scholarly journals Electron bunchers for industrial RF linear accelerators: theory and design guide

2021 ◽  
Vol 136 (4) ◽  
Author(s):  
Sergey V. Kutsaev
Keyword(s):  
High Frequency ◽  
Review Paper ◽  
Relativistic Electrons ◽  
Linear Accelerators ◽  
Velocity Change ◽  
Beam Physics ◽  
Industrial Grade ◽  
Acceleration Rate ◽  
Design Guide ◽  
Relativistic Regime

AbstractThe acceleration of electrons in resonant linear accelerators (linacs) typically consists of three main stages: (1) emission of the electrons from the cathode and their pre-acceleration with a DC field to the energy of tens of keV; (2) grouping the DC electron beam into bunches and their synchronization with the correct phase of high-frequency electromagnetic fields, and (3) accelerating the bunches of relativistic electrons to the required energies. Although many books describe the theoretical and practical aspects of electron linac design, most of them concentrate on beam physics in either the gun stage or in the relativistic regime, while leaving the description of the bunching process rather general. The physics of non-relativistic motion is described in the literature on ion accelerators, but in practice, it cannot be scaled to electron machines due to the significantly different particle mass and acceleration rate, beam velocity change, and frequencies. In this tutorial review paper, we will fill this gap with a detailed description of the bunching process and provide practical advice on the design of bunching sections in industrial-grade electron linacs.

INTERDIGITAL STRUCTURES OF HEAVY IONS LINEAR ACCELERATORS: THEIR TUNING, BEAMS FOCUSING AND USE (REVIEW)

2019 ◽  
pp. 17-22
Author(s):  
О.F. Dyachenko
Keyword(s):  
High Frequency ◽  
Heavy Ions ◽  
Linear Accelerator ◽  
Mass Number ◽  
Linear Accelerators ◽  
New Approaches

The review interdigital H-accelerating structures (IHAS) of the heavy ions linear accelerators developed in NSC KIPT throughout several tens of years is presented. It is shown that in structures with individual stems all kinds of focusings are applicable: quadrupole, grid, alternating-phase (APF, in various variants), high-frequency (in various variants) and their combinations. Corresponding constructive decisions are developed for accelerating structures of different function. Essentially new approaches for their adjustment for the set distribution of an accelerating field and frequency (by countering corner change) and some new regulating elements are offered: the end resonant elements of adjustment (EREA) and inductance-capacitor elements (сontrivances). By results of modelling three real accelerating sections which are created at modernization of the multicharge ions linear accelerator were developed. New variants pre-stripping area of the heavy ions accelerator with the relation of mass number to charge A/q = 20 are offered.

scholarly journals ADJUSTMENT OF RESONANCE FREQUENCY IN H-STRUCTURES ACCELERATING

2021 ◽  
pp. 64-67
Author(s):  
S.O. Vdovin ◽  
Ye.V. Gusev ◽  
L.D. Lobzov ◽  
O.P. Podolayk ◽  
M.G. Shulika
Keyword(s):  
Resonant Frequency ◽  
Resonance Frequency ◽  
High Frequency ◽  
Rf Power ◽  
Linear Accelerators ◽  
Input Devices ◽  
Temperature Mode ◽  
Accelerating Structure ◽  
And Control

It is necessary to adjust the resonant frequency of the accelerating structures during operation of high-frequency linear accelerators on the H-wave. The deviation of the resonant frequency of the resonator from the calculated value is due to the connection of input devices and control of RF power when changing the level of matching of the resonator with the feeder line that transports the RF power to the resonator, as well as when changing the temperature mode of the resonator. The problem is especially urgent when the accelerator structure consists of several resonators. The paper presents the designs of several resonant frequency tuners and the results of their research. The influence of the change of the frequency of oscillations excited in the accelerating structure on the parameters of the accelerated beam is considered.

scholarly journals MYOPATHY AS A DESTABILIZING FACTOR OF MEAT QUALITY FORMATION

2019 ◽  
Vol 4 (3) ◽  
pp. 24-31 ◽  
Author(s):  
Anastasiia A. Semenova ◽  
Tatiana G. Kuznetsova ◽  
Victoria V. Nasonova ◽  
Roman V. Nekrasov ◽  
Nadezhda V. Bogolyubova
Keyword(s):  
Vitamin E ◽  
Meat Quality ◽  
Muscle Tissue ◽  
High Frequency ◽  
Broiler Chickens ◽  
Review Paper ◽  
Mitochondrial Calcium ◽  
Technological Properties ◽  
Pathological Conditions ◽  
Wooden Breast

This review paper is devoted to myopathy of slaughter animals and poultry, and examines a relationship between fast growth of muscle tissue in hybrid pigs, broiler chickens and turkey, and high frequency of detection of spontaneous or idiopathic myopathies. The development of myopathy reduces consumer and technological properties of meat, and leads to emergence of different pathological conditions (PSE or RSE meat, «destructured meat», «white» or «green» meat, punctate hemorrhage, «wooden breast» and others). Two types of myopathic conditions are examined: myopathies caused by stress in animals and nutritional myopathies, which contribution to meat quality deterioration seems to be determinative. It is shown that the basis of the mechanism of the myopathy development is the mechanism of the successive changes in muscle tissue: damage of cell membranes and release of mitochondrial calcium, which causes hypercontraction, dystrophic changes, atrophy and necrosis of muscle fibers. To alleviate the damaging effect of two types of myopathies, different substances-adaptogens (selenium, vitamin E, flavonoids and others) can be used. It is stated that the requirements of animals in adaptogens change with an increase in the indicators of their productivity.

High-Resolution Observations of Centaurus-A and Pictor-A at 160 MHz

1975 ◽  
Vol 2 (6) ◽  
pp. 336-338 ◽  
Author(s):  
O.B. Slee ◽  
K.V. Sheridan
Keyword(s):  
High Resolution ◽  
Radio Emission ◽  
Energy Distribution ◽  
High Frequency ◽  
Angular Resolution ◽  
Radio Galaxies ◽  
Relativistic Electrons ◽  
Frequency Measurements ◽  
Centaurus A

Since early 1974 the radioheliograph operated by the Division of Radiophysics at Culgoora, N.S.W. has been used in a 160 MHz study of ~2000 catalogued sources in the declination range -46° to +35°. In addition to measurements of flux densities and accurate positions at 160 MHz, brightness distributions are obtained for the sources that can be resolved by the 1’.9 × 1’.9 arc beams. A comparison of the brightness distributions at 160 MHz with those obtained from high-frequency measurements with similar angular resolution can yield valuable information about the energy distribution of the relativistic electrons, which are believed to be responsible for the radio emission from most nonthermal sources. Among the first objects to be examined were the strong southern radio galaxies Centaurus-A and Pictor-A.

Recent Progress in Gallium Oxide and Diamond Based High Power and High-Frequency Electronics

2019 ◽  
Vol 28 (01n02) ◽  
pp. 1940004 ◽  
Author(s):  
Md Nazmul Hasan ◽  
Edward Swinnich ◽  
Jung-Hun Seo
Keyword(s):  
High Power ◽  
High Frequency ◽  
Performance Metrics ◽  
Review Paper ◽  
Superior Performance ◽  
Semiconductor Materials ◽  
Device Performance ◽  
Growth Technique ◽  
Performance Matrix ◽  
High Frequency Devices

In recent years, the emergence of the ultrawide‐bandgap (UWBG) semiconductor materials that have an extremely large bandgap, exceeding 5eV including AlGaN/AlN, diamond, β-Ga2O3, and cubic BN, provides a new opportunity in myriad applications in electronic, optoelectronic and photonics with superior performance matrix than conventional WBG materials. In this review paper, we will focus on high power and high frequency devices based on two most promising UWBG semiconductors, β-Ga2O3 and diamond among various UWBG semiconductor devices. These two UWBG semiconductors have gained substantial attention in recent years due to breakthroughs in their growth technique as well as various device engineering efforts. Therefore, we will review recent advances in high power and high frequency devices based on β-Ga2O3 and diamond in terms of device performance metrics such as breakdown voltage, power gain, cut off frequency and maximum operating frequency.

Seismic radiation from circular cracks growing at variable rupture velocity

1994 ◽  
Vol 84 (4) ◽  
pp. 1199-1215
Author(s):  
Tamao Sato
Keyword(s):  
Radiation Pattern ◽  
High Frequency ◽  
Pulse Width ◽  
Present Method ◽  
Body Waves ◽  
Rupture Velocity ◽  
Continuous Change ◽  
Velocity Change ◽  
Acceleration Pulse ◽  
Frequency Radiation

Abstract We have investigated the far-field body waves emitted by a circular fault growing at variable rupture velocity. The slip motion on the fault is constructed by assuming that the self-similar slip distribution holds at every successive instant of rupture formation for a circular crack. The present method permits us to evaluate not only the high-frequency but also the low-frequency radiation. It is also possible to handle both abrupt and continuous change in rupture velocity. The resultant expression for the radiation does not involve an integral. It is expressed in a closed form that contains information about the isochrone properties of the two extreme points having the minimum and maximum distances from the observer. Because of its simplicity and high computational speed, the present method provides us with a basic tool for simulating the radiation from seismic sources with a multitude of irregular rupture growth. The property of acceleration pulse radiated by continuous change in rupture velocity has been investigated. The time duration of the velocity change is assumed to be short but to take a finite time. The shape of the rupture front that is effective in radiating the high-frequency radiation is presumed to be semicircular. The acceleration pulse demonstrates a directivity with respect to both the pulse width and amplitude. The pulse width is, on average, given by the duration of the velocity change, and it is modulated by the directivity factor, which depends on the rupture velocity averaged over the change in rupture velocity. The pulse width radiated toward the growth direction of the semi-circular rupture front is shorter than that radiated toward the opposite side. The spectral amplitude of the acceleration pulse depends linearly on the strain, the radius of the rupture front at which the rupture velocity starts to change, the magnitude of the change in rupture velocity, and the generalized radiation pattern coefficient. The directivity of the radiation pattern coefficient is stronger than that for the case of an abrupt change in rupture velocity. In the case where the rupture stops completely, the radiation pattern coefficient is simply controlled by the magnitude of the change in rupture velocity. If we deal with a partial drop of the rupture velocity, however, we must consider the average rupture velocity as well to fully describe the radiation pattern. A procedure is presented for retrieving the model parameters from acceleration pulse data. The present results with regard to the acceleration pulse do not require the coherent movement of the rupture front over the entire circle. The results are applicable to more general cases where the rupture front moves coherently over a certain restricted segment, though the range of the segment has to become wider as the duration of the change in rupture velocity increases.

FAST continuum mapping of the SNR VRO 42.05.01

2021 ◽  
Author(s):  
Li Xiao ◽  
Ming Zhu ◽  
Xiaohui Sun ◽  
Peng Jiang ◽  
Chun Sun
Keyword(s):  
Spectral Index ◽  
High Frequency ◽  
Supernova Remnants ◽  
Turbulent Medium ◽  
Relativistic Electrons ◽  
Index Distribution ◽  
Shock Density ◽  
Post Shock ◽  
5 Ghz ◽  
Shell Region

Abstract The relativistic electrons rotate in the enhanced magnetic field of the supernova remnants and emit the synchrotron radio emission.We aim to use the Five-hundred-meter Aperture Spherical radio Telescope (FAST) to obtain a sensitive continuum map of the SNR VRO 42.05.01 (G166.0+4.3) at 1240 MHz. The 500 MHz bandwidth is divided into low and high-frequency bands centered at 1085 and 1383 MHz to investigate the spectral index variations within the remnant, together with the Effelsberg 2695 MHz data. We obtained an integrated flux density of 6.2±0.4 Jy at 1240 MHz for VRO 42.05.01, consistent with previous results. The spectral index found from TT-plot between 1240 and 2695 MHz agrees with previous values from 408 MHz up to 5 GHz. The three-band spectral index distribution shows a clear flatter value of α ∼ −0.33 in the shell region and steeper index of α = −0.36 − −0.54 in the wing region. The flatter spectral index in the shell region could be attributed to a second-order Fermi process in the turbulent medium in the vicinity of the shock and/or a higher compression ratio of shock and a high post-shock density than that in elsewhere.

scholarly journals Dispersion relation of low-frequency electrostatic waves in plasmas with relativistic electrons

2016 ◽  
Vol 34 (1) ◽  
pp. 178-186 ◽  
Author(s):  
B. Touil ◽  
A. Bendib ◽  
K. Bendib-Kalache ◽  
C. Deutsch
Keyword(s):  
Dispersion Relation ◽  
Debye Length ◽  
Low Frequency ◽  
Relativistic Effects ◽  
Relativistic Electrons ◽  
Complex Frequency ◽  
Ion Temperature ◽  
Electrostatic Waves ◽  
Relativistic Regime ◽  
Analytic Expressions

AbstractThe dispersion relation of electrostatic waves with phase velocities smaller than the electron thermal velocity is investigated in relativistic temperature plasmas. The model equations are the electron relativistic collisionless hydrodynamic equations and the ion non-relativistic Vlasov equation, coupled to the Poisson equation. The complex frequency of electrostatic modes are calculated numerically as a function of the relevant parameters kλDe and ZTe/Ti where k is the wavenumber, λDe, the electron Debye length, Te and Ti the electron and ion temperature, and Z, the ion charge number. Useful analytic expressions of the real and imaginary parts of frequency are also proposed. The non-relativistic results established in the literature from the kinetic theory are recovered and the role of the relativistic effects on the dispersion and the damping rate of electrostatic modes is discussed. In particular, it is shown that in highly relativistic regime the electrostatic waves are strongly damped.

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