The COMPASS-D tokamak, originally operated by UKAEA at Culham, UK, will be reinstalled at the Institute of Plasma Physics (IPP) AS CR. The COMPASS device was designed as a flexible tokamak in the 1980s mainly to explore the MHD physics. Its operation (with D-shaped vessel) began at the Culham Laboratory of the Association EURATOM/ UKAEA in 1992.The COMPASS-D tokamak will have the following unique features after putting in operation on IPP Prague. It will be the smallest tokamak with a clear H-mode and ITERrelevant geometry. ITER-relevant plasma conditions will be achieved by installation of two neutral beam injection systems (2 × 300 kW), enabling co-and counter-injections. Redeployment of the existing LH system (400 kW) is also envisaged. A comprehensive set of diagnostics focused mainly on the edge plasma will be installed.The scientific programme proposed for the COMPASS-D tokamak installed in IPP Prague will benefit from these unique features of COMPASS-D and consist of two main scientific projects, both highly relevant to ITER -Edge plasma physics (H-mode studies) and Wave-plasma interaction studies.The COMPASS-D tokamak will offer an important research potential as a small, flexible and low-cost facility with ITER-relevant geometry.

Aluminum oxide is a relatively cheap, abundant material that is widely used for plasma-spray applications. This material, however, exists in many crystallographic modifications with different properties. In addition, most of these modifications are metastable and cannot he used in applications employed at elevated temperatures. Usually )', ~, or other phases form after spraying, while ~ phase (corundum) is often the most desirable phase due to high corrosion resistance and hardness. This paper first reviews the method of ~ stabilization in the as-sprayed materials offered in literature. Then, as an example, it summarizes the results of an extensive study of chromia additions to alumina. Chromia was chosen because of its complete solid solubility in alumina and its crystal lattice type, which is similar to that of alumina. It was demonstrated that the addition of approximately 20 wt % chromia results in the formation of one solid solution of (AI-Cr)203 in the s-modification.Finally, this paper discusses the thermal stability of various alumina phases. Phase change routes of heating for different starting alumina modifications are discussed, and a case study of alumina-chromia is presented. Both types of as-sprayed structures, a mixture of cq ~, and y phases, and 100% (AI-Cr)203 were annealed up to 1300 *C and the phase composition checked. At lower te~aperatures and shorter holding times, the amount of c~ phase decreases while another metastable 0 phase appears, and the fraction of)' + fi, if present, increases. At temperature above 1100 ~ the amount of c~ phase increases again.

Thermonuclear fusion is a potential source of cleaner and safer energy for the future. Its technological realization depends on the development of materials able to survive and function in extreme conditions. This article reviews the applications of thermally sprayed coatings for fusion reactor materials. First, the principle and purpose of fusion is briefly introduced, and technological objectives are mentioned. Material-environment interactions are summarized, together with materials requirements and the role of coatings. Then, specific applications-e.g., the plasma facing components-are reviewed, focusing on application issues as well as issues related to thermal spray processing and specific properties of the respective materials. An overview of specific materials testing methods is also provided.

The relative permittivity and loss factor frequency dependence in a weak electric field of plasma sprayed perovskite and ilminite polycrystalline ceramic materials-pure synthetic calcium titanate, as well as magnesium titanate-calcium titanate mixture, were studied. It was observed that plasma-sprayed titanates exhibit a strong relaxation of permittivity and loss factor decrease when they are measured in an as-sprayed state. The frequency dependence of the earlier properties is influenced by chemical composition and spraying parameters, but the relaxation character in general is preserved in all cases. The volume resistivity of the samples in an assprayed as well as subsequently annealed state was studied also. Several aspects of the structural features of plasma deposits and their possible influence on dielectric properties are discussed. #

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