大气压Ar/NH_3同轴介质阻挡放电发射光谱诊断（英文）

Experimental Study of Coaxial Cylinder Dielectric Barrier Discharge in Ar/NH_3 Mixtures under the Atmosphere-Pressure

采用光谱在线技术(OES)检测了大气压Ar/NH_3 DBD等离子体中的主要粒子为NH,N,N^+,N_2,Ar,H_α,OH。NH是NH_3分解的产物,激发态Ar~*和NH_3分子的潘宁碰撞生成激发态中性粒子NH(c^1Ⅱ)和NH(A^3Ⅱ)。674.5 nm处N原子谱线表明等离子体中产生了N活性原子,为大气压Ar/NH_3同轴介质阻挡放电等离子体合成ε-Fe_3N磁性颗粒提供了可能。研究了各主要粒子谱线强度随NH_3流量和外加电压峰峰值的变化规律,研究结果表明:NH_3流量相同时,随外加电压峰峰值升高,各粒子谱线强度均逐渐增强;外加电压峰峰值相同时,各谱线强度随NH_3流量增加先增强后减弱。外加电压峰峰值相同时,随NH_3流量增加,N活性原子谱线强度先增强后减弱,NH_3流量为20 mL·min^(-1)时,N活性原子谱线强度最强。NH_3流量相同时,随外加电压峰峰值升高,N活性原子谱线强度逐渐减小,主要是由于大气压Ar/NH_3DBD放电模式由多脉冲大气压辉光放电转变为丝状放电造成。多脉冲大气压辉光放电的微放电通道之间相互重叠,各个微放电之间相互影响,导致随外加电压峰峰值升高各谱线强度的增加速率较快。当外加电压峰峰值从4 600 V升高到6 400 V时,大气压Ar/NH_3 DBD的放电模式由单脉冲APGD转变为二脉冲APGD,属于均匀大气压介质阻挡放电,随外加电压峰峰值升高谱线强度的增加速率较快,利于合成e-Fe_3N磁性颗粒。

An atmosphere-pressure Dielectric Barrier Discharge in Ar/NH3 mixtures between cylinder elec-trodes is studied by Optical Emission Spectroscopy and the main particles of atmosphere-pressure Ar/NH3 DBD plasma are NH,N,N＋ ,N2 ,Ar,Hα and OH.NH is decomposition products of NH3 ,and NH（c 1Π） and NH（A 3Π）are two kinds of excited-state neutral particles and produced by penning ionization of Ar＊ and NH3 .The nitrogen active atom is detected at 674.5 nm which may provide the experimental foundation for the synthesis ofε-Fe3 N ferroparticles by the atmosphere-pressure Ar/NH3 DBD plasma.The intensities of main particles are analyzed at different NH3 flow rate and applied voltage peak-peak value.The results show that the spectral line intensities of various particles increase with the rise of the applied voltage peak-peak value at the same NH3 flow rate,and first increase and then decrease with the increase of the NH3 flow rate at the same applied voltage peak-peak value.The applied voltage peak-peak value being kept constant,the spectral line in-tensity of nitrogen active atom first increases and then decreases with the increase of the NH3 flow rate.When NH3 flow rate is 20 mL·min-1 ,the spectral line intensity of nitrogen active atom reaches a maximum at the same applied voltage peak-peak value.The spectral line intensity of nitrogen active atom decreases gradually with increasing the applied voltage peak-peak value at the same NH3 flow rate and it is mainly because of the translation of discharge mode from multi-pulse APGD to filamentary discharge in the atmosphere-pressure Ar/NH3 DBD.The microdischarge channels overlap and the microdischarges affect each other in multi-pulse APGD;hence the increasing rate of the spectral line intensity is quicker in multi-pulse APGD than in filamen-tary discharge with increasing the applied voltage peak-peak value.When the applied voltage peak-peak value is up from 4 600 to 6 400 V,the single-pulse and two-pulse APGD mode which are two kinds of homogeneous DBD mode are found in the atmosphere-pressure Ar/NH3 DBD and the increasing rate of the spectral line in-tensity is quicker in multi-pulse APGD than in filamentary discharge which is beneficial to synthesize ε-Fe3 N ferroparticles.