Electron density change of atmospheric-pressure plasmas in helium flow depending on the oxygenitrogen ratio of the surrounding atmosphere

摘要

Laser Thomson scattering was applied to an atmospheric-pressure plasma produced in a helium (He) gas flow for measuring the spatial profiles of electron density (n(e)) and electron temperature (T-e). Aside from the He core flow, the shielding gas flow of N-2 or synthesized air (N-2 : O-2 = 4 : 1) surrounding the He flow was introduced to evaluate the effect of ambient gas components on the plasma parameters, eliminating the effect of ambient humidity. The n(e) at the discharge center was 2.7 x 10(21)m(-3) for plasma generated with N-2/O-2 shielding gas, 50% higher than that generated with N-2 shielding. (C) 2016 The Japan Society of Applied Physics