Nitric oxide (NO) is increasingly being used in medical applications. Currently, a gas cylinder of N2 mixed with a high concentration of NO is used in the NO inhalation system. However, this arrangement is potentially risky due to the possibility of accidental leak of NO from the cylinder. The presence of NO in air leads to the formation of nitric dioxide (NO2), which is toxic to the lungs. Therefore, an on-site generation of NO would be very desirable for patients with acute respiratory distress syndrome and other related illnesses. Previously, our group reported the production of NO using a pulsed arc discharge. In this work, the prototype of the on-site NO generator was developed and the performances of the NO generator were demonstrated for medical applications.

Pulsed streamer discharges have been extensively used in many applications such as control of NOX and SO2 from exhaust gases, treatment of dioxins, removal of volatile organic compounds, generation of ozone and laser excitation. An operation with a high-energy efficiency is necessary for practical applications. It is very important to know the propagation mechanism of streamer discharges in order to improve the energy efficiency of pulsed discharge systems. In this paper, the emission from pulsed streamer discharges in a coaxial electrode system in air at 0.1 MPa was observed using a high-speed gated intensified charge-coupled display camera. A concentric wire-cylinder electrodes configuration was used. Positive and negative pulsed voltages having a width of about 200 ns were applied to the central electrode. From the results, the streamer discharges were initiated at the inner electrode and terminated at the outer electrode. It is suggested that the propagation velocity of the streamer discharges is being influenced strongly by the rise time and the polarity of the pulsed voltage.

In Japan, the treatment of waste concrete scraps has been one of the environmental issues. Therefore, new application using pulsed power discharge has been developed as the recycling method of the coarse aggregates from the waste concrete scraps. In the work, the dependences of the quality of the recycled coarse aggregate by the repetitive pulsed discharge treatments on the consumption energy were investigated. As the results, it was clear that the quality of the recycled coarse aggregate could be controlled by the number of discharge treatments. The recycled coarse aggregate, which satisfied class H under the regulations of Japan Industrial Standard (JIS A5005 and JIS A5021), was produced with the smallest consumption energy when the discharged energy from 0.02 µF of capacitor charged up to 400 kV applied to the waste concrete scraps during single discharge treatment.

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The conventional methods such as selective catalytic reduction method, electron beam method and lime--gypsum method could not treat exhaust gases completely. In addition, the energy efficiency and the cost of the conventional ways are still unfavourable. In recent years, the pollution control techniques using electric discharge plasmas which attract attention as the low cost and high energy efficient exhaust gas treatment methods, have been widely studied. In our laboratory, pulsed streamer discharge plasmas which are one of the non-thermal plasmas have been used to treat exhaust gases. Since a pulse width of applied voltage has a strong influence on the energy efficiency of the removal of pollutants, the development of a short pulse generator is of paramount importance for practical applications. In this work, nanosecond pulse generator which can output the 5 ns pulsed voltage is developed. In addition, the exhaust gas treatment and the ozone production by nanosecond pulse generator were demonstrated.