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.
New prototype of underwater sound source based on the pulsed corona discharge
Abstract 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.
Reduction of Surface Flashover of the Beam Screen of the LHC Injection Kickers
The LHC injection kicker magnets include beam screens to shield the ferrite yokes against wake fields resulting from the high intensity beam. The screening is provided by conductors lodged in the inner wall of a ceramic support tube. Operation with increasingly higher bunch intensity, and narrow bunches, now requires improved ferrite screening. This will be implemented by additional conductors; however the good high-voltage behaviour of the kicker magnets must not be compromised by the supplementary screening. Extensive studies and optimisations have been carried out, to better satisfy the often conflicting requirements for low beam coupling impedance, fast magnetic field rise-time, high vacuum and good high voltage behaviour. A new configuration is proposed which reduces significantly the electric field associated with the screen conductors and the secondary electron yield of the surface of the ceramic tube. Results of high voltage test results are also presented.