Measurements of ozone concentrations at the inlet and outlet of the ozone destructor were carried out proving the thermal decomposition of ozone produced in the ozone generator. The destructor was employed to simulate the ozone zero phenomena (OZP) in an ozone generator, thus which was separated functionally from the ozone source in the ozone generator. It was found that the thermal decomposition of ozone starts around 453 K, and the decrease of ozone concentration similar to OZP occurs at higher temperatures. In this paper, we report that the thermal decomposition of ozone is promoted by increasing the mixing ratio of oxygen atom O contained in the ozonized gas, based on a simple calculation using our measured basic coefficients.

This paper presents an experimental study on electrospray with pulsed streamer discharges from a syringe needle for de-colorization of a blue dye. To spread fine mists of an indigo-carmine solution from the syringe electrode with a constant frequency, a sinusoidal voltage is superimposed onto a positive dc applied voltage. The voltage ripple produce by the ac component has as an important role to repeat the electro-spray intermittently at a phase θ₀=150° of the sinusoidal wave. In addition, high voltage nanosecond pulses are repeatedly superimposed at another phase θ_p to propagate positive streamer discharges from the syringe. Results show that the de-colorization rate of the blue dye increases with decreasing the phase lag φ=θ_p-θ₀. If the phase lag is sufficiently reduced, the electro-spray is immediately followed by the pulsed streamer discharge, so that the streamer discharge channels can be propagated into the gap filled with the mist. We confirm that the streamer discharges from the tip of the water taylor cone can propagate with a high probability when φ=10°. These facts indicate that the timing control of the pulse superposition is very important for the water treatment with the electrospray.

Clarifying the effect of nanofiller material and particle dispersion on dielectric breakdown strength of epoxy nanocomposite contributes to the material selection, design and production. We prepared epoxy nanocomposites in which nanoparticles of silica, alumina, and titania were respectively dispersed, and measured their impulse breakdown strength. As a result, the improvement of the average breakdown strength of epoxy nanocomposites compared to epoxy resin was observed only in epoxy/titania nanocomposite, and it was clarified that the breakdown probability at low electric field on the Weibull distribution decreased by removing agglomerates in all the nanofiller materials.

It has been reported that polymer nanocomposite materials have improved various insulating properties such as treeing resistance. The electric tree is a phenomenon accompanied by partial discharge (PD) and is one of the factors that determine the lifetime of polymer insulating materials. The effect of nanofillers on the electric tree is evaluated by an optical observation and the PD characteristics such as the charge amount or phase angle. Since the characteristics of PD original waveform reflects the condition of the discharge circumstance, it might be possible to evaluate the effect of the filler on the progress of electron avalanche based on the PD waveform characteristics. In this paper, the characteristics of PD waveforms in the electrical tree was analyzed using a measurement system with wideband frequency characteristics. Based on the waveform characteristics, the improvement of dielectric breakdown time by adding filler was discussed.

The dielectric relaxation behavior is investigated in the ferroelectric smectic-A phase, which is a mixture of schiff base dimeric molecules with different alkyl chain lengths. The ferroelectric smectic-A phase shows the Goldstone mode due to its high dielectric strength (relative permittivity excluding the contribution of ion diffusion in the low frequency region). The dielectric strength increases dramatically with increasing the cell thickness. By applying the DC bias fields, the Goldstone mode of the ferroelectric smectic-A phase is quenched, and this phenomenon is explained by the suppression of the dipoles' fluctuation due to the DC bias fields. The Goldstone mode and the high frequency mode of the SmAP_F phase follow the standard Arrhenius equation in the vicinity of the phase transition with the isotropic phase.

Micrometric agglomerates of TiO₂ nanoparticles behave as defects, thus lowering AC breakdown strength of the TiO₂/epoxy nanocomposites. However, the mechanism is unclear. TiO₂/epoxy nanocomposites with different agglomerate size were prepared using fabrication process with centrifugation technique. The effects of sample thickness and agglomerate size on AC breakdown strength of TiO₂/epoxy nanocomposite were evaluated in AC breakdown test using McKeown electrode. Assuming that AC breakdown process was avalanche breakdown, the dependence of impact ionization mean free path on the agglomerate size was obtained using 40 generations theory. Interestingly, the mean free path and AC breakdown strength of TiO₂/epoxy nanocomposites had negative correlation to maximum agglomerate size. Probably, reduction of AC breakdown strength of the nanocomposites remaining micrometric agglomerates is attributed to impact ionization accelerated by electric field distortion.

In this study, the authors designed metamaterial electromagnetic (EM) wave absorbers using a square metallic pattern periodic array sheet with isotropic reflection property and dielectric material. Using measurement in free space, we confirmed that the resonant frequency and the amount of EM wave absorption can be controlled by modifying the structural parameters of the metallic pattern periodic array sheet.