Tatsuo Ishijima

• PhD
• Professor at Kanazawa University

The influence of control parameters was studied on silicon (Si) nanoparticle synthesis using tandem modulated induction thermal plasmas (Tandem-MITP) with time-controlled feeding of feedstock (TCFF) method to optimize the modulation conditions on the basis of machine learning technique. This novel method, developed by our group, creates a time-vary...

A novel method for generating high-temperature gas using a tandem-type inductively coupled thermal plasma (Tandem-ICTP), composed of two vertically arranged coils, was proposed to experimentally evaluate the dielectric properties of hot gases. The dielectric properties of high-temperature insulation gases are critical for determining the success or...

The accurate prediction of radiation intensities in polymer-ablated arcs is crucial for optimizing the design and performance of electrical devices, such as circuit breakers, which rely on polymer ablation for arc control. In this study, both experimental measurements and numerical simulations were conducted to evaluate the radiation intensities of...

In this study, a hybrid numerical simulation model using the moving particle semi-implicit (MPS) method and the finite volume method (FVM) was constructed to analyze vacuum arc discharges. Vacuum arc discharges can be seen in vacuum circuit breakers (VCBs). The VCBs have been receiving much attention from their low environmental impact, because the...

The reliable operation of vacuum circuit breakers (VCBs) plays an important role in the power system's reliability. The common cases which lead to the failure in the VCB are related to the loss of vacuum inside the vacuum interrupters (VIs). VIs commonly loses the vacuum with a higher leakage rate, resulting in a decrease in discharge voltage and p...

An experimental and numerical study was conducted on the polymer ablated arc with an electrode configuration of a one-side gas flow outlet model. The polymers used for molded case circuit breaker and gas circuit breaker, such as PA6, POM, and PTFE, were compared. In the experiment, the polymer ablated arc characteristics of arc voltage, arc energy,...

The paper deals with the numerical simulation on polymer ablation phenomena during electric arc ignition process. The calculations from particle composition of high-temperature polymer vapor to the electromagnetic thermofluid simulation were consistently performed. In the present paper, first, methods and calculation results of the particle composi...

The paper deals with the numerical simulation on polymer ablation phenomena during electric arc ignition process. The calculations from paticle composition of high-temperature polymer vapor to the electromagnetic thermofluid simulation were consistently performed. In the present paper, first, methods and calculation results of the particle composit...

The experimental study on the dynamic behavior of helium atmospheric pressure plasma jet exposed on the surface of different conductivity is reported in this article. Electrical, optical, and gas dynamics characteristics are monitored using a high voltage probe, current probe, and imaging technique. The turbulence-free plasma jet length is estimate...

Surface discharge phenomenon along insulator surface in vacuum is a problem to be solved for expanding application field of vacuum circuit breakers (VCBs). The originality of present research is that the attempt to suppress the vacuum surface flashover by installing a physical barrier on insulator surface, and to achieve an improvement of its withs...

The success or failure of interruption in a gas circuit breaker (GCB) is determined by a dielectric strength of high-temperature gas remaining between electrodes against a transient recovery voltage (TRV). To contribute for a high reliable interruption performance of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3....

Microwave-excited water plasma asher (WPA) is our laboratory's new technology for the photoresist (PR) ashing process in semiconductor manufacturing which uses water vapor as process gas. It has the potential to solve many problems of conventional PR ashing technologies including high temperature, oxidation of metal structure, low ashing rate for i...

This paper describes a numerical study about influence of time duration of intermittent feedstock feeding on Si nanoparticle formation using the pulse-modulated induced thermal plasma (PMITP) with the time controlled feedstock feeding (TCFF). The PMITP+TCFF method has been developed originally by our group to synthesize large amounts of nanoparticl...

Influences of feedstock feeding duration on the size and composition of synthesized nanoparticles produced using tandem-type modulated induction thermal plasma (tandem-MITP) with time-controlled feeding of feedstock (TCFF) were investigated both experimentally and numerically. This tandem-MITP+TCFF method has been confirmed to give highly efficient...

A non-thermal atmospheric pressure plasma jet (APPJ) may stimulate cells and tissues or result in cell death depending on the intensity of plasma at the target; therefore, we herein investigated the effects of non-thermal plasma under non-contact conditions on the healing of full-thickness wounds in diabetic mice (DM+ group) and normal mice (DM- gr...

The influences of upper-coil and lower-coil current modulation of tandem-type modulated induction thermal plasma (tandem-MITP) were studied for silicon nanoparticle synthesis using both experimental and numerical approaches. The modulation condition was set to three conditions of non-modulation, lower-coil current modulation only, and simultaneous...

Characteristics of ignition process of polymer‐ablated arc with different current values were investigated with electromagnetic thermofluid analysis. This thermofluid simulation is based on calculated particle composition, thermodynamic and transport properties of evaporated vapor of polymer material and electrode material. Polymer ablation was ass...

Numerical simulation was conducted for dynamic behavior of copper vapor in arcs under reduced pressure condition using the developed model. The developed model uses MPS method for atoms and ions, while it uses finite volume method for electron energy and electro‐magnetic fields. In this paper, the influence of shield wall inner radius for vapor dyn...

This study examined a substrate bias voltage introduced into a microwave excited water vapor plasma to enable fast ashing of photoresist implanted with high-dose ions without occurring popping. The ashing rate at the center of the ashing distribution for the photoresist implanted with boron with an implantation dose of 1×10¹⁶ atoms/cm² was estimate...

Characteristics of ignition process of polymer-ablated arc with different current values were investigated with electromagnetic thermofluid analysis. This thermofluid simulation is based on calculated particle composition, thermodynamic and transport properties of evaporated vapor of polymer material and electrode material. Polymer ablation was ass...

Numerical simulation was conducted for dynamic behavior of copper vapor in arcs under reduced pressure condition using the developed model. The developed model uses MPS method for atoms and ions, while it uses finite volume method for electron energy and electro-magnetic fields. In this paper, the influence of shield wall inner radius for vapor dyn...

This paper reports dielectric recovery properties of residual CO2/C2F6 gas arcs in a nozzle under free recovery condition, which was realized by operation of insulated gate bipolar transistors (IGBTs) connected in parallel to arcing electrodes. The recovery properties were measured by adjusting the application timings of the quasi transient recover...

A numerical study was conducted of nanoparticle (NP) formation and growth in two-coil tandem-type modulated induction thermal plasma (tandem MITP) with method of moment. Two-coil tandem MITP, which has two induction coils in one plasma torch, has been developed for the synthesis of large amounts of NPs. The two-coil tandem MITP is operated by modul...

This paper describes effects of intermittent Ar/CH4 quenching gas (QG) injection on the size and composition of Si/C nanoparticles synthesized using pulse-modulated induction thermal plasma (PMITP). Time-controlled feeding of feedstock (TCFF), with synchronous and intermittent injection of silicon feedstock powder to the PMITP, was used for high-ra...

Mechanisms of photoresist removal were investigated using microwave-excited plasma in saturated water vapor under a reduced pressure condition (approx. 6 kPa). A few seconds of white emission were observed at the beginning of photoresist removal. To ascertain the species of spectra, optical emission spectroscopy was used for photoresist removal fro...

In this study, the uniformity of a photoresist ashing for a half-inch wafer was improved by a developed antenna structure, a double U-shaped antenna, in microwave-excited water vapor plasma. The optimized double U-shaped antenna structure, obtained by simulating an electric field, generated a spread distribution microwave plasma. Experimentally obt...

In this paper CH4/H2 gas flow rate effect on polycrystalline diamond deposition was studied using a time-series exposure technique of modulated induction thermal plasma (M-ITP) and non-modulated induction thermal plasma (NM-ITP). The M-ITP was used to make nucleation of diamond particles in the first stage, and then non-modulated ITP was used to gr...

This report describes experimentally obtained results on nanoparticle synthesis using two-coil tandem-type modulated induction thermal plasma (tandem-MITP). The developed tandem-MITP is operated by two coils with independently modulated high-frequency coil current. Tandem-MITP can offer unique temporo-spatially controlled high-temperature fields in...

In this paper, the influence of amplitude-modulated coil current waveform on polycrystalline diamond deposition was studied using modulated induction thermal plasma (M-ITP) with numerical and experimental approaches. The M-ITP is useful in undertaking the nucleation of diamond particles necessary for the first stage of diamond film deposition. Firs...

OH density and rotational temperature were measured in a saturated water vapor slot-excited microwave plasma using spatio-temporally resolved laser-induced fluorescence. The microwave power was 20–100 W under continuous wave mode, whereas 40–200 W peak under pulse-modulated mode (30% duty cycle, 100 Hz). The water vapor pressure was 2.3 kPa. An app...

As described in this paper, we proposed the adoption of polyacrylic acid (PAA) with H 2 O, which becomes PAA + H 2 O mixture gel, as an ablation medium for arc quenching in a low-voltage DC circuit breaker. It is well known that H 2 O is a highly arc-quenching medium, but it has been difficult to use H 2 O in liquid phase directly as an arc-quenchi...

In this paper, numerical calculations were made for Ar loop-type inductively coupled thermal plasma (loop-ICTP). The loop-ICTP was developed originally by the authors’ group for rapid surface modification of large areas. Loop-ICTP is sustained with a unique three-dimensional (3D) configuration inside a circular loop quartz tube and on the substrate...

A numerical model was developed on the evaporation process of intermittently fed feedstock into pulse-modulated induction thermal plasma (PMITP). This experimental method combining the PMITP with intermittent feedstock feeding has been developed for the synthesis of large amounts of nanoparticles. To treat this method, a full transient numerical mo...

In plasma arc cutting, suppression of dross adhesion during arc cutting is one of the issues. We have developed an observation system of the molten metal flowing down along the arc plasma jet near the arc cutting surface. This system consists of a YAG laser with high repetition rate and a high‐speed video camera. By using YAG laser strobe photograp...

This paper describes numerical calculations on tandem-type induction thermal plasmas with and without current modulation of the lower coil. The tandem type of induction thermal plasma (tandem-ITP) has been developed with two independent rf coils in one plasma torch for stable operation and spatial control of temperature field in ITP. Furthermore, t...

This paper investigates pressure influence on polycrystalline diamond formation using sawtooth-waveform modulated induction thermal plasma. Modulated induction thermal plasma was used to promote nucleation of diamond particles in the first stage. The operating pressure was set to 32, 60, and 90 Torr. The deposited diamond films were analyzed by fie...

Thermal interaction between titanium feedstock powder and the thermal plasma is calculated using the developed numerical model for an inductively coupled thermal plasma (ICTP) with particle injection. The interaction between titanium powder and thermal plasmas is very important for the stable establishment of the ICTP and effective heating and evap...

A numerical simulation was conducted to simulate behavior of an arc discharge in open air contaminated with metallic vapor for kA‐class high current. This simulation is concerned with a fundamental study on an arc discharge in a high‐energy arcing fault (HEAF), which can be found occasionally in electric equipment inside nuclear power plants. To un...

The present article describes numerical thermofluid simulation results on decaying arc behavior in 80%CO2 + 10%O2 + 10%C5F10O (C5‐PFK) gas considering molecules constituted with more than 9 atoms in a nozzle space on the assumption of local thermodynamic equilibrium (LTE) condition. The gas mixture 80%CO2 + 10%O2 + 10%C5F10O (C5‐PFK) is one of the...

A numerical simulation was conducted to obtain temperature and gas flow fields in tandem-type inductively coupled thermal plasma (tandem ICTP). Tandem ICTP is formed using two coil currents (upper coil and lower coil) in a single plasma torch, that was already developed for nanoparticle synthesis. The temperature distribution of the tandem ICTP and...

Purpose: An investigation was carried out to determine the effect of an ethanolic extract of the natural product of Daun sirih or Piper betle leaves on the effectiveness of plasma jet treatment for cutaneous acute wound healing in a small animal model mimicking a clinical setting. Method: An atmospheric plasma jet using medical grade argon gas as a...

In this review, we discuss the progress of emerging dry processes with atomic precision. Researchers in the field of plasma processing and surface science have addressed the increasingly challenging demands of material selectivity by utilization of synergistic enhancement of etching or deposition. The discussion encompasses major challenges in the...

Semiconductor device production has grown year on year, with high-volume manufacturing supported by advances in plasma processes. In plasma-based processing, ions and reactive species synergistically enhance chemical reactions, whose kinetics is in a nonequilibrium state in the region of the surface subjected to ion bombardment. To control such pro...

The non-thermal nature of chemical reactions in plasma chemistry is considered to be suitable for next-generation energy production from plasma-material syntheses and renewable sources. As emerging multidisciplinary applications, plasma medicine and plasma agriculture are currently topical applications that make use of atmospheric pressure plasmas....

Dramatic advances are being made in dry processing technologies. Atomic scale precision below 10 nm is now possible with fine patterning technologies for high-volume manufacturing of semiconductor devices. The isotropic and anisotropic nature of both film deposition and etching is versatile for nanoscale fabrication of three-dimensional features, s...

Electronic devices such as solar cells and thin-film transistors can be fabricated using thin-film deposition. Low- cost, low-temperature and high-speed deposition methods are required to ensure that the production of devices using thin-film deposition is affordable. Herein, we report the development of a low-cost and simple thin-film deposition me...

This study presented a quantitative evaluation of the performance of a low power miniaturized SDBD source for the production of ozone and nitrogen oxides as benchmarks of long-lived RONS. The effects of varying oxygen and humidity on the trend of the production efficiency are investigated. The oxygen content and the humidity had no noticeable effec...

The influence of the N2 admixture ratio on a He-N2 uniform atmospheric pressure glow discharge (APGD) generated using an asymmetric 20 μs, 10 kHz bipolar applied voltage pulse is systematically investigated, using electrical and optical emission spectroscopic measurements as diagnostic tools. We focused our investigation on understanding the discha...

In this work, feed gas modification by plasma jet is visualized by Schirlen imaging and the spreading of the plasma is observed by digital imaging and by Optical Emission Spectroscopy (OES). It has been shown that the long and short lived excited species and ions strongly modify the gas propagation and the spreading pattern of the plasma on the con...

In this work, feed gas modification by plasma jet is visualized by Schirlen imaging and the spreading of the plasma is observed by digital imaging and by Optical Emission Spectroscopy (OES). It has been shown that the long and short lived excited species and ions strongly modify the gas propagation and the spreading pattern of the plasma on the con...

This study developed a prototype of a wire-plate air bubbling plasma reactor that can be easily scaled up for wastewater treatment. The electrical characteristics, including the discharge current and average power consumed, of the developed reactor were deeply investigated at different operating parameters and solution conductivities. The performan...

A comparative investigation was conducted to determine the effectiveness of Manuka and Indonesian honeys to support the application of plasma jet treatment during the proliferative phase of cutaneous wound healing in 8-week-old, BALB/c male mice. The effect of honey containing different concentrations to reactive oxygen and nitrogen species (RONS)...

The article will be set as "Open Access" in Japanese Journal of Applied Physics. You can download the full text from IOP Science site, soon. In this review, we discuss the progress of emerging dry processes for nanoscale fabrication of high-aspect-ratio features, including emerging design technology for manufacturability. Experts in the fields of...

This paper describes the use of loop-type inductively coupled thermal plasmas (loop-ICTP) for two-dimensional (2D) rapid oxidation processing. The unique and original loop-ICTP torch has been developed for large-area rapid materials processing. We applied the loop-ICTP to surface oxidation of a Si substrate as an example of materials processing. A...

This paper focuses on a fundamental experimental approach to thermal arc re-ignition processes in a variety of gas flows in a nozzle. Using power semiconductor switches in the experimental system, the arc current and the voltage applied to the arc were controlled with precise timing. With this system, residual arcs were created in decaying phase un...

Treatment of distilled water by plasma jet in atmospheric air results the plasma treated water (PTW) which has the bactericidal properties. To improve the understanding and the methodology of the inactivation process, PTW has been applied on bacteria cell (E. coli) as the bacteria inactivation tool. PTW of different chemical strength is produced by...