| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS-ThP |
| Session: | Plasma Science Poster Session |
| Presenter: | C. Miron, Nagoya University, Japan |
| Authors: | C. Miron, Nagoya University, Japan M.A. Bratescu, Nagoya University, Japan N. Saito, Nagoya University, Japan O. Takai, Nagoya University, Japan |
| Correspondent: | Click to Email |
Pulsed electrical discharges in water have shown to produce hydrogen, ozone, oxygen, hydroxyl radicals and other chemically active species, making these techniques useful for several applications, such as water purification, nanoparticles synthesis. The electrical discharges in liquids were realized using different types of electrodes, such as copper, tungsten, stainless steel. During the experimental work many difficulties have been encountered due to the sparks and electrodes erosion process. Electrodes of high melting point, corrosion-resistant and high stability are required in realizing the electrical discharges in liquids. The objective of the present work is to investigate the optical properties of a pulsed glow discharge in ultrapure water between two electrodes with low work function, such as lanthanum hexaboride and tungsten. The effect of the electrode material on some physicochemical processes generated in solution plasma was realized by using time-resolved optical spectroscopy technique. Lanthanum hexaboride (LaB6) cathode has high stability and a very low work function (2.5 eV) in high vacuum, which changes when temperature is increased. Also is an excellent electron emitter material due to the oxygen adsorption on the lanthanum sites. The lifetime of these cathodes is 10 – 15 times longer than that of the tungsten cathodes. The behavior of the plasma and some properties of the LaB6 and tungsten electrodes, their effects on the time evolution of the reactive species generated in the electrical discharges in water were investigated in the present work. Time-resolved optical spectroscopy of the reactive species generated in the plasma showed a different evolution in time, depending on the electrode material, the life time of the excited species, and pulse polarity of the applied pulsed voltage. The electron temperature in the plasma was very low when LaB6 electrodes were used in the process, compared to the electron temperature obtained in the atmospheric pressure air plasmas. The low value of the electron temperature explains the broad band spectrum of the molecular species acquired in the electrical discharges generated in ultrapure water.