Characteristics of Pulsed Discharge Plasma in Water

Recently, pulsed discharge plasma produced underwater has been an attractive method to treat wasted water. It is well known that pulsed discharge in water has some physical effects, such as an intense electric field at a tip of discharge plasma, an ultraviolet radiation, a chemically radical formation and shockwave generation, for cleaning water. However, the physical characteristics of the pulsed discharge plasma induced underwater are still unclear. For the optimization of the water treatment system utilizing pulsed discharge in water, it is essential to have knowledge about the plasma feature generated by electrical discharge underwater. In this paper, the temperature of and the electron density in the discharge plasma underwater are described. The magnetic pulse compressor (MPC) was developed and was used to cause the electrical breakdown in water. The developed MPC is all-solid state and is, therefore, maintenance-free generator. Two kind of spectroscopic measurements called as the line-pair method and the Stark broadening carried out for define the temperature of and the electron density in plasma produced underwater. According to experimental results, the temperature of and electron density in the discharge plasma between point- plane electrodes immersed in water are determined 15,000 K and 10¹⁸/cm³, respectively.