用于光阴极的光纤激光研制实验

为获得高亮度低发射度的电子束,研制高重复频率高平均功率的光阴极驱动激光系统非常关键。利用光纤激光技术,设计了100 MHz和1.3GHz的激光系统。激光系统为全光纤结构,采用了掺镱光子晶体光纤作为放大器增益介质。在初步验证实验中,红外激光输出27 W,倍频后绿光达到6 W。     

Study of radiation background at the north crossing point of the BEPC in collision mode

Understanding the radiation background at the north crossing point (NCP) in the tunnel of BEPCII is crucial for the performance safety of the High Purity Germanium (HPGe) detector, and in turn of great significance for long-term stable running of the energy measurement system. Therefore, as the first step, a NaI(Tl) detector is constructed to continuously measure the radiation level of photons as background for future experiments. Furthermore, gamma and neutron dosimeters are utilized to explore the radiati...     

Electro-optical sampling non-synchronous delay scanning measurement of electron beam bunch length at BFEL

The Electro-optical sampling delay scanning technique can be used for electron beam bunch length measurement. A novel non-synchronous delay scanning technique based on the electro-optical sampling measurements is presented. Based on Beijing Free Electron Laser （BFEL）, the electron beam bunch length was measured with the electro-optical sampling technique for the first time in China. The result shows that the electron beam bunch length at BFEL is about 5.6±1.2 ps.     

利用扫描近场红外显微镜对化学样品组分进行成像研究

介绍了用北京自由电子激光为光源的扫描近场红外显微镜对化学样品组分进行的成像研究，通过所得到的近场微区图像，可以对样品在微区范围内的成分组成，混合的均匀程度等作出比较清晰的判断. 关键词： 自由电子激光 近场光学 扫描近场红外显微镜     

高能所光阴极驱动激光系统研制

能量回收型直线加速器(ERL)可能提供低发射度、高平均流强的连续电子束团,其电子枪的光阴极需要高重复频率、高平均功率的驱动激光系统。采用先进的光纤激光技术,特别是在激光系统中采用了掺镱光子晶体增益光纤,能实现高重复频率高平均功率激光输出。利用啁啾脉冲放大(CPA)技术,通过优化设计,将重复频率100 MHz和1.3 GHz的两套激光振荡源集成到同一个激光系统,整个激光系统的结构简化,使用方便。两种重复频率激光倍频效率分别达到50%和30%,绿光能达到5 W以上,满足光阴极实验平台的使用要求。     

电光采样(EOS)法测量超短电子束束团长度中的模拟计算与误差分析

随着高能物理的发展, 高能量正负电子对撞机, X射线自由电子激光器, 先进的同步光源等, 都需要产生高流强超短脉冲的相对论电子束团. 于是, 亚皮秒电子束束团诊断成为加速器物理新发展的关键技术, 电子束长度的监测是其中的一部分. 电光采样(EOS)法测量超短电子束团长度有非侵入、非破坏、实时测量的特点, 具有较好的应用前景. 本文介绍该方法的原理, 通过模拟计算分析电子束束团与探测光间距、电子束电场与电光晶体晶轴夹角、探测光偏振方向与电光晶体晶轴夹角等实验参数与束团长度测量的关系, 做系统误差分析, 对实际实验有指导意义.     

Design studies on a 500 kV DC gun photo-injector for the BXERL test facility

BXERL is a proposal for a test facility (Beijing X-ray Energy Recovery Linac), which requires its injector to provide an electron beam of 5 MeV, 77 pC/ bunch at a repetition rate of 130 MHz (average current of 10 mA). In this paper, we present the design of the injector, which consists of a 500 kV photocathode DC gun equipped with a GaAs cathode preparation device, a 1.3 GHz normal conducting RF buncher, two solenoids, and one cryomodule containing two 1.3 GHz 2-cell superconducting RF cavities as the energy booster. The detailed beam dynamics show that the injector can generate electron bunches with a RMS normalized emittance of 1.49 πmm·mrad, a bunch length of 0.67 mm, a beam energy of 5 MeV and an energy spread of 0.72%.     

Design studies on the ERL-FEL test facility at IHEP, Beijing

A proposed compact ERL test facility at IHEP, Beijing, is presented in this paper, and includes the design parameters, the essential lattice, and the key components features, such as the photocathode DC gun and the CW superconducting accelerating structures. Some important beam physics issues such as the space charge effect, the coherent synchrotron radiation (CSR) effect and the beam break-up (BBU) effect are briefly described with the simulation results.