽  
Yaping Li ◽  
Zhen Pan ◽  
Zhe Liu
Keyword(s):  
Electromagnetic Waves ◽  
Structural Complexity ◽  
Measuring Point ◽  
Conductivity Property ◽  
Structure Line ◽  
Design Production ◽  
Point To Point ◽  
Representative Points ◽  
The Relationship ◽  
Resistance Value

Live working shielding clothing must be worn when working under the high-pressure environment. High voltage and electromagnetic waves are shielded by conducting principle, so as to reduce the harm to human body. At present, the relationship between the point to point resistance and the structure of clothing is not clear in the production and research of shielding clothing, its design, production, and test lack of theoretical guidance. In this paper, the electrical conductivity of the clothing is studied by measuring the point to point resistance of shielding clothing. The suitable method of measuring point to point resistance is designed, and test platform is build by U610E's digital multimeter and homemade special electrode and other equipment. The representative points are selected from the main latitude lines of clothing and the parts of contacting electrified equipment when wearing clothes, then measure the resistance value between different points. Through the analysis of the experimental results it can be found that, on the basis of good connection, the farther the distance between two points, the smaller the resistance value and the better the connectivity; the resistance value of the points that frequently contact with electrified equipment is significantly smaller than others; about the same distance of two points, if there is structure line in the middle, the resistance value is large; the structural complexity is proportional to the resistance value. It is concluded that the point to point resistance of shielding garment is related to the parts of contacting with electrified equipment during operation, the complexity of structure, and other relevant factors. In the design and production, we should focus on reducing the resistance value between the most distal of clothing, the parts of contacting electrification equipment and limbs, in order to increase its connectivity; the structural design of clothing should be simplified.

scholarly journals Electrometry by optical charge conversion of deep defects in 4H-SiC

2018 ◽  
Vol 115 (31) ◽  
pp. 7879-7883 ◽  
Author(s):  
G. Wolfowicz ◽  
S. J. Whiteley ◽  
D. D. Awschalom
Keyword(s):  
Electric Fields ◽  
High Frequency ◽  
Room Temperature ◽  
Field Energy ◽  
Active Point ◽  
Rate Dependent ◽  
Host Materials ◽  
All Optical ◽  
Field Energy Density ◽  
Optical Charge

Optically active point defects in various host materials, such as diamond and silicon carbide (SiC), have shown significant promise as local sensors of magnetic fields, electric fields, strain, and temperature. Modern sensing techniques take advantage of the relaxation and coherence times of the spin state within these defects. Here we show that the defect charge state can also be used to sense the environment, in particular high-frequency (megahertz to gigahertz) electric fields, complementing established spin-based techniques. This is enabled by optical charge conversion of the defects between their photoluminescent and dark charge states, with conversion rate dependent on the electric field (energy density). The technique provides an all-optical high-frequency electrometer which is tested in 4H-SiC for both ensembles of divacancies and silicon vacancies, from cryogenic to room temperature, and with a measured sensitivity of 41±8(V/cm)2/Hz. Finally, due to the piezoelectric character of SiC, we obtain spatial 3D maps of surface acoustic wave modes in a mechanical resonator.

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