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《核技术(英文版)》2018,(11)
Harmonic RF cavities are commonly used in storage rings to lengthen the bunches and thus suppress the beam's instabilities and increase its Touschek lifetime. The voltage and phase of the electromagnetic fields in the harmonic cavity are of great importance for stretching the bunch. In the Hefei Light Source storage ring, a passive fourth-harmonic cavity is installed, and the cavity is monitored and controlled by an analog control module provided by its manufacturer. To vary and maintain the voltage of the harmonic cavity in a more effective way, a digital proportional, integral, and derivative feedback system based on the Experimental Physics and Industrial Control System is developed on top of the analog control module. This paper reports the details of the development of this voltage control system. Some test and operational results are also presented. 相似文献
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Fang-Zhou Chen Zhi-Chu Chen Yi-Mei Zhou Ning Zhang Bo Gao Xing-Yi Xu Yong-Bin Leng 《核技术(英文版)》2019,30(9)
Continuous tracking of bunch charges is the key to maintain stable operations in a storage ring in top-up mode. Recently, a precise bunch-by-bunch beam-current measurement(BCM) system has been developed at the Shanghai Synchrotron Radiation Facility. To avoid the influence of longitudinal oscillation on the amplitudes of the sampling points, a method called two-point equilibrium sampling is introduced. The results, obtained during routine operation time, show that the relative resolution of the measurement of the bunch charges is better than 0.02%.With this high resolution, the new BCM system is able to monitor the bunch-by-bunch beam lifetime. By using the filling pattern information, the Touschek lifetime and the vacuum lifetime can also be calculated. In this paper, the principle of the new method and the experiments is presented in detail. 相似文献
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束团长度是中国散裂中子源(CSNS)快循环同步加速器(RCS)束流动力学的关键参数,通过对束团长度的研究,可了解RCS的机器性能并进一步指导机器优化研究。本文对RCS 100 kW时的束团长度进行精确测量,100 kW引出时的束团长度为105 ns。RCS 500 kW时束团长度可能超过无损引出允许值,需压缩束团长度。理论上提高腔压可压缩束团长度,本文模拟研究500 kW时束团长度随腔压曲线的变化规律,模拟结果表明提高加速后半阶段的腔压可压缩束团长度,给出了500 kW时无束流损失引出的腔压曲线。基于100 kW束流条件实验验证了通过提高加速后半阶段腔压来压缩束团长度的有效性和可行性,实验测量结果与模拟结果一致。因此,提高加速后半阶段腔压是500 kW时无损引出束流的有效方法。 相似文献
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武汉光源一期工程计划建造一台第4代同步辐射装置,由1台1.5 GeV的低能量储存环和1台全能量直线注入器组成。储存环设计周长180 m,由8个标准混合型的7BA磁聚焦结构单元周期组成,能够储存500 mA的1.5 GeV电子。储存环自然发射度优化至222.8 pm·rad,可达到软X射线的衍射极限。为了满足用户对硬X射线的需求,每个标准单元的中心处安装了1台3-5 T的超强二极铁。同时为了提高因发射度减小造成的低寿命和动力学孔径过小造成的注入困难等问题,储存环的设计中还使用了三次谐波腔用于束团拉伸以及替换式注入系统等措施。全能量直线加速器位于储存环地下6 m处,采用S波段加速结构。本文将对武汉光源一期工程加速器系统进行更加详细的介绍。 相似文献
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A. V. Makulkin 《Atomic Energy》2011,110(5):352-359
The use of a subminiature electron storage ring in the weak-current regime (I
b = 0.02 mA) as a source of coherent mm-range synchrotron radiation and a laboratory facility for studying electron scattering
in a bunch is studied. The weak-current regime considerably simplifies the construction of a magnetic system and decreases
the likelihood of the development of bunch instabilities. To make a more accurate assessment of some basic parameters of a
subminiature storage ring, a calculation of the effective accelerating voltage was performed taking account of the transit
factor of the rf-system cavity. 相似文献
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Udaybir Singh Nitin Kumar Anil Kumar L. P. Purohit A. K. Sinha 《Journal of Fusion Energy》2011,30(2):105-110
In this paper, the design and the numerical simulation of the 84 GHz, 500 kW gyrotron at first harmonic operation for technological applications is described. The operating mode of the gyrotron is TE10, 4. Various in-house developed and commercially available computer codes are used for the design purpose. The triode-type magnetron injection gun with the accelerating voltage 70-kV, the beam current 10-A and the maximum transverse velocity spread less than 5% is designed. The preliminary design is obtained by using some trade-off equations. The mode selection, the cold cavity and the beam-wave interaction analysis are discussed for the design of weakly tapered open resonator type of the interaction cavity. The parametric analysis of the interaction cavity and the electron gun is also presented. 相似文献
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Photocathode RF gun is widely used for particle accelerators as an electron source.When driving an RF electron gun at the fundamental frequency and a higher harmonic frequency simultaneously with proper field ratio and relative phase,it generates electron beams of ultralow emittance and a linear longitudinal phase space distribution.Such a gun provides high quality electron beam with low energy spread,small traverse emittance and high brightness.In this paper,the RF design of a 1.5 cell cavity is presented.Simulation results of beam dynamics for the two-frequency gun and a standard single-frequency RF gun are also shown in this paper.In addition,bunch compression with a two-frequency gun is explored. 相似文献
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《核技术(英文版)》2018,(12)
Herein, a feasible method is proposed to compensate the high-order effect during bunch length compression, thereby enhancing the peak current of a highrepetition-rate X-ray free-electron laser source. In the proposed method, the corrugated structure is inserted downstream of the high-order harmonic cavities to function as a passive linearizer and enhance the longitudinal profile of the electron beam. Three-dimensional simulations are performed to analyze the evolution of the longitudinal phase space, and the results demonstrate that the profile of the electron beam is improved and the peak current can be easily optimized to over 2 kA with a bunch charge of 100 pC. 相似文献
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The Shanghai Advanced Proton Therapy facility employs third-integer slow extraction. In order to achieve accurate treatment, high-quality spill is needed. Therefore,parameters that may affect slow extraction should be investigated by simulation. A computer model of the synchrotron operation slow extraction was constructed with MATLAB~. By simulating the motion of the circulating protons, we could quantify the influence of machine and initial beam parameters on properties of the extracted beam, such as ripple, uniformity, stability, on-and off-time of the spill and spill width in the synchrotron.Suitable design parameters including the horizontal tunes,power supply ripple, longitudinal RF cavity voltage, RFKO and the chromaticities were determined. 相似文献
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V. L. Auslender M. M. Karliner B. A. Lazarenko S. G. Popov I. K. Sedlyarov A. N. Skrinskii I. A. Shekhtman 《Atomic Energy》1967,22(3):235-238
The authors have made experiments on various types of phase instability in the V'EPP-2 and V'EP-I storage rings. They studied phase auto-oscillations of a bunch as a whole and the decay of a bunch into two parts which oscillate separately, They observed excitation of auto-oscillations during interaction between the bunch and the resonator at the 18th harmonic. They measured the threshold currents versus the tuning of the principal and auxiliary resonators.Translated from Atomnaya Énergiya, Vol. 22, No. 3, pp. 194–197, March, 1967. 相似文献
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A. V. Makul’kin 《Atomic Energy》2006,101(5):846-852
The possibility of using a weak-focusing ultraminiature synchrotron for generating stable coherent synchrotron radiation at
wavelengths 0.5–5 mm is examined. An ultraminiature synchrotron has the following optimized working parameters: electron enegy
E = 24 MeV, radius of curvature of the beam orbit R0 = 0.01592 m, average working beam current Iwork = 0.022 A, beam lifetime τ = 1000 sec, injection frequency finj = 0.1 Hz, number of bunches in a beam K = 1, and bunch length σ
L = 0.283·10−3 m. The use of a source greatly simplifies user access to stable coherent synchrotron radiation and expands the range of applications
of this radiation.
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Translated from Atomnaya énergiya,Vol. 101, No. 5, pp. 388–394, November, 2006. 相似文献
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Harmonic cavities (HCs) are widely used in electron storage rings, mainly to increase the Touschek lifetime by lengthening bunches. HCs have become critical com... 相似文献
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Dao Xiang Wen-Hui Huang 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2005,240(4):855-862
Coherent radiation, e.g. synchrotron radiation, transition radiation and diffraction radiation etc. are widely used for electron bunch length and longitudinal profile characterizations. Incoherent synchrotron radiation and transition radiation are usually used for beam’s transverse profile measurements. When the study for a whole bunch is to be performed, the collective behavior of electrons in the radiation process should be properly considered. In this paper, the collective behavior in radiation process is studied in detail with random walk model. It is found that the microscopic discreteness and randomness of electrons within the bunch plays a great role in the radiation process especially for the incoherent radiation component. Only when the discreteness and randomness of electrons is taken into account can the theoretical prediction for incoherent radiation intensity and angular distribution of a whole bunch coincide with experimental results. The results derived from random walk model are in good agreement with experimental results and show clearer physical picture in the radiation process. 相似文献
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The bunch length can be measured by comparison of two frequency components of a synchrotron beam signal.An online bunch length measurement system has been implemented based on this method.Working frequencies of 3 GHz and 500 MHz were selected,and the raw data was acquired by digital oscilloscope and was resampled and analyzed using the MATLAB software platform at bunch-by-bunch rate.The constructed system was employed to study the bunch length synchronous oscillation phenomenon during injection.The beam experiments demonstrated a time resolution of less than 0.5 ps. 相似文献
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腔式探头具有高信噪比和高灵敏度的特性,TM010模式下在近轴附近的腔体输出信号与束流横向位置无关,信号幅度与电荷量呈正比,信号相位由束团到达时间决定,因此非常适用于高分辨率的束团到达时间测量。上海硬X射线自由电子激光装置(SHINE)对束团到达时间的测量精度要求非常高,期望运用基于谐振腔的束团到达时间监测系统,可实现在100 pC电荷量下分辨率好于25 fs的技术指标。对于高Q的谐振腔信号,单点采样的信噪比随信号的衰减而降低,因此肯定存在一最佳的信号处理窗口。为分析最佳处理窗口与相关参数的定量关系,采用数值仿真和束流实验相结合的办法来研究这个问题。分析发现,存在最佳数据处理时间窗口,该参数只与信号衰减时间常数有关,而与系统采样率、系统信噪比、系统模拟带宽无关。在最佳数据处理时间窗口条件下,束流到达时间测量不确定性可获得最佳值。 相似文献