Educational Activities

Graduate School: Plasma Diagnostics, Plasma Applications
Undergraduate School: Electricity and Magnetism, Applications of Electrostatic and Electromagnetic Fields, Ionized Gases

Research Activities

Plasma contains reactive species, excited species, and ions. It is reactive and widely used for various applications including material processing, environment, biomedicine, energy, light source. We are working on the application and fundamental researches of atmospheric-pressure plasma, which can be generated under atmospheric environment.

1) Fundamental research on plasma (measurement and simulation)
We measure the densities of various reactive species and electrons in plasma using laser spectroscopy and develop a simulation of the plasma that can reproduce the measurement results (Ref. 1-4). Our final goal is to understand the production and loss processes of reactive species and to understand the whole physical and chemical processes in the plasma.

2) Plasma medicine (immunotherapy of cancer)
Plasma can be used for medical treatments including cancer and wounds. We demonstrated in experiments with mice that plasma could be used for cancer immunotherapy for the first time (Ref.5, 6). Plasma irradiation to a tumor in mice induced tumor-specific immune responses, which caused anti-tumor effect to another tumor that has not been irradiated with plasma. The mechanism of immune response activation by plasma irradiation is also studied.

3) Aerospace application using plasma When plasma is generated on the airfoil of an airplane, the airflow around the airfoil can be controlled through reactions in the plasma such as ionization and dissociation. The fluid control using plasma is simple and light weight, and it provides high controllability because it is electric based. A small wind tunnel is used for the experiments. This technology is expected to be also used for drones and Mars probes. We also work on decomposition of CO2 (Mars atmosphere) for future manned exploration of Mars to produce oxygen and CO, the latter of which is used for the fuel for return to the earth.

4) Surface treatment using plasma
In order to investigate the surface and medical treatment effects of a specific type of reactive species such as OH and O in plasma, we develop a method to produce only a specific type of reactive species using photodissociation with vacuum ultraviolet light instead of using plasma that produces many types of reactive species simultaneously. The reactive species are irradiated to a surface to investigate the treatment effect of the reactive species. We also use this technique to model and simulate the surface reactions of reactive species.

5) Other applications
In addition to the researches mentioned above, we have worked on many other applications using plasma, including environmental pollution gas control, water treatment, plasma assisted combustion, ignition, surface treatment of dye-sensitized solar cell, and semiconductor processing. We are further exploring various applications using plasma and reactive species.

Literature

1) R. Ono: Optical diagnostics of reactive species in atmospheric-pressure nonthermal plasma, J. Phys. D: Appl. Phys., Vol. 49, No. 8, 083001 (2016) (invited Topical Review; Highlights of 2016 in J. Phys. D).
2) 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: Appl. Phys., Vol. 47, No. 12, 125401 (2014) (Highlights of 2014 in J. Phys. D).
3) A. Komuro and R. Ono: Two-dimensional simulation of fast gas heating in an atmospheric pressure streamer discharge and humidity effects, Vol. 47, No. 15, 155202 (2014) (Highlights of 2014 in J. Phys. D).
4) Y. Inada, K. Aono, R. Ono, A. Kumada, K. Hidaka and M. Maeyama: Two-dimensional electron density measurement of pulsed positive primary streamer discharge in atmospheric-pressure air, J. Phys. D: Appl. Phys., Vol. 50, No. 17, 174005 (2017).
5) K. Mizuno, K. Yonetamari, Y. Shirakawa, T. Akiyama, and R. Ono: Anti-tumor immune response induced by nanosecond pulsed streamer discharge in mice, J. Phys. D: Appl. Phys., Vol. 50, No. 12, 12LT01 (2017) (invited; Highlights of 2017 in J. Phys. D).
6) K. Mizuno, Y. Shirakawa, T. Sakamoto, H. Ishizaki, Y. Nishijima, and R. Ono: Plasma-induced suppression of recurrent and re-inoculated melanoma tumors in mice, IEEE Trans. Radiat. Plasma Med. Sci., Vol. 2, No. 4, pp. 353-359 (2018).
7) R. Ono and S. Murakami: Quantitative measurement of the effect of OH radicals on the surface treatment of polypropylene, Plasma Process. Polym., Vol. 17, No. 7, e2000024 (2020).

Other Activities

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
Plasma Science for Materials, JSPS 153 Committee
Institute of Electrical and Electronics Engineers (IEEE)

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 is suitable for various technologies, particularly those related to the energy, environment, biology and medicine, and materials. I welcome challenging students who enjoy researching the wide range of fields such as high-voltage engineering, laser spectroscopy, reaction engineering of charged particles and chemical species, biology and medicine, and numerical simulation.

URL

http://streamer.t.u-tokyo.ac.jp/homepage-e.html