Equivalence of Radiation Particles for Permanent Damage in Semiconductor Devices

Selected transistors and diodes have been irradiated by various types and energies of dislocating radiation. Irradiation by protons of 10-Mev, neutrons of a reactor spectrum, electrons of 5, 10, and 25-Mev, gamma rays from cobalt-60, and bremsstrahlung from stopping of 5-Mev electrons are discussed. Passive and dynamic monitoring of permanent radiation damage was performed for exposures ranging from "threshold" to failure doses, utilizing various exposure rates. Changes in transistor forward current gain and changes in diode lifetime are presented in terms of integrated "particle" flux. From such analysis, the feasibility of ascribing an equivalence of radiation particles for aermanent damage in transistors and diodes has been successfully shown. Comparative damage curves, correlations of operational degradation with defect densities, and preliminary equivalences are presented.     

Experimental investigation of injection efficiency in a betatron

Experiments are described which have been carried out on the synchrotron of the Institute of Physics Acad. Sci. USSR (30 Mev electrons) for the purpose of investigating the physical effects involved in electron trapping in betatron acceleration. A detailed study was made of the effects on injection efficiency arising as a result of variable magnetic and electric fields which were artificially produced inside the acceleration chamber at the instant of time corresponding to electron injection. It is shown that both the auxiliary magnetic field, the effect of which on the particle may be compared with the effect of a rotational electric field (Kerst hypothesis), as well as the field of the artificial space charge can have a strong effect on the -radiation intensity only at small emission currents. However, qualitative estimates show that the effect of induction contraction, in accordance with the Kerst hypothesis, must be small compared with the Coulomb interaction in normal betatron operation. It is also shown that, in general, artificial methods such as diese are ineffective in increasing Intensity. It is suggested that only methods which allow a considerable change in the stabilizing forces of the magnetic field can lead to a significant increase in yield since the majority of betatrons operate under conditions approximating limiting current. In conclusion, several models are presented to represent the possible role of the Coulomb Interaction in the particle-trapping process in a stationary betatron orbit.The author wish to take this opportunity to express their gratitude to Corr. Mem. Acad. Sci. USSR V.I. Vcksler and Dr. of Math-Phys. Sciences M.S. Rabinovich for many discussions of the results of this work and valuable critical comments. The authors also wish to thank their colleagues who operated the 30-Mev synchrotron of the Institute of Physics Acad. Sci. USSR.     

Electromagnetic dispersion characteristics of a high energy electron beam guided with an ion channel

Taking self-fields into consideration,dispersion properties of two types of electromagnetic modes for a high energy electron beam guided with an ion channel are investigated by using the linear perturbation theory.The dependences of the dispersion frequencies of electromagnetic waves on the electron beam radius,betatron frequency and boundary current are revealed.It is found that the electron beam radius and betatron frequency have different influences on the electromagnetic waves dispersion behavior by compared with the previous works.As the boundary current is taken into account,the TM modes will have two branches and a lowfrequency branch emerged as the new branch in strong ion channel case.This new branch has similar dispersion behavior to the betatron modes.For TE modes,there are two branches and they have different dispersion behaviors in strong ion channel case.However,in weak ion channel case,the dispersion behaviors for both of the low frequency and high frequency branches are similar.     

Effects of Boundary Current on Electromagnetic Dispersion Characteristics for a Relativistic Electron Beam

With betatron oscillation characteristics of the electron beam and ion channel effect taken into account,dispersion characteristics of electrostatic modes and TM modes for a relativistic electron beam guided by ion channel are studied.Dispersion relations are derived and solved numerically to investigate the dependence of the dispersion characteristics for electrostatic modes and TM modes on the betatron oscillation frequency and the ratio of the relativistic electron beam radius to the waveguide radius.The effects of the boundary current on the dispersion characteristic of the TM modes and the interaction between the betatron modes and TM modes are analyzed.When considering the boundary current,for a strong ion channel,a new low-frequency branch of the TM modes arises and the interaction frequency between the betatron modes and the TM01 modes is increased with the same parameters.     

Induced ion-channel instability

In this paper, a new mechanism of electromagnetic instability, the induced ion-channel instability, is studied. It is based on the transverse driven betatron oscillation of relativistic electron beam induced by an additional magnetic undulator with a period close to the betatron wavelength in an ion channel. As its amplitude is sensitive to the electron beam energy, the driven betatron oscillation may determine electron beam grouping in the ponderomotive potential by selecting the undulator strength and period, and it provides a new mechanism of electron bunching, resulting in electromagnetic instability. Under proper condition, a new free-electron laser based on this mechanism may be realized.     

合肥800MeV电子储存环的色品测量与校正

介绍了合肥800MeV电子储存环的色品测量与校正。采用改变二极铁电流方法测量了自然色品和采用改变RF频率方法测量了校正色品,并对这2种测量方法进行了理论分析和公式推导。还给出了自然色品、校正色品以及六极铁电流对校正色品影响的测量结果。     

The investigation of the transitional acceleration stage in a synchrotron with a betatron initial stage

This paper is devoted to an application of the theory of the transition stage (the process of transition from betatron to synchrotron acceleration) to the FIAN 250 Mev synchrotron for the case when the accelerating field is established adiabatically. From the experiments and calculations that have been carried out it is possible to judge the correctness of the theory as applied to accelerators of this type. Some characteristics of the electron beam during the betatron stage, for example, the electron energy distribution, have been obtained from the experimental data.It is also shown that it is possible to use the dependence of the accelerated-particle beam intensity on the amplitude of the accelerating potential to determine the voltage amplitude at the resonant cavity.The authors express their gratitude to M. S. Rabinovich for his advice on numerous occasions and for fruitful discussions.     

High Energy Electron Accelerators

The Cambridge Electron Accelerator is now in full-scale operation for research at energies up to 6 Bev, five times higher than earlier electron accelerators. The machine, a synchrotron, uses a ring of 48 alternating gradient magnets in a circle 236 feet in diameter. Electrons are accelerated by RF fields produced in a set of sixteen resonant cavities spaced around the orbit. The frequency used is 476 Mc/s, the 360th harmonic of the orbital frequency. Injection of 30-Mev electrons is accomplished by using a linear accelerator operating at 2855 Mc/s. The main machine accepts and-accelerates to maximum energy beam currents of up to 1.2 x 1012 electrons/sec. The quality of the beam is fully as good as that from a linear accelerator. The CEA laboratory operates five days a week on a three-shift basis and has a staff of 160 people.     

Design principles and basic data of betatron facilities at the Moscow Transformer Works

The present article gives the principles underlying the design of betatron accelerator facilities for nondestructive testing, medical, physical, and other research uses. The conditions under which azimuthal asymmetry of the betatron magnetic field may take shape, and methods for coping with it, are considered. The multiyoke electromagnet design for betatrons, developed at the Moscow Transformer Works (MTZ), is described; this design confers improved azimuthal homogeneity on the magnetic field. Data are also provided on specialized betatron designs of the following types at MTZ: a stationary 4-yoke model with accelerated-electron energies from 20 to 50 Mev, a rotating suspended-type betatron, 25 Mev, for medical purposes, a movable rotating 25 Mev model for nondestructive testing, and a 15 Mev pendulum-type tilting betatron, for medical purposes.     

Measurement of channeling radiation using a 45 MeV betatron

An experimental setup for the measurement of channeling radiation from relativistic electrons in single crystals is described. A betatron with a maximum beam energy of 45 MeV is used as electron source. The beam divergence is tuned to less than 0.3 mrad by means of a beam optic system. Results of the measurement of channeling radiation in silicon and beryllium crystals are reported and compared with calculations.     

上海同步辐射光源工作点稳定性研究

上海同步辐射光源（SSRF）是一台第3代高性能同步辐射装置,已稳定运行超过10年。储存环的线性光学模型稳定是光源稳定运行的基础。工作点反馈系统可实时地校正工作点,并间接地以降维的方式反馈难以在线测量到的线性光学函数。工作点反馈系统在SSRF的稳定运行验证了此方法的可行性,该反馈系统不仅使得工作点稳定度显著提升,也使得束流发射度、注入效率以及束流寿命等重要参数的稳定度得到大幅提升。衍射极限储存环光源是现阶段被广泛研究和建设的新一代同步辐射光源,工作点反馈系统也将发挥更重要的作用。本文分析电子储存环线性光学函数和工作点的稳定性,回顾SSRF工作点反馈系统的实际运行情况,介绍工作点反馈系统在SSRF衍射极限环lattice（SSRF-U）的模拟。工作点反馈在SSRF的实际运行情况和在SSRF-U的模拟结果显示,该系统可将工作点稳定在±0.001范围内,可满足储存环光源稳定运行和线性差耦合共振圆束斑模式对工作点稳定度的需求。     

25MeV电子感应加速器对石油钻井钻头进行无损探伤

用25MeV电子感应加速器产生的韧致辐射,对40个表面镶有金刚石的石油钻头进行了无损探伤,搞清了钻头的结构,并发现6个钻头有裂纹性缺陷。加速器探伤具有探伤厚度大(最大可达500mm)、对工件表面光洁度无特殊要求、有较高的灵敏度(一般可达1％)、直观性好(能直接反映出工件内缺陷的形状及其位置)等优点,适用于复合材料及不同密度材料组成的工件的探伤。     

Application of the principle of automatic correction of the magnetic field in cyclic superhigh-energy accelerators

The possibility of utilizing the method of automatic magnetic field control with respect to data on the position of the beam of accelerated particles in cyclic accelerators is considered.Special disturbing pulses, which cause coherent betatron oscillations, are supplied for the purpose of measuring the frequency of betatron oscillations. The magnetic field deviations are determined with respect to the position of the instantaneous orbit. Methods for securing the first revolution before the magnetic field is corrected are considered. The approximate parameters of 300- and 1000- Bev accelerators, which were obtained by using the automatic correction principle, are given.     

Multi-layer structure formation of relativistic electron beams in plasmas

A two-dimensional electromagnetic particle-in-cell simulation model is proposed to study the density evolution and collective stopping of electron beams in background plasmas. We show here the formation of the multi-layer structure of the relativistic electron beam in the plasma due to the different betatron frequency from the beam front to the beam tail. Meanwhile, the nonuniformity of the longitudinal wakefield is the essential reason for the multi-layer structure formation in beam phase space. The influences of beam parameters (beam radius and transverse density profile) on the formation of the multi-layer structure and collective stopping in background plasmas are also considered.     

Suppression of betatron oscillations in strong-focusing electron synchrotrons

Different methods are considered for obtaining radiation damping of synchrotron and betatron oscillations in a strong-focusing accelerator. Formulas are given for the calculation of the damping decrements. It is noted that the curvature of the orbits in the damping magnets must be different from the curvature in the main sectors. It is shown that the sum of damping decrements is the same in all cases and is independent of the type of damping system which is employed.     

Measurements of Beam Behavior in the Karlsruhe Cyclotron

From the measurements made during the first operation period of the Karlsruhe cyclotron those of radial beam density, phase width and axial beam distribution are mentioned. Because of the satisfactory separation of the single orbits in a large radial range it has been easy to obtain information on the energy gain per turn, the amplitudes of the coherent radial oscillation and the radial dependence of the radial and axial betatron frequencies.     

The Application of a Digital Computer to the Control and Monitoring of a Proton Linear Accelerator

Preliminary design studies have been carried out on the control system for an 800-Mev proton linear accelerator based on the use of an on-line digital computer as the main controlling element. The accelerator system is divided into fifty-two subsections or modules. A module has complete control of all the equipment associated with it. Selected data and monitoring signals are transmitted on a time-shared basis to a central control computer. The functions which the computer performs in the control of the accelerator may be classified into Operational Control, Operational Supervision, and Data Monitoring and Handling. The operator gives instructions to the computer through interrupt lines. Commands to the modules and displays for the operator time-share a common channel in the computer output system. Synchronization of the input and output data flow is controlled by the computer through a timing unit. A comparison has been made of the computer-based control system with a possible alternate system which does not use a computer. The computer replaces much of the control and data handling equipment required by the alternate system. As a result, the costs of the two systems are comparable. However, the computer-based system is preferable since it has many functional advantages over the alternate system.     

数字束流位置处理器在合肥光源束流诊断中的应用

数字束流位置处理器Libera可直接用于测量宽带束流位置信号,在束流参数测量与诊断中得到广泛应用。本工作利用Libera在合肥光源储存环上完成了工作点、相空间和横向振荡阻尼时间常数等的测量,并给出测量结果。     

Parametric X-rays generated by electrons in multilayer mirrors mounted inside a betatron

The measured characteristics of tunable, quasi-monochromatic X-rays from thin multilayer mirrors used as radiators mounted inside a 35 MeV betatron chamber are presented. Parametric X-ray radiation (PXR) was generated by 15-33 MeV electrons passing through two radiators consisted of a few hundreds of W/B4C bilayers with period of 14.86 and 18 A. Shifts of the PXR spectra were measured as the orientation of the multilayer radiators relative to the incident electron beam was changed. The PXR flux was determined by comparison with the yield of L fluorescence generated by electrons in the W layers of the multilayer.