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Ryo Ono / Associate Professor / Division of Transdisciplinary Sciences
Department of Advanced Energy / / Plasma Science and Engineering
http://streamer.t.u-tokyo.ac.jp/

Career Summary
1995: Obtained a B.S. in Engineering from the University of Tokyo
2000: Obtained a Ph.D. in Engineering from the University of Tokyo
2000: Research Associate, The University of Tokyo
2003: Researcher, National Institute of Advanced Industrial Science and Technology (AIST)
2005: Associate Professor, The University of Tokyo
Educational Activities
Graduate School: Plasma Diagnostic Techniques, Plasma Applications
Undergraduate School: Electricity and Magnetism, Applications of Electrostatic and Electromagnetic Fields, Electrical Engineering from an Environmental Point of View, Energy and Environment
Research Activities
Plasma is generated using a high-voltage electrical discharge in a gas (e.g., air, argon). In the plasma, electron-impact reactions with gaseous atoms/molecules produce a number of chemically active species such as ions, excited species, and radicals. Plasma is a highly reactive gas. We use the chemical reactivity of plasma for energy technologies, medicine, and environmental pollution control. In addition, we study the reaction mechanisms of plasma using laser spectroscopy and simulation.

1) Energy technologies using plasma
We use the plasma for enhancement of ignition and combustion and for reduction of pollutants in combustion exhaust. Fuels such as hydrogen and methane are activated using plasma before combustion, or ignited using plasma.
Another topic is the plasma treatment of dye-sensitized solar cells (DSSCs). We improve the energy conversion efficiency of DSSCs by applying plasma treatment to TiO2 nanoporous photoelectrodes. In addition to improving energy conversion efficiency, the plasma treatment dramatically reduces the sintering temperature of TiO2 photoelectrodes, which is required for manufacturing DSSCs. This enables us to make DSSCs out of low heat-resistant materials such as plastic rather than glass (Refs. 1 & 2).
Energy technologies using plasma (plasma-assisted ignition and combustion, dye-sensitized solar cell).
Energy technologies using plasma (plasma-assisted ignition and combustion, dye-sensitized solar cell).


2) Plasma medicine
Plasma has recently been shown to be effective for cancer treatment, blood coagulation, wound healing, tissue regeneration, skin regeneration, dental work, and other procedures. It is believed that active species (OH, O, NO, O2*) inactivate cancer cells or conversely activate damaged cells. We use plasmas to treat cultured cells and mice and then observe the activation/inactivation of the cells to investigate which active species produce these medical effects. At the same time, we measure active species in medical plasma using laser diagnostics. We also study sterilization using plasma (Ref. 3).
>Plasma medicine (analysis of plasma-irradiated cancer cells and plasma sterilization).
Plasma medicine (analysis of plasma-irradiated cancer cells and plasma sterilization).


3) Environmental technologies using plasma
We use plasma for water treatment. Plasma in water produces a large amount of OH radicals from H2O. The OH radical is a very strong agent that decomposes organic chemical products and bacteria in water. Conventional water treatment using OH radicals without discharge is called advanced oxidation process (AOP). In conventional AOP, OH radicals are produced by UV photodissociation of dissolved H2O2 or O3. In contrast, we use plasma for OH production in water. We also decompose gaseous environmental pollutants from combustion exhaust and chemical plants (Ref. 4).
Environmental technologies using plasma (water treatment and gaseous pollution control).
Environmental technologies using plasma (water treatment and gaseous pollution control).


4) Fundamental study of plasma reactions
Fundamental study of plasma reactions is essential for developing plasma application technologies, where active species produced in the plasma play important roles. We measure the active species using laser diagnostics and develop a simulation to study the plasma reactions. The active species are measured using laser-induced fluorescence (LIF) and laser absorption. The simulation includes electric field calculation, hydrodynamics, collision of charged particles, and chemical reactions (Refs. 5 & 6).
Fundamental study of plasma reactions (measurement of active species using laser-induced fluorescence and plasma simulation).
Fundamental study of plasma reactions (measurement of active species using laser-induced fluorescence and plasma simulation).
Literature
1) S. Zen, D. Saito, R. Ono and T. Oda: Low-temperature-sintered dye-sensitized solar cell using surface treatment of TiO2 photoelectrode with ultraviolet light, Chem. Lett., Vol.42, No.6, pp.624-626 (2013).
2) R. Ono and T. Oda: Measurement of OH density and gas temperature in incipient spark-ignited hydrogen-air flame, Combust. Flame, Vol.152, No.1-2, pp.69-79 (2008).
3) S. Yonemori and R. Ono: Flux of OH and O radicals onto a surface by an atmospheric-pressure helium plasma jet measured by laser-induced fluorescence, J. Phys. D, Vol.47, No.12, 125401 (2014).
4) S. B. Han, T. Oda, and R. Ono: Improvement of the energy efficiency in the decomposition of dilute trichloroethylene by the barrier discharge plasma process, IEEE Trans. Ind. Appl., Vol.41, No.5, pp.1343-1349 (2005).
5) R. Ono, Y. Nakagawa, and T. Oda: Effect of pulse width on the production of radicals and excited species in a pulsed positive corona discharge, J. Phys. D, Vol.44, No.48, 485201 (2011).
6) A. Komuro, R. Ono, and T. Oda: Behavior of OH radicals in atmospheric-pressure streamer discharge studied by two-dimensional numerical simulation, J. Phys. D, Vol. 46, No. 17, 175206 (2013).
Other Activities
American Physical Society (APS)
Institute of Electrical and Electronics Engineers (IEEE)
Institute of Electrostatics Japan (IEJ)
Institute of Electrical Engineers of Japan (IEEJ)
The Japan Society of Applied Physics (JSAP)
The Japan Society of Plasma Science and Nuclear Fusion Research (JSPF)
Combustion Society of Japan
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Future Plan
We aim to develop plasma application technologies utilizing the high reactivity of plasma on the basis of measurements and simulations of plasma reactions. Our present interest is not limited to the topics mentioned above. We intend to expand our research scope in the future.
Messages to Students
Plasma has applications suitable for various technologies, particularly those related to the energy, environment, bio-medicine, material, and chemical processing fields. I welcome challenging students who enjoy researching a broad range of fields such as high-voltage engineering, laser spectroscopy, reaction engineering of charged particles and chemical species, bio-medicine, and numerical simulation.
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