Generation of double-frequency radiation in monotron with three-gap cavity

2021 ◽  
Vol 29 (6) ◽  
pp. 915-926
Author(s):  
Vadim Muchkaev ◽  
◽  
Anton Onishchenko ◽  
Vladislav Tsarev ◽  
◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Characteristic Impedance ◽  
Electronic Conductivity ◽  
Total Efficiency ◽  
Third Harmonic ◽  
Millimeter Wavelength ◽  
Simultaneous Excitation ◽  
Double Frequency ◽  
Linear Dimensions ◽  
Frequency Radiation

Purpose of this work is to study modes and conditions that make it possible to excite the highest type of microwave oscillations, the frequency of which is a multiple of the frequency of the main type, in a monotron with a three-band resonator. Method of the investigation is a numerical 3D modeling, used to calculate the dimensions and electrodynamic parameters of the resonator (characteristic impedance, coupling coefficient, relative electronic conductivity); operation modes of the monotron are considered, which are characterized by excitation of oscillations in the highest type oscillations. Result. In the resonator under consideration, it is possible to achieve a multiple (equal to three) ratio between the frequency of the 25th highest type of oscillations and the frequency of the π/2-type. It was shown that in such resonator simultaneous excitation of electromagnetic field on those frequencies can be made. The maximum of an output power achieved at 100.22 GHz is 15.4 W with an accelerating voltage of 7825 V and an electronic beam microperveance 0.36 µA/V3/2 . The maximal efficiency on a third harmonic is 0.83% while the total efficiency (generating electromagnetic waves of the first and the third harmonics) is up to 17%. Conclusion. It was set that the described method of generation of terahertz range radiation is promising for further investigation, as it solves problem that orthodox microwave devices meet in the millimeter wavelength range, such as small linear dimensions of the components and critical current density of the electronic beam.

scholarly journals Acoustic impedance measurement of snow density

1998 ◽  
Vol 26 ◽  
pp. 92-96 ◽  
Author(s):  
O. Marco ◽  
O. Buser ◽  
P. Villemain ◽  
F. Touvier ◽  
Ph. Revol
Keyword(s):  
Porous Media ◽  
Acoustic Wave ◽  
Gamma Rays ◽  
Electromagnetic Waves ◽  
Characteristic Impedance ◽  
Impedance Measurement ◽  
Acoustic Properties ◽  
Laboratory Measurements ◽  
Snow Density ◽  
Acoustic Parameters

Today, it is possible to estimate the density of snow in many different ways (gravimetry, attenuation of gamma rays and velocity of electromagnetic waves). In this paper, we suggest using the acoustic properties of snow. First, we recall the main studies on the acoustic properties of snow. Then, we show, from laboratory measurements, the correlation between density and the acoustic parameters of snow. We found a very good correlation between density and the modulus of the normalized characteristic impedance. We also show that use ofa three-parameter model simulating the propagation of an acoustic wave in porous media allows one to calculate the density of snow from its acoustic porosity.

scholarly journals Acoustic impedance measurement of snow density

1998 ◽  
Vol 26 ◽  
pp. 92-96 ◽  
Author(s):  
O. Marco ◽  
O. Buser ◽  
P. Villemain ◽  
F. Touvier ◽  
Ph. Revol
Keyword(s):  
Porous Media ◽  
Acoustic Wave ◽  
Gamma Rays ◽  
Electromagnetic Waves ◽  
Characteristic Impedance ◽  
Impedance Measurement ◽  
Acoustic Properties ◽  
Laboratory Measurements ◽  
Snow Density ◽  
Acoustic Parameters

Today, it is possible to estimate the density of snow in many different ways (gravimetry, attenuation of gamma rays and velocity of electromagnetic waves). In this paper, we suggest using the acoustic properties of snow. First, we recall the main studies on the acoustic properties of snow. Then, we show, from laboratory measurements, the correlation between density and the acoustic parameters of snow. We found a very good correlation between density and the modulus of the normalized characteristic impedance. We also show that use ofa three-parameter model simulating the propagation of an acoustic wave in porous media allows one to calculate the density of snow from its acoustic porosity.

scholarly journals Analysis Method for the Heating of the Human Eye Exposed to High Frequency Electromagnetic Fields

2007 ◽  
Vol 3 (1) ◽  
pp. 3 ◽  
Author(s):  
Andrés Peratta ◽  
Dragan Poljak
Keyword(s):  
Electromagnetic Scattering ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Specific Absorption Rate ◽  
Scattering Problem ◽  
Analysis Method ◽  
Human Eye ◽  
Time Harmonic ◽  
Standard Finite Element Method ◽  
Frequency Radiation

The paper studies the thermal rise in the human eye caused by time harmonic electromagnetic waves. An eye has been illuminated by a high frequency plane wave with powerdensity 5.0 mW/cm2. Such a problem has been considered as an electromagnetic scattering problem since part of EM energy is transmitted to the eye and part of it is reflected. The total electric field inside an eye and related Specific Absorption Rate (SAR) has been calculated in a frequency range from 0.7 to 4.4 GHz via a hybrid BEM/FEM approach. Knowing the SAR distribution inside the eye provides the calculation of related temperature rise in the human eye due to high frequency radiation by solving Bio-Heat Transfer Equation via standard finite element method.

Generation and radiation of third harmonics by s-polarized electromagnetic waves incident on a narrow inhomogeneous magnetoactive plasma layer

1989 ◽  
Vol 41 (1) ◽  
pp. 31-36 ◽  
Author(s):  
A. M. Hussein
Keyword(s):  
Electromagnetic Waves ◽  
Plasma Layer ◽  
Magnetoactive Plasma ◽  
Wave Generation ◽  
Inhomogeneous Layer ◽  
Harmonic Waves ◽  
Third Harmonic ◽  
Unmagnetized Plasma ◽  
Incident Waves ◽  
Inhomogeneous Magnetoactive Plasma

An investigation is made of wave generation and radiation of third harmonics by s-polarized electromagnetic waves incident on a narrow inhomogeneous layer of a magnetoactive plasma. The amplitudes of the radiated third-harmonic waves are calculated. In contrast with second harmonics, third harmonics are radiated for the case of normally incident waves on an unmagnetized plasma.

scholarly journals Effectiveness of Rack-Level Fans—Part I: Energy Savings Through Consolidation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Richard Eiland ◽  
John Edward Fernandes ◽  
Bharath Nagendran ◽  
Veerendra Mulay ◽  
Dereje Agonafer
Keyword(s):  
Energy Savings ◽  
Total Efficiency ◽  
Single Server ◽  
Case Scenario ◽  
Double Peak ◽  
Similar Reduction ◽  
Worst Case ◽  
Linear Dimensions ◽  
Initial Characterization

In general, smaller fans operate at lower efficiencies than larger fans of proportional linear dimensions. In this work, the applicability of replacing smaller, 60 mm baseline fans from within the chassis of web servers with an array of larger, geometrically proportional 80 mm and 120 mm fans consolidated to the back of a rack is experimentally tested. Initial characterization of the selected fans showed that the larger fans operate at double peak total efficiency of the smaller fans. A stack of four servers were used in a laboratory setting to represent a rack of servers. When all four servers were stressed at uniform computational loadings, the 80 mm fans resulted in 50.1–52.6% reduction in total rack fan power compared to the baseline fans. The 120 mm fans showed similar reduction in rack fan power of 47.6–54.0% over the baseline. Since actual data centers rarely operate at uniform computational loading across servers in a rack, a worst case scenario test was conceived in which the array of larger fans were controlled by a single server operating at peak computational workload while the other three in the rack remained idle. Despite significant overcooling in the three idle servers, the 80 mm and 120 mm fan configurations still showed 35% and 34% reduction in total rack fan power compared to the baseline fans. The findings strongly suggest that a rack-level fan scheme in which servers share airflow from an array of consolidated larger fans is superior to traditional chassis fans.

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