The Development And Characterization Research Of A Charged Particle Source Based On Low Work Function Inorganic Materials

Electrofluid exists in many forms,including charged liquids or gases,two phase flow composed by charged liquid drops with gas,or by charged micro solid particles with gas.Electrofluid is a frontier interdiscipline which combines fluid mechanics and Electrical science with high research value,and is widely used in industrial and peoples'daily life,such as mass spectrometry,electrostatic spraying,atomization inhalation and so on.The formation of electrofluid requires a"particle source"that can stably emit charged particles in scientific research and practical applications.In order to produce a stable radiation-free and low energy consuming charged particle source,a low power inorganic charged particle source based on Cs2CO3 was developed.The main research contents are as follows:Firstly,the electron emission mechanism of low power functional materials was discussed with quantum mechanics in semi-classical method.With low barrier on the surface,electrons can easily emit from the surface with very low voltage.The particle source made of this material has the advantages of low energy consumption,high charge density and easy control.Subsequently,metal electrode substrates were prepared before coating.Considering the thermal stability,chemical stability and electrical conductivity,three kinds of substrates,pure W,CuW and AgW alloys,were selected.The surface roughness and its characteristics of the treated substrate were tested by grinding machine.The results showed that the surface roughness of the treated substrate could reach 50-100nm,which met the deposition requirements,and had good corrosion resistance and oxidation resistance.Finally,Cs₂CO₃ was used as the source of low-power functional material on the prepared metal substrates,and Ag and Al with high stability were co-evaporated in a 7:4 ratio on the vacuum coating machine.After evaporation,the characteristics of the coatings and the electron emission ability of various types of particle sources were tested.The results showed that a pit like structure was easy to appear on the surface of 10nm thick film,and the film was not uniform and compact enough.The surface roughness of 20nm and 30nm thick film was better,but only 20nm thick film conformed to the preset composition ratio.The surface work function of CsAg and CsAl alloy film deposited by vacuum evaporation was significantly lower than that of the original substrates.The surface work function value of20nm thick films was relatively stable,and the films had strong oxidation resistance.It was found that CsAg alloy thin film with 20nm thick AgW substrate had the strongest electron emission ability.