High power accelerators in fundamental physics and nuclear technology

The trends of the high power accelerators development are outlined. The natural examples of their applications in nuclear physics and technology are discussed: muon physics, physics of rare decays, intense 14 MeV — neutron source based on muon catalyzed fusion (INS — MCF) and accelerator driven system (ADS) for nuclear waste incineration. The accelerator with power ˜ 10 MW and particle energy ˜ 1 GeV/nucl is considered as the best candidate for these purposes.     

多能量档电子直线加速器用栅控电子枪电源研究

本文介绍了一种应用于多能量档电子直线加速器栅控电子枪的专用电源。根据栅控电子枪的工作需求,电子枪的阴极处于-50 kV高压上,电源的3路输出,包括灯丝电源、偏压电源和栅控脉冲电源,均通过高压隔离变压器,将信号输送到高压端的灯丝、阴极和栅极上。利用主控计算机精确调节了电子枪发射束流的大小和脉冲宽度,以满足加速器多能量输出的需求。高压端均为无源器件,以降低故障率。此电源结构简单、调节方便、工作稳定,已在多能量档电子直线加速器上连续工作近4 a,运行状态良好。     

Accelerators with stable joined particle trajectories

A new class of accelerators is considered; in these accelerators the magnetic system consists of several sectors which are separated by gaps characterized by very weak fields. The magnetic system has two mutually perpendicular planes of symmetry but does not have an axis of symmetry nor a center of symmetry. All the particle orbits pass through a common point at which the acceleration element, a cavity resonator, is located. The stability of particle motion is provided by virtue of the effect of the fringing magnetic fields of the sectors. The magnetic system being considered may be used in cyclotrons and microtrons. The advantages of this new class of accelerators are the higher ion-beam intensity, the lower power supply requirements, the possibility of extracting panicles at any orbit and the possibility of varying the particle energy in the extracted beam over wide limits.     

Advanced topics on RF amplitude and phase detection for low-level RF systems

Low-level radio frequency(LLRF) systems stabilize the electromagnetic field in the RF cavities used for beam acceleration in particle accelerators. Reliable, accurate, and precise detection of RF amplitude and phase is particularly important to achieve high field stability for pulsed accelerators of free-electron lasers(FEL). The digital LLRF systems employ analog-to-digital converters to sample the frequency down-converted RF signal and use digital demodulation algorithms to calculate the RF amplitude and phase. Different sampling strategies and demodulation algorithms have been developed for these purposes and are introduced in this paper. This article focuses on advanced topics concerning RF detection,including accurate RF transient measurement, wideband RF detection, and RF detection with an asynchronous trigger, local oscillator, or clock. The analysis is based on the Swiss FEL measurements, but the algorithms introduced are general for RF signal detection in particle accelerators.     

Electron dumps for ITER HNB and DNB beamlines

The negative ion accelerators that produce the high-energy particle beams for the neutral injection systems for the International Tokamak Experimental Reactor (ITER) also produce unwanted particles such as electrons. These electrons are emitted in a wide angular spectrum that allows some of them to directly intercept sensitive beamline components such as the cryogenic pumps. As the electrons are also subject to backscattering, indirect interception always occurs. In this article the electron spectra produced by the Heating Neutral Beam (HNB) and Diagnostic Neutral Beam (DNB) accelerators are calculated. It is shown that these are very different. It is proposed to install electron dumps in the beamlines to intercept electron power directed towards inconvenient places in the HNB and DNB beamlines.     

High Power Klystrons

This paper will review the evolution of high power klystrons and their applications in supplying rf energy for linear accelerators. Other types of possible rf sources were considered for SLAC, and the reasons for the selection of klystrons will be given. A brief review of klystron types in use for various accelerators will also be given, but the emphasis will be on the work done by Stanford and its subcontractors in developing klystrons capable of achieving peak powers in excess of 20 MW and average powers of 20 kW for use with the two-mile Stanford linear accelerator.     

Analog Computer for Quadrupole Magnet Design

In the design of particle accelerators, magnets are sometimes used to bend the paths of charged particles in linear accelerators for focusing and defocusing purposes. These magnets, in the present case, are known as quadrupoles. Their design hinges on the solution of certain mathematical expressions of particle trajectories. A computer of the analog type was constructed to solve the equations and so facilitate magnet design. The analog computer for this application has dials labeled "L", "?", and "?". The settings of these dials represent the design parameters under study. The operator can set the dials of each stage to any of thousands of different combinations of L, ?, and ?. The results of his settings may be observed on a CRO screen. He can then proceed to search for the best combination of control settings with regard to their effect on particle trajectories. Once having found a satisfactory combination, the corresponding magnet design parameters are obtained from the settings of the controls. Three features of construction required special consideration. These were: the high gain, minimum phase shift, and minimum crosstalk. These items and others are discussed in the article from the practical as well as the theoretical point of view.     

The matrix method for radiological characterization of radioactive waste

Beam losses are responsible for material activation in some of the components of particle accelerators. The activation is caused by several nuclear processes and varies with the irradiation history and the characteristics of the material (namely chemical composition and size). Once at the end of their operational lifetime, these materials require radiological characterization.The radionuclide inventory depends on the particle spectrum, the irradiation history and the chemical composition of the material. As long as these factors are known and the material cross-sections are available, the induced radioactivity can be calculated analytically. However, these factors vary widely among different items of waste and sometimes they are only partially known.The European Laboratory for Particle Physics (CERN, Geneva) has been operating accelerators for high-energy physics for 50 years. Different methods for the evaluation of the radionuclide inventory are currently under investigation at CERN, including the so-called “matrix method”. This paper provides a mathematical formulation of the matrix method highlighting its advantages and limits of validity.     

强流质子直线加速器中束晕现象研究

从束流包络方程与单粒子运动方程联立模型出发，考虑了纵向能量方程的耦合，研究了强流质子直线加速器中的束晕现象。采用相交间的Ｐｏｉｎｃａｒｅ截面方法和实空间Ｐｏｉｎｃａｒｅ截面方法，研究了周期聚焦系统失配的情况下束晕的形成以及加速对束晕形成的影响。     

Impact of Accelerators on Technology

Accelerators and accelerator technology has rapidly expanded into Medicine and Industry. The 2500 accelerators in the USA, which represent about 2/3 the worldwide census of accelerators are primarily devoted to practical applications, although the major impact on technology has been produced by a relatively few excellent facilities. Approximately 80% of the current accelerators in the USA are found to be in medical and industrial use representing a capital investment by industry of $200,000,000. Of greater importance is their impact on the treatment of cancer, and the improvement or creation of better products for industrial and consumer use. The development of new accelerators and techniques are required in order to insure continuing benefits to the public.     

同步加速器慢引出束流频谱定量分析及其应用

引出束流的时间均匀性是同步加速器慢引出研究领域中的重要研究方向,优化时间均匀性需先判断引出束流不均匀性即束流纹波的主要来源。引出束流频谱在分析束流纹波时起关键作用,但常规的引出束流频谱分析仅通过频谱幅度判断主要的束流纹波来源,遇到宽频束流纹波时常规方法无法正确反映宽频纹波对时间均匀性的影响。为此,本文提出引出束流频谱定量分析方法,并将该方法应用于西安200 MeV质子应用装置同步加速器引出束流的时间均匀性的分析及优化中。该方法可正确反映宽频纹波对时间均匀性的影响,根据该方法可对不同来源的束流纹波进行分类,定量计算不同类型的束流纹波对不均匀性的贡献,实现量化比较不同类型纹波影响,明确需优化的目标。     

Electrostatic charged-particle accelerators

A survey is given of studies on electrostatic particle accelerators. The main attention is given to problems of increasing the energy of the accelerated particles and the beam power in electrostatic generators. A comparison of the different methods of voltage stabilization is made. In conclusion a brief discussion is given of cascade generators designed for the production of high-power beams.     

加速管锻炼的光电监测

静电型加速器特别是大型串列式加速器的核心部件是昂贵的加速管。加速管的耐压能力在达到其额定电压之前要经历一个锻炼过程,正确地控制锻炼过程的进度是确保加速管安全迅速地达到额定电压的关键。目前国内静电型加速器加速管锻炼时用的监测方法主要是监测X射线的强度和加速管内真空度的变化,这些方法在直场加速管的情况下是有效的,但在斜场加速管的情况下,由图1可见加速管内能够获得最大能量的粒子是由A点出发到C点终止的粒子,其他二次粒子均受到邻近电极的拦截。若加速管电极在倾斜方向的孔径为d,电极之间的轴向距离为P,轴向电压梯度为E,电极倾角为θ,则二次粒子能够     

On the possibility of accelerating heavy pulsed currents in linear electron accelerators

The applicability of various linear electron accelerators for the acceleration of heavy pulsed currents is estimated. It is shown that linear standing-wave electron accelerators, which use the high-frequency power stored in resonant cavities, for the acceleration of particles offer greater possibilities in comparison with ordinary linear traveling-wave electron accelerators. The possibility of accelerating currents of the order of 100 amp in pulses with a duration of approximately 1 sec is demonstrated.In conclusion, we hereby express our deep gratitude to K. D. Sinel'nikov and Ya. B. Fainberg for the valuable discussions.     

The Intense Neutron Generator and Future Factory Type Ion Accelerators

A neutron factory is likely to sell its product in the form of isotopes. Today neutron factories are nuclear reactors. Ion accelerators may also produce isotopes by direct interaction and, at high enough energies, mesons and hyperons. The challenge of the electrical production of neutrons goes far beyond the isotope market. It challenges the two popular concepts for long term large scale energy, the fast breeder reactor and controlled thermonuclear fusion. For this use about 4% of nuclear generated power would be applied in a feedback loop generating extra neutrons. Competition rests on operating and processing costs. The Intense Neutron Generator proposal now cancelled would have been full scaloe for such a use, but much further advance in accelerator engineering is required and anticipated. Perhaps most promising is the application of the ion drag principle in which rings of fast electrons are accelerated along their axis dragging ions with them by electrostatic attraction. Due to the much larger mass of the ions they can acquire much higher energy than the electrons and the process could be efficient. Such accelerators have not yet been made but experimental and theoretical studies are promising.     

Accelerators with similar orbits

We obtain the conditions that must be satisfied by a magnetic system in order that the frequencies of radial and vertical betatron oscillations be independent of the particle momenta (in this case the orbits are called dynamically similar). In such systems mere should in principle be no excitation of betatron oscillations associated with synchrotron oscillations and other phenomena. A magnetic field\(H_0 \left( {\theta } \right)\left( {{{r_0 } \mathord{\left/ {\vphantom {{r_0 } r}} \right. \kern-\nulldelimiterspace} r}} \right)^{\Pi _0 } \) with n₀ = const produces both geometric and dynamic similarity of the orbit. In weak-focusing accelerators with segments (race tracks) and in strong-focusing proton synchrotrons, the orbits are not dynamically similar. In order to obtain this kind of similarity in the first case, in addition to n₀ = const it is necessary that the magnet sectors have a common center. Different types of annular synchrocyclotrons are considered. In the first type the centers of neighboring magnet sectors are located on different sides of the doughnut and in the second type at the same point (at the center of the accelerator). In the second type the orbits are dynamically similar, unlike those of the first. It is shown mat it is possible to design an annular synchrocyclotron in which the particles can move with stability simultaneously in both directions within the doughnut.     

CAMAC Systems at LAMPF

The use of CAMAC has been proposed in the experimental area of one of the nation's newest particle accelerators. This paper will describe briefly the computer-based data system to be implemented and how CAMAC might solve the interface problem.     

Sterilization complexes based on ILU-type electron accelerators

This paper describes the industrial electron accelerators of the ILU type and their usage for sterilization.The ILU machines produced by Budker Institute of Nuclear Physics have energy range of 0.8-10 MeV and beam power up to 100 kW,and they are working in industries all over the world.The ILU-10 and ILU-14 machines are described as well as the industrial sterilization facility based on ILU-6,ILU-10 and ILU-14 machines.     

Evaluating the economic feasibility of using special heavy concretes for radiation shielding

The first part of this article is a survey of the work of foreign authors dealing with the economics of using various concretes for biological radiation shielding at nuclear reactors and at charged particle accelerators. Several of these authors affirm that it is economically justifiable to use heavy concretes for these purposes. However, others advocate the use of common concretes with mineral aggregates. The second part of the article gives the results of corresponding economic analyses conducted in the USSR. These analyses lead to the conclusion that the use of special heavy concretes is justifiable only in exceptional cases.