| Discharge plasma in water has attracted a lot of interest in recent years due to its rapid developments for different environment and energy-related applications. In this paper, the discharge plasma in water is studied. The research work is carried out in the aspects of its related properties and application.There are many methods to produce the plasma in water, much attention has been focused on the pulse corona discharge in water, which exhibits a lower temperature, higher energy efficiency, and minimum electrode erosion. In this paper, the characteristics of pulsed corona discharge in water are studied. The influence of different parameters, including voltage amplitude, polarity, pressure, water conductivity, has been studied. The pulse width of high voltage pulse is one of the most important parameter for underwater breakdown process. The research on the influence of pulse width on breakdown process is relatively scarce. The current paper investigates the effect of pulse width on the streamer channel known as plasma channel of pulse corona discharge in water. The width of a 9.5 k V square wave pulse was varied from 200 ns to 100 ?s, and the images for the breakdown process were recorded. It was demonstrated that the streamer length generally increased with the pulse width, while the breakdown filaments showed different structure and emission color for nanosecond and microsecond cases. Besides, there is currently little study on the dynamic development process of pulsed corona discharge in water. In this paper, high speed camera was used to study the dynamic development process of pulse corona discharge in water with different pulse width. The change of the low density area near the tip of the needle was recorded and analyzed in microsecond time scale.There are many applications on discharge plasma in water, among them plasma optical emission spectroscopy is a promising tool for elemental analysis. This paper discusses the feasibility of using pulsed corona discharge plasma emission spectrum to detect the trace elements in liquid samples. The detection method utilized the reactor containing two plane electrodes separated by diaphragm in which the pin-hole is made to produce the pulse corona discharge in a 200-?m-diameter microchannel in water without electrode contact, so as to avoid the interference of the electrode ablation and other unwated situations. Using this method to detect the mixed solution of sodium chloride and calcium chloride,Na and Ca emission lines were detected,so the qualitative analysis of liquid samples was realized. And the intensities of sodium and calcium lines are linearly proportional to their respective concentrations,and then the quantitative analysis of the concentration of Na and Ca elements in unknown samples can be realized. The results demonstrate the possibility of sensing multiple elements simultaneously, as long as their emission lines don't overlap with each other. Through the further optimization, the method will be a practical one. The device can be further scaled down to be integrated with microfluidic systems sensing for water pollution monitoring.There are many different types of discharge plasma in water, and their characteristics are different. Particularly, underwater electrical wire explosions result in the generation of nonideal, strongly coupled plasmas characterized by a coupling parameter greater than one. In this paper, the aim of the experiment was to study the plasma column and other phenomena generated by underwater electrical wire explosions in water. However, due to the limitations of the experimental conditions and the time, the preparatory work about the experiment has not completely finished. But the design and processing of Marx generator, water forming line and load target chamber have been carried out. And some related tests were made. |
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