Research

Collisionless shocks play a role as an energy converter in space. In the vicinity of a collisionless shock, extremely large amplitude waves as well as nonthermal particles are often observed. However, the mechanisms how they are generated are not well understood. Our aim is to understand the physical processes associated with collisionless shocks by using theory, numerical simulation, spacecraft data analysis, and high power laser experiment.

It is quite important to understand why and how extremely high amplitude waves and turbulence are generated and developed in space, since it is directly related with the behavior of background plasma as well as high energy particles. We aim to reveal the origin and the basic features of nonlinear waves and turbulence in space plasma by using theory, modeling, numerical simulations, and spacecraft data analysis.

Cosmic rays are high energy charged particles observed in space as well as on the ground. The energy distribution of cosmic rays shows power law nature in wide range of energy. The reason why such energy distribution is formed has not been well understood. We study acceleration/transport of charged particles by using theory, modeling, and numerical simulations.

Since the plasma surrounding a high energy astrophysical object has extremely high energy, relativistic effects need to be taken into account in order to understand the phenomena occurring there. Basic properties of a relativistic plasma have been unresolved yet. We study some relaxation processes occurring in relativistic plasmas using theory, modeling, and numerical simulations.

A radio-frequency plasma source is essential to our society as it is used for the electric propulsion system of satellite and the plasma processing for manufacturing semiconductor. A high-density plasma source will become more important with increasing needs of high-power thruster in the future long-term missions such as human Mars exploration and to realize more efficient and high-speed plasma processing. In our laboratory, we investigate the production mechanism of radio-frequency plasmas by numerical simulation and developing more efficient and high-density plasma source.