The hot electron temperature and electron energy spectrum of intense laser plasma interactions are reexamined from a viewpoint of the difference in laser wavelength. The hot electron temperature measured by a particle-in-cell simulation is scaled by Iλ⁻¹ rather than Iλ² at the interaction with overdense plasmas, where I and λ are the laser intensity and wavelength, respectively.

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Formation of a high performance plasma with β_p = 3.6, β_N = 1.6, H_H98y2 = 1.6 without the use of the Ohmic heating solenoid was demonstrated for the first time. Plasma start-up and plasma current ramp-up were accomplished by vertical field and shaping coils, combined with heating and current drive by EC, LH and NBI. The q profile is deeply reversed with q_min = 5.6 at r/a = 0.7, and the bootstrap current fraction was at least 90%. This result opens up the possibility of eliminating the Ohmic heating solenoid, which has a great impact on improving tokamak and ST reactor designs.

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The features of superconducting coils for nuclear fusion devices include large size, high field, and high current density. A large conductor is needed for such a large coil to suppress the voltage increase. Since the ability of pool-cooling becomes relatively less with the increase of conductor size, new technologies are necessary to achieve both sufficient mechanical strength and cryogenic stability with high current density. A composite conductor of the 20 kA class was developed for the LHD helical coils. The conductor consists of a pure aluminum stabilizer, a copper sheath, and NbTi/Cu strands. New electromagnetic phenomena, which are Hall current and slow current diffusion into the stabilizer, deteriorate the cryogenic stability. The mechanism and countermeasures are described. Furthermore, a perspective on pool-cooled coils is discussed.

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An intuitive account is given of the polarized emission line of atoms and ions, both classically and quantum mechanically. Polarization is a result of the population imbalance among the magnetic sublevels, or of the alignment, in the upper level. The history of Plasma Polarization Spectroscopy (PPS) is reviewed. Various polarization phenomena are divided into three classes. For each of the classes, typical experiments undertaken so far are reviewed. The advantages, limitations, and challenges regarding PPS are discussed.

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Plasma polarization spectroscopy experiments are reviewed. The OV and CV impurity emission lines from the WT-3 tokamak are found to be polarized. In the GAMMA 10 tandem mirror machine, the OV and low-ionization stage Fe and Cr lines are also found to be polarized. This polarization is ascribed to the anisotropic distribution of electron velocities. The PACR (Population-Alignment Collisional- Radiative) model is introduced, which interprets the experimental polarization data in terms of the anisotropic velocity distribution. The present status of development of the model is presented with the CV ion taken as an example.

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PPS experiments on laser-produced plasmas are reviewed. Polarization is interpreted in terms of the an isotropic velocity distribution of electrons due to non-local transport. The polarization of an x-ray laser, and recent results regarding the recombining plasma are also presented. X-ray polarization spectroscopy experiments on heliumlike ion lines from a vacuum spark and from a plasma focus are presented: in both cases, the resonance line of the heliumlike ions shows polarization in the direction perpendicular to the discharge axis. Two possible interpretations are suggested.

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Magnetic fields play a fundamental role in driving various dynamical phenomena of the solar atmosphere, and the precise measurement of photospheric magnetic fields is of vital importance in solar physics research. A measurement of the spectral line polarizations produced by the Zeeman effect provides the most powerful means for investigating solar magnetic fields. The principle of measurements and some aspects of recent observational results are presented.

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This report discusses the various problems which are encountered when a crystal spectrometer is used for the purpose of observing polarized x-ray lines. A polarimeter is proposed based on the novel idea of using two series of equivalent atomic planes in a single crystal. The present status of the astronomical x-ray detection techniques are described with emphasis on two dimensional detectors which are polarization sensitive.

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The nonlinearity in the Navier-Stokes equation leads to the infinite number of hierarchy of coupled moment equations. It has been a long challenging problem in the theory of turbulence how to close it by reasonable analysis.Here, a promising perturbation thoery is discussed, which is based upon quite different idea from the standard perturbation theory. The present theory is similar in some respects to Kraichnan's direct-interaction approximation (DIA). But they are essentially different in idea, procedure as well as applicability. After a brief review of previous works of closure problem, we introduce the sparse direct-interaction perturbation (SDIP) method and formulate it for a quadratic nonlinear dynamical system. The basic assumptions and procedures of this perturbation theory are explained in detail. The results are compared with the direct numerical simulation of the system.

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Nonlinear dynamics of a nonuniform vortex sheet has been considered for aninterface with a density jump, related to nonlinear evolution of the Richtmyer-Meshkov and Rayleigh-Taylor instabilities. Velocity circulation on the interface is not conserved because of baroclinic effect when the density jump exists. The nonuniform vorticity and density jump lead locally to stretching and shrinking of the sheet. The problem may provide a new paradigm in nonlinear science.

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It is shown that the interaction of large amplitude electromagnetic waves with a relativistic electron-positron plasma leads to a bunching of mass, energy, and angular momentum in stable, long-lived structures. This structure contains a quantized angular momentum, and is called Vortex soliton. The correspondence between the nonlinear Schrdinger equation and Euler equation is reviewed. Problem related with the creation of angular momentum is also addressed.

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The Navier-Stokes (NS) system of equations is a central paradigm of nonlinear partial differential equations describing nonintegrable dynamics. The mathematical analysis of the NS system invokes a priori estimates for the energy and enstrophy. The difficulty stemming from the vortex-tube stretching effect is explained. By replacing the convective nonlinear term by a random noise term, one can develop a statistical model of turbulence. The mathematical framework of such modeling is also reviewed.

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Modern high-power lasers can generate extreme states of matter that are relevant to astrophysics, equation-of-state studies and fusion energy research. Laser-driven implosions of spherical polymer shells have, for example, achieved an increase in density of 1,000 times relative to the solid state. A new laser technology ‘ultra-intense’ laser is now opening a new ground of the laser fusion research, which is called as fast ignition. During the last several years, we have extensively studied elementary physics relevant to the fast ignitor. Based on these results, we have succeeded enforced heating of imploded plasmas with a 100 TW laser as the first demonstration of this new approach. The experimental result implies the future possibility of breakeven and ignition with significantly small laser energies. This new approach provides a route toefficientfusionenergy production.

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