Yuji Ikeda

Yuji Ikeda
i-Lab. Inc · R&D

Dr. Eng
Plasma diagnostics, Microwave enhanced LIBS, combustion, measurement, microwave device instrument,

About

229
Publications
11,872
Reads
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2,276
Citations
Introduction
Plasma diagnostics, Microwave enhanced LIBS, Plasma assisted ignition, Combustion, SI engine.

Publications

Publications (229)
Article
Full-text available
A copper helical coil antenna was developed, characterized, and optimized for 2.45 GHz operations supplied by a microwave semiconductor oscillator. The application field of interest is laser-induced breakdown spectroscopy enhanced by microwave. Simulations using the Ansys HFSS demonstrate the superior localized E-field strength of the helical coil...
Article
Full-text available
We developed a semiconductor microwave system to improve the ignition process in a combustion system. Under atmospheric pressure conditions, large plasma was successfully ignited by a 2.45 GHz microwave, and it is characterized in comparison with standard spark plug ignition and laser ignition. The size of the microwave power source was also effect...
Article
Remote sensing is indispensable to decommissioning the post-accident Fukushima Daiichi nuclear power station set to begin in 2021. High radiation levels make containment and reactor vessels inaccessible. Fibre-coupled Laser-induced breakdown spectroscopy (FC-LIBS), with a 50-m long, 800 μm diameter fibre-optic cable has been considered for the pre-...
Chapter
Plasma-assisted ignition and combustion, and microwave-enhancement of exhaust gas catalytic conversion in automobiles are presented in this chapter. Both processes within and outside of the engine are implemented using a 2.45 GHz semiconductor-oscillated microwave (MW) source or device. The latent potential of fast catalyst light-off was evaluated...
Article
Elemental analysis of fine powder metals and their mixtures using plasma ball spectroscopy has been developed. This method is suitable for in situ and on-site industrial/ non-industrial monitoring applications; pre-treatment or powder fixation methods which are necessary for laser-induced breakdown spectroscopy were not required. The metals analyse...
Article
Full-text available
Among multiple factors that affect the quality of combustion, the intricate and complex interaction between in-cylinder flow/turbulent field and flame propagation is one of the most important. In this study, true simultaneous, crank-angle resolved imaging of the flame front propagation and the measurement of flow-field was achieved by the applicati...
Conference Paper
We present in this study, the optimization of a 2.45 GHz semiconductor microwave-enhanced fiber-coupled laser-induced breakdown spectroscopy (FC-LIBS) system, which enlarges and sustains the laser-induced plasma by microwave (MW) superposition. The MW pulse width, pulse period, pulse delay can be varied from tens of nanoseconds to milliseconds orde...
Article
Full-text available
The stringent regulations that were placed on gasoline vehicles demand significant improvement of the powertrain unit, not only to become cleaner but also more efficient. Therefore, there is a strong need to understand the complex in-cylinder processes that will have a direct effect on the combustion quality. This study applied multiple high-speed...
Conference Paper
Implementing triple injection strategies in partially premixed charge- based gasoline compression ignition (GCI) engines has shown to achieve improved engine efficiency and reduced NOx and smoke emissions in many previous studies. While the impact of the triple injections on engine performance and engine-out emissions are well known, their role in...
Conference Paper
The present study aims to evaluate fuel injection strategies and their effects on the efficiency and fuel consumption of gasoline compression ignition (GCI) engines. Specifically, single-injection-based GCI combustion is compared to the double injection strategy implementing early, near-BDC first injection for the formation of a premixed charge fol...
Article
This paper aims to improve a knowledge base of methyl decanoate, a long alkyl-chain biodiesel surrogate fuel gaining popularity in engine combustion research. To this end, a comparative study on diesel and methyl decanoate combustion has been conducted with a focus on high temperature flame structures and soot distributions in an optically accessib...
Article
This study evaluates the ignition performance of a new miniaturised igniter that operates based on microwave resonance phenomenon. This igniter, named Flat Panel Igniter (FPI), consists of a flat ceramic panel with a metal strip inlay on the top surface acting as a resonance cavity. The FPI and a standard spark plug is used to ignite air-propane mi...
Article
Microwave Discharge Igniter (MDI) is an ignition device that operates based on the microwave resonance phenomenon. Receiving the microwave pulses from a semiconductor generator, the MDI generates non-thermal plasma to enhance the combustion. A new igniter plug consists of multiple MDIs in its structure is developed to achieve leaner operation limit...
Conference Paper
Full-text available
The present study explores the effect of in-cylinder generated non-thermal plasma on hydroxyl and soot development. Plasma was generated using a newly developed Microwave Discharge Igniter (MDI), a device which operates based on the principle of microwave resonation and has the potential to accentuate the formation of active radical pools as well a...
Conference Paper
The characteristics of a microwave-enhanced laser ignition of methane/air lean premixed mixture in the constant volume combustion vessel is experimentally investigated. The microwave-enhanced plasma is applied as an advanced ignition source due to the controllability of the plasma life time. The parameters of the microwave are varied for elucidatin...
Article
Full-text available
The effect of microwave enhanced plasma (MW Plasma) on ignition delay of diesel spray combustion was investigated inside a constant volume high pressure chamber. A microwave-enhanced plasma system, in which plasma discharge generated by a spark plug was amplified using microwave pulses, was used to introduce plasma to the injected spray before the...
Conference Paper
The present study aims to evaluate the effects of engine speed on gasoline compression ignition (GCI) combustion implementing double injection strategies. The double injection comprises of near-BDC first injection for the formation of a premixed charge and near-TDC second injection for the combustion phasing control. The engine performance and emis...
Article
High speed, time resolved Particle Image Velocimetry (PIV) diagnostics was applied to an optical SI engine to study the interactions between in-cylinder flow field and flame development. Optimisation and certain adaptations have been made to the diagnostic setup to enable time-resolved, simultaneous measurements of both PIV data and flame tomograph...
Article
The current gasoline engines are being pushed by researchers as well as the manufacturers to meet with the stringent demands and regulations regarding its efficiency, fuel economy and harmful emissions. Ultra-lean burning accompanied by higher turbulence and flow level are currently the best options for these engines to successfully meet these crit...
Article
The effects of microwave-enhanced plasma ignition on unsteady, expanding, premixed propane-air flames were studied using Schlieren technique in a constant volume chamber at various equivalence ratios and different microwave exposure durations. The plasma was generated by a spark discharge in engine-like conditions. Under these conditions, the domin...
Article
Laser ignition provides an innovative method to improve internal combustion engine performance in diluted conditions. It is well known that ignition under highly diluted conditions can cause an initial flame kernel instability, and strong cycle-to-cycle fluctuations. In order to achieve a stable combustion and high thermal efficiency, enlarging ini...
Conference Paper
Extending the lean limit or/and exhaust-gas-recirculation (EGR) limit/s are necessary for improving fuel economy in spark ignition engines. One of the major problems preventing the engine to operate at lean conditions is stable and successful initial ignition kernel formation. A repeatable, stabilized ignition and early flame development are quite...
Article
We adopted laser Thomson scattering for measuring the electron density and the electron temperature of microwave plasmas produced in helium at the pressures higher than the atmospheric pressure. The electron density decreased while we observed the increase in the electron temperature with the pressure. These are reasonable results by considering th...
Patent
Full-text available
A high frequency switch device includes a branch transmission line corresponding to each output terminal provided with a switching part. In the branch transmission line, the switching part includes a transmission side diode provided in such a manner that a cathode thereof is arranged on a side of an input terminal 41 and an anode thereof is arrange...
Article
Effects of the variation of microwave duty ratio on minimum laser ignition energy was investigated in microwave-enhanced laser ignition of methane/air mixture. A reduction of incident energy required for the laser ignition was achieved in microwave input energy with duty ratio.
Article
Full-text available
Diesel engines are most frequently used in vehicles because of their high efficiency and durability. However, nitrogen oxide (NOx) and particulate matter (PM) from diesel engines are became problem. Recently, the premixed charged compression ignition (PCCI) technique has been studied specifically to reduce NOx and PM emissions simultaneously. While...
Patent
Full-text available
The plasma generation device 30 is provided with a high frequency generation device 37 that generates a high frequency wave, and a high frequency radiator 15 that radiates the high frequency wave outputted from the high frequency generation device 37 to a target space 10, and generates plasma by supplying energy of the high frequency wave to the ta...
Patent
Full-text available
A mixer for mixing pulse voltage energy and electromagnetic wave energy in the same transmission line is provided with a first input terminal to which an electromagnetic wave is inputted, a second input terminal to which pulse voltage is inputted, a mixing output terminal from which the pulse voltage and the electromagnetic wave are outputted, a ba...
Article
Full-text available
A microwave-enhanced plasma generation technique was combined with laser-induced ignition to improve ignition characteristics. A locally intensified microwave field was formed near the laser-induced breakdown plasma. As the plasma absorbed the microwaves, the plasma emission intensity increased. The plasma lifetime could be controlled by changing t...
Article
This study aims to develop the innovative plasma combustion system to improve fuel economy and achieve the higher efficiency without any modification of current engine configuration. The microwave plasma ignition system was developed and applied to practical multi-cylinder engine. The relationship between initial combustion period and IMEP was inve...
Article
Spatially and spectrally resolved chemiluminescence were measured in the reaction zone of a laminar premixed methane/air flame at equivalence ratios of 0.9–1.5 in atmospheric pressure using a new Cassegrain mirror system and a spectrometer with an intensified charge-coupled device. The measurement volume of the Cassegrain optics was estimated to be...
Article
The enhancement of laminar flame development using microwave-assisted spark ignition has been investigated for methane–air mixtures at a range of initial pressures and equivalence ratios in a 1.45 l constant volume combustion chamber. Microwave enhancement was evaluated on the basis of several parameters including flame development time (FDT) (time...
Patent
Full-text available
In order to provide an ignition control device 30 which can efficiently control timing of thermal ignition of gaseous mixture in a combustion region 10, the peak estimation part 32, the ignition timing determination part 33, the control timing determination part 34, and the plasma control part 35 control timing of thermal ignition of the gaseous mi...
Conference Paper
Semiconductor microwaves (MWs) was applied for plasma generation system. Laser or electric spark is used as initial plasma igniter, and then the plasma was steadily sustained by the MWs. The emission of OH radical shows us the perfect controllability in time and space of the plasma by MW control. Even in continuous wave operation of MWs, the low en...
Article
Full-text available
A microwave-assisted spark plug was used to extend the lean operating limit (lean limit) and reduce emissions of an engine burning methane-air. In-cylinder pressure data were collected at normalized air-fuel ratios of 𝜆=1.46, 𝜆=1.51, 𝜆=1.57, 𝜆=1.68, and 𝜆=1.75. For each 𝜆, microwave energy (power supplied to the magnetron per engine cycle) was vari...
Article
In-cylinder flow transition during a piston compression stroke was measured under motoring conditions using particle image velocimetry (PIV). A single-cylinder optical engine (bore diameter: 86 mm, stroke length: 86 mm, displacement volume: 500 cc) was used. This engine had quartz windows in the side of a pent roof, a quartz cylinder liner, and a q...
Article
This study developed an innovative microwave plasma combustion system to improve fuel economy and achieve higher efficiency for spark ignition (SI) engines. Microwave plasma technology was combined with an active ignition system, which generates plasma by applying a high-frequency voltage to the standard spark discharge. A standard ignition coil wa...
Article
A plasma combustion system was developed to improve fuel economy and efficiency without modifying the engine configuration. Non-thermal plasma generation technology with microwave was applied. Plasma was generated by spark discharge and expanded using microwaves that accelerated the plasma electrons, generating non-thermal plasma. Even at high pres...
Article
Characteristics of the plasma light source of microwave (MW) plus laser-induced breakdown spectroscopy (LIBS) or spark-induced breakdown spectroscopy (SIBS) were studied. The plasma was initially generated by laser- or spark-induced breakdown as a plasma seed. A plasma volume was then grown and sustained by MWs in air. This MW plasma had a long lif...
Conference Paper
A plasma-assisted spark plug is tested in a single cylinder, 34 cubic centimeter, 4-stroke internal combustion engine of the type used in small scale unmanned aerial systems. The spark plug, developed by Imagineering, Inc. of Japan, couples 2.45 GHz microwave frequency energy from a commercial magnetron into the electrodes of a standard geometry no...
Conference Paper
A new microwave (MW)-enhanced laser-or spark-induced breakdown spectroscopy (LIBS or SIBS) instrument for atomic and molecular spectra was developed. Plasma was initially generated by laser-or spark-induced breakdown and then sustained only by MWs. The plasma lifetime was easily controlled by the MW input power and duration, which afforded steady a...
Article
This study developed an innovative microwave plasma combustion system to improve fuel economy and achieve higher efficiency for spark ignition (SI) engines. Microwave plasma technology was combined with an active ignition system, which generates plasma by applying a high-frequency voltage to the standard spark discharge. A standard ignition coil wa...
Article
In-cylinder flow transition during a piston compression stroke was measured under motoring conditions using particle image velocimetry (PIV). A single-cylinder optical engine (bore diameter: 86 mm, stroke length: 86 mm, displacement volume: 500 cc) was used. This engine had quartz windows in the side of a pent roof, a quartz cylinder liner, and a q...
Article
The enhancement of turbulent flame development using a microwave-assisted spark plug has been investigated in methane-air and methane-oxygen-argon mixtures, where the mole fraction of argon in the oxygen-argon mixture is the same as that of nitrogen in air. Experiments are conducted using a 1.45 liter constant volume combustion chamber with a fan m...
Article
Rotational Raman scattering was adopted for measuring the spatiotemporal evolutions of the rotational temperature (Tr) and the density (nN2) of molecular nitrogen at the electronic ground state in spark-plug assisted atmospheric-pressure microwave discharge. The rotational temperature had a spatial distribution with the peak at the plasma center. T...
Conference Paper
Full-text available
The extension of the lean stability limits of gasoline-air mixtures using a microwave-assisted spark plug has been investigated. Experiments are conducted on a 1200 RPM single-cylinder Waukesha Cooperative Fuel Research (CFR) engine at two compression ratios: 7:1 and 9:1; and four different levels of microwave energy input per cycle (prior to accou...
Article
The enhancement of laminar flame development using a microwave-assisted spark plug has been investigated in methane-air mixtures. Experiments are conducted using a 1.6 liter constant volume combustion chamber with various levels of microwave energy input at a range of initial pressures, equivalence ratios, and nitrogen dilution. Microwave enhanceme...
Article
A multi-parameter test matrix has been completed in an ethanol-fueled single-cylinder Waukesha ASTM-Cooperative Fuel Research (CFR) engine for studying microwave-assisted spark ignition performance under varied conditions, notably increased compression ratio, increased preheat, and increased charge dilution. Independent variables include compressio...
Article
We propose microwave-enhanced spark-induced breakdown spectroscopy with the same measurement and analysis processes as in laser-induced breakdown spectroscopy, but with a different plasma generation mechanism. The size and lifetime of the plasma generated can contribute to increased measurement accuracy and expand its applicability to industrial me...
Article
This study determined the local equivalence ratio of a CH4/air mixture in a laminar premixed flame using spark-induced breakdown spectroscopy (SIBS) with a fiber-coupled intensified charge coupled device (ICCD) spectrometer. Spectrally resolved emission spectra of plasma generated by a spark plug were investigated for their potential to measure loc...
Article
The objective of this study was to develop an innovative microwave-induced plasma ignition system to improve the fuel economy of a current engine and achieve a higher efficiency without any configuration modifications. A new plasma generation technique was proposed for a stable and intense ignition source. A microwave plasma combustion system was d...
Article
This study aims to develop innovative plasma combustion system to improve fuel economy and achieve higher efficiency without any modification of current engine configuration. A new plasma generation technique, that used a combination of spark discharge and microwave, was proposed. This technique was applied to gasoline engine as an ignition source,...
Article
Images and emission spectra of sparks produced by laser-induced breakdown of methane and propane air mixtures were investigated with a high degree of spatial and temporal resolution. The laser-induced breakdown was generated by focusing a 532-nm nanosecond pulse from a Q-switched Nd:YAG laser. The data were collected using an intensified high-speed...
Conference Paper
A new plasma generation technique that uses spark discharge and microwaves is proposed. The spark discharge generates a small plasma source enhanced by microwave power, increasing its volume and brightness. Using this new technique, plasma was produced successfully, even at a pressure of 2.0 MPa. As the microwave plasma was generated, the emission...
Article
The combustion characteristics of eight cylinders, four valves per cylinder racing engine have been studied by using flame chemiluminescence sensors. The time-series chemiluminescence of OH^*, CH^*, and C^*_2 were measured by optical filters and photomultipliers. The flame emissivities and a pressure signal were obtained simultaneously. And the loc...
Article
The reduction of total hydrocarbon (THC) emissions during cold start conditions is very important in order to achieve a tight control over exhaust emissions. The key factors to reduce these emissions include the spray characteristics, mixture formation, ignition, and injection control. In order to understand cold start combustion in a cylinder, the...
Article
In order to reduce emissions of particulate matter and nitrogen oxides by diesel engines, it is very important to understand the physics and chemistry of spray combustion in a real engine. However, most research into the characteristics of diesel spray combustion has used a constant volume combustion chamber or an optical access engine. This paper...
Article
This paper describes laser ignition process in a laminar premixed mixture of propane and air. The plasma was generated by focusing a second harmonic and several-nanosecond pulse emitted from a Q-switched Nd : YAG laser. Minimum ignition energy (MIE) was measured in different equivalence ratio. The growth process in the plasma and the hot kernel (fl...
Article
In order to reduce emissions of particulate matter and nitrogen oxides by diesel engines, it is very important to understand the physics and chemistry of spray combustion in a real engine. However, most research into the characteristics of diesel spray combustion has used a constant volume combustion chamber or an optical access engine. This paper...
Article
The combustion characteristics of eight cylinders, four valves per cylinder racing engine have been studied by using flame chemiluminescence sensors. The time-series chemiluminescence of OH*, CH*, and C2* were measured by optical filters and photomultipliers. The flame emissivities and a pressure signal were obtained simultaneously. And the local f...
Article
There are many ways to reduce diesel engine exhaust emissions. However, NOx emission is difficult to reduce because the hydrocarbon (HC) concentration in a diesel engine is not sufficient for NOx conversion. Therefore, in order to create stoichiometric conditions in the De-NOx catalyst, a secondary injection system is designed to inject liquid HC i...
Article
Images and emission spectra of sparks produced by laser-induced breakdown in air were investigated with a high degree of spatial and temporal resolution. The laser-induced breakdown was generated by focusing a 532-nm nanosecond pulse from a Q-switched Nd:YAG laser. The data were collected using a framing intensified charged coupled device (CCD) cam...
Conference Paper
The local equivalence ratios of CH4/air and C3H 8/air mixtures were measured using a laser-induced breakdown spectroscopy technique with a fiber-coupled ICCD spectrometer with Cassegrain optics. Localized breakdown plasma was generated from the pulse of a Q-switched Nd:YAG laser with a wavelength of 532 nm. This system allowed us to measure laser-i...
Conference Paper
We investigated laser-induced breakdown in air using a framing intensified charged coupled device (ICCD) camera and fiber-coupled ICCD spectrometer with Cassegrain optics. Localized breakdown plasma was generated from the laser pulse of a Q-switched Nd:YAG laser with a wavelength of 532 nm, and we obtained the temporal evolution of the air plasma s...
Article
Spray characteristics were investigated to determine the optimum aerosol spray for insecticides while considering volatile organic carbon (VOC) reduction. Our ultimate goal is to improve the efficiency of killing insects while using less aerosol spray, which contains chemicals, oil, and dimethyl ether (DME). Most of the oil and propellant fail to r...