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Napoli, Italy

Mirizzi F.,Consorzio CREATE | Spassovsky I.,ENEA | Ceccuzzi S.,ENEA | Dattoli G.,ENEA | And 9 more authors.
Fusion Engineering and Design | Year: 2015

ECRH&CD systems are extensively used on tokamak plasmas due to their capability of highly tailored power deposition, allowing very localised heating and non-inductive current drive, useful for MHD and profiles control. The high electron temperatures expected in DEMO will require ECRH systems with operating frequency in the 200-300 GHz range, equipped with a reasonable number of high power (P ≥ 1 MW) CW RF sources, for allowing central RF power deposition. In this frame the ENEA Fusion Department (Frascati) is coordinating a task force aimed at the study and realisation of a suitable high power, high frequency reliable source. © 2014 Elsevier B.V. All rights reserved. Source

Crescenzi F.,ENEA | Marini F.,ENEA | Nardi C.,ENEA | Pizzuto A.,ENEA | And 5 more authors.
Fusion Engineering and Design | Year: 2011

Pre-compressions rings have been designed to improve the ITER magnets structural support. They are made of high strength unidirectional S-2 glass fibres wound in an epoxy matrix. In order to obtain very high strength properties, ENEA developed and characterized this composite with a high volumetric glass content (∼68%). Benefits of this solution include high strength, no interference with magnet fields and long expected service life. This work illustrates the mechanical characterization of the material used to manufacture the rings. At first, linear specimens were produced to perform tensile and creep tests. Then, reduced scale ring mock-ups have been fabricated and tested in ENEA Fusion-Laboratories. One ring was used for the machining of several specimens for compression and shear tests. Standard and non standard specimens were machined from different geometric directions (longitudinal, radial and transversal with reference to the fibre-glass direction) and tested at room temperature and at liquid nitrogen (77 K) temperature to complete characterization with compression and shear tests. The experimental campaign has been carried out following as close as possible the related ASTM standards in order to evaluate material strength, Young and shear moduli. Test results showed high mechanical strength of the composite in fibre-glass longitudinal direction but lower values in transversal direction. © 2011 EURATOM ENEA Association-ENEA Fusion Unit. Source

Rossi P.,ENEA | Capobianchi M.,ENEA | Crescenzi F.,ENEA | Massimi A.,ENEA | And 7 more authors.
Fusion Engineering and Design | Year: 2011

ENEA has developed and characterized a high strength glass fibre-epoxy composite as reference material for the manufacture of the two sets of 3 pre-compression rings located at top and bottom of the inner straight leg region of the ITER Toroidal Field (TF) coils. These rings will provide a radial force of about 70 MN/coil at cryogenic temperature pulling the TF coils into contact and reducing toroidal tension in the four outer intercoil structures. The paper describes the ultimate tensile strength (UTS) testing campaign carried out at ENEA Frascati laboratories on six different rings manufactured winding S2 glass fibers on a diameter of 1 m (1/5 of the full scale) by both vacuum pressure epoxy impregnation and filament wet winding techniques. The volumetric glass content was around 70%. The rings were expanded with radial steps of 0.1 mm into a dedicated hydraulic testing machine consisting of 18 radial actuators working in position control with a total capability of 1000 tons. All the mock-ups showed very high tensile strength (1550 MPa is the average of the mean hoop stresses at failure) and a practically constant tensile modulus. The test results are reported and discussed. © 2011 EURATOM ENEA Association-ENEA Fusion Unit. Published by Elsevier B.V. All rights reserved. Source

Ravera G.L.,ENEA | Ceccuzzi S.,Third University of Rome | Cardinali A.,ENEA | Cesario R.,ENEA | And 3 more authors.
AIP Conference Proceedings | Year: 2014

The preliminary assessment of a Lower Hybrid Current Drive (LHCD) system for the DEMOnstration power plant (DEMO) is mainly focused on the R&D needs of the less conventional RF components of the Main Transmission Line (MTL) and of the launcher. 500 kW, CW klystrons will be used to deliver the RF power to independent Passive Active Multijunction (PAM) launcher modules at 5 GHz. This paper describes the criteria followed to investigate the optimum solution for the RF window used as vacuum barrier between the MTL and the launcher, an open issue in the LHCD system for ITER too. The best candidate, capable of withstanding a power level of, or above, 0.5 MW in CW operation and to satisfy the electrical and thermonuclear requirements, is a Pill-Box assembly, based on a thin single disk of CVD-diamond as dielectric, water cooled at the edge. A thickness of 3 mm, much shorter than half a wavelength of the TE°11 mode in the dielectric as in the conventional window (unfeasible and too expensive with CVD-diamond at these frequencies), is sufficient to limit the exerted stress at the edge under the fracture stress for a maximum pressure applied of 0.9 MPa. In this paper the simulation results of conventional and thin CVD-diamond vacuum windows are presented comparing S-parameters, losses and electric fields in both matching condition and with VSWR = 2, using WR284 and WR229 as input/output rectangular waveguide. © 2014 American Institute of Physics. Source

Cau F.,Fusion for Energy F4E | Bessette D.,ITER Organization | D'Amico G.,Fusion for Energy F4E | Portone A.,Fusion for Energy F4E | And 4 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2016

The ITER magnet system, which is composed of toroidal field (TF) and poloidal field (PF) coils, central solenoid (CS), correction coils, and all their structural supports, is cooled by supercritical helium flow at 4.5 K. Eddy currents are induced in the metallic components during normal operation, due to the variation of PF and CS coils current, and to the plasma ramp-up and ramp-down. In addition, during disruptions, as well as other fast plasma transient events, the eddy currents circulating in these structures reach very high values due to the high induced electric fields. An effective cooling is therefore needed to limit the temperature increase of the magnets and their supports. The Joule energy dissipated in the cold structures of the ITER magnet system has been computed by means of the electromagnetic finite-element code CARIDDI. A model of a 40 degree sector of the ITER magnet has been built in order to represent in detail the connections between the CS and the TF coils, PF and CS supports, and all the intercoil structures and the metallic part of the TF coils (radial plates, case, etc.). Vacuum vessel, thermal shield, and cryostat have also been modeled. The reference 15-MA inductive scenario (with plasma current ramp-up duration of 80 s and ramp-down of 200 s) and a 15-MA fast inductive scenario characterized by the fastest plasma current ramp-up (50 s) and the fastest plasma current ramp-down (65 s) have been analyzed. In addition, several plasma instabilities have been simulated considering the reference electrical connections between the metallic parts. © 2016 IEEE. Source

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