Design of EPU oscillator cavity in femtosecond accelerator

We adopt the groove guide as the cavity of the undulator to reduce the diffraction effect. The groove guide has the advantages of lower surface energy loss, larger power capacity, less modes, and larger structure dimension over the traditional method waveguide. The attenuation calculation is given in this paper including the cavity optimization. And the dispersive character indicates that the oscillator can work in different modes with the change of the electron beam energy.     

Design of a new compact THz source based on Smith-Purcell radiation

In recent years, people are dedicated to the research work of finding compact THz sources with high emission power. Smith-Purcell radiation is qualified for the possibility of coherent enhancement due to the effect of FEL mechanism. The compact experiment device is expected to produce hundreds mW level THz ray. The electron beam with good quality is provided under the optimized design of the electron gun. Besides, the grating is designed as an oscillator without any external feedbacks. While the beam passes through the grating surface, the beam bunching will be strong and the second harmonics enhancement will be evident, as is seen from the simulation results.     

上海深紫外自由电子激光的非线性谐波辐射研究

 自由电子激光中的非线性谐波辐射能达到较高的谐波功率,可以用来得到短波长辐射或者降低第4代先进光源对电子束团品质的严厉要求。基于3维自由电子激光软件,深入详细地研究了上海深紫外自由电子激光装置的非线性谐波辐射,并且提出了谐波辐射实验和测量建议。研究表明上海深紫外自由电子激光装置3次非线性谐波辐射的功率可以达到基波功率的2%水平。     

Design of cascading two stages of high gain harmonic generation scheme based on Shanghai deep ultraviolet free electron laser

Cascading stages of high gain harmonic generation free electron laser (FEL) seem to be a feasible way to generate short wavelength radiation. With help of the analytical estimates, we design a two-stage cascading scheme to achieve 131nm DUV radiation on the basis of the Shanghai deep ultraviolet free electron laser test facility. Detailed studies on the FEL performance, the stability and the sensitivity of the output power to parameter variation have been achieved by GENESIS1.3, and design of the lattice structure is presented.     

Three dimensional study of harmonic operation at the Shanghai deep ultraviolet free electron laser

With the right choice of parameters in the free electron laser （FEL） scheme, the undulator can be primarily operated at high order harmonic modes and the harmonic radiation is expected to be significantly enhanced. Recently, the possibility of proof-of-principle harmonic operation experiments on the basis of the Shanghai deep ultraviolet （SDUV） FEL test facility has been studied. In this paper, the principle of harmonic operation, three dimensional numerical approaches, and detailed performances of proposed harmonic operation at SDUV FEL are presented.     

Physics design of SSRF synchrotron radiation security

High brightness of SSRF brings about synchrotron radiation security problems, which will be solved in physics design. The main radiations are generated from bending magnets and insertion devices. Since the fact that radiation power and radiating area are different in these two kinds of synchrotron radiation, the arrangements of photon absorbers, diaphragms and other vacuum components need to be treated distinctively. In addition, SSRF interlock protection threshold is defined and the beam orbit in the straight line is limited. Hence, beam orbit in the bending magnets and IDs are also restricted by the threshold. The orbit restriction is calculated and helps us to arrange the vacuum components. In this paper, beam orbit distortion restricted by interlock protection threshold, radiation power, radiation angle and illuminating area are calculated. From the calculation results, the physics designs in manufacture and installation vacuum components are put forward. By commissioning, it is shown that physics requirements are met rigidly in the engineering process.     

杭州应加大引进外资银行的力度

正当外资银行在一些大城市与中资银行剑拔弩张的时候，杭州却是一片寂静，寂静的让人有些心痛。作为经济发展较快的省会城市杭州市，目前却仍未有一家外资银行入驻。而同在浙江省的宁波却拥有3家外资银行。设立外资银行对地方经济的发展有着重要的作用，杭州必须加大引进的力度。尽管外资银行要到2006年才能在杭州经营人民币业务，但我国在入世后已经取消了外资银行办理外汇业务的地域和客户限制，所以外资银行随时都可选择杭州，认真应对这个问题也已经刻不容缓。     

Preliminary result of bunch length measurement using a modified Michelson interferometer

Based on the femtosecond accelerator device which was built at the Shanghai Institute of Applied Physics （SINAP）, recently a modified far infrared Michelson interferometer has been developed to measure the length of electron bunches via the optical autocorrelation method. Compared with our former normal Michelson interferometer, we use a hollow retroreflector instead of a flat mirror as the reflective mirror. The experimental setup and results of the bunch length measurement will be described in this paper.     

上海同步光源定时系统物理设计

正在建造中的上海光源(SSRF)设计为一台能量为3.5GeV的第三代同步辐射光源, 其定时系统的物理设计使其能够满足储存环的不同运行模式, 如单束团模式、多束团模式、混合模式及Top-up运行模式, 定时系统具有高的稳定性和低的时间晃动. 基于EPICS控制系统的定时系统可提供精确的可编程序事件驱动信号序列, 根据不同需求提供电子枪、调制器、增强器和储存环高频, 注入引出及束测等设备的触发信号.     

具有非标准增长条件的微分形式的Caccioppoli不等式及其高阶可积性（英文）

本文主要研究了微分形式中的相关不等式.利用A-调和方程的性质及与该方程相关的弱逆Holder不等式和一类满足非标准增长条件的Young函数的性质,获得了一类特殊的微分形式(即非齐次A-调和张量)在该类Young函数作用下的Caccoppoli不等式及其高阶可积性.该结论将微分形式中Caccoppoli不等式由Lp空间推广到了由该类Young函数构成的Orlicz空间,同时验证了该Caccoppoli不等式可以用于微分形式的定量估计和定性分析.