Discharge characteristics of plasma sheet actuators

R. SOSA,; G. ARTANA,; D. GRONDONA,; H. KELLY,; A. MÁRQUEZ,; F. O. MINOTTI

JOURNAL OF PHYSICS - D (APPLIED PHYSICS)

Año: 2007 vol. 40 p. 663 - 673

0022-3727

The electrical characteristics of a plasma sheet device used for subsonic  airflow control are studied in this paper. Experiments are undertaken with a  two-wire asymmetrical (different diameters, opposite polarity) electrode  configuration connected to dc high voltage sources in the presence of a  dielectric plate and under different gases (dry air, nitrogen and oxygen). For  large distances electrode-plates it has been found that the discharge current  consists of a purely dc component. The proximity of the plate reduces  notably this dc current component until a limit situation for which the  electrodes practically lay on the plate and a current pulsed regime is  superimposed on the dc (small) component, thus establishing a plasma sheet  regime. This regime could be reached only when the small wire was  positive. This work establishes that the pulsed regime may be associated  with a succession of positive streamers (cathode directed) which formation  is promoted by different parameters of the gas and surface characteristics  (thresholds of photoionization and photoemission, charge deposition,...). The dc component seems to be produced by a small number of electrons  originated in the ionization region of the negative corona that are amplified  in the ionization region of the positive corona. The charged particles  produced during the streamer propagation could contribute appreciably to  the ion momentum transfer to the gas. This transfer should be due very  likely to the drift of the charged species present in the streamer channel  during the streamer collapsing phase. The source of momentum transfer  associated with the dc current would always persist with a magnitude that  depends on the intensity of this current.