Citation
‘Theoretical establishment of the strongly
coupled plasma sciences and their applications not only to laboratory plasmas
and plasmas in solid or liquidstate materials including fusion plasmas but
also to important astrophysical plasma phenomena including radiation and
nuclear reactions.’
Scientific
Accomplishments
‘Setsuo Ichimaru led a theoretical group at the University of Tokyo,
studying basic issues of STRONGLY COUPLED PLASMA SCIENCES from the fundamental
point of view, concerned not only with magnetized fusion plasmas and hydrogen
matter but also with dense substances in astronomical setting such as Sun,
Jupiter and white dwarfs. Objects treated include dense classical plasmas,
quantum electron liquids, plasma materials such as liquid metallic hydrogen,
nonneutral cryogenic plasmas, and twodimensional layers of electrons.
Subjects investigated include thermodynamic properties (e.g., equation
of states, phase diagrams, and phase transitions), transport processes
(e.g., electrical and thermal conductivity and viscosity), fluctuations,
relaxations, turbulence, and nuclear reactions. Approaches adopted include
density functional formalisms, dielectric formulation with static and dynamic
localfield corrections, and Monte Carlo simulations. He has been
extremely active and productive with more than 150 original contributions
to leading academic journals including the ones with extremely high citations.
Ichimaru organized a number of International Conferences on Strongly Coupled
Plasma Sciences facilitating their advances in Asia Pacific area and exposing
younger generations to research frontiers. His highlycited comprehensive
review articles and wellorganized and wellread textbooks have been quite
useful even for experienced researchers as well as for starting graduate
students.’
Professor Setsuo Ichimaru developed and established the theory of strongly
coupled plasmas on the basis of statistical physics.
His scientific accomplishments summarized above cover all major issues
of the strongly coupled plasma sciences as follows.
(1)
Dense classical plasmas and quantum electron liquids
Strongly
coupled systems of charged particles have no small parameters available for
expansionbased schemes and their theory requires novel and powerful
concepts. For both classical and
degenerate plasmas, we have the domains of parameters where the onecomponent
plasma (OCP) serves as a welldefined model.
For OCP models in both cases, he developed the theory based on the
stateoftheart theoretical methods for the manybody systems and then took
the effect of ionelectron coexistence into account. In addition to comparisons with classical
systems via simulations and observations of ion clouds in traps, he
systematically developed the formulation for electron liquids at metallic
densities, obtaining static and dynamic properties such as the plasmon
dispersion, and successfully compared the results with experiments, showing
usefulness of the method.
(2)
Dense hydrogen and plasma materials
In order to
apply to dense materials such as liquid metals and liquid metallic hydrogen, he
further developed the theory emphasizing the aspect of twocomponent plasma
(TCP) so as to obtain various thermodynamic quantities and transport
coefficients, such as electric and thermal conductivities and shear viscosity,
the stopping power and also the convergent collision terms. Resultant values are shown to be in good
agreement with available experimental results.
Thermodynamic functions, freezing transition, and phase diagram of dense
carbonoxygen mixtures in white dwarfs are obtained for applications to
Supernova. Studies of equations of
state, phase diagram, and metalinsulator transition in dense hydrogen are
compared with Livermore shockcompression experiments, giving the
interpretation in terms of the firstorder metalinsulator transition.
(3) Enhanced
fluctuations, turbulence, and transport
As
correlations in strongly coupled charged particle systems in thermal equilibrium,
fluctuations also play the major role in systems out of thermal
equilibrium. In his first paper which
appeared in Physical Review Letters, he clarified the connection of the
enhanced fluctuation spectrum in plasmas to the scattering of electromagnetic
waves: This is the first expression of
this kind in plasma physics. Starting
from formulations firmly based on statistical physics, he explicitly derived
the formulas for transport properties and applied them to important problems of
magnetized fusion plasmas and astrophysical plasmas including the reconnection
of magnetic fields. The source of energy
in astrophysical phenomena such as solar flares is often attributed to the
reconnection of magnetic field. He
estimated the resistivity of electromagnetically turbulent plasmas and thereby
gave proper explanation for empirical Alfven scaling of reconnection
velocities.
(4)
Nuclear reactions
The rate of
thermonuclear reactions can be modified by the correlation between reacting
nuclei and ambient electrons. In dense plasmas, there exists the possibility of
enormous enhancement of the rate through the argument of the exponential
function giving its value. While the
enhancement is not so significant in inertial confinement fusion plasmas and
the solar interior, the enhanced rate in dense astrophysical object such as
white dwarfs has significant influence on their evolution and Supernova
explosion. Based on the theory of
strongly coupled plasmas he constructed, he gave accurate estimations of
reaction rate and applied to various cases.
He also applied his methods to the socalled cold fusion in metal
hydrides and showed the most reliable result for the DD reaction at the room
temperature which is too small to explain the claimed experiments.
(5)
Astrophysical applications
Most of astrophysical activities take place
in plasmas. They need serious
applications of the plasma theory and, at the same time, serve as a test. The origin and behavior of extraordinary
radiations from compact astrophysical objects have been homework for plasma
physicists. For Cygnus X1, the first
Xray star of 1971 identified as a black hole, he gave the account for the
bimodal behavior of radiation spectra in terms of the bimodal behavior
associated with the onset of radiativethermal instability for the first
time. This view has been supported by
recent observations and the original paper in 1977 has been highly cited. He also contributed to the problems including
magnetohydrodynamic turbulence and magnetic field fluctuation in Galaxy,
magnetic reconnections in solar flares and magnetospheres, and the solar
neutrino problems.
Highly cited top author papers as of 2014 Web of science
Cites

Journal/IF

Year

Title of the
paper

890

Rev. Mod.
Phys. / 44.982

1982

Strongly Coupled Plasmas: HighDensity Classical Plasmas
and Degenerate Electron Liquids

413

Phys. Rev. B
/ 3.767

1981

Analytic Expression for the Dielectric Screening Function
of Strongly Coupled Electron
Liquids
at Metallic and Lower Densities

395

Astrophys.
J. / 6.733

1977

Bimodal
Behavior of Accretion Disks: Theory and Application to Cygnus X1 Transitions

354

Phys.
Reports/ 22.929

1987

Statistical Physics of Dense Plasmas: Thermodynamics,
Transport Coefficients and
Dynamic
Correlations

134

Rev. Mod.
Phys. / 44.982

1993

Nuclear
Fusion in Dense Plasmas

97

Phys. Rev. A
/ 3.042

1985

Theory of Interparticle Correlations in Dense,
HighTemperature Plasmas. V. Electric and Thermal Conductivities

93

Ann. Phys. /
3.318

1962

Theory
of Fluctuations in a Plasma

83

Phys. Rev. A
/ 3.042

1985

Theory of Interparticle
Correlations in Dense, HighTemperature Plasmas

82

Phys. Rev. A
/ 3.042

1970

Dielectric Response Function
of Electron Liquids

