CSRm高频系统控制器

HIRFL-CSR（Heavy Ion Research Facility at LanZhou-Cooling Storage Ring兰州重离子冷却储存环）是国家重大科学工程，其控制系统是一个庞大的系统，由许多分控制系统组成，高频系统是其重要组成部分之一。加速器的加速过程都是由高频系统来完成的。由于高频控制系统的控制对象就是高频腔体，控制系统的稳定性和输出频率的精确性将直接影响到加速器系统的正常工作，而对于高频系统的状态回读又直接决定了对于高频系统的远程监控能力，所以高频控制系统的设计非常重要。本设计基于现场可编程逻辑门阵列FPGA和数字信号专用处理器DSP搭建， 一方面可以完成从控制中心远程控制高频腔体，另一方面也可以完成对于当前状态的读取，所经过的通道也是多样化的，包括CPCI总线通信，CANBUS总线通信或者是485总线通信。本文的内容包括了1>对于高频控制系统控制对象的分析以及各种控制参数要求。2>组成此系统的硬件部分分析选择以及硬件系统的搭建过程。3>对FPGA和DSP进行程序设计的过程和方法。本文的价值不仅在于对高频系统的控制上，对于其他数据采集系统，远程控制系统以及总线通信和数据分析算法上也有着参考价值

CSR电源调节器硬件平台设计

HIRFL-CSR（Heavy Ion Research Facility at LanZhou-Cooling Storage Ring兰州重离子冷却储存环）是国家重大科学工程，其控制系统是一个庞大的系统，由许多分控制系统组成，磁场电源控制系统是CSR控制系统中很重要的一部分。加速器运行的所有过程都为电源所控制，所以我们的控制系统的直接控制对象就是磁场电源。为了保证CSR正常运行，控制过程波形的跟踪精度、速度和稳定度，是数字电源调节器的关键所在。电源控制系统以嵌入式处理器ARM、现场可编程门阵列FPGA为核心，实现了远程数据采集、网络通讯和自动控制等功能。本系统可以进行现场监控与调试，也可以通过集成的100Mbps以太网接口电路进行远程监测与控制，CSR上各处输出电压值和电源运行状态自动传送到中央控制中心，中控中心也可以发送命令查询当前电源设备状态和各种读数。本文主要介绍了基于ARM和FPGA的嵌入式电源控制系统的设计与实现。内容主要包括：(1)系统各部分硬件电路设计与电源控制功能实现 ，硬件系统调试 。(2)装载嵌入式Linux操作系统，测试平台接口信号，通过FPGA生成多路数字PWM波形。本文目的是解决CSR电源控制系统问题，但对于许多远程数据采集与控制等问题的解决有重要参考价值

电荷测量与时序逻辑电路的研究

中国科学院近代物理研究所大科学工程HIRFL-CSR（Heavy Ion Research Facility at LanZhou-Cooling Storage Ring兰州重离子冷却储存环）已建成并处于调试和验收阶段，实验探测系统也正在建设当中。CSRm实验探测系统由外靶系统和内靶系统构成，主要用于核物理实验研究。CSRm TOF测量系统是现阶段CSRm实验探测系统的主要任务之一。 针对CSRm TOF测量系统电荷测量部分，论文阐述了一种采用前端ASIC-SFE16（Saclay Front End 16）芯片实现电荷测量的新型方法。它替代了采用分立元件和电子学插件构建系统的传统方法，着重解决了近代核物理实验中越来越突出的多路多道需求和高性能指标要求。根据我所多丝漂移室探测器的实际情况，我们设计了基于ASIC芯片的电荷测量前端电路板，结合中国科技大学的时间测量数字获取板，我们初步完成了对系统软硬件的测试，给出的实验室性能测试指标，为其在实验探测系统中的应用奠定了坚实的基础。 同时为了选出测量中的有用事例，需要进行事例判选，因此我们研制了多路延迟/脉宽调节时序逻辑电路，主要功能是针对提供的多路逻辑时序信号进行延迟和脉宽调节，支持NIM负信号输入和输出。 文中最后一部分论述了根据在调试过程中出现的实际问题所提出的解决方法，主要是针对电路的可靠性设计和噪声的处理

兰州CSRm小丸内靶热力学和流体力学的研究

兰州CSRm内靶终端是进行强子物理实验的平台，可开展奇异介子产生和衰变的研究、重子谱的研究、多夸克态的研究及介子介质效应和手征对称破缺与恢复等多方面的研究。这些物理目标都需要内靶实验终端提供足够多的事件率，并能进行准确的径迹构建。在众多候选的内靶装置中，小丸靶具有其它内靶所欠缺的优点，如可以获得与外靶实验相比拟的实验亮度，可以配置4π立体角的探测器单元等。因此，小丸靶被确定为CSRm内靶实验终端中的主要内靶之一。小丸内靶（Pellet Internal Target）就是将氦以外的某种气体通过低温冷却而形成的固体微球。小丸内靶靶束与储存环离子束在反应室正交并发生相互作用，其反应事例被反应室周围环绕的探测器单元探测到并被记录下来。这篇论文对小丸内靶装置的结构进行了简要的介绍，并对小丸在反应室内的热力学行为进行了模拟。计算表明，靶丸速度是影响靶丸在反应区正常运行的重要因素之一。靶丸速度越大，靶丸在反应室内爆炸的可能性越小。通过对小丸的速度进行的流体动力学分析，发现即使对所有实验条件进行优化，小丸内靶的速度至多能达到100 m/s左右

CSR束流输运系统

国家重大科学工程兰州重离了冷却储存环（HIRFL-CSR）正在兴建当中，本文对其中的束流输运系统进行了详细的光学设计及束流动力学研究。低能束运线传输来自分离扇回旋加速器的束流并匹配注入CSR主环。高能束运线连接着主环和实验环，它的中间一段是放射性次级束流线，设计最大磁刚度为10.64Tm。经过细致的三阶像差校正后，次级束流线的实际动量分辨本领为1200。在研究过程中，用李代数方法证明了一般的四极磁铁在孔径增加时三阶像差反而减小。高能束线有两个分支，分别给物理实验提供高品质的初级束和中高能放射性次级束。另外还设计了一条特殊的束运线，它是基于圆形束方法和能动扫描方案的旋转机架，用重离子（3 < Z < 10）治疗人体深部的肿瘤，并对各种机架的结构进行了比较。最后，讨论了磁铁的误差影响，并简要介绍了束流线的诊断系统。

Experimental investigation of parallel optical data storage using pyrrylfulgide photochromic material

The optical storage characteristics of a new kind of organic photochromic material-pyrrylfulgide were experimentally investigated in the established parallel optical data storage system. Using the pyrrylfulgide/PMMA film as a photon-mode recording medium, micro-images and encoded binary digital data were recorded, readout and erased in this parallel system. The storage density currently reaches 3 x 10(7) bit/cm(2). The recorded information on the film can be kept for years in darkness at room temperature.

Experimental study on polarization holographic storage in genetic mutant BR-D96N film

Recording with both parallel and orthogonal linearly polarized lights, polarization holographic storage in genetic mutant BR-D96N film is reported with both transmission type geometry and reflection type geometry. Polarization properties of diffraction light and scattering light are discussed for two different cases, parallel polarization recording and orthogonal polarization recording. It shows that, compared with recording with parallel polarization lights, orthogonal polarization holography can separate the diffraction light from the scattering noise, therefore improving the signal-to-noise ratio. It also shows that, compared with reconstruction with reference light, reconstruction with phase conjugated wave of the reference light can improve the signal-to-noise ratio of the reconstructed diffraction image, and also the wave-front aberration of the object light introduced by irregular phase object in the optical pass-way can also be corrected effectively, which ensures that the reconstructed diffraction image has a better fidelity. The preliminary angle-multiplexed volume holographic storage multiplexed by transmission type geometry and reflection type geometry is demonstrated in the BR-D96N film. Experiment shows that there is no cross-talk between the two pages of images except for some scattering noises.

Experimental investigation of an unstable ring resonator with 90-deg beam rotation for a chemical oxygen iodine laser

We report the experimental results of an unstable ring resonator with 90-deg beam rotation for a kilowatt class chemical oxygen iodine laser (COIL). The distributions of near-field phase and far-field intensity were measured. A beam quality of 1.6 was achieved when the COIL average output power was approximately 5 kW. (C) 1999 Optical Society of America.

Design and construction of a static tester for blue ray optical storage

Blue ray optical storage is one of the important trends in the area of information storage, and attracts a number of researchers. Static tester for blue ray optical storage plays an important role in storage media research. We designed and constructed a static tester, in which modularization makes it very convenient to expand function. Employment of modulation/demodulation technique weakens test error so as to increase test precision. Focus move mode and the nano-positioners facilitate the relocation of recording marks. Only one laser with wavelength 406.7 nm is used. In this paper, system design and characteristics are represented in detail, and some experimental results are also given to show that the static tester can perform successfully, acting as research platform for blue ray optical storage. (c) 2005 Elsevier GmbH. All rights reserved.

Riboflavin sensitized photopolymer materials for holographic storage

Riboflavin is employed as the photosensitizer of a novel photopolyrner material for holographic recording, This material has a broad absorption spectrum range (More than 200nm) due to the addition of this dye. The experimental results show that our material has high diffraction efficiency and large refractive index modulation. The maximum diffraction efficiency of the photopolymer is about 56%. The digital data pages are stored in this medium and the reconstructed data page has a good fidelity, with the bit-error-ratio of about 1.8 X 10(-4). it is found that the photopolymer material is suitable for high-density volume holographic digital storage.

A feasible approach to optical-electrical hybrid data storage using phase change material

We present our experimental results supporting optical-electrical hybrid data storage by optical recording and electrical reading using Ge2Sb2Te5as recording medium. The sheet resistance of laser- irradiated Ge2Sb2Te5. lms exhibits an abrupt change of four orders of magnitude ( from 10 7 to 10 3./ sq) with increasing laser power, current- voltage curves of the amorphous area and the laser- crystallized dots, measured by a conductive atomic force microscope ( C- AFM), show that their resistivities are 2.725 and 3.375 x 10- 3., respectively, the surface current distribution in the. lms also shows high and low resistance states. All these results suggest that the laser- recorded bit can be read electrically by measuring the change of electrical resistivity, thus making optical electrical hybrid data storage possible.

Structure and properties of amorphous thin film for optical data storage

In this paper the magnetic and magneto-optical properties of amorphous rare earth-transition metal (RE-TM) alloys as well as the magnetic coupling in the multi-layer thin films for high density optical data storage are presented. Using magnetic effect in scanning tunneling microscopy the clusters structure of amorphous RE-TM thin films has been observed and the perpendicular magnetic anisotropy in amorphous RE-TM thin films has been interpreted. Experimental results of quick phase transformation under short pulse laser irradiation of amorphous semiconductor and metallic alloy thin films for phase change optical recording are reported. A step-by-step phase transformation process through metastable states has been observed. The waveform of crystallization propagation in micro-size spot during laser recording in amorphous semiconductor thin films is characterized and quick recording and erasing mechanism for optical data storage with high performance are discussed. The nonlinear optical effects in amorphous alloy thin films have been studied. By photo-thermal effect or third order optical nonlinearity, the optical self-focusing is observed in amorphous mask thin films. The application of amorphous thin films with super-resolution near field structure for high-density optical data storage is performed. (c) 2007 Elsevier B.V. All rights reserved.

All solid-state, injection-seeded Ti:sapphire ring laser

In this letter, we present an all solid-state, injection-seeded Ti:sapphire laser. The laser is pumped by a laser diode pumped frequency-doubled Nd:YAG laser, and injection-seeded by an external cavity laser diode with the wavelength between 770 and 780 nm. The single longitude mode and the doubling efficiency of the laser are obtained after injection seeding. The experimental setup and relative results are reported. It is a good candidate laser source for mobile differential absorption lidar (DIAL) system.

Experimental study of a pulsed ytterbium-doped fibre laser with fast and slow saturable absorbers in a linear cavity

We present a linear-cavity stretched-pulse fibre laser with mode locking by a nonlinear polarization rotation and by semiconductor saturable-absorber mirrors. A Q-switched mode-locking cw train and a mode-locking pulse train are obtained in the experiment. We investigate the effects of the equivalent fast saturable absorber and the slow saturable absorbers in experiment. It is found that neither the nonlinear polarization evolution effect nor a semiconductor saturable absorber mirror is enough to produce the stable cw mode-locking pulses in this experiment. A nonlinear polarization evolution effect controls the cavity loss to literally carve the pulses; semiconductor saturable absorber mirrors provide the self-restarting and maintain the stability of the mode-locking operation.

Coherent transport through a quantum dot embedded in a double-slit-like Aharonov-Bohm ring

Coherent transport through a quantum dot embedded in one arm of a double-slit-like Aharonov-Bohm (AB) ring is studied using the Green's function approach. We obtain experimental observations such as continuous phase shift along a single resonance peak and sharp inter-resonance phase drop. The AB oscillations of the differential conductance of the whole device are calculated by using the nonequilibrium Keldysh formalism. It is shown that the oscillating conductance has a continuous bias-voltage-dependent phase shift and is asymmetric in both linear and nonlinear response regimes.