Research On Mass Spectrometry Data Acquisition System

Mass spectrometer is a kind of analysis instrument by using charge-mass ratio separation ways to detect substances.It is being widely used in energy,pharmaceutical,life science and space exploration and other fields.Its working principle is capture the output signal of detector by data acquisition systems,analyzing and processing the data by computer,and finally getting complete mass spectrum diagram.Embarked from the working principle of the portable ion trap mass spectrometer and based on the research of data acquisition key technology of signal synchronization control and data storage etc,we designed a system of advanced data acquisition system according to the requirements of project.The data acquisition system is divided into control module,signal conditioning module,data acquisition module,communication module.Control module is to realize the signal control of the whole system.this paper is mainly focused on realizing multiple signal synchronization control according to the sequence of system;Signal conditioning module realize convert current and voltage,amplification,filtering processing of the weak original signal of detector in order to meeting the requirements of ADC chip acquisition;Original signal acquisition and storage is implemented by the data acquisition module,its using the technique of Direct Memory Access(Direct Memory Access,DMA).This technology not only improve the work efficiency of the CPU,but also solve the problem of speed mismatching;Communication module adopts Ethernet W5500 to implement data communication of the upper software and hardware,transmit data of mass spectrum.Switch control and data read of molecular pump is realized by using the RS-485 serial interface mode.In addition,w5500 satisfying the requirements of data transmission bandwidth to ensure the stability of the communication.Different modules are respectively analysis and exploration from two aspects of hardware and software design.The radio frequency signal and radio frequency auxiliary signal(AC signal)of circuit design is being simulate and verificate.Finally each module has beed gone through the hardwaretest and code debugging,including synchronous sequential control,RF signal control,signal acquisition and processing,ethernet communication,and other functions.Test results show that the module of signal output stability and high precision.In addition,the system complete the control and data acquisition task in a set time by the machine test,meet the design requirements of this paper.