Complex Plasma System

Advanced Energy Conversion Division Complex Plasma System Research Section

Associate Professor : Shinichiro KADO
Assistant Professor : Satoshi YAMAMOTO

Nonlinear and synergetic physics of high-temperature plasma is investigated experimentally and theoretically with special regard to the magnetic confinement improvement of fusion plasma, which would also contribute to the complex plasma systems research.

Controlled thermonuclear fusion energy is regarded as one of the promising future base load power plants from the viewpoints of resource abundance, less environmental load and nuclear proliferation resistance. Its realization relies on the investigation of high-temperature, high-density magnetized plasma confinement. The research of plasma -- the fourth state of matter -- includes its feature of collective particles of electrons and ions in motion and its feature of magneto-fluid. Energy distribution of the particles or the orbit in the magnetic field will be a key issue in the former case, while the treatment of instability and turbulence will be a key in the latter case. In our laboratory, we are investigating such a complex plasma behavior in Heliotron J, a helical plasma confinement device, by means of various kinds of diagnostics or simulations. For the purpose of achieving better plasma particle and energy confinements, "plasma control schemes", such as magnetic configurations, heating conditions and fueling scenarios, are being investigated.

Emission of wide-range electromagnetic wave from plasmas

Light, or electromagnetic wave, plays various roles in the plasma research, such as in heating, controlling and diagnosing plasmas.

Probing What Is Real in Plasma Using Optical Emission

Optical emission from plasmas includes plenty of information such as density, temperature, ionic species and their fluctuations. "Know the enemy (plasma) and know yourself (measurement methods and data), then you can fight the hundred battles without fear" --- the real plasma properties that have never been known to anyone will be in our hands.

Spectral images of plasma that varies for each element and its ionization state

Plasma emits various line spectra as can be seen through a simple grating film. One can draw huge amount of information from the high-grade spectrographs.

Performance improvement of magnetically confined plasmas by suppression of fluctuations

We are aiming at having good plasma confinement by means of the control and suppression of several kinds of unfavorable fluctuation in high-temperature plasmas, based on experimental and numerical studies. In particular, I am interested in the resonant wave-particle interaction, which leads to destabilization of fluctuations that degrade the fusion plasma confinement and is commonly observed in nature.

Nonlinear resonant interaction of wave and particle

Shear Alfvén wave which is the magnetohydrodynamics (MHD) wave in plasma would be resonantly excited by the energetic ions of which velocity is similar to phase velocity of Shear Alfvén wave.