Development of the Two-Stage Planar Fem for the Terahertz Band on the Basis of the ELMI Accelerator

2012 ◽  
Vol 7 (1) ◽  
pp. 5-14
Author(s):  
Andrey Arzhannikov ◽  
Naum Ginzburg ◽  
Vladislav Zaslavkiy ◽  
Irina Zotova ◽  
Petr Kalinin ◽  
...  
Keyword(s):  
High Power ◽  
High Frequency ◽  
Scattered Radiation ◽  
Electron Beams ◽  
Low Frequency ◽  
Stimulated Scattering ◽  
Two Stage ◽  
Terahertz Band ◽  
Bragg Structures ◽  
Cathode Unit

Project of the two-stage FEM-generator based on the ELMI accelerator with two parallel sheet electron beams formed in a single cathode unit is under development currently. In this scheme the first beam is used in the low-frequency section of the FEM for generating of high-power 75 GHz radiation. This radiation than goes through the coupling waveguides to the second channel and operates as a pumping wave which scatter on the second beam into the terahertz band. Our paper is devoted to modeling of various stimulated scattering regimes in this high-frequency section. Regime of the selfamplified spontaneous emission (SASE) is considered as well as a generator with resonator for the scattered radiation formed with advanced Bragg structures, based on coupling of traveling and quasi-critical waves

Scattering of electromagnetic waves by hybrid waves in a two-electron-temperature plasma

1991 ◽  
Vol 46 (1) ◽  
pp. 99-106 ◽  
Author(s):  
S. K. Sharma ◽  
A. Sudarshan
Keyword(s):  
Growth Rate ◽  
Electron Temperature ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Lower Hybrid ◽  
Stimulated Scattering ◽  
Coupled Modes ◽  
Temperature Plasma ◽  
Electrostatic Perturbation

In this paper, we use the hydrodynamic approach to study the stimulated scattering of high-frequency electromagnetic waves by a low-frequency electrostatic perturbation that is either an upper- or lower-hybrid wave in a two-electron-temperature plasma. Considering the four-wave interaction between a strong high-frequency pump and the low-frequency electrostatic perturbation (LHW or UHW), we obtain the dispersion relation for the scattered wave, which is then solved to obtain an explicit expression for the growth rate of the coupled modes. For a typical Q-machine plasma, results show that in both cases the growth rate increases with noh/noc. This is in contrast with the results of Guha & Asthana (1989), who predicted that, for scattering by a UHW perturbation, the growth rate should decrease with increasing noh/noc.

scholarly journals Piezoelectric Energy Harvesting with an Ultrasonic Vibration Source

Actuators ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 8
Author(s):  
Tao Li ◽  
Pooi Lee
Keyword(s):  
Energy Harvesting ◽  
High Power ◽  
High Frequency ◽  
Energy Harvester ◽  
Impedance Matching ◽  
Low Frequency ◽  
Vibration Source ◽  
Piezoelectric Energy ◽  
Power Ultrasonic ◽  
Ultrasonic Cutting

A piezoelectric energy harvester was developed in this paper. It is actuated by the vibration leakage from the nodal position of a high-power ultrasonic cutting transducer. The harvester was excited at a low displacement amplitude (0.73 µmpp). However, its operation frequency is quite high and reaches the ultrasonic range (24.4 kHz). Compared with another low frequency harvester (66 Hz), both theoretical and experimental results proved that the advantages of this high frequency harvester include (i) high current generation capability (up to 20 mApp compared to 1.3 mApp of the 66 Hz transducer) and (ii) low impedance matching resistance (500 Ω in contrast to 50 kΩ of the 66 Hz transducer). This energy harvester can be applied either in sensing, or vibration controlling, or simply energy harvesting in a high-power ultrasonic system.

Theory of stimulated scattering of large-amplitude waves

1999 ◽  
Vol 61 (1) ◽  
pp. 129-134 ◽  
Author(s):  
L. STENFLO
Keyword(s):  
Dispersion Relation ◽  
High Frequency ◽  
Large Amplitude ◽  
Pump Wave ◽  
Low Frequency ◽  
Nonlinear Dispersion ◽  
Stimulated Scattering ◽  
Nonlinear Dispersion Relation

A nonlinear dispersion relation that governs the interaction between a high-frequency pump wave and the low-frequency modes in a plasma is derived. Previous results are generalized and discussed.

Dynamic hysteresis and scaling behaviours of lead-free 0.94Bi0.5Na0.5TiO3–0.06BaTiO3 bulk ceramics

RSC Advances ◽  
2016 ◽  
Vol 6 (36) ◽  
pp. 30148-30153 ◽  
Author(s):  
Chun-Ming Wang ◽  
Kenny Lau ◽  
Qian Wang
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Lead Free ◽  
Linear Scaling ◽  
Two Stage ◽  
Dynamic Hysteresis

The dynamic hysteresis and scaling behaviours of MPB composition BNT-6BT were investigated, which exhibits three-stage evolution of scaling behaviors at medium-high frequency and two-stage linear scaling behaviors at low frequency in the E0 term.

scholarly journals Брэгговские дефлекторы волновых потоков для мощных релятивистских мазеров

2019 ◽  
Vol 89 (5) ◽  
pp. 762
Author(s):  
A.В. Аржанников ◽  
Н.С. Гинзбург ◽  
В.Ю. Заславский ◽  
П.В. Калинин ◽  
Н.Ю. Песков ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Microwave Radiation ◽  
High Power ◽  
Scattered Radiation ◽  
Transverse Direction ◽  
Propagation Direction ◽  
Planar Waveguides ◽  
Bragg Structures ◽  
Power Wave

AbstractQuasi-optical Bragg structures that represent sections of planar waveguides with tilted (with respect to the beam propagation direction) corrugation are studied. It is shown that such structures may serve as efficient deflectors for high-power wave fluxes and, hence, can be used for separation of microwave radiation and electron beam in relativistic masers. The corrugation configuration is optimized to increase the efficiency of transformation of wave fluxes to the transverse direction and improve uniformity of the spatial distribution of scattered radiation. The simulated results are verified using cold electrodynamic tests.

Vibration Isolation on Lightweight Floor Structures

2002 ◽  
Vol 9 (4) ◽  
pp. 257-269 ◽  
Author(s):  
P Hammer ◽  
J Brunskog
Keyword(s):  
High Frequency ◽  
Vibration Isolation ◽  
Low Frequency ◽  
High Mobility ◽  
Frequency Range ◽  
Two Stage ◽  
One Stage ◽  
Straight Line ◽  
Floor Structure

A theoretical and experimental study of vibration isolation for a source on a lightweight floor structure is presented. The effectiveness of one-stage and two-stage isolator systems is studied. Approximate formulae are presented for both low and high frequency for the receiver, the floor structure. For the mobility, a comparison between approximate formulae, numerical exact results and experimental results are presented. The low frequency asymptote for the approximate mobility is valid up to l/λp ≈ 1/4. The high frequency asymptote is valid from l/λp ≈ 1/2. A straight line can be drawn between these two points for the intermediate range 1/4 < l/λp < 1/2. Finally, a case study is presented. A fan is mounted on a wooden joist floor. The effect of both one and two stage isolation is demonstrated. It is clearly seen that the high mobility situation for the receiver is increased by adding a rigid body to the mount. Hence, in the frequency range of interest, the ‘receiver’ acts more or less as a blocked termination. A two-stage isolator almost completely eliminates the structure borne sound and compared to a one-stage isolator it reduces the sound by 20 dB at the rpm for the fan.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

SEM image sharpness analysis

1996 ◽  
Vol 54 ◽  
pp. 142-143
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Quantitative Information ◽  
Primary Electron ◽  
Image Sharpness ◽  
Critical Dimensions ◽  
Sem Image ◽  
Frequency Changes ◽  
Electron Microscopes ◽  
Scanning Electron

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at NIST and the fundamentals and results are discussed in this paper.In scanning electron microscopy, two of the most important instrument parameters are the size and shape of the primary electron beam and any image taken in a scanning electron microscope is the result of the sample and electron probe interaction. The low frequency changes in the video signal, collected from the sample, contains information about the larger features and the high frequency changes carry information of finer details. The sharper the image, the larger the number of high frequency components making up that image. Fast Fourier Transform (FFT) analysis of an SEM image can be employed to provide qualitiative and ultimately quantitative information regarding the SEM image quality.

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