Experimental study of a 20kJ multi-electrodes sparker

Sparkers can be used for the production of acoustic pulses as a seismic source for sub-bottom profiling in the sea. A multi-electrodes (2000 electrodes) sparker with a stored energy of 20 kJ had been developed for high resolution seismic profiling in deep water. The sparker was mainly composed of a high voltage high frequency charging unit, energy storage capacitors, a solid state discharging switch (Thyristor), a 75-m long transmission cable and a 2m×2m multi-electrodes arrays. The H-bridge high frequency inverter was adopted in the charging unit, the average charging rate is approximately 5 kJ/s. A Thyristor was used as the discharging switch. The discharging electrodes consisted of ten groups of the high voltage electrodes and a ground electrode, each group consisted of 200 high voltage electrodes. The electro-acoustic characteristics of the multi-electrodes sparker had been measured, the discharging current was 44 kA at 4.5 kV, and the acoustic spectrum distributed in the range of 200-1200 Hz, the maximum SPL at 1 m was 241 dB. Good record in the South China Sea was obtained.