Research

The universe is filled with tenuous gasses. The average number density of the Milky Way Galaxy is only about 1 / cc. Although it is such a high vacuum that cannot be produced on the ground, it behaves as a fluid from the macroscopic point of view (because of large volume). Since the gasses in space are almost always (fully or partially) ionized, it is believed that the magnetic field plays an essential role in many ways. For instance, aurora seen in high latitudes are produced by energetic electrons accelerated along the magnetic field in space that penetrate and hit the upper atmosphere. There are also many interesting phenomena occurring in astrophysical plasmas observed far from the Earth. One of examples is high energy radiation from young supernova remnants (SN1006 is shown below). Understanding of plasma physics is now indispensable to account for these phenomena.

Supernova Remnant SN1006 (NASA Chandra's X-ray Image)

I am working on those space and astrophysical plasmas. Currently, I am particularly interested in the following subjects.

  • [Collisionless Shocks]
  • [Relativistic Plasmas]
  • [Earth’s Magnetosphere]
  • Development of New Simulation Techniques

Collisionless Shocks

The collisionless shock is a hydrodynamic shock wave where collective plasma phenomena (such as wave-particle interactions), instead of binary Coulomb collisions, plays the role for the dissipation required for the formation of a shock wave. Since shock waves in space are expected to be natural particle accelerators (through the 1st order Fermi process), it has been studied for decades as a possible origin of high-energy cosmic rays.

I have been working on theoretical aspect of collisionless shock physics with particular emphasis on associated particle acceleration processes. Below is an example of numerical simulation of collisionless shocks. As seen in the figure, various waves are generated in the transition region of collisionless shocks which may play a role for the generation of energetic particles.

2D Particle-In-Cell (PIC) Simulation of Collisionless Shocks

Relativistic Plasmas

Under Construction

Two-fluid Simulation of Pulsar Wind Termination Shock

Earth’s Magnetosphere

Under Construction

Ring-Current Simulation

Resume

Appointments

Aug. 1, 2016 - present Associate Professor
Department of Earth and Planetary Science,
Graduate School of Science, The University of Tokyo
Mar. 16, 2012 - Jul. 31, 2016 Assistant Professor
Department of Earth and Planetary Science,
Graduate School of Science, The University of Tokyo
Apr. 1, 2009 - Mar. 15, 2012 Designated Assistant Professor
Division of Particle and Astrophysical Science,
Graduate School of Science, Nagoya University
Apr. 1, 2008 - Mar. 31, 2009 Postdoctoral Researcher
Solar-Terrestrial Environment Laboratory,
Nagoya University

Education

Mar. 2008 Ph.D degree
Department of Earth and Planetary Science,
Graduate School of Science, The University of Tokyo
Mar. 2005 MS degree
Department of Earth and Planetary Science,
Graduate School of Science, The University of Tokyo
Mar. 2003 BS degree
Department of Earth and Planetary Physics,
School of Science, The University of Tokyo

Awards

  • 2018 Young Researcher Award (under 40 yrs. old) from Association of Asia Pacific Physical Societies, Division of Plasma Physics (AAPPS-DPP)
  • 2015 Obayashi Early Career Scientist Award from Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS)
  • 2005 JSPS (Japan Society for the Promotion of Science) Research Fellowship for Young Scientists (DC1)