Indexed by:期刊论文

Date of Publication:2019-03-06

Journal:JOURNAL OF PHYSICS D-APPLIED PHYSICS

Included Journals:SCIE、Scopus

Volume:52

Issue:10

ISSN No.:0022-3727

Key Words:surface micro-discharge; plasma diagnostics; laser-induced fluorescence; hydroxyl radicals

Abstract:This work presents the transport behaviour of OH radicals in an atmospheric pressure pulse-modulated surface micro-discharge in helium. Laser-induced fluorescence is employed to measure the time development of OH radicals density distribution during the pulse duration and the inter-pulse period. It is shown that convection caused by electrohydrodynamic force enhances and dominates the transport of OH radicals from the surface plasma layer to the afterglow region with a distance up to 8 mm away from the dielectric surface. Interestingly, after the plasma switches off, OH density decreases quickly near the electrode but the downstream distribution region keeps constant, showing that the impact of convection is still present during the post-discharge. Additionally, the propagation velocity of OH declines monotonously with time. The maximum value is estimated as 1.86 m s(-1) during the first 1 ms when the plasma is on. The influence of power delivered to plasma is investigated, and the results indicate that the OH density everywhere in the detection zone is directly proportional to the applied power. However, the input power has no significant influence on the propagation velocity and delivery distance, suggesting that it is unrealistic to increase the delivery distance of reactive species by increasing the power delivered to plasma.