December 22, 2014
Association of Asia-Pacific Physical Societies (AAPPS)
Division of plasma physics (AAPPS-DPP)

Subramanyan Chandrasekhar Prize of Plasma Physics- Prof. Em. Setsuo Ichimaru is selected as 1st Laureate (2014) –The Division of Plasma Physics (Chair: Mitsuru Kikuchi) under
Association of Asia Pacific Physical Societies (President:Seunghwan Kim) selected Prof. Em. Setsuo Ichimaru of theUniversity of Tokyo as the first Laureate of S. Chandrasekhar Prizeof Plasma Physics, which is awarded to a scientist who has madeseminal / pioneering contribution in the field of plasma physics.
Citation：For his contributions to the establishment of the theoreticalbasis of the science of strongly coupled plasmas and theirapplications, not only to laboratory plasmas and plasmas in solid- orliquid-state materials including fusion plasmas, but also to important
astrophysical plasma phenomena including radiation and nuclear
reactions.

Contact point：AAPPS-DPP Chair, Mitsuru Kikuchi(Japan Atomic Energy Agency, Naka Fusion Institute)
TEL: +81-29-270-7294, +81-90-2564-0837
FAX: +81-29-270-7264

AAPPS-DPP Homepage Address：
http://aappsdpp.org/AAPPSDPPF/index.html
Haruo Nagai（Former Managing Director of the Physical Society ofJapan）
TEL: 080-1096-4575

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On the achievement of Prof. Setsuo Ichimaru

Prof. Em. S. Ichimaru(Department of physics, Faculty of Science, the University of Tokyo)
The plasmas in magnetic confinement fusion research and solar flare arecalled the “weakly coupled plasma” since the Coulomb potential energy ismuch smaller than the kinetic energy. The plasma in the central region of theSun, Jupiter, White Dwarfs, Pulsar, or Neutron Stars are on the other handcalled the “strongly coupled plasma” since Coulomb potential energy becomesmuch larger than the kinetic energy. Typical example of the strongly coupledplasma in laboratory plasma is dusty plasma.
Prof. Ichimaru is the founder of the theoretical framework of the strongly
coupled plasma and his paper published in the Reviews of Modern Physics in1982 made a big impact to this field having citations close to 900. The
applications of his strongly coupled plasma theory include dielectric
properties of electron liquids at metal densities, transition from Coulomb
crystal to glass state in the strongly coupled plasma, metal-insulator phasetransition in the high-density hydrogen plasma, etc. In addition, he formulated
the large enhanced fusion reaction as a specific phenomena in the strongly
coupled plasma applied to the white dwarfs.
Prof. Ichimaru also made seminal contributions in elucidating the physicalprocess in dense astrophysical plasmas accreting onto a compact object in abinary system such as a stellar black hole or a neutron star, and thereby
clarified the mechanisms by which huge gravitational energies liberated insuch accreting plasmas are converted into copious electromagnetic radiation
mostly in X-rays.

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Appendix-1: Ichimaru’s achievement on Metal-insulator transition indense hydrogen plasma

Fig. 1 Phase diagram of dense hydrogen. CMI and CGL denote the criticalpoints of the metal-insulator and gas-liquid transitions, respectively. Here,“Molecular” implies insulator.

Appendix-2: Ichimaru’s achievement on accretion disk (Cygnus x-1)
In 1977, Prof. Ichimaru accounted for bimodal transitions between highand low-state in the spectral distributions of X-rays observed with Cygnus X-1(shown in Fig. 2 A) and thereby provided a subsidiary proof of it being astellar black hole.
Essence of the bimodal behavior is depicted in Fig. B, where high- and lowstates exist in accretion disks; a transition from one state to the other may takeplace near inner radii (~ 2x108 cm, in Fig. B), where an onset of thermal
instability may transfer a disk in high-state into one in low-state.

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Fig.
2 A. Schematic diagrams of X-ray spectrum.

Fig. 2 B. Bimodal behavior of accretion

disks with black holes: “soft X-ray” in Fig. A arises from the region: r ~ 2x108 cm; “hardX-ray” in Fig. A arises near the critical radius, r > 107 cm.

Appendix-3: Certificate of S. Chandrasekhar prize of plasma physics
Certificate and medal will be given at the 2016 APPC in Australia.

4Glossary
1. Subrahmanyan Chandrasekhar
Astrophysicist born in India. He received Nobel Prize in physics due to his
seminal contribution on black hole (Chandrasekhar limit) in 1983. This
research area is broad and the contribution to the plasma physics is significant
which can be seen from his texts “Principles of Stellar Dynamics (1942)” and“Hydrodynamics and Hydromagnetic Stability (1981)”.
2. AAPPS: Association of Asia-Pacific Physical Societies（HP: http://www.aapps.org/main/index.php）
Association of physical societies in the Asia Pacific region founded by theNobel Prize in physics Laureate, C.N. Yang and Prof. Akito Arima in 1983.
AAPPS held 12th Asia Pacific Physics Conference under the president (at thattime) Shoji Nagamiya in Makuhari, Japan. Current president is Prof. SwanKim, Postech, Korea.
3. AAPPS-DPP: Division of Plasma Physics, AAPPS（HP : http://aappsdpp.org/AAPPSDPPF/index.html ）The first division under AAPPS based on the success of the plasma physics
program in the APPC-12. This division is formed January 2014 based on therecommendation of Prof. Nagamiya at the AAPPS council.

4. S. Chandrasekhar Prize of Plasma Physics
Plasma physics prize founded by the AAPPS-DPP sponsored bySouthwestern Institute of Physics on July 2014. This prize is given to a plasma
physicist annually who has made pioneering and/or seminal contribution to theplasma physics and sponsored by Southwestern Institute of Physics, China.
The first selection committee is held during November to December. The
chairman is Prof. Won Namkung (former director of Pohang accelerator lab.).
Members are Profs B. Buti (India), A. Sen (India), R. Dewar (Australia), T.
Murphy (Australia), Liu Chen (China), B. Wan (China), T.S. Hahm (Korea),
Lin I (Taiwan), K. Mima (Japan), T. Terasawa (Japan).

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