Use of underwater discharge plasmas to keep aquarium environment

Many researches to treat wasted water have been performed around the world since the water plays essential role in our life. In the present situation, the discharge plasma produced in water has been an attractive technique to treat wasted water, as the result of development of pulsed power technology. However, there is still much unclear knowledge about the physical characteristics of underwater discharge plasma. In this work, therefore, in order to get the electron density in underwater discharge plasma as one of the important plasma parameter, the spectroscopic measurement of discharge emission was performed. For the calculation of time-history of electron density during underwater discharge, the emission from Hα was recorded by the streak camera equipped with spectrometer and the Stark broadening analysis was performed. According to the result, it is found that the electron density of the underwater discharge plasma is almost constant during discharges and its value is approximately 6∼7×10¹⁸ cm⁻³. In addition, the long-term experiment of water treatment using underwater discharges has been done from January 2007.