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Plasma Sci. Technol. ›› 2018, Vol. 20 ›› Issue (10): 105402.doi: 10.1088/2058-6272/aad082

• Low Temperature Plasma • Previous Articles     Next Articles

Investigation on the characteristics of an atmospheric-pressure microplasma plume confined inside a long capillary tube

Shuqun WU (吴淑群), Fei WU (武菲), Xueyuan LIU (刘雪原), Wen CHEN (陈文), Chang LIU (刘畅) and Chaohai ZHANG (张潮海)   

  1. Center for More Electric Aircraft Power System, College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, People’s Republic of China
  • Received:2018-04-30 Published:2018-06-28
  • Supported by:

    This work was partially supported by National Natural Sci- ence Foundation of China (No. 51607090), the Natural Sci- ence Foundation of Jiangsu Province (No. BK20160796), the Delta Research and Educational Foundation (No. DREG2017008), and Fundamental Research Funds for the Central Universities (No. XCA17003–03). Dr Shuqun Wu gratefully acknowledges financial support from the China Scholarship Council.


An atmospheric-pressure microplasma plume of diameter 10 μm is generated inside a long tube. The length of the microplasma plume reaches as much as 2 cm. First, with the assistance of an air dielectric barrier discharge (DBD), the ignition voltage of the microplasma decreases from 40 kV to 23.6 kV. Second, although the current density reaches as high as (1.2−7.6)×104 A cm −2 , comparable to the current density in transient spark discharge, the microplasma plume is non- thermal. Third, it is interesting to observe that the amplitude of the discharge current in a positive cycle of applied voltage is much lower than that in a negative cycle of applied voltage. Fourth, the electron density measured by the Stark broadening of Ar spectral line 696.5nm reaches as high as 3×1016 cm−3 , which yields a conductivity of the microplasma column of around 48 S m−1 . In addition, the propagation velocity of the microplasma plume, obtained from light signals at different axial positions, ranges from 1×105 m s −1 to 5×10 5 m s−1 . A detailed analysis reveals that the surface charges deposited on the inner wall exert significant influence on the discharge behavior of the microplasma.

Key words: microplasma, atmospheric pressure plasma, non-thermal plasma, microdischarge