A Marx generator using MOSFET switches was built and studied in this paper for water purification. In order to replace the spark gap type of pulse power sources, with miss fire problems and short mechanical lifetime. In case of Marx Generator which generates negative pulses, a maximum output voltage of 3.6 kV, rise time of 40 ns and pulse width of 600 ns, was obtained. Discharge energy of one pulse was about 801 μJ for negative polarity at -2.4 kV. In case of positive pulses, a maximum output voltage of 3.6 kV, rise time of 75 ns and pulse width of 750 ns, was obtained. Discharge energy of one pulse was about 1120 μJ at 2.4 kV. The discharge was generated in bubbling water using a Marx Generator with MOSFET switches. The discoloration of indigo carmine solution was carried out to investigate the feasibility of low voltage discharge in bubbling water. As a result, indigo carmine solution was decolorized, although the discharge voltage was about -2.4 kV. The treatment performance was improved when oxygen was fed in the solution. The discoloration rate was 100 % after treatment time of 15 min with oxygen used as carrier gas. Emission of OH was confirmed and considered to play a role for water purification.

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A pulsed high-voltage generator has been developed using semiconductor opening switch (SOS), based on inductive-energy-storage scheme. It is very compact and is capable of continuous repetitive operation at 1 kHz. A static-induction thyristor is used as the primary switch and a saturable magnetic core is used as both the step-up transformer and the magnetic switch. With DC power supply of 1.6 kV, it generates pulsed high-voltage output of ∼27 kV on resistive load of 500Ω, with pulse width of ∼30 ns.

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We discussed amorphous-carbon, including diamond-like-carbon (DLC), film deposition using atmospheric pressure transient glow-microplasmas with a miniature gas flow. We developed a novel scheme for generating the transient glow microdischarge powered by high-voltage pulse trains. They were obtained by a burst pulse generator with a nonlinear transmission line (NLTL), which consisted of ceramic capacitors as a nonlinear element. Repetitive high-voltage burst pulses with a pulse width of 40 ns, the equivalent frequency of 12.5 MHz, were generated. A stabilization effect of the highly repetitive pulse trains on the discharge made it possible to deposit the amorphous-carbon film on a stainless steel plate cathode under atmospheric pressure with the deposition rate of 1.5μ/min. The film was characterized using SEM observation, Raman spectroscopic analysis and hardness measurement with a nanoindentor.

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Nanosecond pulse voltages of several pulse widths were applied to a cylindrical plasma reactor for ozone synthesis with high energy yield. Nanoseconds pulse voltages were produced by inductive energy storage system pulsed power generators using semiconductor opening switch (SOS) diodes. First recovery diodes were used as SOS diodes in the inductive energy storage system to produce short-pulsed high voltage with high-repetition rate. The short pulse voltage of 9.5 ns width and 33 kV peak voltage was produced at charging voltage of 15 kV and was applied to a 1 mm diameter center wire electrode in the plasma reactor. The copper cylinder of 19 mm inner diameter was used as outer electrode and was connected to a ground. The ozone yield of 271 g/kWh was obtained using the 9.5 ns width pulse voltage at synthesized 412 ppm of ozone concentration. The yield 271 g/kWh was more than twice as much as the yield 114 g/kWh at 401 ppm using a 60 ns pulse voltage.

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Effects of discharge-induced disturbance on the spectrum characteristics of highly repetitive ArF excimer laser were investigated by using an acoustic wave simulation. We made the acoustic wave simulation for duration of 10 msec in whole region of the laser chamber. The results explained, fairly well, the behavior of fluctuation observed in a prototype ArF excimer laser. Although the results showed a weak accumulation effect of the fluctuation on the spectrum output, the effect was rather limited. Results also indicated that suppression of acoustic waves traveling between the electrodes together with a re-design of the structure around the electrodes is important for stable operation of the highly repetitive, narrow-bandwidth laser.

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A method for decomposing organic compound by spraying water solution into non-equilibrium plasma in gas phase was investigated using a pulsed-corona discharge reactor. The corona reactor used consists of a discharge wire and a cylindrical electrode. Water solution of sodium dedecylbenzensulfonate (C₁₂-LAS) with a concentration of 100mg/L was sprayed into the reactor from a showerhead. The sprayed water solution was circulated into the reactor. C₁₂-LAS was decomposed up to about 90 % by one time exposure in the discharge for the discharging power of 6 W. C₁₂-LAS was mostly decomposed for 30 minutes of a treatment. However by-products were generated by the treatment. It is speculated that the by-product after treating for 300 minutes was CH₃(CH₂)₂-O-(CH₂)₄-O-(CH₂)₃CH₃.

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Pulsed power technology enables production of non-thermal plasmas with a large volume in gases by generating a high electric field at the tip of streamer discharge plasmas. Recently, all solid-state pulsed power generators which are operated with a high repetition rate, long lifetime and high reliability, have been developed aiming for industrial applications. Here, a new high-repetition-rate pulsed power generator for discharge plasmas in water is developed. The generator consists of semiconductor switches and saturable inductors. The semiconductor switches are thyristors in parallel and series circuits. An output peak voltage over 20kV is generated with a voltage rise time of 100ns, and streamer-like discharge plasmas in water are produced repetitively.

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Employing an inductive energy storage system, a stable and high-repetitive sub-microsecond pulse generator is developed for generation of micro-plasma jets. Its operation is based on the current interruption by an SI Thyristor, coupled with MOSFETs connected in series. While being operated without loads, the pulse generator can reliably generate high-voltage pulses of ∼20 kV with pulse duration of about 400 ns at the repetition rate up to 10 kHz. At the operating frequency of 1 kHz, a maximal energy transfer efficiency of ∼57 % has been obtained with 3 kΩ resistor as a dummy load. Driven by this pulse generator, a 6 mm long N₂ plasma plume at atmospheric pressure was successfully produced.

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Conventional ozonizer with a high ozone output using silent or surface discharges needs a cooling system and a dielectric barrier, and therefore becomes a large machine. A compact ozonizer without the cooling system and the dielectric barrier has been developed by using a pulsed power generated discharge. The wire to plane electrodes made of metal have been used. However, the ozone output was low. Here, a compact and high repetition rate pulsed power generator is used as an electric source of a compact ozonizer. The ozone output of 6.1 g/h and the ozone yield of 86 g/kWh are achieved at 500 pulses per second, input average power of 280 W and an air flow rate of 20 L/min.

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Carbon-neutral materials, which do not affect the density of CO₂ in the atmosphere even if they burn, have attracted much attention form the viewpoint of environmental friendliness. In this study, lignocellulose/epoxy composites were newly prepared as carbon-neutral insulation materials, and their properties were evaluated. Hydrothermal reaction lignocellulose, which is composed of lignin and crystalline cellulose, was prepared by a treatment of corncob under high-pressure hot water at 190°C, 1.8 MPa for 10min. The ¹³C-NMR spectra showed that the amounts of non-crystalline cellulose in the hydrothermal reaction lignocellulose were less than those of non-hydrothermal reaction lignocellulose. Moreover, hydrothermal reaction and oligoesterification lignocellulose was obtained by a reaction of maleic anhydride and glycidyl ether with the hydrothermal reaction lignocellulose. The epoxy resin containing the hydrothermal reaction and oligoesterification lignocellulose had lower water absorption and viscosity than those of the epoxy resin containing the non-hydrothermal reaction lignocellulose. The epoxy resin containing the hydrothermal reaction and oligoesterification lignocellulose with SiO₂ fillers showed an insulation breakdown strength as same as conventional material (an epoxy resin containing SiO₂ fillers). In addition, mechanical and thermal properties of the epoxy-based composite were also comparable with a conventional material. Therefore, the epoxy-based composite seems to be a candidate as practical carbon neutral insulation materials.

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For most modern corporations, engineering is an essential element. While the public increasingly demands social responsibility in business activities, the importance of the interweaving relationship between business ethics and engineering ethics has been recognized. In this paper, firstly the change in the business environment is overviewed. Then, a new concept for designing and implementing a business ethics program, named the EAB (Ethics Across the Business) approach, is proposed. The EAB approach is highly adaptable for engineering-oriented corporations in their business ethics program activities because it derives from a process approach which has been much used by many companies to perform such activities as quality assurance and environment management. Finally, a newly developed method to monitor employee consciousness in terms of engineering ethics is introduced together with trial results.

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In this research, we are aiming at the development of the tactile display that information presentation is expressed with phantom sensation and apparent movement by few tactile elements. And new personal identification, which system constitutes tactile sense information using tactile stimuli and based on the cardinal trait of the tactile sense, is proposed. Tactile stimuli is composed of the stimuli by electricity. The identification system that makes direction information expressed by tactile stimuli an attestation key is examined. Therefore, it is necessary to interpret the information that the user is reproduced direction information when composed of the tactile stimuli is made an identification key, and to recognize as an identification key. In this paper, we did the direction answer experiment for confirmation. As the result, the average of transmission accuracy of 21 subjects became about 38.8°. Based on this result, the correction processing was performed with using the BP type neural network. In case of 4 direction, 3 direction, and 2 direction are input, the calibration processing is examined.

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Polyethylene is widely used as insulation for power cables. In this paper, the effect of temperature and voltage application time on the decay of space charge in LDPE and HDPE is described. When the applied voltage of 18kV was removed negative space charge was mainly found in the bulk region of the LDPE samples, whereas positive space charge was predominantly observed in HDPE samples. The space charge decay time in LDPE was shorter than that in HDPE suggesting that trapped positive charge was not de-trapped easily in HDPE. The space charge decay time also decreased with increasing magnitude of the anode (LDPE) and cathode (HDPE) field measured just before voltage was removed. The value of the apparent activation energy of space charge decay was estimated from the Arrhenius plot of the relaxation time of the residual space charge was found to be larger in HDPE than in LDPE. It is suggested that the trap level of positive charge in HDPE was deeper than that of negative charge in LDPE.

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