A review of mainly the past two years is undertaken of the industrial applications of pulsed power. Repetitively operated pulsed power generators with a moderate peak power have been developed for industrial applications. These generators are reliable and have low maintenance. Development of the pulsed power generators helps promote industrial applications of pulsed power for such things as food processing, medical treatment, water treatment, exhaust gas treatment, ozone generation, engine ignition, ion implantation and others. Here, industrial applications of pulsed power are classified by application for biological effects, for pulsed streamer discharges in gases, for pulsed discharges in liquid or liquidmixture, and for material processing.Index Terms -Pulsed power, industrial application, bioelectrics, exhaust gas treatment, discharge in liquid, material processing.

The dependence of ozone generation on the types of dielectric electrode material has been investigated using an ozone generator constructed with the piezoelectric transformer developed in our laboratory. The ozone generator is based on the excitation of the dielectric barrier discharge (DBD), which has the advantage of a compact configuration for generating ozone. Four kinds of dielectric materials are prepared for dielectric barrier electrodes. Electrical properties of the DBD and the ozone generation characteristics are investigated for the different dielectric materials. Differences in the discharge mode among the barrier electrode materials are recognized and discussed on the basis of the results of the Lissajous figures and voltage-current waveforms. During the continuous running of the generator, a temporal decrease in ozone concentration is observed owing to the temperature increase inside the reactor. Although the ozone generation characteristics are influenced by many properties of dielectrics, two important factors for achieving high-efficiency ozone generation are identified in this study. One is the use of a high-thermal conductivity material for the dielectric electrode, which functions well as a heat sink for transferring the generated heat to the outside through the material. The other factor is the control of the discharge mode. Our results show that the discharge mode that is considered as Townsend-like DBD is suitable for high-efficiency ozone generation.

No abstract

No abstract

The effective lifetime of ozone in a cylindrical cell filled with oxygen was measured in a wide range of gas pressures and temperatures by the HgI photoabsorption method. The observed effective lifetime of ozone increased with the gas pressure from 20 to 500 Torr, reached a maximum at approximately atmospheric pressure and then decreased in inverse proportion to the gas pressure. These characteristics were investigated at temperatures of 293–423 K and good agreement was observed with theoretical results derived by diffusion equation analysis of the ozone concentration in the photoabsorption cell. From the gas pressure and temperature dependencies of the effective lifetime of ozone, the diffusion coefficient of ozone in oxygen was determined together with the reflection coefficient of ozone at the surface, which was used to derive the loss rate of ozone at the surface of the cell at low gas pressures below 200 Torr. Moreover, we also simultaneously determined the rate coefficients for the decomposition of ozone by collisions with oxygen molecules and atoms which were used to derive the loss rate of ozone in the gas phase at high gas pressures of above 200 Torr. We have revealed that the Arrhenius plots, expressing the observed rate coefficients, comprised two linear portions with different slopes that transitioned from one to the other at around 353 K. Considering that the two trends reflected the decomposition of ozone by interactions with molecular and atomic oxygen, we obtained coefficients k(O2) and k(O) taking into account the diffusion effect of ozone molecules. We derived the rate coefficient k(O2)  =  7.28  ×  10−14exp(−9300/T) (cm3 s−1) as a re-evaluated value in the present paper and k(O)  =  9.52  ×  10−12exp(−2080/T) (cm3 s−1) which was consistent with data compiled in the original databases.