Luigi Muzzi

Bio: Luigi Muzzi is an academic researcher from ENEA. The author has contributed to research in topics: Electromagnetic coil & Tokamak. The author has an hindex of 21, co-authored 127 publications receiving 1625 citations. Previous affiliations of Luigi Muzzi include European Atomic Energy Community.

Design of an Industrially Feasible Twisted-Stack HTS Cable-in-Conduit Conductor for Fusion Application

Abstract: Taking advantage of the large experience of the ENEA Superconducting Laboratory in the manufacture and characterization of large scale superconducting systems, a project was launched, aimed at using High Temperature Superconductor (HTS) 2G wires for the manufacture of a cable-in-conduit conductor (CICC). In particular, the main aim was the definition of a conductor design fully compatible with existing cabling technologies, to be promptly transferred to an industrial scale production. The considered layout is based on 150 HTS tapes, arranged as five layered structures of twisted tapes wound on a helically slotted core with external round jacket. All manufacturing steps (slotted core production, tape stacking and insertion into the ducts, external wrapping and jacketing) are fulfilled by using equipments and technologies available at TRATOS Cavi S.p.A. These CICCs are intended for operation using forced flow of Helium. A 2D local thermal model has been developed for the optimization of the cooling configuration. This conductor is designed to target 20 kA at 4.2 K and 15 T (or, alternatively, higher temperature, in self-field and LN2 cooling) corresponding to a Je of about 55 A/mm2. The production of a short dummy sample revealed that the exploited industrial production process is very promising for the development of HTS CICC.

Cable-in-conduit conductors: lessons from the recent past for future developments with low and high temperature superconductors

Abstract: We review progress in the design of high field superconducting cable-in-conduit conductors (CICCs) for fusion applications, with special attention to the results of recent key experiments, leading to the state-of-the-art CICC technology: the ITER Toroidal Field and Central Solenoid programs, the EFDA Dipole conductor development program, the NHFML Hybrid Magnet project, the EU-TF Alt conductor demonstration, and the CRPP React & Wind flat cable test. For these projects, the main CICC design driver was the mitigation of Nb3Sn conductor performance degradation with electro-magnetic loading cycles. This was achieved by proper choice of cable layout and of conductor geometry, depending on the specific operating conditions and project requirements. In all cases, the necessity to limit cable movements inside the conductor jacket was identified to be of crucial importance. The main aspects of CICC manufacture are also discussed here, at least for what is the experience gained by the authors in both CICC jacketing and cabling processes. Finally, the state of the art of high-temperature superconducting (HTS) cables is discussed: at present, this technology is still in its infancy, but it is highly likely that major technological improvements could eventually lead to a widespread use of HTS CICCs.

Test Results of Two European ITER TF Conductor Samples in SULTAN

Abstract: Four conductor lengths were prepared according to the ITER TF conductor design and assembled into two SULTAN samples. The four lengths are not fully identical, with variations of the strand supplier, void fraction and twist pitch. Lower void fractions improve the strand support and increased twist pitches also lower the strand contact pressure but both tend to increase the AC loss and the lower void fraction also increases the pressure drop so that the mass flow rate in the strand bundle area of the cable is reduced. The assembly procedure of the two samples is described including the destructive investigation on a short conductor section to assess a possible perturbation of the cable-to-jacket slippage during the termination preparation. Based on the DC performance and AC loss results from the test in SULTAN, the impact of the void fraction and twist pitch variations is discussed in view of freezing the ITER conductor design and large series manufacture. A comparison with the former generation of conductors, using similar strands but based on the ITER Model Coil layout, is also carried out. The ITER specifications, in terms of current sharing temperature, are fulfilled by both samples, with outstanding results for the conductor with longer twist pitches.

Overview of Progress on the EU DEMO Reactor Magnet System Design

Abstract: The DEMO reactor is expected to be the first application of fusion for electricity generation in the near future. To this aim, conceptual design activities are progressing in Europe (EU) under the lead of the EUROfusion Consortium in order to drive on the development of the major tokamak systems. In 2014, the activities carried out by the magnet system project team were focused on the toroidal field (TF) magnet system design and demonstrated major achievements in terms of concept proposals and of consolidated evaluations against design criteria. Several magnet system RD and 2) the HTS R&D activities building upon the consolidated knowledge acquired over the past years.

Development of advanced high heat flux and plasma-facing materials

Abstract: Plasma-facing materials and components in a fusion reactor are the interface between the plasma and the material part. The operational conditions in this environment are probably the most challenging parameters for any material: high power loads and large particle and neutron fluxes are simultaneously impinging at their surfaces. To realize fusion in a tokamak or stellarator reactor, given the proven geometries and technological solutions, requires an improvement of the thermo-mechanical capabilities of currently available materials. In its first part this article describes the requirements and needs for new, advanced materials for the plasma-facing components. Starting points are capabilities and limitations of tungsten-based alloys and structurally stabilized materials. Furthermore, material requirements from the fusion-specific loading scenarios of a divertor in a water-cooled configuration are described, defining directions for the material development. Finally, safety requirements for a fusion reactor with its specific accident scenarios and their potential environmental impact lead to the definition of inherently passive materials, avoiding release of radioactive material through intrinsic material properties. The second part of this article demonstrates current material development lines answering the fusion-specific requirements for high heat flux materials. New composite materials, in particular fiber-reinforced and laminated structures, as well as mechanically alloyed tungsten materials, allow the extension of the thermo-mechanical operation space towards regions of extreme steady-state and transient loads. Self-passivating

Progresses and challenges in the development of high-field solenoidal magnets based on RE123 coated conductors

Abstract: Recent progresses in the second generation REBa2Cu3O7 − x (RE123) coated conductor (CC) have paved a way for the development of superconducting solenoids capable of generating fields well above 23.5 T, i.e. the limit of NbTi−Nb3Sn-based magnets. However, the RE123 magnet still poses several fundamental and engineering challenges. In this work we review the state-of-the-art of conductor and magnet technologies. The goal is to illustrate a close synergetic relationship between evolution of high-field magnets and advancement in superconductor technology. The paper is organized in three parts: (1) the basics of RE123 CC fabrication technique, including latest developments to improve conductor performance and production throughput; (2) critical issues and innovative design concepts for the RE123-based magnet; and (3) an overview of noteworthy ongoing magnet projects.