1,721,066 research outputs found
Modeling of epoxy resin spacers for the 1 MV dc gas insulated line of ITER neutral beam injector system
No full textThe spacers for the Gas Insulated Transmission Line for the ITER neutral beam injector will be designed to withstand the operating voltage of 1 MV dc. Electric charging processes of the spacer surface are then expected to play an important role in the final electric field distribution. Aim of the paper is to investigate the effects of the different conductivity properties of the SF6-Spacer insulating structures on the surface charge set-up, and to identify a procedure to minimize this charge. Based on the most updated literature, the paper presents and discusses the results of two newly developed simulation tools: the first consisting of a quasi-static non linear model for epoxy spacer based on finite element method code ANSYSTM, the other consisting of a spacer profile optimization package, whose kernel is based on a genetic algorithm. The numerical tools have been applied to post and disk spacer models of the gas insulated line; in particular, the optimization package has been used on the disk spacer, and the comparison between un-optimized and optimized spacer in terms of electric charge accumulated are presented and discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Electromagnetic analyses for the dynamic control of RFX equilibrium with a new shell
No full textThe experiments proposed with active MHD mode control in RFX require the installation of new saddle coils and the substitution of the present thick stabilizing shell with a much thinner one. In this framework, the dynamic behaviour of plasma, shell and poloidal field circuit has been simulated to verify the operating scenarios of the modified machine, the dynamic control of plasma axisymmetric equilibrium and on the gas ionisation conditions, also based on the past operation experience. The results have given indications and constraints for the design of a layout, which assures the existence of an operating region compatible with both plasma active position control and gas ionisation
Magnetic compatibility of standard components for electrical installations: Tests on low voltage circuit breakers and contactors
No full textThe components of the electrical distribution system installed in the ITER Tokamak Building are subjected to a constant or slowly variable magnetic field, an environmental condition unusual for standard components used in low voltage electric distribution systems. Wide typologies of breakers, contactors and protection relays and a complete Low Voltage Distribution Board have been extensively tested to assess their behaviour when subjected to magnetic field. The results allowed to establish a magnetic field limit for their regular operation and to investigate upon overall functionality of a Low Voltage Distribution Board and upon the shielding effect of its iron structure
Design developments for the ITER in-Vessel equilibrium pick-up Coils and Halo current Sensors
No full textThe ITER magnetic diagnostics must provide essential information for plasma diagnostic purposes and for the machine control. The sensors will be installed in a hostile environment characterized by severe neutron irradiation and heat loads, which can reduce the sensor lifetime and also generate undesired DC signals, which might compromise the accuracy of the measurements obtained by time-integration. The paper is focused on the design development and optimisation of the in-vessel tangential pick-up coils and blanket halo sensors. The work is aimed at achieving the required measurement precision in spite of the thermal effect due to the neutron irradiation. Within the limits of several tight engineering constraints, a new concept of magnetic pick-up coil has been developed. A winding made of a ceramic-coated conductor (instead of a mineral insulated cables) and "impregnated" with ceramic filler is proposed. Similar issues are also related to the halo sensor design
The design of 192 saddle coils for RFX
No full textThe paper presents the various aspects of the new set of 192 saddle coils (SC), designed for the active control of MHD
plasma modes in the RFX experiment. The choices necessary to fulfil the electromagnetic specifications and the
geometrical constraints of the system are described. The methods and results of thermal, electrodynamic and
mechanical analyses carried out for the proper design of the coils are also reported. The technological solutions
proposed for the construction, presently in progress, are illustrated
Evaluation of electrodynamic forces on the passive components of the new RFX load assembly
No full textThis paper deals with the design of a new system developed for the stabilization and the active control of the magnetic
configuration of RFX. The system consists of a conductive shell and a set of saddle coils closely fitting the plasma
region, supported by a stainless steel toroidal structure. These new components are intended for replacing the present
shell, keeping the existing vacuum vessel, the poloidal field coils and the toroidal field coils unchanged. The paper
presents the electromagnetic analyses, performed by means of 2D integral formulation and 3D finite element codes,
which provided basic inputs for the design of the new passive components and for the mechanical assessment of the
existing ones, in the new foreseen operating conditions
Magnetic field immunity of the low voltage current breakers installed inside the ITER tokamak building
No full textTwo typologies of circuit breakers for Low Voltage distribution system have been extensively tested immersed in a static magnetic field, an environmental condition similar to what is expected inside the ITER Tokamak Building. Functionality tests with and without load, protection relay tests and life tests at nominal ratings have been performed. The results allowed to point out a magnetic field limit for regular operation irrespective of the installation, to find the operability limits for higher magnetic field and to assess if magnetic field changes the wearing during the life
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