Development Of Quadrupole Mass Spectrometer

Mass spectrometer is an important analytical method for identifying the composition of substances.It has the advantages of fast analysis,high sensitivity and specificity.Mass spectrometer,which plays an increasingly important role in the fields of aerospace,food safety,drug analysis,vacuum diagnosis,life science and counter-terrorism emergency,has rapidly developed and expanded the market.Miniaturization and portability has become an important direction of mass spectrometer development due to the limitation of usage environment.Quadrupole mass spectrometer,as a typical simple and high functional mass spectrometer,can be used as an analytical instrument for accurate identification of conventional gas.Its mass analyzer can build a three stage series quadrupole mass spectrometer structure to achieve multiple mass spectrometric analysis and rapid screening of target compounds.Quadrupole mass spectrometer used in China is widely derived from abroad at present.Therefore,a quadrupole mass spectrometer for gas composition analysis in vacuum environment has been developed based on the comprehensive analysis of the structural characteristics and advantages of the International advanced mass spectrometer.This paper presents a general design scheme for the quadrupole mass spectrometer which includes simulation and mechanical structure design based on the theoretical calculation and structural requirements of the quadrupole mass spectrometer.The device has six parts which consist the ion generator,the quality analysis device,the ion detection device,the power supply and insulation device,the cavity connection device and the reserve device.Simulation analysis focuses on the quadrupole filter.The particle tracking module is used to simulate the motion trajectory of charged particles in the quadrupole field.The ion transmission rates of the quadrupole filter under the different pole size are obtained by the method of electric field scanning.The key parameters of the pole electrode are optimized by comparing the mass spectrum performance under different size parameters.The electronic ionization source,the quadrupole filter,the Faraday cup and other parts are designed to complete the parts making and assembling according to the requirements of the vacuum environment and use of the quadrupole mass spectrometer.The power source of the electronic ionization source is designed at the same time,and the RF power supply for the experiment is selected.A set of small vacuum system experimental platform,which consists of vacuum chamber,vacuum pump,vacuum gauge and gas importing device,is set up in order to test the performance of the quadrupole mass spectrometer.The test results of the quadrupole mass spectrometer show that the optimum value of the filament current of the ion source is 2.6A,the detection range of the mass number can reach 65amu.A good mass spectrogram can be obtained after mass spectrometry.And it has good quality resolution and precision at the same time.The measured results of the quadrupole mass spectrometer meet the design standard and can be used for gas analysis and monitoring of vacuum chambers.The successful research and development of this quadrupole mass spectrometer has accumulated design technology experiences for the field of vacuum equipment in China,which is of great significance for promoting the independent innovation of the mass spectrometer industry.