【作者】 郭静；

【导师】 田地；

【作者基本信息】 吉林大学 ， 精密仪器及机械， 2015， 硕士

【摘要】 飞行时间质谱仪（TOF-MS: Time-of-Flight Mass Spectrometer）是一种高分辨率、高灵敏度、分析速度快及理论上无质量检测上限的质谱仪，在同位素分析、基因及基因组学、核物理和环境科学等研究领域有广泛的应用。与国外相比，国内关于TOF-MS的研究仍然在起步阶段，还没有成形的仪器产品，全部靠进口购买。国内对TOF-MS的数据采集系统的研究也相对较少，在性能上还有待于提高。目前大多数TOF-MS仪器的数据采集系统使用高精度的时间数字转换器（TDC: Time-to-digital converter）来测量离子的飞行时间，以实现对离子种类的辨别。TDC的性能影响飞行时间质谱仪的灵敏度和质量精度等参数，因此研究高性能的时间数字转换器对TOF-MS具有重要意义。本文针对飞行时间质谱仪高分辨率、宽质量范围的特点，设计了一种基于TDC技术的高精度、大量程的数据采集系统。整个数据采集系统分为前端信号调理模块、时间数字转换模块和FPGA时序控制模块。前端信号调理模块首先对离子检测器的信号进行放大，通过比较器对放大后的信号进行幅度甄别来筛选离子信号，之后将筛选出的信号进行电平转换输出至TDC的stop通道；时间数字转换模块以德国ACAM公司生产的专用时间间隔测量芯片TDC-GPX为核心，负责测量离子飞行时间，测量后的数据传输至FPGA；FPGA时序控制模块负责系统的时序控制，采用自顶向下的结构进行程序的编写，程序主要由TDC-GPX的初始化与控制、FIFO数据缓存和USB2.0数据传输三个功能单元构成，其中USB2.0读写模块采用时分复用技术实现了双向数据传输。系统测试结果表明，单通道测量精度小于100ps，测量范围大于500μs，可同时进行8个通道测量，对应一个start脉冲能够测量超过128个stop脉冲，可以满足飞行时间质谱仪数据采集系统的需求。此外，所设计的数据采集系统也适用于其他TOF系统中。更多还原

【Abstract】 Time-of-Flight mass spectrometer (TOF-MS) is a high resolution, highsensitivity, fast analysis speed and no theoretical quality testing upper limit of themass spectrometer. It has a wide range of research applications such as the isotopeanalysis, gene and genome science, nuclear physics and environmental science andso on. Compared with developed countries, domestic research on TOF-MS is still inits infancy and instrumentation products have not yet formed, all rely on imports.Domestic research on TOF-MS data acquisition system is also relatively less and theperformance should be improved. At present, in order to achieve ion speciesidentification, most data acquisition system of TOF-MS use the high precisiontime-to-digital converter (TDC) to measure the flight time of ions. As theperformance of TDC affects sensitivity, mass accuracy and other parameters ofTOF-MS, research of high-performance TDC is of great significance for TOF-MS.As the high resolution and wide mass measurement range characteristics of atime-of-flight mass spectrometer, a high precision and wide range data acquisitionsystem was designed in this paper. The entire data acquisition system is divided intofront-end signal conditioning module, time to digital converter module and FPGAtiming control module. Firstly, front-end signal conditioning module doesamplification for ion detector signal, and by comparator to filter the ion signal, thenthe filtered out signal through level converter to the TDC stop channel; Thededicated time interval measurement chip TDC-GPX produced by ACAM Germancompany is the core of time to digital converter module which is responsible formeasuring the ion flight time and after measurement transfers data to FPGA; FPGAtiming control module is responsible for the system’s timing control, using atop-down structure of programming. The program mainly consists of TDC-GPXinitialization and control, FIFO data buffer and USB2.0data transfer three functionalunits. USB2.0reading and writing unit using time division multiplexing technology enables bidirectional data transmission.System test results show that the single-shot precision is less than100ps，therange of measurement time is beyond of500μs,8-channel measurements can becarried out at the same time, and corresponding to a start pulse capable of measuringmore than128stop pulses to meet the needs of the time of flight mass spectrometerdata acquisition system. In addition, the design of the data acquisition system is alsoapplicable to other TOF systems.更多还原