第二个重要极限存在性证明的新方法

本文通过分析第二个重要极限现存的两类典型证明方法,进而提出一种借助本文中证明的一个不等式,得到第二个重要极限存在性证明的新方法.     

飞秒电子束装置的初步实验结果

上海应用物理研究所建造并调试了一台飞秒电子束装置。这台装置主要由一把S波段热阴极微波电子枪、一台alpha磁铁和一根SLAC型加速管组成。这台装置可以产生能量为 20~30 MeV,峰值电流为100 A,微束团长度为250 fs的电子束。这篇文章报道了这台装置的调试和电子束团参数的测量。     

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.     

100 MeV电子直线加速器的物理设计

 能量为100 MeV左右的高性能电子直线加速器是第三代同步辐射光源注入器和自由电子激光注入器的重要组成部分,采用热阴极栅控电子枪、聚束系统和4根SLAC型加速管作为加速器主体结构,一套45 MW的速调管调制器系统和波导系统作为微波功率源系统。设计中,使用了国际通用的模拟软件对加速器的动力学特性进行了数值模拟和参数优化,电子束能量达到100 MeV以上,能散小于1%,归一化发射度小于30 mm·mrad。     

532 nm激光照射碳纳米管光场致发射电子枪

报道了碳纳米管光场致发射电子枪的初步研究结果。在532 nm激光照射下碳纳米管光场致发射电子枪在极间高压为27 kV时得到的最大的脉冲流强可以达到3.364 A,其脉冲电流发射密度可达6.728 A/cm2,对应脉冲电荷量为38.7 nC。碳纳米管的量子效率通过公式计算为3.73×10-5,给出了在532 nm激光照射下碳纳米管光场致发射电子枪发射电流随激光功率和极间电压的变化关系。     

Characterizing THz Coherent Synchrotron Radiation at Femtosecond Linear Accelerator

The generation and observation of coherent THz synchrotron radiation from femtosecond electron bunches in the Shanghai Institute of Applied Physics femtosecond accelerator device is reported. We describe the experiment setup and present the first result of THz radiation properties such as power and spectrum.     

Numerical modeling of a high power terahertz source in Shanghai

On the basis of an energy-recovery linac, a terahertz source with a potential for kilowatts of average power is proposed in Shanghai, which will serve as an effective tool for material and biological sciences. In this paper, the physical design of two free electron laser (FEL) oscillators, in a frequency range of 2--10 THz and 0.5--2 THz respectively, are presented. By using three-dimensional, time-dependent numerical modeling of GENESIS in combination with a paraxial optical propagation code, the THz oscillator performance, the detuning effects, and the tolerance requirements on the electron beam, the undulator field and the cavity alignment are given.     

Design of Smith-Purcell emitter in femtosecond accelerator

Based on the femtosecond accelerator device, we are planning to build a broad band and tunable THz source using the Smith-Purcell radiation mechanism. Coherent Smith-Purcell radiation could be achieved owing to the super-short bunch produced in the device. To shorten the distance between the beam and grating, we use Transport to match the beta function producing a sheet beam on the grating surface. The optimization of grating length, groove depth and groove width are given in the paper. Then the radiation power for the shallow and deep grating using these parameters are presented. The detection devices and methods are also briefly discussed.     

钍基熔盐堆核能系统

裂变核能是保障能源增长需求和促进节能减排的重要手段。钍基核能具有中子增殖性能好、产生高放废料少和储量丰富等特点;熔盐堆作为第四代先进反应堆的6个候选堆之一,具有钍高效利用、高温制氢、无水冷却、适合小型模块化设计等优势和潜力。发展钍基熔盐堆,对中国的核能战略发展具有重要意义,将会有助于解决中国的能源和环境双重挑战。2011 年1 月,中国科学院启动战略性先导科技专项——钍基熔盐堆核能系统(TMSR),采取液态熔盐堆和固态熔盐堆两种堆型研发同时部署和相继发展的技术路线,致力于实现基于熔盐堆的钍资源高效利用和核能综合利用,为我国核能发展赢得先机。     

杭州发展网上证券交易的对策思考

作为中国证券业未来发展方向的网上证券交易，在杭州虽然已取得了一些成绩，但整体水平落后于一些地方性券商，针对目前杭州在开展网上证券业务中存在的问题，提出了以下对策，加强网络的安全防范建设，实行“券商＋IT公司＋银行”的新型经营模式，创新营销策略，进行品牌攻略。