Faculty Members

SAITOH Haruhiko

(Associate Professor/Division of Transdisciplinary Sciences)

Department of Advanced Energy/Plasma Science and Engineering

Career Summary

October 2018: Associate Professor, The University of Tokyo
July 2013: Research Scientist, Max Planck Institute for Plasma Physics, Germany
April 2006: Research Associate, The University of Tokyo
April 2005: Postdoctoral Researcher, RIKEN Atomic Physics Laboratory
March 2005: Ph.D. Advanced Energy, The University of Tokyo
April 2002: JSPS research fellow (DC1)
March 2000: B.S. Physics, Kyoto University

Educational Activities

Graduate school: Nonlinear Science, Basic Course on Plasma Physics

Research Activities

My research field is experimental plasma physics. Specifically, I study physics of plasmas in a dipole magnetic field configuration aiming for the advanced fusion concept and the realization of electron-positron plasmas.

1. High-temperature plasmas and non-neutral plasmas in RT-1
The RT-1 device is a magnetospheric dipole geometry suitable for the confinement of both high-temperature and non-neutral plasmas. Based on the understanding of plasma phenomena in planetary magnetospheres with this experiment, we aim to realize an advanced fusion concept by using high-beta plasma confinement in the dipole geometry [1]. Also, we have realized stable (more than 300s) trapping of pure electron plasmas in RT-1, which is potentially applicable to the realization of a novel charged particle trap. This self organization of the plasma structure is realized after the selective decay of turbulence component of the electrostatic fluctuations of plasmas [2,3].

The RT-1 magnetospheric experiment and stabilization of electron plasmas observed in RT-1 [H. Saitoh et al., Phys. Plasmas 17, 112111 (2010)].

2. Formation of electron-positron plasmas
As a collaboration work between Japan (UT and NIFS), Germany (IPP and TUM), and US (UCSD and Lawrence University), we aim to create electron-positron pair-plasmas in a laboratory by using an intense positron source at the FRM-II reactor. We plan to use a compact dipole geometry with a high-temperature superconducting coils for the simultaneous trapping of positrons and electrons, based on our experience in the RT-1 experiment. So far we have realized efficient injection, long (more than 1s) trapping, and radial compression of positron beam in a prototype dipole trapping geometry generated by a permanent magnet [4-6].

Prototype dipole trap with a permanent magnet used for experiments at positron beamline [H. Saitoh et al., New J. Physics 17, 103038 (2015)].


1) "High-beta plasma formation and observation of peaked density profile in RT-1", H. Saitoh, Z. Yoshida, J. Morikawa, Y. Yano, T. Mizushima, Y. Ogawa, M. Furukawa, Y. Kawai, K. Harima, Y. Kawazura, Y. Kaneko, K. Tadachi, S. Emoto, M. Kobayashi, T. Sugiura and G. Vogel, Nuclear Fusion 51, 063034 (2011). 2) "Magnetospheric vortex formation: Self-organized confinement of charged particles", Z. Yoshida, H. Saitoh, J. Morikawa, Y. Yano, S. Watanabe, and Y. Ogawa, Physical Review Letters 104, 235004 (2010).
3) "Confinement of pure electron plasmas in a toroidal magnetic-surface configuration" H. Saitoh, Z. Yoshida, C. Nakashima, H. Himura, J. Morikawa, and M. Fukao, Physical Review Letters 92, 255005 (2004).
4) "Efficient injection of an intense positron beam into a dipole magnetic field", H. Saitoh, J. Stanja, E. V. Stenson, U. Hergenhahn, H. Niemann, T. Sunn Pedersen, M. R. Stoneking, C. Piochacz, and C. Hugenschmidt, New Journal of Physics 17, 103038 (2015).
5) "Lossless Positron Injection into a Magnetic Dipole Trap", E.V. Stenson, S. Nissl, U. Hergenhahn, J. Horn-Stanja, M. Singer, H. Saitoh, T. Sunn Pedersen, J.R. Danielson, M.R. Stoneking, M. Dickmann, and C. Hugenschmidt, Physical Review Letters 121, 235005 (2018).
6) "Confinement of Positrons Exceeding 1 s in a Supported Magnetic Dipole Trap"
J. Horn-Stanja, S. Nissl, U. Hergenhahn, T. Sunn Pedersen, H. Saitoh, E.V. Stenson, M. Dickmann, C. Hugenschmidt, M. Singer, M.R. Stoneking, and J.R. Danielson, Physical Review Letters 121, 235003?@(2018).

Other Activities

The Physical Society of Japan
The Japan Society of Plasma Science and Nuclear Fusion Research
Japanese Positron Science Society

Future Plan

As well as further understanding of magnetospheric plasmas through experiments at RT-1, we plan to realize a compact dipole geometry suitable for the trapping of various charged particles including antiparticles.

Concept of a compact superconducting dipole for positron trapping and high-temperature SC windings developed at NIFS.

Messages to Students

Plasma physics has a variety of research topics including the large-scale thermonuclear fusion project to relatively small-scale experiments in Universities. I hope you will find your strength and advantages through your fulfilling study and research life with us.