Papers by Gian Mario Polli
IEEE Transactions on Applied Superconductivity, Jun 1, 2011
The preliminary design of the heat exchanger part for the pair of 30 kA hybrid current leads that... more The preliminary design of the heat exchanger part for the pair of 30 kA hybrid current leads that will be installed in the ENEA 12 T CICC facility is presented. To limit the overall length and the amount of cooling gas to be employed, a hybrid re- sistive/HTS configuration has been conceived. Regarding the resis- tive part, a screw-like solution
Fusion Engineering and Design, Nov 1, 2021
Abstract The Divertor Tokamak Test (DTT) facility is an experimental facility under design and co... more Abstract The Divertor Tokamak Test (DTT) facility is an experimental facility under design and construction at ENEA C.R. Frascati. The aim of DTT is to investigate the power exhaust problem in a tokamak, providing possible alternative divertor solutions, with respect the conventional one, which can be extrapolated to DEMO fusion reactor. One of the main components of DTT facility is the Vacuum Vessel (VV), which has the function of providing an enclosed, vacuum environment for the plasma, acting also as a first confinement barrier. Starting from geometrical constraints, imposed by the desired plasma scenario and the configuration needed for the magnetic coils, the conceptual design of the VV was developed and dedicated research activities were carried out to verify design choices. A multiphysical approach was adopted with the aim of identifying a feasible and reliable solution for the VV, taking into account functional and design requirements, relevant aspects and issues. In particular, to assess and to optimize the VV design, fluid-dynamic, thermal and structural analyses were carried out, which are presented in the paper, as well as the progresses of the design.
Fusion Engineering and Design, Oct 1, 2011
The recently developed 4C thermal-hydraulic code, currently under validation, is used to compute ... more The recently developed 4C thermal-hydraulic code, currently under validation, is used to compute the temperature margin of the superconducting NbTi toroidal field coil of the ITER satellite tokamak JT-60SA, for the nominal burn operation of the machine. Repetitive conditions in the simulation are reached after two plasma pulses. For given (computed) thermal load distribution on winding and coil case due to nuclear heating only, helium temperature ∼4.4 K at the winding inlet, reference strand, and the most recent conductor and winding layout, the computed minimum margin occurs in pancake #7 at the peak field location and turns out to be ∼0.2-0.3 K above the design value of 1.2 K.
IEEE Transactions on Applied Superconductivity, Jun 1, 2011
Superconductor Science and Technology, Mar 19, 2010
One of the design features which yet offers interesting margins for performance optimization of c... more One of the design features which yet offers interesting margins for performance optimization of cable-in-conduit conductors (CICCs), is their geometry. For relatively small size Nb3Sn CICCs, operating at high electromagnetic pressure, such as those for the EDIPO project, it has been experimentally shown that a design based on a rectangular layout with higher aspect ratio leads to the best performance,
IEEE Transactions on Applied Superconductivity, Jun 1, 2012
The outsert coils of the Series-Connected Hybrid magnets for the National High Magnetic Field Lab... more The outsert coils of the Series-Connected Hybrid magnets for the National High Magnetic Field Laboratory and Helmholtz Zentrum Berlin each contain approximately 4000 kg of ${\rm Nb}_{3}{\rm Sn/Cu}$ cable-in-conduit conductor (CICC). There are three different sizes of CICC that grades the amount of superconductor. Significant progress has been made in all aspects of the CICC fabrication. The ${\rm Nb}_{3}{\rm Sn}$
Appropriate disposal of the non-neutronic energy and particle exhaust in a reactor is universally... more Appropriate disposal of the non-neutronic energy and particle exhaust in a reactor is universally recognized as one of the high priority challenges for the exploitation of fusion as an energy source. The new Divertor Tokamak Test (DTT) facility, which will be built in Italy, is a tool to address that challenge in high-field, high performance tokamak with complete integration between core and edge plasma scenarios.
IEEE Transactions on Applied Superconductivity, Jun 1, 2016
The JT-60SA superconducting tokamak is being constructed in Japan under the Broader Approach agre... more The JT-60SA superconducting tokamak is being constructed in Japan under the Broader Approach agreement between Japan and the EU. ENEA is responsible for the in-kind supply of 18 toroidal field coil casings for JT-60SA, and contracted the company Walter Tosto (Chieti, Italy) for fabrication of two sets of nine casings each to be delivered to the coil manufacturers ASG Superconductors (Genoa, Italy) and Alstom (Belfort, France). After the completion of the detailed design of the casing components' stainless-steel materials were acquired and the manufacturing processes were qualified on mock-ups representative of the components. The complete resolution of all design and technical issues required the replacement of the forged stainless-steel material and a revision of the time schedule. On the basis of the manufacturing experience of the first two different sets of casing components, the production process has been improved, and the fabrication of the complete procurement is now ongoing. This paper reviews the main steps of the fabrication of the casing components, highlighting the critical issues encountered and reporting the status of the manufacturing activities.
Nuclear Fusion, Jun 30, 2015
ABSTRACT
Fusion Engineering and Design
Abstract The Divertor Tokamak Test (DTT) facility is an experimental facility under design and co... more Abstract The Divertor Tokamak Test (DTT) facility is an experimental facility under design and construction at ENEA C.R. Frascati. The aim of DTT is to investigate the power exhaust problem in a tokamak, providing possible alternative divertor solutions, with respect the conventional one, which can be extrapolated to DEMO fusion reactor. One of the main components of DTT facility is the Vacuum Vessel (VV), which has the function of providing an enclosed, vacuum environment for the plasma, acting also as a first confinement barrier. Starting from geometrical constraints, imposed by the desired plasma scenario and the configuration needed for the magnetic coils, the conceptual design of the VV was developed and dedicated research activities were carried out to verify design choices. A multiphysical approach was adopted with the aim of identifying a feasible and reliable solution for the VV, taking into account functional and design requirements, relevant aspects and issues. In particular, to assess and to optimize the VV design, fluid-dynamic, thermal and structural analyses were carried out, which are presented in the paper, as well as the progresses of the design.
2022 IEEE 21st Mediterranean Electrotechnical Conference (MELECON)
IEEE Transactions on Applied Superconductivity, 2022
At the ENEA's research center of Frascati, the DTT (Divertor Tokamak Test) facility is currently ... more At the ENEA's research center of Frascati, the DTT (Divertor Tokamak Test) facility is currently under construction. The activity of this experimental nuclear fusion reactor, will be focused on the optimization of the power exhaust management in view of DEMO. The project has been started during year 2014, when also the superconducting magnet system has been initially designed, basing on the available inputs coming from physics and on the desired goals for the machine. At present, the coils engineering design has almost been completed and the production of crucial components, such as the superconducting strands, conductors, toroidal and poloidal field coils, have already been started. For the remaining superconducting elements, the engineering design is being finalized. The result is a compact and flexible tokamak, with highly demanding requirements in terms of superconducting and structural performances, sometime close to the intrinsic mechanical limits of the adopted materials. Tight constraints on time, budget and resources forced the design team to walk through a complex path in these years for reaching a sound and satisfactory design of the complete magnet system. In fact, it was not possible to rely entirely on state-of-the-art and already assessed superconducting technologies, as was initially assumed. In particular, the trade-off between limiting the R&D phase and extending the performance demonstrated in other projects to the specific DTT requirements, pushed the team to take some risks, while providing a robust and fully performing magnet system design.
La proposta di progetto DTT, Divertor Tokamak Test facility, rappresenta una proposta innovativa ... more La proposta di progetto DTT, Divertor Tokamak Test facility, rappresenta una proposta innovativa e completa nella roadmap verso l’implementazione dell’energia da fusione termonucleare. Il progetto coinvolge un centinaio di ricercatori provenienti da universita e laboratori italiani e stranieri. Approvato dalle autorita italiane, il progetto potra beneficiare di finanziamenti governativi e regionali e di un ampio sostegno europeo, ottenuto nell’ambito del Piano europeo per gli investimenti in infrastrutture. La pubblicazione intende fornire i dati chiave aggiornati del complesso e articolato progetto.
Fusion Engineering and Design, 2021
Abstract The construction of a Divertor Tokamak Test (DTT) facility is fully included in the Euro... more Abstract The construction of a Divertor Tokamak Test (DTT) facility is fully included in the European effort towards the realization of fusion energy with the aim of studying possible alternative solutions, with respect to the ITER research program, to tackle the problem of power exhaust. This means that the machine must be compatible with different possibilities for the divertor cassette design and the plasma scenario. The design of first “reference” divertor is largely based on the ITER-like divertor, but in the future other solutions are going to be tested, including liquid metal divertors. To provide a justification basis for the design of the reference cassette and guidelines for the future experimentations it is fundamental to define the requirements of this power exhaust system, in particular the heat flux compatibility and the interfaces with the surrounding interacting systems of the tokamak (the water cooling pipes, the divertor magnetic coils, the divertor diagnostics, etc.). This work shows how the divertor system can be included in a wider Requirement Management procedure that has been defined for DTT highlighting the relevant interface parameters. Additionally, a data analysis tool has been developed to provide an interactive visualization of requirements traceability to directly show the impact of changes in the divertor on the design and operations of the machine and viceversa. In this way, during future studies on alternative design divertors or plasma scenarios, the limiting constraints on both sides can be easily individuated and traced to their motivation, and possibly discussed.
Fusion Engineering and Design, 2018
In the framework of the Broader Approach program, ENEA is in charge of supplying the Toroidal Fie... more In the framework of the Broader Approach program, ENEA is in charge of supplying the Toroidal Field (TF) coil casings for JT-60SA tokamak. ENEA commissioned the manufacture of the full set of eighteen casings for the integration of the TF coils plus two additional spare casings to the company Walter Tosto (WT, Chieti, Italy). The main casing components are one outboard straight leg, an outboard curved leg and three inboard covers. The preliminary design of the casing components has been coordinated by Fusion for Energy (F4E) and the following detail design has been finalized involving the industrial companies in charge of the subsequent integration of the coils. The principal milestones of the five year contract are here summarized. The contract started in 2012 with the realization of two sets of mock-ups representative of the principal casings cross sections of the two legs. In 2013 detail design of the casing components was completed; qualifications of special manufacturing processes were performed and manufacturing procedures were defined. Casing manufacturing activities started in 2014. Seven casings were manufactured during 2015, other seven casings in 2016 and the last four casings were delivered in the first quarter of 2017. The full procurement was then completed with the fabrication of two additional casings in July 2017. This paper provides an overview of the casing procurement describing the production process and manufacturing improvements, reporting the satisfactory acceptance results confirmed by the subsequent proper integration of the superconducting TF coils.
Fusion Engineering and Design, 2017
h i g h l i g h t s • Superconducting magnet manufacturing. • In casing insertion. • Casing weldi... more h i g h l i g h t s • Superconducting magnet manufacturing. • In casing insertion. • Casing welding. • Interface machining. • Piping assembly.
2015 IEEE 26th Symposium on Fusion Engineering (SOFE), 2015
The JT-60SA experiment will be the world's largest superconducting tokamak when it is assembl... more The JT-60SA experiment will be the world's largest superconducting tokamak when it is assembled in 2019 in Naka, Japan (R=3m, a=1.2m). The superconducting magnet system includes 18 D-shaped toroidal field coils, each 7m high and 4.5m wide, 6 pulsed equilibrium field coils up to 12m in diameter and 4 central solenoid modules. Manufacturing of the superconducting magnets for JT-60SA is well established in Japan and in Europe. Conductor manufacturing is almost complete, half of the superconducting coils have been wound and the first cold test results for production coils will be available later in 2015. Challenges remain to integrate the coils with their mechanical structures and to assembly them into the tokamak.
Nuclear Fusion, 2015
ABSTRACT
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Papers by Gian Mario Polli