Optics System Design of Microwave Imaging Reflectometry for the EAST Tokamak

A front-end optics system has been developed for the EAST microwave imaging reflectometry for 2D density fluctuation measurement.Via the transmitter optics system,a combination of eight transmitter beams with independent frequencies is employed to illuminate wide poloidal regions on eight distinct cutoff layers.The receiver optics collect the reflected wavefront and project them onto the vertical detector array with 12 antennas.Utilizing optimized Field Curvature adjustment lenses in the receiver optics,the front-end optics system provides a flexible and perfect matching between the image plane and a specified cutoff layer in the plasma,which ensures the correct data interpretation of density fluctuation measurement.     

A New Non-destructive Technique for Hydrogen Level Assessment in Zirconium Alloys using EMAR Method

In order to study the applicability of EMAR (electromagnetic acoustic resonance) method to non-destructive hydrogen level assessment in fuel spacer bands at pool side, an ultrasonic transmitter and receiver together with an EMAT (electromagnetic transducer) were used. Unirradiated Zircaloy-2 thin plates were hydrogen charged for the measurements. An irradiated fuel cladding tube was also used to examine the detection sensitivity of the resonance spectrum of the irradiated material. The following results were obtained. Acoustic anisotropy Δf, defined by using two resonance frequencies for shear waves with different polarization, was adopted as a parameter to express the ultrasonic resonance property. A hydrogen concentration dependence of Δf was observed in the range up to 1,200 ppm. Specimen thickness and oxide thickness were found to have negligible effect, on Δf, and liftoff of the sensor up to 1mm did not affect the Δf value. The acoustic anisotropy proposed in this paper was not sensitive to any of specimen dimension, surface condition, or sensor liftoff.     

中国先进研究堆堆水池窄量程液位测量方案选择及误差分析

介绍了中国先进研究堆（CARR）水池窄量程液位测量的4种方案：远传隔离法兰差压法、安全级吹气法、绝压变送器测量法、差压变送器测量法，并对这4种测量方案进行比较、分析，最后对选定的测量方案进行了误差分析。结果表明：差压变送器测量法满足测量要求。     

CARR热工过程测量系统变送器选型

详细介绍了几种系列的压力/压差变送器。它们分别是:1151电容式压力/压差变送器、115l智能型压力,压差变送器、3051智能型压力/压差变送器、应变桥式智能型压力/压差变送器和应变谐振式压力/压差变送器。对这些压力/压差变送器的性能进行了比较,最后结合CARR的实际情况进行了定型选择。     

TDC-GPX-based synchronization scheme for QKD system

To meet the needs of signal alignment between the transmitter and receiver in a quantum key distribution(QKD) system, we put forward a TDC-GPX-based synchronization scheme, which is based on high-precision time measurement. We send a low-frequency repeat optical pulse synchronized with associated quantum signals on the receiver's side by using a time-to-digital converter(TDC)module, the time intervals between quantum signals, and synchronization signals measured and converted to corresponding temporal orders to complete the synchronization.We state the principle of the synchronization scheme in detail and then verify it in an actual QKD test bed. The test results show that our TDC-GPX-based synchronization can obtain a time resolution better than 100 ps, and the proposed scheme shows full feasibility for an actual QKD system.     

Fast, Microprocessor Driven, Data Acquisition for Fermilab Experiment E-705

Data rate in excess of 105 16-bit CAMAC words/sec, with peak rates of up to 2×106 words/sec, are expected from Fermilab experiment E-705. To handle such rate, a fast Data Acquisition System was designed, composed of several CAMAC Smart Controllers, sending their data, in a combined serial/parallel organization, to a VME based data collection and forwarding system. Such a system, contained in a VME Crate, consists of homebuilt data receiver and transmitter boards, a Motorola VME110, 68000 based, Single Board Computer acting as a supervisor, and a large (?4 Mbytes) buffer memory. Data filtering capabilities will be added to the system with the inclusion of several MK 75602 Single Board Computers, acting as processing cells.     

Studies on microdomain structure in segmented polyether polyurethaneureas by positron annihilation lifetime and small—angle X—ray scattering

The microdomain structure of segmented polyether polyurethaneureas is investigated by means of positron annihilation lifetime spectroscopy,small-angle X-ray scattering and differential scanning calorimetry.The experimental results show that the decrease in the domain volume and free volume results from the increase in the hard segment (polyurethaneurea segment)contents as the number-average molecular weight Mn of the soft segments (polyethylene glycol segments)is the same,and that the increase in domain volume and free volume result from the increase in the Mn of the soft segments when the hard segment content is the same or nearly the same.These results demonstrate that positron annihilation lifetime spectroscopy is a sensitive technique to probe the microdomain structure in polymers.     

A cathodic arc enhanced middle-frequency magnetron sputter system for deposition of hard protective coatings

1Introduction Hard coating is a type of coating that includes metallic nitrides,metallic carbides,diamond,dia-mond-like carbon(DLC),and ceramic.These coatings can effectively reduce friction coefficients and wear rates of the workpieces and increase surface hardness,toughness,and resistance to chemical corrosion;hence,they are widely used as protective coatings on cutting tools and on wear-exposed components.[1-3]Plasma chemical vapor deposition(PCVD),magnetron sput-tering,and cathode arc d…     

Water level measurement uncertainty during BWR instability

This paper addresses the performance of the water-level measurement system in a boiling water reactor (BWR) during severe instability oscillations which, under some circumstances, can occur during an anticipated transient without SCRAM (ATWS). Test data from a prototypical mock-up of the water-level measurement system was used to refine and calibrate a water-level measurement system model. The model was then used to predict level measurement system response, using as boundary conditions vessel pressures calculated by RETRAN for an ATWS/instability event.The results of the study indicate that rapid pressure changes in the reactor pressure vessel which cause oscillations in downcomer water level, coupled with differences in instrument line lengths, can produce errors in the sensed water level. Using nominal parameters for the measurement system components, a severe instability transient which produced a 0.2 m peak-to-minimum water-level oscillation in the vessel downcomer was predicted to produce pressure difference equivalent to a 0.7 m level oscillation at the input to the differential pressure transmitter, 0.5 m oscillation at the output of the transmitter, and an oscillation of 0.3 m on the water-level indicator in the control room. The level measurement system error, caused by downcomer water-level oscillations and instrument line length differential, is mitigated by damping both in the differential pressure transmitter used to infer level and in the control room display instrument.     

Design and offline processing of an ultrafast digitizer based on internal cascaded DRS4

In this paper, we present an ultrafast digitizer utilizing the DRS4 switched capacitor array applicationspecific integrated circuit to achieve an ultrafast sampling speed of at most 5 GS/s. We cascaded all eight channels(sub-channels) of a single DRS4 chip for increased storage depth. The digitizer contains four DRS4 chips, a quadchannel analog-to-digital converter,a controlling fieldprogrammable gate array, a PXI interface, and an SFP+connector. Consequently, each DRS4 channel has a depth of 8192 points and a vertical resolution of 14 bits. The readout sequences should be broken into several segments and then reordered to obtain the correct sequential data sets, and this offline procedure varies in different readout modes. This paper describes the design and implementation of the hardware; in particular, the respective processing procedures are described in detail. Furthermore, the offset error is calibrated and corrected to improve the precision of the captured waveform in both single-channel and highresolution modes.     

The new Melbourne nuclear microprobe system

The spatial resolution in a nuclear microprobe system has been stalled at around 1 μm for many years. In Melbourne we are presently constructing a new facility which aims to break this barrier. The key ingredients of the new facility are: (i) a novel magnetic quadrupole lens quintuplet probe forming system that is a further optimised version of the CSIRO/MARC system presently in operation in Sydney, (ii) high solid angle detectors for particles, X-rays and secondary electrons and (iii) a fast data acquisition system able to cope with greater than 20 kHz count rates from up to four detectors with full deadtime correction. This paper describes the optimised probe forming lens system which is comprised of four thin lenses and one thick lens to produce an orthomorphic probe forming lens system with a demagnification of 150.     

A new thermal neutron detector for protein crystallography

A new position-sensitive detector is being developed for protein crystallography studies at a spallation source. Based on eight, independent, wire proportional chamber segments housed in a curved pressure vessel, the device covers a scattering angle of 120 degrees, and has a collecting area of 1.5 m by 20 cm. The position resolution will be about 1.3 mm FWHM, with a total counting rate in excess of one million per second. Timing resolution, essential for a spallation source application, is of order 1 μs and provides neutron energy determination that is well suited for crystallography. Advanced features of this device include a digital centroid finding scheme, a seamless readout between segments, and a wire array design that minimizes anode modulation. Details of the mechanical design are given, together with digital centroid measurements that illustrate accurate, uniform response     

Performance assessment of Class 1E pressure transmitters subjected to environmental stresses

An experimental investigation into the performance of Class 1E electronic pressure transmitters exposed to environments within and beyond the design basis has been conducted. Emphasis was placed on determining the instruments' failure and degradation modes in separate and simultaneous environmental exposures. Five unaged ITT Barton Model 763 pressure transmitters were tested. Each transmitter was exposed to a unique environment.Evaluation of transmitter response showed that temperature is the primary environmental stress affecting performance. Large errors were observed at the onset of accident environment exposure. These errors decreased with time-at-temperature. We believe the source of these errors to be a common-mode design weakness in the transmitter's calibration potentiometers resulting from a dielectric property temperature dependency. The modification recommended by the manufacturer to reduce this temperature effect proved to work reasonably well in the long term. A second potential common failure mode which activates slowly with time-at-temperature was also identified. We believe this failure mechanism is catalyzed by the presence of a specific lubricant used in the production of some potentiometers. The transmitters tested proved to be exceptionally hard to radiation effects and there appeared to be no significant synergistic effects between radiation and temperature. The observed responses of the transmitters offer support for the position forwarded by IEEE 381–1977 recommending that electronic modules be aged to varying degrees of advanced life before testing.     

Achievement of 1.9 MW for 300 s during the commissioning of the KSTAR ICRF transmitter

KSTAR (Korea Superconducting Tokamak Advanced Research) is a national tokamak aiming at the high beta operation based on AT (Advanced Tokamak) scenarios in Korea and ICRF (Ion Cyclotron Ranges of Frequency) is one of the essential heating and current drive tools to achieve this goal. The ICRF heating and current drive scenario requires 4 units of 2 MW transmitters with a frequency range from 25 to 60 MHz. The first KSTAR transmitter is a modified FMIT (Fusion Material Irradiation Test) transmitter consisting of four amplifier stages. An amplitude-modulated 1 mW frequency source drives a 500 W solid state wideband amplifier, which in turn drives three tuned triode/tetrode amplifier stages. The tube employed in the final power amplifier is a 4CM2500KG tetrode fabricated by CPI (Communications & Power Industries). After the fabrication of the cavity and power supply was completed in 2004, several failures of the tube during a factory and a site acceptance test occurred before eventually achieving 1.9 MW for 300 s at 33 MHz in 2007. The electrical efficiency of the FPA (Final Power Amplifier) is about 70%. Although this is a very encouraging result for the development of an ICRF transmitter for ITER (International Thermonuclear Experimental Reactor), continued efforts for a reliable operation are required to achieve the final goals of the KSTAR and ITER ICRF system.     

ASD/BLR及其测试平台的设计

ASD/BLR是稻草管探测器读出系统的核心电路,具有很强的功能,详细了解该电路的工作原理,是用好ASD/BLR的基础,对于采用稻草管探测器的读出系统是非常有意义的.给出了ASD/BLR的测试方法及其测试电路的原理.     

便携式γ能谱仪闪烁探头改进设计及性能研究

为满足当前便携式γ能谱仪对高性能闪烁探头的需要,本文提出了采用CsI(Tl)晶体耦合雪崩光电二极管的方式代替NaI(Tl)晶体耦合光电倍增管以构成新的闪烁探测器,并设计了低噪声电荷灵敏放大器作为探测器读出电路。根据唯一变量原则分别测试了能量分辨率随温度与偏压的变化规律,并对多种放射源的γ射线进行能谱响应实验。实验结果表明：当温度为23 ℃且偏压为370 V时,该闪烁探头对¹³⁷Cs、²²⁶Ra、⁶⁰Co和¹⁵²Eu源的γ射线具备优异的能谱响应特性,其中,对¹³⁷Cs源的γ射线能量分辨率可达4.98%,输出信号信噪比可达21∶1,上升时间为80 ns。可见,改进后的闪烁探头的性能有大幅提升,具备能量分辨率更佳、体积更小、抗机械性能与适用性更强等优点。     

Hybrid Pixel Particle-Detector Without Bump Interconnection

A hybrid pixel particle-detector which does not require bump-interconnection is presented. The sensor signals are transmitted from the sensor to the readout chip using capacitive (AC) coupling. In order to facilitate the signal transmission, simple preamplifiers are implemented in the sensor pixels. The sensor chip with 100% fill-factor and in-pixel amplification is implemented in a standard high-voltage CMOS technology. Depleted high-voltage n-well/p-substrate diodes are used as sensors. CMOS charge-sensitive amplifiers are placed inside the sensor-collecting electrodes (n-wells) using twin-wells. The outputs of the preamplifiers are connected to transmitter electrodes implemented in the top metal-layer of the sensor chip. The inputs of the receivers in the readout chip are also connected to electrodes in the top metal-layer. When the readout chip is precisely flipped and glued onto the sensor chip, the sensor- and receiver electrodes form capacitors that allow AC signal transmission. The first test results obtained with a small test-matrix containing 14 times 14 pixels of 78 times 60 mum²-size are presented. Noise, threshold dispersion and radioactive source spectra are measured.     

Products of research and development in NDT

The Nondestructive Ultrasonic Testing and Evaluation is directed to describe flaws microstructure, structure residual stress, reliability or quality insurance. An overview is given on the scientific background, interpretation capability based upon mathematic-numerical models, new design of equipments and demonstrated at components containing relevant flaws. Emphasis is laid upon SNR-improvement in the UT of austenitic weldings. Examples are shown using the backscattering technique with linear polarized shear waves. Stress measurements are performed with electromagnetic ultrasonic probes (EMAT). The surface inspection with magnetic imaging of the eddy current field or the multi-frequency eddy current methods are described. The possibilities of detection, classification and reconstruction of flaws are demonstrated in the time- and frequency domain with the satellite pulse echo technique, focal probes and the synthetic aperture methods like ALOK, Phased Array, Holography and SAFT.     

γ相机准直器的质量指标对比研究

对比研究γ相机准直器的3个主要质量指标对评价和检测准直器质量的价值。用同型号低能通用低能高分辨平行孔准直器4只,参照NEMA标准（1994）,分别测试各准直器的系统均匀性,同时测试系统空间分辨率及灵敏度,对测试结果进行比较和分析。结果表明,同型号准直器的系统空间分辨率与灵敏度两项指标基本接近,而均匀性指标存在较大差异（当部分准直器存在质量问题时）。其中系统积分和微分均匀性分别超过6％和3％的3只准直器被证实存在质量问题。说明系统均匀性定量和定性地反映准直器的性能,是反映准直器质量问题的最基本和最有效指标。