Speaker
S. Park
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.3002.pdf
Origin of Electric Wind in Atmospheric-Pressure Plasma Jets
S. Park1, U. Cvelbar2, W. Choe1,3, S.Y. Moon4
1
Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science
and Technology (KAIST), Daejeon, Republic of Korea
2
Jožef Stefan Institute, Ljubljana, Slovenia
3
Department of Physics, Korea Advanced Institute of Science and Technology (KAIST),
Daejeon, Republic of Korea
4
Department of Quantum System Engineering, Chonbuk National University, Jeonju,
Republic of Korea
It is essential to understand the interactions between ionized matter and neutral particles in
order to discover their impact on the natural phenomena. One such phenomenon is the
electric wind, which supposedly occurs because of the so-called c-n coupling, i.e.
interaction between charged particles and neutral particles in systems of weakly ionized
plasmas, however this mechanism remains elusive until now. We here report a direct
evidence demonstrating that the electric wind is caused by an electrohydrodynamic (EHD)
force generated by the charged particle drag, as a result of the momentum transfer from the
electrons/ions to the neutrals. The model experiments are based on an atmospheric pressure
μs-pulsed helium plasma jet. From helium gas flow trajectories observed using Schlieren
photography, the electric wind speed along the jet axis is estimated. Studying the changes
in the electric wind speed at different pulse parameters allows one to distinguish between
the effects of streamer propagation and space charge drift causing the electric wind. In
addition, the study permits to determine the role of electrons and (positive) ions in the wind
generation. Our key finding is that the contribution of the moving streamer to the EHD
force generation is negligible, while the EHD force is mainly caused by the residual space
charges after the plasma streamer propagates and collapses. Another important finding is
that electrons are also a main player as well as negative ions. This will be the first clear
report of the electric wind in the atmospheric-pressure plasma jets.
[1] S. Park, U. Cvelbar, W. Choe, and S. Y. Moon, Nature Communications 9, 371 (2018).
