New progress on beam availability and reliability of PKU high intensity CW proton ECR ion source

The stability and reliability of an ion source and its beam availability are extremely significant for any accelerator,especially for those high current long term CW operation ones like ADS. Although the first high quality 306-hours continuous wave(CW) operating curve at 50 m A@35 ke V has been successfully obtained with a standard compact 2.45 GHz ECR ion source at Peking University(PKU), but the uncertainties that caused beam trips before are unacceptable during an accelerator real operation and should be eliminated. Meanwhile, no permission will be given when the beam power is upgraded from 50 m A@35 ke V to 50 m A@50 ke V. To improve the PKU CW proton source quality, several upgrades were done recently. After those improvements, a new long term CW proton beam experiment at 50 m A@50 ke V was carried out in June 2016. The total running time is 300.5 hours, including near 6 hours ion source preparation and 294 hours non-disturb continuous operation. Within the continuous 13 days operation, no beam-off happened, no spark was observed,no beam drop appeared, no interrupting action was needed, and only a few beam fluctuations caused by the air conditional failure occurred. Beam availability and reliability within the 294 hours is 100%. The root-mean-square(RMS) emittance of this 50 m A@50 ke V CW proton beam is about 0.186 π.mm.mrad. A careful inspection of the ion source was done after this long term operation and no obvious damage was found. The restart experimental results obtained after the ion source inspection prove the high repeatability of PKU PMECRIS. In addition, a 130-m A H+beam was obtained at 50 k V with duty factor of 10%(100 Hz/1 ms) with this source. Details will be presented in this paper.     

Stable single longitudinal mode erbium-doped silica fiber laser based on an asymmetric linear three-cavity structure

We present a stable linear-cavity single longitudinal mode (SLM) erbium-doped silica fiber laser. It consists of four fiber Bragg gratings (FBGs) directly written in a section of photosensitive erbium-doped fiber (EDF) to form an asymmetric three-cavity structure. The stable SLM operation at a wavelength of 1545.112 nm with a 3-dB bandwidth of 0.012 nm and an optical signal-to-noise ratio (OSNR) of about 60 dB is verified experimentally. Under laboratory conditions, the performance of a power fluctuation of less than 0.05 dB observed from the power meter for 6 h and a wavelength variation of less than 0.01 nm obtained from the optical spectrum analyzer (OSA) for about 1.5 h are demonstrated. The gain fiber length is no longer limited to only several centimeters for SLM operation because of the excellent mode-selecting ability of the asymmetric three-cavity structure. The proposed scheme provides a simple and cost-effective approach to realizing a stable SLM fiber laser.     

微型光谱分析系统检测食品添加剂山梨酸的研究

基于对微型光谱仪的二次深度研发,构建了新型食品安全检测微型光谱分析系统,并采用标准加入法,对牛肉粒中的食品添加剂山梨酸进行快速定量检测。结果表明,采用标准加入法消除了样本基体成分的干扰,牛肉粒中山梨酸在0～10.0 mg·L-1质量浓度范围内有良好的线性关系(R2=0.998 9),山梨酸加标回收率为99.2%～99.5%,RSD(n=5)为0.14%。该微型光谱分析系统在食品添加剂检测应用方面表现出良好的实用化前景。     

落球法测液体黏度实验的改进

落球法测液体黏度的实验中,通过对实验仪器进行设计与改进,消除小球进入液体的水平速度,并采用录像和Vegas等软件进行测量分析小球下落速度,从而减少实验系统误差,提高了液体粘滞系数测量精确度。     

Dark Energy Density in Brane World

We present a possible explanation to the tiny positive cosmological constant under the frame of AdS5 spacetime embedded by a dS4 brahe. We calculate the dark energy density by summing the zero point energy of massive scalar fields in AdS5 spacetime. Under the assumption that the radius of AdS5 spacetime is of the same magnitude as the radius of observable universe, the dark energy density in dS4 brahe is obtained, which is smaller than the observational value. The reasons are also discussed.     

刺激响应型AIE水凝胶研究进展

刺激响应水凝胶可以对环境的微小变化产生较大的物理化学变化,在药物传递、生物分离、生物传感器和组织工程等领域具有广泛的应用。但受聚集导致荧光猝灭(ACQ)效应的影响,其在发光相关领域的应用受到限制,聚集诱导发光(AIE)概念的提出解决了这一难题。将AIE分子引入水凝胶体系,获得刺激响应型AIE水凝胶,在生物医学、信息防伪、3D水凝胶驱动器以及软体机器人的开发等多个高科技领域崭露头角。本文将近年来报道的刺激响应型AIE水凝胶按刺激因素分为物理因素(温度和光)、化学因素(pH、溶剂和离子)和生物因素(酶)三大类,分别阐述了水凝胶的制备、响应机理及潜在应用,并针对刺激响应型AIE水凝胶面临的问题和挑战进行了展望。     

Mechanical Reinforcement and Piezoelectric Properties of PZT Ceramics Embedded with Nano-Crystalline

The double-scale lead zirconate titanate （PZT） piezoelectric ceramics were prepared by the solid state processing with PZT nano-crystalline and micro-powder. The microstructures, electrical and mechanical properties of the double-scale PZT are investigated. All the sintered ceramics exhibit a single perovskite structure and the grain size of the dou ble-scale PZT reduces due to the incorporation of PZT nano-crystalline. Compared to normal PZT, the mechanical properties increase significantly and the piezoelectric properties decrease slightly. Mechanisms responsible for the reinforcement of the double-scale PZT are discussed.     

开放型大学物理实验教学的探讨

论述了在高校实施开放型物理实验教学的必要性,提出了开放型实验教学的两种形式,教学内容的开放和教学时间的开放,分析了各自的特点和应用场景.最后讨论了建设开放型实验室所需要的条件,如开通网上选课系统,引进近代物理实验仪器等.     

便携式近红外漫反射中药质量监控仪的研制

介绍了便携式近红外漫反射中药质量监控仪的设计思想、基本结构、测试条件和使用方法。该光谱仪具有体积小、重量轻、成本低等特点,现场监控中药质量是非常便利的。     

反射型磁光多层膜隔离器工作稳定性的研究

与单纯的磁光晶体相比,由磁光介质与电介质周期性或准周期性排列构成的一维磁光光子晶 体能够显著增强磁光效应,可以用于实现小尺度的磁光隔离器,从而大大减小器件的尺寸. 给出更为一般的可用于求解斜入射情况下偏振光在各向异性介质中传播时的传输矩阵方法, 并用这种方法在波长为1053μm处,针对两种“三明治”型的反射磁光多层膜隔离器的 结构,具体讨论了器件应用时入射角度及工艺制作时膜层制备厚度对它们工作稳定性的影响 .发现中心磁光介质夹层较厚的结构具有膜层数目少、工作稳定性好的优点. 关键词： 光隔离器 磁光效应 一维光子晶体