Analysis and tests of TF magnet insulation samples for the JET upgrade to 4 tesla

The JET Toroidal Field (TF) coils were originally designed for operation at 3.4 tesla. In order to upgrade the field to 4 tesla and thus improve the performance of the JET machine, new mechanical tests and analysis were carried out on the insulation of TF coil samples. They are aimed at investigating the mechanical properties and the status of the insulation in order to set allowable stresses and force limits. In particular since the shear stress in the insulation is strongly affected by the shear modulus of elasticity G, it is important to measure this parameter. A method for the measurement of G in glass-resin fibres, the V-notched beam method (Iosipescu method) , was applied. The particular shape of the rectangular Iosipescu V- notched sample and the particular modality of force application produce pure shear stress for a reliable measurement of the G value and of the shear strength of the insulation. The effect of temperature on these mechanical properties was also investigated. Results show higher average shear strength with lower scatter compared with previous tests on conventional rectangular samples, thus confirming the reliability of the method. Micrographic analysis of the insulation and comparison between the straight and curved regions of the magnet, where the highest stress occurs, confirm the good quality of the impregnation of the coil. Glass-resin content, void content, micros and TG measurements have been performed on different samples and correlation between the different properties of the insulation investigated. Moreover fatigue tests at different temperatures were performed and data analyzed with the cumulative damage technique, which allows for an extrapolation of the fatigue curve with less samples than the standard method. (6 refs)

Design and process study of Pd membrane reactors

Palladium-silver thin wall tubes are produced by an innovative procedure based on the diffusion welding: these permeators are proposed for separating and producing high-pure hydrogen in both separators and membrane reactors. The reliability of these dense metallic permeators is strongly related to the design configuration of the membrane modules. In fact, as a consequence of hydrogenation and thermal cycles, the dense metallic tubes vary significantly in their length: in case of constraints between the membrane and the module, cyclic axial stresses are applied to the thin wall tube involving the rupture of the permeator. In our applications, a finger-like assembly of the permeator tube has been designed: it permits the free elongation and contraction of the palladium alloy tube avoiding any mechanical stress. In this work, different configurations of palladium membrane reactors used for separating ultra pure hydrogen are described and a study of a membrane process for producing ultra pure hydrogen from ethanol reforming is also presented. © 2008 International Association for Hydrogen Energy. 10.1016/j.ijhydene.2008.05.03

Long-term tests of Pd-Ag thin wall permeator tube

Thin wall permeator tubes have been produced by diffusion welding of Pd-Ag foils. These dense metal membranes are proposed for separating and producing ultra-pure hydrogen as a result of their complete hydrogen selectivity. Furthermore, they present high hydrogen permeation fluxes as well as reduced costs on account of their reduced metal thickness. The reliability of these membrane tubes has been continuously tested during over 12 months of experimental campaign in presence of thermal and hydrogenation cycles. The permeability tests have been carried out measuring the hydrogen fluxes under controlled conditions of temperature and trans-membrane differential pressure. In particular, the behaviour of the membrane tube has been investigated in a wide range of temperatures (150-400 °C) and pressures (100-200 kPa) in order to simulate the use within permeators and membrane reactors where processes for producing hydrogen from hydrocarbons takes place. At temperature of 350-400 °C hydrogen permeability values around 1.0 × 10-8 mol m-1 s-1 Pa-0.5 have been measured and they are comparable with the literature data. A new mechanical design (finger-like configuration) of the membrane module has ensured the long life of the Pd-Ag permeator. The complete hydrogen selectivity of the membrane has been demonstrated by the tests. © 2006 Elsevier B.V. All rights reserved. 10.1016/j.memsci.2006.08.00

THE FTU MAGNETIC STRUCTURE

Le Tokamak doit travailler à des champs magnétiques toroïdaux et poloïdaux très élevés pour plus de 104 chocs, afin d'atteindre les performances désirées. Pour vérifier la possibilité de construire des bobines de champ toroïdal capables de soutenir les contraintes mécaniques, des analyses aux éléments finis à trois dimensions et d'importants programmes d'essais mécaniques à température cryogénique ont été effectués. Les principaux résultats obtenus sont présentés. Les performances, les charges et les contraintes des bobines de champ sont aussi résumées.The FTU Tokamak, in order to produce the required performance must be operated at very high levels of toroidal and poloidal magnetic field and for a large number of shots (> 104). In order to assess the feasibility of a magnet capable of this performance, a three dimensional finite element stress analysis and an extensive material cryogenic test program has been developed. The main results obtained are illustrated. The objectives, the loads and the stresses on the poloidal field windings are also reported

Design and process study of Pd membrane reactors

Palladium-silver thin wall tubes are produced by an innovative procedure based on the diffusion welding: these permeators are proposed for separating and producing high-pure hydrogen in both separators and membrane reactors. The reliability of these dense metallic permeators is strongly related to the design configuration of the membrane modules. In fact, as a consequence of hydrogenation and thermal cycles, the dense metallic tubes vary significantly in their length: in case of constraints between the membrane and the module, cyclic axial stresses are applied to the thin wall tube involving the rupture of the permeator. In our applications, a finger-like assembly of the permeator tube has been designed: it permits the free elongation and contraction of the palladium alloy tube avoiding any mechanical stress. In this work, different configurations of palladium membrane reactors used for separating ultra pure hydrogen are described and a study of a membrane process for producing ultra pure hydrogen from ethanol reforming is also presented. © 2008 International Association for Hydrogen Energy. 10.1016/j.ijhydene.2008.05.03

Analysis and Tests of TF Magnet Insulation Samples for the JET Upgrade to 4 Tesla Analysis and Tests of TF Magnet Insulation Samples for the JET Upgrade to 4 Tesla

ABSTRACT The JET Toroidal Field (TF) coils were originally designed for operation at 3.4 tesla. In order to upgrade the field to 4 tesla and thus improve the performance of the JET machine, new mechanical tests and analysis were carried out on the insulation of TF coil samples. They were aimed at investigating the mechanical properties and the status of the insulation in order to set allowable stresses and force limits. In particular since the shear stress in the insulation is strongly affected by the shear modulus of elasticity G, it is important to measure this parameter. A method for the measurement of G in glass-resin composites, the V-notched beam method (Iosipescu method), was applied. The particular shape of the rectangular Iosipescu V-notched sample and the particular modality of force application produce pure shear stress for a reliable measurement of the G value and of the shear strength of the insulation. The effect of temperature on these mechanical properties was also investigated. Results show higher average shear strength with lower scatter compared with previous tests on conventional rectangular samples, thus confirming the reliability of the method. Micrographic analysis of the insulation and comparison between the straight and curved regions of the magnet, where the highest stress occurs, confirm the good quality of the impregnation of the coil. Glass-resin content, void content, micros and TG measurements have been performed on different samples and correlation between the different properties of the insulation investigated. Moreover fatigue tests at different temperatures were performed and data analyzed with the cumulative damage technique, which allows for an extrapolation of the fatigue curve with less samples than the standard method

Analysis and tests of TF magnet insulation samples for the JET upgrade to 4 tesla

The JET Toroidal Field (TF) coils were originally designed for operation at 3.4 tesla. In order to upgrade the field to 4 tesla and thus improve the performance of the JET machine, new mechanical tests and analysis were carried out on the insulation of TF coil samples. They were aimed at investigating the mechanical properties and the status of the insulation in order to set allowable stresses and force limits. In particular since the shear stress in the insulation is strongly affected by the shear modulus of elasticity G, it is important to measure this parameter. A method for the measurement of G in glass-resin composites, the V-notched beam method (Iosipescu method), was applied. The particular shape of the rectangular Iosipescu V-notched sample and the particular modality of force application produce pure shear stress for a reliable measurement of the G value and of the shear strength of the insulation. The effect of temperature on these mechanical properties was also investigated. Results show higher average shear strength with lower scatter compared with previous tests on conventional rectangular samples, thus confirming the reliability of the method. Micrographic analysis of the insulation and comparison between the straight and curved regions of the magnet, where the highest stress occurs, confirm the good quality of the impregnation of the coil. Glass-resin content, void content, micros and TG measurements have been performed on different samples and correlation between the different properties of the insulation investigated. Moreover fatigue tests at different temperatures were performed and data analyzed with the cumulative damage technique, which allows for an extrapolation of the fatigue curve with less samples than the standard method. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:4672.262(99/57) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Main mechanical and thermal problems of the FTU Tokamak machine

Consiglio Nazionale delle Ricerche, Biblioteca Centrale, P.le Aldo Moro, 7, ROMA (Italia) / CNR - Consiglio Nazionale delle RichercheSIGLEITItal