"Are Microbubbles Necessary for the Breakdown of Liquid Water Subjected" by R. P. Joshi, J. Qian et al.
Are Microbubbles Necessary for the Breakdown of Liquid Water Subjected to a Submicrosecond Pulse?
Electrical breakdown in homogeneous liquid water for an ∼ 100 ns voltage pulse is analyzed. It is shown that electron-impact ionization is not likely to be important and could only be operative for low-density situations or possibly under optical excitation. Simulation results also indicate that field ionization of liquid water can lead to a liquid breakdown provided the ionization energies were very low in the order of 2.3eV. Under such conditions, an electric-field collapse at the anode and plasma propagation toward the cathode, with minimal physical charge transport, is predicted. However, the low, unphysical ionization energies necessary for matching the observed current and experimental breakdown delays of ∼ 70 ns precludes this mechanism. Also, an ionization within the liquid cannot explain the polarity dependence nor the stochastic-dendritic optical emission structures seen experimentally. It is argued here that electron-impact ionization within randomly located microbubbles is most likely to be responsible for the collective liquid breakdown behaviors.
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Applied Physics, 96 (9) 5129-5139 and may be found at http://dx.doi.org/10.1063/1.1792391.
Joshi, R. P.; Qian, J.; Zhao, G.; Kolb, J.; Schoenbach, K. H.; Schamiloglu, E.; and Gaudet, J., "Are Microbubbles Necessary for the Breakdown of Liquid Water Subjected to a Submicrosecond Pulse?" (2004). Electrical & Computer Engineering Faculty Publications. 204.