New prototype of underwater sound source based on the pulsed corona discharge

Two types of underwater pulsed discharge, spark discharge and corona discharge, have been studied in this paper. The pulsed corona discharge current under voltages ranging from 2 to 4 kV and conductivities of liquid ranging from 325 μS/cm to 20 mS/cm have been measured and the process of bubble's growth has been observed. Several results could be summarized from our experiments: (a) there is no conducting plasma channel in the underwater corona discharge; (b) effect of corona discharge does not depend on the distance of the gap between both electrodes; (c) discharge currents in corona discharge are highly dependent on conductivity which may prompt the fact that ionic current play a major role in the discharge process; (d) the underwater pulsed corona discharge can generate acoustical pulses when the conductivity is high enough. The corona acoustic intensity is similar to that of spark under the same conditions. A new model was put forward based on these experimental results.