A two-dimensional multi-fluid model is developed to investigate the effects of dilution gas on microplasma properties and nanoparticle behavior in atmospheric-pressure radio-frequency acetylene discharges.The percentage of dilution gases(argon and helium)percentage varied from 0％to 90％,with the pressure kept constant.Simulation results show that the dilution gas percentage has a significant influence on the spatial distributions of the electron density and temperature,as well as on the formation of nanoparticles in acetylene microplasmas.With increasing dilution gas percentage,the electron density profile changes continuously from being high at the edge to high in the center.A mode transition from a mixed discharge mode with bothα regime and drift-ambipolar regime into α regime occurs,which is associated with a sudden decrease in the electron density of the presheaths and an increase in the electron temperature of the bulk plasma.The mode transition point corresponds to the lowest number density ratio of hydrocarbon ions to acetylene.The highest number density ratio is observed at a dilution percentage of 90％,and causes more effective nucleation and coagulation of nanoparticles.Furthermore,owing to the high ionization potential of helium,the transition point moves to a larger dilution gas percentage in C2H2/He microplasmas.Finally,the growth of nanoparticles via coagulation is studied.

School of Science,Qiqihar University,Qiqihar 161006,People's Republic of China;School of Physics,Dalian University of Technology,Dalian 116024,People's Republic of China

[1]Xiangmei LIU;Xiaotian DONG;Hongying LI;Shuxia ZHAO-.The effects of dilution gas on nanoparticle growth in atmospheric-pressure acetylene microdischarges)[J].等离子体科学和技术（英文版）,2022(10):105-112

microdischarges,microplasma,microplasmas,presheaths

effects,dilution,growth,atmospheric,pressure,acetylene,two,dimensional,multi,fluid,model,developed,investigate,properties,behavior,radio,frequency,percentage,gases,argon,helium,varied,from,kept,constant,Simulation,results,show,that,has,significant,influence,spatial,distributions,electron,density,temperature,well,formation,nanoparticles,With,increasing,profile,changes,continuously,being,edge,center,transition,mixed,both,regime,drift,ambipolar,into,occurs,which,associated,sudden,decrease,increase,bulk,point,corresponds,lowest,number,ratio,hydrocarbon,highest,observed,causes,effective,nucleation,coagulation,Furthermore,owing,ionization,potential,moves,larger,C2H2,He,Finally,via,studied

0.446372