A simulation experiment of high temperature plasma transport using low temperature plasma having dimensionless parameters similar to those of a high temperature plasma is currently underway in the Compact Helical System. To produce such a plasma, 2.45 GHz microwaves up to 20 kW were injected perpendicularly to the toroidal field at B_t < 0.1 T. In the case at B_t = 0.0613 T, the maximum electron density reached three times that of the O-mode cutoff density. The measured power deposition was localized in the plasma core region beyond the Left-hand cutoff layer. These results clearly suggest that the over-dense plasma was produced and heated by electron Bernstein waves converted from launched X-mode in the peripheral region with a steep density gradient.

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We carried out spectroscopic measurements of extreme ultraviolet (EUV) emissions from xenon (Xe) plasmas generated in the Compact Helical System (CHS) by a grazing incidence spectrometer with a spectral resolution of 0.05 nm. Spatial pro les of the electron density and temperature of the plasmas have been measured by laser Thomson scattering diagnostic system. A remarkable variation in spectral features by different electron temperatures was observed, and was attributed to the difference in dominant charge states of Xe ions in the plasma.

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This intensive course gives fundamentals of probe measurement and its advanced applications. The first part reviews the theory of the electrostatic probe used in the plasma and methods for determining plasma parameters (space potential, electron temperature, plasma density, energy distribution, etc.). Several types of conventional probes are presented. The second part presents new methods and techniques that have been developed to measure complicated cases: electronegative plasma, flowing plasma, strongly magnetized (fusion) plasma, space plasma and (high pressure) microplasma by giving some examples.

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Hopes for achieving a new source of energy through nuclear fusion rest on the development of superconducting technology that is needed to make future equipments more energy efficient as well as increase their performance. Superconducting technology has made progress in a wide variety of fields, such as energy, life science, electronics, industrial use and environmental improvement. It enables the actualization of equipment that was unachievable with conventional technology, and will sustain future “IT-Based Quality Life Style”, “Sustainable Environmental” and “Advanced Healthcare” society. Besides coil technology with high magnetic field performance, superconducting electoronics or device technology, such as SQUID and SFQ-circuit, high temperature superconducting material and advanced cryogenics technology might be great significance in the history of nuclear fusion which requires so many wide, high and ultra technology. Superconducting technology seems to be the catalyst for a changing future society with nuclear fusion. As society changes, so will superconducting technology.

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A tutorial review on microturbulence simulation studies for the magnetic confinement fusion is given in focussing on the basic concepts and assumptions as well as a historical background. This article is also intended as an introduction to the succeeding chapters where the Lagrangian and Eulerian gyrokinetic simulation methods are explained in detail.

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Alfvén eignemode experiments have been carried out by using the negative-ion-based neutral beam in JT-60U. For bursting instabilities in the frequency range of Alfvn Eigenmodes, two types of mode activity have been observed. In one type called Abrupt Large-amplitude Event (ALE), enhanced transport of the energetic ions was detected. The enhanced transport showed the clear energy dependence based on measurements performed using a natural diamond detector. In another type of bursting event called the fast Frequency Sweeping (fast FS) mode, frequency up-down chirping is observed on the time-scale of a few ms, much faster than equilibrium changes in the background plasma. This frequency chirping was well reproduced by the non-linear simulation code, MEGA, for magnetohydrodynamics (MHD) with energetic particles. The slow up-frequency sweeping of the Reversed-Shear-induced Alfvén Eigenmode (RSAEs), due to the slow evolution of qmin was also observed. These experiments were analyzed by using the NOVA-K code. It is shown that the most unstable modes are localized around the minimum in the magnetic safety factor (qmin) in the analysis.

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In tokamak H-mode, a large poloidal flow exists in an edge transport barrier, and the electrostatic potential and density profiles can be steep both in the radial and poloidal direction. Two-dimensional structures of the potential, density and flow velocity near the edge of a tokamak plasma are investigated. The model includes the nonlinearity in bulk-ion viscosity and turbulence-driven shear viscosity. For the case with a strong radial electric field (H-mode), a two-dimensional structure in a transport barrier is obtained, giving a poloidal shock with a solitary radial electric field profile. The poloidal electric field induces convective transport in the radial direction, and poloidal asymmetry makes the flux-surface-averaged particle flux direct inward with a pinch velocity on the order of 1 [m/s]. A large poloidal flow with radial shear enhances the inward pinch velocity. The abrupt increase of this inward ion and electron flux at the onset of L-to-H-mode transition explains the rapid establishment of the density pedestal at the transition.

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