[en] The feasibility of superconducting center conductors in spherical tokamaks has been studied. The advantage of superconducting center conductors is evaluated from the view point of loss reduction, increasing q and reduction of required β_p. The magnetic field dependence of the critical current density is taken into account. The center conductor is divided radially into several layers, and the operating current density of each layer is optimized. If A > 1.3 and β_p > 0.6, the electric power loss can be reduced by the application of superconducting center conductors where κ ∼ 3 and q ∼ 10. In spherical tokamak reactors with low electric power loss, larger q can be attained by the application of superconducting center conductor. In other word, the β_p required for the specified q can be reduced. (author)

No abstract available

No abstract available

[en] Beryllium as a candidate material for plasma facing components will work in the ITER divertor and first wall under a considerable temperature drop. In this case the temperature on the beryllium surface facing the plasma will be sufficiently high and reach 800 deg.C even under the stationary regime conditions. As beryllium has very high cross-section of helium accumulation on fast neutrons, the problem of its resistance to high temperature radiation embrittlement seems to be urgent. But the data on the beryllium radiation resistance and extremely scanty. Researches in the effect of irradiation temperature (within the temperature range of 300-800 deg.C) on the mechanical properties of beryllium are almost nowhere to be seen

[en] Two aspects of high heat flux components are considered for a volumetric neutron source based on spherical torus: a possibility of in-situ repair of Be tiles on divertor surface and the first wall materials and design. Some different first wall design versions and Be-deposition techniques are discussed and compared. (author)

[en] Long carbon fiber reinforced copper (CFR-Cu) is a promising candidate for heat sink materials for fusion application, as this class of materials provides a good thermal conductivity and a low coefficient of thermal expansion (CTE). The latter is especially important to overcome the problems of CTE mismatch when joining e.g. carbon tiles to copper. The aim of this work is to demonstrate the fabrication of plates as well as tubes of CFR-Cu with the desired thermophysical properties, and finally to design a demonstrator mock-up based on a CFR-Cu tube with an inlay of un-reinforced copper and/or a steel liner. (author)

[en] Results of experimental research during the interaction of powerful plasma flow with aluminum and graphite targets are presented. The experiments were carried out at plasma energy density of up to 5 MJ/m² and time duration of up to 600 μs. Strong damage of target materials was observed as a result of the plasma flow interaction as well as the formation and the ejection of macroscopic particles from the target surface. The ejected particle size and spatial distribution were measured as well as the velocity of these particles during the experiments. The method of laser scattering was applied for these measurements. (author)

[en] The Inner First Wall (IFW) is the main limiter in Tore Supra for long and powerful discharges. The original graphite IFW was partly damaged by 8 years of operation and a sector of 60 deg. was replaced between 1995 and 1997 by CFC brazed elements. They are designed to accept twice as much flux (2 MW/m²) as the older ones and are expected to be more resilient. The new elements gave the opportunity to install diagnostics (thermocouples and Langmuir probes) on a poloidal sector, to characterise the behaviour of the new IFW and especially the heat flux profile. The pattern does not follow the cosine law and is governed by strong perpendicular heat flux and abnormal deposition at the contact point between the limiter and the plasma. The most energetic shots of the last campaign showed that the IFW could be loaded with twice the power deposited during these shots. (author)

[en] Fusion experimental reactor is supposed to operate in pulse mode. If a huge electromagnetic force by a plasma disruption is applied to a first wall component with a crack it may cause severe functional loss. In this paper, stress analyses are conducted by using models of bonded joint of dissimilar materials with interfacial crack, and the effect of electromagnetic force on the strength of the joint is investigated. (author)

[en] Laboratory experiments to simulate plasma disruptions have contributed significantly in many aspects to the understanding of the physical processes occurring during high-energy deposition on target material surfaces due to plasma instabilities. Laser light, electron beams, and plasma guns have been used worldwide to study disruption effects and erosion damage of candidate divertor materials. The differences among these simulation experiments are examined. The net power flux reaching the originally exposed surface depends on many parameters, such as type of energy deposited, target material, pulse duration, and geometrical factors. Experimental results have been evaluated and compared with theoretical predictions, and the overall relevance of simulation experiments to reactor conditions has been critically examined. (author)