Superconducting rectifier fluxpump for magnet system of the CMD-2detector

A superconducting rectifier fluxpump has been used for the dc power supply of the magnet system of the CMD-2 detector on the VEPP-2M collider at the Budker Institute of Nuclear Physics in Russia since 1989. The fluxpump provides a complete pumping cycle: charging the magnet system, stabilization of the magnetic field, and discharging. The fluxpump consists of an air-core current step-up superconducting transformer and two groups of thermally controlled superconducting switches arranged as a fullwave rectifier. Critical output current during the test was 5.4 kA. The accuracy of the field stabilization provided by the fluxpump is 2.5·10^-5. The fluxpump has exhibited reliable and safe operation during its entire history of use     

Superconducting diode as high-frequency sound detector

The properties of a broadband sound detector utilising microwave-phonon-assisted tunnelling in superconductors are described. Using Al?Pb tunnel diodes at 1.3°K, the sensitivity of the detector to 9.3 × 109 c/s sound waves was found to be approximately 2 × 10?4 V/W cm?2. At high frequencies the sensitivity is expected to increase as the square of the sound frequency.     

Superconducting magnet system containing Bi-2212/Ag Coil Generates 21.8 T at 1.8K

We fabricated a Bi-2212/Ag double stacked pancake coil of 13 mmØ) in inner bore and of 46.5 mmØ in outer diameter, by using Bi-2212/Ag tapes prepared by the combination of continuous dip-coating process and melt-solidification technique. This small superconducting magnet was used as an insert magnet of a conventional superconducting magnet system and tested at saturated superfluid helium temperature (～ 1.8K) in various bias fields. The generated field of Bi2212/Ag coil was 0.9 T, with I_c of 310 A(criterion 10^-13Ω·m), in the bias field of 20.9 T. Thus, this superconducting magnet system achieved generation of magnetic field of 21.8 T in the full superconducting state.     

Superconducting superferric dipole magnet with cold iron core for the VLHC

Magnetic system of the stage I Very Large Hadron Collider (VLHC) is based on 2 Tesla superconducting magnets with combined functions. These magnets have a room temperature iron yoke with two 20 mm air gaps. Magnetic field in both horizontally separated air gaps is generated by a single, 100 kA superconducting transmission line. An alternative design with a cold iron yoke, horizontally or vertically separated air gaps is under investigation. The cold iron option with horizontally separated air gaps reduces the amount of iron, which is one of the major cost drivers for the 233-km magnet system of future accelerator. The vertical beam separation decreases the superconductor volume, heat load from the synchrotron radiation and eliminates fringe field from the return bus. Nevertheless, the horizontal beam separation provides lowest volume of the iron yoke and, therefore, smaller heat load on the cryogenic system during cooling down. All these options are discussed and compared in the paper. Superconducting correction system combined with the magnet that allows increasing the maximum field is also discussed. Preliminary cost analysis is performed for all these options.     

Quench detection of multiple magnet system

Magnet protection mandates the detection of any normal zone so that the magnet can be safely discharged. This is usually achieved by having a center voltage tap and two voltage taps at both ends of the windings. The voltage across the two sections of the winding is compared and balanced for inductance. Any voltage signal is then due only to the presence of a normal zone. This method is shown to be inadequate for mutually coupled magnet systems. As a solution to this problem a theory of voltage detection for mutually coupled magnets is presented along with a voltage detection circuit based on Gaussian elimination. The method is confirmed by experiment. Two equivalent solutions are presented which involve either additional voltage taps or the incorporation of dI/dt signals from the coupled magnets     

Vela satellite system detector electronics

The block diagrams of detector electronics used in the Vela Satellite Program are discussed in this paper. The auxiliary ground equipment used in conjunction with these instruments is mentioned along with details on the design of two circuits more commonly used in the Vela Satellite detectors.     

New design concept of the magnet system generating the high pulsed field in combination with the bias field of the superconducting magnet

A new design concept of the axisymmetric magnet system generating the very high pulsed magnetic field which is superimposed on the bias magnetic field of the superconducting magnet is presented. The pulsed magnet consists of two coaxial coils which are wound in opposite directions. The geometry of both pulsed coils, i.e. the working (inner) one and the compensating (outer) one is designed in such a way that the mutual coupling between the small pulsed magnet and the outer superconducting magnet is practically zero. This configuration prevents the rise of the high induced voltage on the current leads of the superconducting magnet when the pulsed magnet is being energised, hence resulting naturally in protection of the system (superconducting magnet and the current source) against possible damage. Further, it is predicted that the stray field of the pulsed magnet, which gives rise e.g. to the eddy currents in the winding of the superconducting magnet, is considerably decreased. The simple theory enabling the design of the geometry of the compensating pulsed coil is derived. The advantages of this new concept are demonstrated on the results of the theoretical analysis using, as an example, one of the pulsed coils that were designed and fabricated in the Clarendon Laboratory, in connection with the Oxford Instrument superconducting magnet (Clarendon hybrid outer) which can generate a steady magnetic field up to 10 T in a room temperature working space with a diameter of 240 mm.     

PDA detector For DS-CDMA cooperative system

This paper considers the uplink of a cooperative Code-Division Multiple-Access (CDMA) sys-tem where parts of mobile nodes serve as source nodes while the others serve as relay nodes at any instant in time. When the non-orthogonal spreading codes are adopted, Multiple Access Interference (MAI) will exist at both the relay nodes and the base node, causing diversity gain to diminish. To mitigate MAI and exploit full advantages of cooperation, the Probabilistic Data Association (PDA) is developed at the relay nodes and the base node. Simulation results demonstrate that some performance gains can be obtained by the PDA de-tector over the Minimum Mean Square Error (MMSE) detector at high Signal-to-Noise Ratio (SNR) and conversely at low SNR.     

液体CT探测器控制系统的设计与实现

为加强航空器的安全防范工作,实现液体的不开瓶安全检测而研发的液体CT探测器是一种用射线源对液体进行CT检测的装置。本文针对液体CT探测器设计了基于PLC的控制系统,实现了液体CT扫描探测所需的扫描运动控制,旋转台的自动精密定位,射线源自动训管,射线源高低压及束流控制选择、以及PLC与主机的RS232双向链接闭环控制,PLC与探测器板的RS232通信,自动报警等功能,并在VB6．0环境下,开发了上位机监控程序,实现了上位机对PLC的系统初始化、控制命令发送、系统状态显示等任务。整个系统结构简单,可靠,调试方便,为CT成像实验建立了一个精密量化的,可视的,参数可调的数控实验平台。     

套管损伤探测仪信号采集系统研究

本文以瞬变电磁理论为基础,设计出基于单片机的套管探测仪的采集系统,通过对获取的磁探头信号信息进行分析,可以对套管损伤程度进行评估,能准确地了解井下套管的损坏状况,为套管的修复和采取的预防措施提供科学依据。文中重点介绍了信号采集的原理、方法,以及相应的硬件电路和软件设计。其中,硬件电路主要由前置放大电路、可变增益放大电路、积分电路和AD采样电路组成,软件主要利用PIC单片机进行相关时序控制。本采集系统能够完成对多路磁探头信号的分时采集,电路设计简单,控制简便,采样精度高,抗干扰能力强。     

Single-port-access surgery with a novel magnet camera system

In this paper, we designed, built, and tested a novel single-port access laparoscopic surgery (SPA) specific camera system. This device (magnet camera) integrates a light source and video camera into a small, inexpensive, portable package that does not compete for space with the surgical tools during SPA. The device is inserted through a 26-mm incision in the umbilicus, followed by the SPA port, which is used to maintain an insufflation seal and support the insertion of additional tools. The camera, now in vivo, remains separate from the SPA port, thereby removing the need for a dedicated laparoscope, and, thus, allowing for an overall reduction in SPA port size or the use of a third tool through the insertion port regularly reserved for the traditional laparoscope. The SPA camera is mounted to the abdominal ceiling using one of the two methods: fixation to the SPA port through the use of a rigid ring and cantilever bar, or by an external magnetic handle. The purpose of the magnet camera system is to improve SPA by: 1) eliminating the laparoscope SPA channel; 2) increasing the field of view through enhanced camera system mobility; and 3) reducing interference between the camera system and the surgical tools at the port, both in vivo and ex vivo.     

A superconducting magnet system for free-electron cyclotron maser

A superconducting magnet system for free-electron cyclotron maser is developed. This system includes a main superconducting magnet, a gradient superconducting magnet, a normal magnet, a cryostat and some accessories. The designed magnet system has the advantages of having a small size, high stable magnetic field and suitable field profile. It is very suitable for a 4mm wavelength free-electron cyclotron maser. The design and some experimental results are given.     

永磁同步电机伺服系统的模糊控制

为了克服参数的不确定性,提高永磁同步电机伺服系统的快速跟踪能力,文中提出了一种自校正模糊控制器。该自校正模糊控制器与传统控制器相比,具有在线计算简单、减小稳态误差的优点。同时将其应用于永磁同步电机伺服系统的速度控制,证明了该模糊控制器的优越性。     

TDI型红外探测器在机载侦察设备中的应用

TDI型红外探测器作为第二代红外探测器,具有比其他类型传感器更高的温度灵敏度,可适应更大的扫描成像视场.将TDI型红外探测器应用于机载侦察系统,即能实现大扫描视场、高空间分辨率的图像要求,又能在适应较快飞行速度的情况下,保持较高的温度灵敏度.为保证缩短飞机的滞空时间提供了技术支持.     

分布式探测器系统测量数据的无线传送

为了在一个广阔区域中监测水质变化,需要布居多个智能传感器,采用无线数据传送是理想的数据汇总方式。分析比较了无线射频模块、GSM模块、GPRS模块的特性,给出了本地单片机与这3种模块进行连接的方法,以及如何通过这3种模块进行无线数据传送;同时也给出了在一种分布式系统中对终端数据信息的识别方法。所建立的基于无线传输的分布式水环境监测系统已投入试验应用。     

单探测器共孔径多光谱成像系统设计

为了解决多光谱成像系统的轻小型设计难点,采用单探测器多谱段成像方案进行了同时刻四谱段成像系统的光学系统设计。分光原理为,在物镜组前方设置四片楔形滤光棱镜,并在棱镜表面镀上透过不同谱段的透过薄膜;物体辐射经过棱镜后不同谱段的辐射发生不同方向的偏折,即在焦平面的不同位置形成了分离的光谱像。设计过程中,采用渐晕的方法解决谱段间的重叠问题。设计得到的光学系统波段数为4,工作波长为8.20~8.60 m、9.40~9.80 m、10.60~11.20 m及11.20~12.20 m,焦距为55 mm,全孔径为80 mm,光学系统的弥散圆直径小于40 m,并分析了系统的像差特性。分析结果表明,该系统具有良好的成像质量,满足多谱段成像要求。     

采用CMOS太赫兹波探测器的成像系统

太赫兹波成像技术在生物医疗和安全检测等领域具有广阔的应用前景。针对新一代信息技术对便携式太赫兹波成像设备的需求,设计了基于CMOS太赫兹波探测器的成像系统。该系统包括一款CMOS太赫兹波探测器、片外模数转换器（ADC）、FPGA数字信号处理器、二位步进机、四个抛物面镜和太赫兹波辐射源等。CMOS太赫兹波探测器集成了片上贴片天线以及作为检波元件的NMOS晶体管,探测器由180 nm标准CMOS工艺制成。太赫兹波探测器的输出被片外模数转换器（ADC）采集并转换为数字信号,该数字信号被FPGA采集并传输到电脑上成像。所有上述元件均被装备在印刷线路板（PCB）上以减小系统体积。该系统实现了透射式太赫兹波扫描成像而无需斩波-锁相技术,并给出在860 GHz的太赫兹波照射下隐藏在信封内部金属的成像结果。     

生物芯片电化学检测仪的嵌入式系统设计

随着生物芯片的快速发展,相应的芯片检测技术也在不断更新。与传统的光学检测仪不同,设计的电化学检测仪具有可微型化,集成化及自动化等诸多优点。通过硬件电路和软件编程两方面结合,介绍了生物芯片电化学检测仪的嵌入式系统。系统以C8051F020为核心,结合MAX396,CY7C68001,A／D,D／A等芯片实现了检测仪的嵌入式系统设计,最后给出检测仪的测试结果。     

红外探测器信息获取系统噪声特性

从理论上完成了红外图像传感器信息获取电路的噪声建模,并且分别从仿真和测试两个方面对电路的噪声进行分析。三种分析方法的结果基本相同,均为0.11mv左右。从原理和实验两个方面证明了基于仪放的模拟信号调理电路可以满足噪声低至0.2mv的红外探测器航天应用需求。在完成噪声量大小分析的同时进行了噪声频谱特性分析,证明了信息获取电路噪声主要成分是1/f噪声和白噪声,二者均满足高斯分布。