High-density implosion of fuel targets for laser-driven inertial confinement fusion has been intensively studied for many years. High temperature and high density of the imploded core plasmas up to 10 keV and 600 g/cm³, respectively were achieved successfully. Then, hydrodynamically equivelent plasma (HEP) with central spark/main fuel structure has been demonstrated for central spark ignition scheme. On the other way, implosion for fast ignition scheme, particularly nonuniform implosion of target with cone for entrance of heating laser, has recently been studied. Thermonuclear ignition and burn of inertial confinement fusion by laser are expected to take place near the year 2010.

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The first demonstration of fast heating of highly imploded fusion plasmas has been made by using a novel target geometry (cone shell target) with an ultra-intense short pulse laser. Significant enhancement of thermal neutron yield has been realized with sub-ps PW laser heating, confirming that the high heating efficiency is maintained as the short-pulse laser power is substantially increased to near equivalent power to the ignition condition. The efficient heating could be caused by the efficient guiding of heating pulse with the hollow cone and self-organized relativistic electron transport (conductivity channel) from the recent basic experimental results. According to all the results, we are now developing a 10 kJ-PW laser system to study the ignitionequivalent temperature heating physics. The development of such high energy PW lasers will also promote new scientific applications such as high energy-density physics.

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The fast ignition concept is attractive because a high gain is achieved by small laser energy. Based on fast ignition targets the design windows of laser fusion modular power plants, which have several reactors with 100 ~ 200 MJ fusion pulse energies, and with 100 ~ 240 MWe electric powers, are analyzed. The feasibilities of a small-sized laser fusion experimental reactor suitable for developing their practical power plants are discussed. A road map for laser fusion energy and a new concept of a small-sized fast ignition experimental reactor are proposed.

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Overall fluid dynamics of the implosion, laser-plasma interaction and super hot electron generation, and super hot electron energy deposition within the core are key issues in the Fast Ignition scheme. As both time and space scales of these phenomena are much different, it is impossible to simulate all phenomena with one code, and we must simulate each phenomenon with individual codes and integrate them. We will run these codes individually, that are collaborating each other with data transfer via the computer network. Since communication among these codes is very straightforward, we design a lightweight protocol, Distributed Computing Collaboration Protocol (DCCP), to transfer data. We have planned to simulate the Fast Ignition with self consistent fields in a full range of parameters using DCCP and just started challenging Fast Ignition Integrated Interconnecting code project.

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We describe properties of laser produced plasmas (LPP) for extreme ultra violet (EUV) light source for next generation lithography as an industrial application of LPP. We briefly present three topics related to the LPPEUV light source; laser intensity dependence of conversion efficiency from laser light to EUV light with 13.5nm wavelength with 2% bound width with tin target, present understanding of EUV emission from xenon target, and atomic processes in those targets.

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Plasma is an attractive medium for the advanced accelerator. When combined with an ultra-intense laser, it makes an acceleration field one thousand times greater than that produced by current microwave accelerators. The major fields, which now require the particle accelerator, are not high energy physics, but the medical, industrial and low energy material fields. Over the last ten years, laser accelerator research has advanced the electron gain from 22 MeV to 200 MeV. Recently, use of a glass capillary has succeeded in increasing the plasma length, the acceleration length, from 2 mm to 10 mm. This will be a breakthrough in the development of the second generation advanced accelerator.

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Target injector is an essential device to be established for a laser-fusion reactor. This paper describes current status of the injector research and introduces our research results of a coil gun. The drive circuits and trigger timing of the coil gun were optimized to improve injected projectile speed. The maximum speed at the first stage achieved to 8.7 m/s after optimization. The laser shot demonstration was carried out by the coil gun with an optically triggered Nd:YAG laser. The design guideline for a coil gun is discussed with experimental results and numerical simulation.

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The feasibility was examined of using a Bessel beam (J0 beam) for laser micro drilling. A J0 beam, generated using a nanosecond pulse laser and an Axicon, was used to drill into 20 μm-thick SUS304 stainless steel foil. The fairly precise columnar penetration holes were about 3 μm in diameter, with an aspect ratio of approximately 7. A J0 beam can be used to process both transparent and opaque materials. The major problems of the present laser micro drill will be solved by using a J0 beam. It is thought that the excellent characteristics of laser drill using a J0 beam is given by the extremely deep focal depth a J0 beam has.

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An unusual light beam, long range nondiffracting beam (LRNB) is presented. The LRNB propagates over a long range keeping its narrow beam width as if it does not diffract, while general light beams spread by the diffraction effect. The new beam can be generated by a technique of wave front control, e.g., by a distorted concave spherical wave front that can be formed by a Galilean transmitting telescope with an eyepiece that has a spherical aberration. We will introduce some results of experiments as well as theoretical analyses of the LRNB generation using an unique optical system with a telescope and a laser.

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This paper presents a new procedure for in-process monitoring and adaptive control that has been developed for micro-spot lap welding of A3003 aluminum alloy sheets of 0.1 mm and 1 mm in thickness. The objective of this process is to consistently produce sound laser partial-penetration welds. Observations revealed that the reflected laser beam and the heat radiated from the weld area were effective as process-monitoring signals in detecting melting, keyhole formation and hole generation during laser irradiation. Laser pulse width and peak power during the irradiation of a fundamental YAG laser beam were controlled at regular 0.15ms intervals on the basis of the heat radiation signal being employed to detect hole generation. Investigation of 20 samples revealed that only four non-bonded welds with holes were formed under conventional conditions. In contrast sound partially penetrated spot welds were produced in all 20 samples subjected to laser lap welding under the proposed in-process monitoring and adaptive control method.

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To seal the end of hollow fibers for medical uses, a sealing cap for Er:YAG laser light is fabricated by fusing a glass ball onto the end of a glass capillary. The cap has a focusing effect and the focal point is located near the cap surface. Optical properties of the caps with a diameter of 1 mm are evaluated, and the lowest insertion loss of 0.27 dB and the highest transmitted pulse energy above 750 mJ have been obtained for the cap made of lowOH silica glass.

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