Experimental study of the underwater plasma based on the phased array vibrator system
In this paper, a set of underwater plasma vibroseis system was developed, which included three big systems, i.e. charge system, discharge system and trigger system. At the same time, an experimental platform was set up through tketornix digital oscilloscope, seismic detector and desktop computer for collecting and processing data. On this basis, three working stages (breakdown, detonation and spread) of the underwater plasma were carried out the experimental research and summary. By experiment, the electrical properties of the underwater plasma were investigated under the different electrode materials, different number of electrodes, different voltages, different electrode gap spacing conditions. By using the ORIGIN data analysis software, the plasma channel resistance and the trend of the change of discharge power in time domain were obtained. It laid a foundation for choosing the optimal transducer structure and its material. In addition, the process of pulsed discharge in water was analysed. By comparing and summarizing, it found that the efficiency of corona discharge significantly is higher than that of arc discharge. This research provides references for the design of the plasma source in water.
Development of a phased array sparker
Most of the metallogenic belt of metal ores are in the orogenic belt, the surface and subsurface geological conditions are very complicated, the conventional seismic exploration techniques can not meet the requirements of the seismic exploration, such as dynamite source, vibrator, airgun and the sparker. A phased array sparker was developed for this potential application, which mainly consists of nine modular sparker, a programmable pulse generator and nine ground transducers which can be easily inserted into the ground. Each sparker includes an isolated diode, a capacitor with a stored energy of 500 J and a thyristor discharge switch. The programmable pulse generator was used to control the discharging time of each sparker. The transducer used to convert the electric energy into the seismic wave energy has a hermetical discharging chamber filled with salt solution. The preliminary tests were presented.
Electrical network-based time-dependent model of electrical breakdown in water
A time-dependent, two-dimensional, percolative approach to model dielectric breakdown based on a network of parallel resistor–capacitor elements having random values, has been developed. The breakdown criteria rely on a threshold electric field and on energy dissipation exceeding the heat of vaporization. By carrying out this time-dependent analysis, the development and propagation of streamers and prebreakdown dynamical evolution have been obtained directly. These model simulations also provide the streamer shape, characteristics such as streamer velocity, the prebreakdown delay time, time-dependent current, and relationship between breakdown times, and applied electric fields for a given geometry. The results agree well with experimental data and reports in literature. The time to breakdown (tbr) for a 100 μm water gap has been shown to be strong function of the applied bias, with a 15–185 ns range. It is also shown that the current is fashioned not only by dynamic changes in local resistance, but that ...