23P125-B
Progress of Physics Understanding in Steady State Tokamak Research
定常トカマク研究における物理的理解の進展
Mitsuru Kikuchi1, Masafumi Azumi2
菊池 満,安積 正史
1. Japan Atomic Energy Agency, Naka Fusion Institute, 801-1, Mukoyama, Naka, Ibaraki 311-0193, Japan
2. AZM Techno Science Soft, 6-16-3-209,Chitosedai, Setagaya, Tokyo 157-0071, Japan
1. 原子力機構那珂核融合研究所核融合研究開発部門、〒311-0193 茨城県那珂市向山801-1
2. AZM テクノサイエンスソフト、〒157-0071 東京都世田谷区千歳台6-16-3-209

Tokamak showed an excellent plasma confinement capability with its symmetry but has intrinsic drawback with itspulsed operation with inductive operation. Efforts have been made in these 20 years to realize steady state operation
best utilizing bootstrap current. In this review, progresses of understanding of tokamak physics related to steady state
operation are reviewed to cope into the scientific feasibility of steady state tokamak fusion power system.

Fig. 1 Flow physics in the steady state tokamak reactor (From lecture in POSTECH, Oct. 5)( Blue :feedforward, Orange: feedback, dotted green : region of flow physics)

1. Introduction
The tokamak is a front-runner in fusion research,which is the reason why the tokamak concept is selectedfor ITER. The tokamak has geometrical symmetry in thetoroidal direction, which provides robustness in keeping
nested flux surface against various parametrical changes[1] and good confinement leading to the achievement ofequivalent break-even condition in large tokamaks suchas JT-60U[2] and JET[3], and significant DT fusion
power production in TFTR and JET[4]. While tokamakshows such superiority in plasma confinement, thissymmetry is created by inducing the current in the hightemperature plasma through transformer action [5].
Therefore, the operation of the reactor becomes pulsed if
we can not develop efficient non-inductive methods tosustain plasma current. Since present power sources suchas oil/coal/natural gas fired plants, fission plants operatecontinuously, it is highly desirable for tokamak reactor to
be a steady-state power station. Review of non-inductive
current drive methods shows needs for large power tosustain large plasma current for the reactor [6]. Nature
blesses human being by providing an intriguing physicalprocess, called bootstrap current to realize efficient
steady state operation of the tokamak[7]. Utilization ofbootstrap current is fundamental for the efficient steadystate operation of tokamak reactor[8],[9]. Since then,extensive research initiatives to advance tokamak
physics relevant for steady state operation has been
started in tokamak researches such as JT-60U[10] andDIII-D[11] and called advanced tokamak research.
Extensive experimental and theoretical works have been
done for last two decades. In this presentation, brief
introduction of magnetic confinement, the Steady State
Tokamak Reactor, advanced tokamak operating regimes,collisional parallel transport in tokamak essential andcritical for the steady state operation, ideal, resistive andkinetic MHD instabilities related to high bootstrap
current fraction and the steady state are described. The
transport properties in advanced tokamak regimes will bedescribed as well [12], [13].

The inter-linkage of physics of steady state
tokamak research is given in Fig.1 stressing role offlows on magnetic surface in tokamak physics.
2. Table of Topics
Following topics will be covered in thepresentation.
1 Introduction2 Magnetic Confinement Fusion
2.1 Magnetic Confinement Topology
2.2 Integrability and Symmetry
3 Steady State Tokamak Regime
3.1 Steady State Tokamak Reactors
3.2 Advanced Tokamak Research
3.2.1 Weak Positive Shear Operation
3.2.2 Negative Shear Operation
3.2.3 Current Hole Operation
4 Parallel Transport in tokamak
4.1 Collisional Moment Equation
4.1.1 Moment Equation
4.1.2 1st Order Flow
4.1.3 Friction and Viscous flows
4.2 Generalized Ohm's Law
4.2.1 Generalized Ohm's Law
4.2.2 Electrical Conductivity
4.2.3 Bootstrap Current
4.2.4 Neutral Beam Current Drive
4.2.5 EC Current Drive
4.3 Rotation Physics
4.3.1 Neoclassical Rotations
4.3.2 Neoclassical Toroidal Viscosity
5 MHD modes in AT regime
5.1 Progress in linear ideal MHD
5.1.1 Spectral Property in MHD
5.1.2 2D Newcomb Equation
5.1.3 Flow effect on ideal MHD
5.2 Resistive MHD modes
5.2.1 Classical tearing mode
5.2.2 Neoclassical tearing mode
5.2.3 Double tearing mode
5.2.4 Resistive Wall Modes
5.3 Localized MHD
5.3.1 Ballooning and Peeling modes
5.3.2 Infernal modes
5.3.3 Edge localized mode
5.3.4 Barrier localized mode
5.4 Alfven Eigenmodes
5.4.1 Wave-particle interaction
5.4.2 Toroidal Alfven Eigenmode5.4.3 Linear mode structure
5.4.4 Non-linear behavior
5.4.5 Flow effect
5.5 Stability of Current Hole
5.5.1 Equilibrium Bifurcation

5.5.2 Ideal Stability
5.5.3 Resistive Stability
6 Turbulent Transport in AT regime
6.1 Understanding L-mode
6.1.1 Drift Wave Turbulence
6.1.2 Self-organized criticality
6.1.3 Magnetic shear and turbulence
6.2 Turbulence suppression mechanism
6.2.1 General flow shear suppression
6.2.2 Equilibrium flow shear
6.2.3 Zonal flow and GAM
6.3 Internal transport barrier
6.2.1 ITB in NS
6.2.2 ITB in WPS
6.3 Pedestal transport
6.3.1 GAM/Zonal flow in L-H transition
6.3.2 Transport between ELM
6.3.3 Pedestal width
6.4 Particle and impurity transport
6.4.1 Neoclassical impurity transport
6.4.2 Turbulent impurity transport
Acknowledgments
This work is dedicated to the past Director
Hiroshi Kishimoto for his strong leadership inadvanced tokamak research in JT-60.
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