高精度中频数字鉴相器在FPGA上的实现

介绍了一种高精度中频数字鉴相器的鉴相原理,以及在设计过程中以数字滤波器为主的参数选择方法,并且将其在FPGA上硬件实现。该鉴相器采用数字I/Q技术,鉴相精度达到0.029°,利用该高精度中频数字鉴相器对3.71875 MHz中频信号进行鉴相,实际鉴相结果为:绝对相位鉴相结果好于0.05°,均方根值为0.0076°;相对相位鉴相结果好于0.1°,均方根值为0.0287°。     

数字化I/Q技术用于磁控管频率控制

采用磁控管做功率源的低能电子直线加速器在医疗、辐照、X射线检测等领域得到较为广泛的应用。磁控管产生的微波信号输入到加速管,对电子束进行加速,磁控管的工作频率稳定性对加速器电子束能量、能散及发射度产生直接的影响。但磁控管是一种振荡器,其频率受到温度、振动、负载牵引的影响会产生漂移,所以需要一套自动频率控制系统(Automatic Frequency Control,AFC)机构对磁控管进行频率控制。目前普遍采用的AFC机构主要是行波控相或双腔鉴频,对两路检波信号差分放大进而控制伺服电机进行调谐的方法实现磁控管的频率稳定。随着数字化I/Q和FPGA(Field-Programmable Gate Array)技术的不断发展,运用该技术进行磁控管的频率控制完全具备可行性。本文从理论和工程设计上阐述了数字化I/Q技术在磁控管频率控制上的应用。     

一种基于三项误差模型的I／Q解调器校准方法

I/Q解调器的误差决定了PAD的相位测量精度.本文在I/Q解调器以往的两项误差模型基础上引入三项误差模型,并给出了相应的误差校准方法.实验结果表明,这种校准方法是合理有效的.在BEPCⅡ工作频率2856 MHz上,经校准的I/Q解调器的误差范围减小为-1.8 °～O.5 °,且360 °范围内任意相位值的测量误差均得到了抑制.     

基于FPGA技术的数字鉴相器的设计与仿真

1数字鉴相器简介 数字三态鉴相器具有三个稳定状态，状态之间的转换由输入信号F1和F2的上升沿触发。状态2称为“滞后状态”，输出为吸入（Sink）电流；状态1称为“超前状态”，输出为提供（Source）电流；状态0称为“同相状态”，无输出操作。数字鉴相器的输出通过I/V转换线路后可变换得到与混频器类似的鉴相曲线。     

放射性125I种子源自动生产装置的研制

为提高¹²⁵I种子源的自动化生产水平,研制了一种放射性¹²⁵I种子源自动生产装置。该装置安装在铅屏蔽工作箱中,可自动完成源壳装夹、源芯入壳、焊接、卸料收集等一系列动作。该装置具有焊接成功率高、减少操作人员劳动强度、有效保证操作人员辐射安全等特点。     

HLS800MeV直线加速器相位控制系统的研制

介绍了合肥光源(HLS)800 MeV直线加速器相位控制系统的研制进展,该系统包括相位稳定系统和相位翻转系统两部分。其中前者主要由I/Q解调器、电控移相器和虚拟示波器等组成;后者由脉冲信号发生器和I/Q调制器组成。目前样机制作已完成,测试表明前者的相位分辨率为±0.1°,在线测量精度为±0.3°,闭环相位稳定度可达±0.5°;后者的精度为(180±2)°,样机各项参数均达到设计指标。     

放射性Na~(131)I液体药品自动灌装装置的研制

研制了一种医用放射性Na131I液体药品自动灌装装置,该装置安装于洁净度为百级的防辐射屏蔽工作箱中,可执行放射性液体精确、连续自动灌装和自动上胶盖操作。该装置实现了强辐射环境下放射性液体药品的批量化分装,提高了放射性液体药品自动化生产水平,能更好地满足放射性药品生产的GMP规范要求。     

~(125)I单光子吸收仪的研制

本文根据γ光子与物质相互作用的原理,设计和研制了主要用于测量人活体桡骨矿物质含量的~(125)I单光子骨矿物质分析仪。文中介绍了分析仪的原理、基本结构、性能分析、数据处理方法、曲线刻度方法、误差分析和临床初步应用等。该仪器测量结果的线性和重复性均良好,测量精度好于±5％,性能可靠,操作方便,测量迅速,能定量分析,是一种无创伤的检查仪,可以推广应用于医学研究和临床。     

治疗用Na^131I胶囊的研制及其动物实验

本工作进行了治疗用Na     

2 ^125I巩膜敷贴器的研制与临床观察

视网膜母细胞瘤和脉络膜黑色素瘤是分别发生于婴幼儿和中老年人群中的眼科肿瘤。近年来，国外在临床上采用了保留器官的作法，用高能β射线（如^106Ru／^106Rh）和低能γ射线（如^125I）治疗眼内肿瘤，疗效明显确切，使用安全可靠。不仅能保留眼球，且相当部分病人保存了视力。     

Digital RF phase detector for Linac in FEL accelerator

The digital RF (Radio Frequency) phase detector based on commercial PXI (PCI eXtensions for Instrumentation) modules for the Linac is fully described in the paper. The DBM (Double Balance Mixer) is used as the phase detector and its control and data acquisition system is based on the PXI bus. The software adopts a curve fitting algorithm. The prototype has been tested in the laboratory and the good resolution, accuracy, reproducibility and reliability are expected. The system does not present the problems of analog solution.     

Laser-RF synchronization based on digital phase detector

Laser oscillator synchronization with RF reference signal is ultra-important for a modem light source based on the accelerator.For Tsinghua Thomson scattering X-ray source,we have synchronized the mode-locked laser oscillator to RF reference signal with 48.2 fs RMS relative jitter.Both fundamental and harmonic signals derived from photo diode detection are used for laser-RF synchronization in our scheme.The fundamental signal is for coarse laser-RF synchronization and multiple laser oscillator synchronization.The harmonic signal is for high precise phase locking.The digital phase detector is implemented in the synchronization scheme for less noise,replacing the mixing to DC phase detection scheme.The digital processing algorithm for synchronization is commonly used in low-level RF control field.In order to test the phase locking loop logic without damaging the real laser oscillator,a laser oscillator emulator was developed for phase locking.This paper will report the laser-RF synchronization scheme and its performance.The laser oscillator emulator system will also be introduced here.     

RF front-end for digital beam position monitor signal processor

RF circuit board has a significant impact on performance of the Digital Beam Position Monitor (DBPM) in storage ring of a synchrotron radiation facility.In this paper,a front-end RF board is designed for DBPM,and schematics of the RF board and the test results are given.In view of the inevitable inconsistency in the multi-channel circuit,a calibration circuit is designed to reduce such an influence.The test results show that the calibration method is useful for beam current dependence which is sensitive to channels inconsistency.     

Beam test results of high Q CBPM prototype for SXFEL

In pursuit of high-precision beam position measurements at micrometers or submicrometers for the Shanghai soft X-ray free-electron laser (SXFEL) facility which is under construction in the vicinity of the Shanghai Synchrotron Radiation Facility,a high Q cavity beam position monitor (CBPM) with a resonant frequency of 4.7 GHz is developed by the Shanghai Institute of Applied Physics,and the relevant BPM electronics with a dedicated RF front end,and a digital BPM,are completed.The cavity design,cold test,system architecture,and first beam test are performed at the Shanghai deep ultraviolet free-electron laser (Zhao et al.in Nucl Instrum Meth A 528(1-2):591-594,2004.doi:10.1016/j.nima.2004.04.108) facility.Results of the beam experiment show that the performance of the CBPM is consistent with basic expectations,and the beam position resolution can fulfill the requirements for the SXFEL project if the beam conditions are optimized.     

SPECT V/Q断层显像半定量分析联合测定血浆D-二聚体诊断肺栓塞的价值

研究V/Q断层显像半定量分析联合测定血浆D-二聚体早期、准确诊断肺栓塞的价值,尤其在小面积肺栓塞诊断中的应用优势。疑诊肺栓塞来核医学科行V/Q断层显像患者共156例,以CT肺血管造影（computed tomographic pulmonary angiography, CTPA）检查及临床诊断为分组标准,肺栓塞组患者101例,非肺栓塞组患者55例。比较SPECT V/Q断层显像、血浆D-二聚体测定以及SPECT V/Q断层显像联合血浆D-二聚体测定三种方法对肺栓塞的诊断效能。应用Philips公司Oasis图像后处理软件对栓塞面积进行半定量分析,进一步评估对于肺栓塞面积占双肺容积≤15%的小面积肺栓塞的诊断价值。结果显示,血浆D-二聚体测定对于肺栓塞的诊断有较高的灵敏度（70.3%）,但是特异性（61.8%）差;SPECT V/Q断层显像半定量分析对于肺栓塞的诊断具有较高的灵敏度和特异性,分别为85.1%、90.9%;而二者联合应用,诊断肺栓塞效能最高,灵敏度和特异性分别为91.1%、98.2%。 其中SPECT V/Q断层显像半定量分析对于肺栓塞面积小于15%的小面积肺栓塞诊断有优势。放射性核素SPECT V/Q断层显像联合测定血浆D-二聚体能显著提高肺栓塞的诊断效能,是临床实用、安全有效的肺栓塞疑诊患者诊断策略。     

A One-Dimensional Hybrid Simulation of DC/RF Combined Driven Capacitive Plasma

We developed a one-dimensional hybrid model to simulate the DC/RF combined driven capacitively coupled plasma for argon discharges. The numerical results are used to analyze the influence of the DC source on the plasma density distribution, ion energy distributions （IEDs） and ion angle distributions （IADs） on both the RF and DC electrodes. The increase in DC voltage drives more high-energy ions to the electrode applied to the DC source, which makes the IEDs at the DC electrode shift towards higher energy, and the peaks in the IADs shift towards small angle regions. At the same time, it also decreases the ion energy at the RF electrode and enlarges the incident angles of the ions, which strike the RF electrode.     

压水堆核电厂冷却剂碘同位素活度比值131I/133I与燃料完整性关系研究

压水堆核电厂正常运行期间燃料元件破损会造成一回路裂变产物活度升高,碘同位素活度比值131I/133I是行业内最常用的判断燃料破损情况的指标之一。本文介绍了压水堆正常运行期间冷却剂131I和133I的产生来源和迁移过程,建立模型估算了燃料完整、小破口和大破口情况下131I/133I范围,并通过在运CPR1000型压水堆核电厂的运行监测数据对计算模型进行了验证,两者符合得较好。     

基于FPGA的CSR高频控制系统相位求解模块设计

CSR高频控制系统需要对高频正弦波激励信号的幅度、相位、频率进行稳定控制。相位arctan(Q/I)求解是必不可少的模块。论述了一种新的基于FPGA平台和对称查找表法(SBTM)的求解相位arctan(Q/I)的方法,做了详细的理论分析,给出了具体实现的代码和结果。该模块精度高,消耗资源少,可直接应用于CSR高频控制系统。