Steady-state plasma heating was successfully performed and sustained for more than 30 min in the LHD. By using ICRF heating and additional EC and NBI heating, a total input energy of 1.3 GJ was achieved. The average input power was 680 kW and the plasma duration was 31 min 45 sec. The hardware of the ICRF and divertor plates was much improved and the position of the ICRF antenna was optimized. The heat load to the divertor plates was effectively dispersed by the magnetic axis swing technique, which caused large changes in the heat load distribution along the divertor leg traces.

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Presently high energy-density plasmas produced by gas discharges (DPP) are the most powerful EUV source for the next generation’s high volume semiconductor manufacturing(HVM). This paper describes the radiation process in Z-pinch plasmas based on non-equilibrium ionization process and the fundamental Z-pinch plasma physics. Several schemes to control the pinching process and plasma parameters are shown. Also the present status of EUV sources developments and the critical issues to develop the DPP based EUV sources are discussed.

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Plasma is an attractive medium for the advanced accelerator. When combined with the ultra-intense lasers, it makes the acceleration field one thousand times the field of the current microwave accelerators or the size one thousandth the size. The fields, which require now the particle accelerator, are not only the high energy physics, but also the medical, industrial and low energy material fields. In these 10 years, the laser accelerator research has advanced the electron gain of from 22 MeV to 200 MeV. Recently, it has produced 200 MeV electrons from a 2 mm-long plasma. This corresponds to 100 GV/m. On the other hand, a glass capillary has this year succeeded in making the plasma length, the acceleration length, from 2 mm to 10 mm. Mono-energetic peaks were also found. These will be the breakthrough to the second generation of the advanced accelerator development.This review introduces these topics as well as the development of the ion acceleration studies.

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Principles of laser-plasma acceleration, mainly electron acceleration, are briefly reviewed. Necessary experimental setup is first given, and follow descriptions of processes involved in the acceleration; that is, plasma creation, plasma wave excitation, test bunch generation and loading. Problems are described on short acceleration distance, broad energy spectrum of the accelerated particles, unstable operation, etc., and their solutions are suggested.

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An ultra-intense laser injected a 15 J of power at 1.053 m in 0.5 ps into a glass capillary of 1-cm long and 60 m in diameter and accelerated plasma electrons to 100 MeV. 1- and 2-dimensional particle codes describe that a laser wakefield is excited with a gradient of 10 GV/m, accelerating electrons. The blue shift of the laser spectrum supports the plasma of 10¹⁶cm^-3 inside the capillary. A bump at the high energy tail suggests the electron trapping in the wakefield.

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The realization of an advanced compact accelerator based on laser-driven plasma acceleration is expected. Although energetic electron beams have been obtained, the energy spreads of the accelerated electrons have so far been large. The key issue in realizing a laser-driven plasma accelerator is the monoenergetic beam generation. Recently, monoenergetic electron beam generation has been reported. This is a breakthrough for the realization of a laser-driven plasma accelerator. Recent results related to the monoenergetic electron beam generation are introduced.

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Over many years collective ion acceleration has been considered, but only recently, some exciting experimental results of collective acceleration based on intense laser driven ion acceleration have been obtained. Currently, the highest proton energy driven by an ultra-intense lasers is >50MeV with high efficiency of >5% as well as very low transverse emittance of 0.004 mm•mrad. The paper reviews the recent achievement of such ion generation studies. First, the mechanisms of the ion generation are described including the plasma sheath model which describes energetic proton generation driven by sub-ps high energy lasers. A pre-pulse plays a significant role especially for the fs laser driven ion generation. The under-dense plasma model described here is one of the mechanisms, which utilize pre-pulses. The quasi-mono-energetic ion beam obtained theoretically and computationally is reviewed. Then the experimental results on the ion generation driven by sub-ps large energy lasers as well as fs lasers are reviewed. Although lower maximum proton energy and efficiency compared with those driven by sub-ps lasers at present, the results given by the fs lasers are precisely described because the fs lasers may be closer to real applications. Finally the present project on the ultra small ion accelerator development for cancer therapy and related topics are reviewed.

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Magnetic fusion reactors need a superconducting coil system with the huge magnetic energy of approximately 100 GJ. A number of superconducting fusion experimental devices have been constructed since 1970. Accumulated technologies and experiences for the past 35 years now allow us to design the actual reactors. However, there still remain some engineering problems in order to design the commercial reactors that will need a low construction cost, a high field and high reliability. It is necessary to develop high-strength supporting materials, next-generation superconductors and high-current-capacity conductors.

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The role of the pedestal structure in ELMy H-mode plasmas for the core energy confinement and for the ELM energy losses were investigated in two tokamak-type devices, JT-60U and ASDEX Upgrade. The confinement degradation seen at higher densities is attributed to the reduction of the pedestal temperature limited by the ELM activities and the stiffness of the temperature profiles. In high triangularity or impurity seeded H-modes, in which higher energy confinement is generally achieved, a higher pedestal temperature is obtained by improving the edge MHD stability or the density profile peaking, respectively. The upper bound of the ELM energy loss is characterized by the pedestal energy. The ELM energy loss can become smaller at fixed pedestal energy when the pedestal collisionality is raised. Raising the pedestal collisionality also enhances the inter-ELM perpendicular transport loss and reduces the ELM loss power fraction. In ASDEX Upgrade, the continuous pellet injection is shown to effectively mitigate ELM losses while preserving the core confinement quality. In JT-60U, the operation regime of grassy ELM is investigated and shown to achieve highly integrated performance of high energy confinement with small ELMs in the low collisionality regime.

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In the GAMMA 10 tandem mirror, a high power ECRH experiment at the plug region is now in progress. As the first step of this experiment, high power operation of existing gyrotrons for plug ECRH has been carried out at a power P_plug exceeding their nominal powers of 200 kW. In this step, the highest recorded value of the axial ion confining potential φ_c for a hot ion mode plasma is 1.4 kV at P_plug=240 kW. Then, in the second step, a newly developed high power gyrotron has been installed at one side of the both end plugs. The value of φ_c increased with P_plug and attained 2.1 kV at P_plug=370 kW. The potential difference ΔΦ from the plug potential to the end plate potential exceeded 5 kV. The effective temperature T_eff as a mean energy of the end loss electrons reached 3 keV, and the scaling between ΔΦ and T_eff has been expanded. Functions of the plug ECRH on electrons are studied from the viewpoint of velocity space diffusion, and a picture of ECRH-induced axial electron motion is presented.

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Tritium and deuterium depth profiles of the TFTR tile exposed to deuterium-tritium plasmas have been measured to reveal the hydrogen isotope behavior at the surface region by means of deuteron induced nuclear reaction analysis. The analyzed sample was a part of a tile made of a four-dimensional carbon fiber composite, which was placed at K bay, column C, row 16 of the TFTR vacuum vessel. Four kinds of elements, deuterium, tritium, lithium -6 and lithium -7, were identified. The tritium concentration had a peak at 0.5 μm with an atomic density of 7.4×10²⁵ T/m³ in depth profile, whereas the deuterium showed a broad distribution up to the depth of 1.5 μm with atomic densities of 3.4×10²⁷ D/m³. It is found that a fraction of the retained tritium from the surface to 1.5 μm, 8.1×10¹⁹ T/m², corresponded to 2% of that from the surface to 1 mm, 1.0×10²¹ T/m², which was measured for the KC-18 tile using the combustion method.

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In the Large Helical Device (LHD), electron pressure profiles in gas-fueled high-density discharges tend to have a similar shape, as if these were frozen. This frozen profile is insensitive to variations in the magnetic field strength and moderate changes in the neutral beam heat deposition profile. At the same time, however, the absolute value of the electron pressure itself increases with the heating power, the electron density, and the magnetic field strength. In this study, a reference model for the electron pressure is proposed which consists of the frozen profile and parametric dependences derived from experimental observations. It is possible to define an operational regime where this typical profile appears by comparing the electron pressure profiles with this model. In the standard configuration, at which the maximum plasma stored energy in LHD has been obtained, the frozen profile appears in the plateau to the Pfirsh-Schlüter regimes. As the collisionality decreases to the collisionless regime, the electron pressure becomes smaller than the prediction of the model and the deterioration is significant in the plasma core region. This tendency is enhanced in the configuration with the outward-shifted magnetic axis. The global energy confinement time, τ_E, in the high-collisionality regime has a weaker density dependence together with the mitigated power degradation, scaling as τ_E∝n_ebar^0.28P^-0.43 (n_ebar and P are the line-averaged density and the heating power, respectively), compared with the International Stellarator Scaling 95, where τ_E∝n_ebar^0.51P^-0.59.

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The vibration experiments of the support structures with flexible plates for the ITER major components such as toroidal field coil (TF coil) and vacuum vessel (VV) were performed using small-sized flexible plates aiming to obtain its basic mechanical characteristics such as dependence of the stiffness on the loading angle. The experimental results obtained by the hammering and frequency sweep tests were agreed each other, so that the experimental method is found to be reliable. In addition, the experimental results were compared with the analytical ones in order to estimate an adequate analytical model for ITER support structure with flexible plates. As a result, the bolt connection of the flexible plates on the base plate strongly affected on the stiffness of the flexible plates. After studies of modeling the bolts, it is found that the analytical results modeling the bolts with finite stiffness only in the axial direction and infinite stiffness in the other directions agree well with the experimental ones. Using this adequate model, the stiffness of the support structure with flexible plates for the ITER major components can be calculated precisely in order to estimate the dynamic behaviors such as eigen modes and amplitude of deformation of the major components of the ITER tokamak device.

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