Effects of gas inlet orientation on discharge characteristics of coaxial dual-channel cross-field atmospheric plasma jet

Abstract

In this paper, the effect of the gas inlet orientation on the discharge characteristics of the coaxial dual-channel cross-field plasma jet is investigated. A working gas helium is separately flowed into the annular space between the hollow needle tube and the quartz tube (called Q-Jet), as well as the hollow needle tube (called N-Jet). With the same discharge parameters, the results show that the radial and axial dimensions of Q-Jet plasma jet are larger than that of N-Jet. Compared with the latter, the discharge current amplitude of the former increases by about 3.8-fold, the net charge transferred increases by about 8.8-fold, and the variety and density of reactive species produced are remarkably increased. For Q-Jet, the 706-nm spectral band is distributed inside and outside the quartz tube, while the 391-nm spectral band is mainly distributed outside the quartz tube, and the plasma jet forms a conical luminous pattern in the quartz tube during the positive half cycle of the voltage, due to the influence of helium viscosity. For N-Jet, 706- and 391-nm spectral bands are only just distributed in the axis of the quartz tube, and the charges left by the first discharge in the axial position of the quartz tube remarkably amplify the intensity of the second discharge in the positive half cycle.