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20/09/2021, 12:25
The High Luminosity upgrade of the Large Hadron Collider (HiLumi-LHC) foresees the installation
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of Nb3Sn based dipoles (11T Dipole) and quadrupoles (MQXF) at select points of the
accelerator. The precise knowledge of its thermal characteristics and heat extraction performance in response to deposited loads is essential
in determining safe operating margins of the magnets. These... -
20/09/2021, 12:50
High Temperature Superconductor (HTS) tapes are expected to enable future magnets to reach magnetic fields beyond 20 T. Detailed knowledge on how these composite coated conductors behave is needed to design reliable magnet applications. The mechanical strain causes the YBCO layer within the tape to degrade, meaning that its critical current I_c drops, leading to under-performing devices. The...
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20/09/2021, 13:15
Until today several designs of the Nb3Sn Cable-In-Conduit Conductors (CICCs) have been developed for different high-performance tokamak magnets. The Nb3Sn strands composing the conductors are submitted to mechanical stresses of electromagnetic (EM) and thermal origin, inducing local deformations and affecting the strands critical current carrying capability. Even though it is possible to test...
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20/09/2021, 13:50
In the framework of the commissioning of JT-60SA Tokamak (Japan, beginning of 2021), all the coils (TFC, CS and EF) have to be energized with a set of reduced and then nominal current after they became superconducting at 4.5 K cooling temperature with supercritical helium flow in Cable-In-Conduit Conductors (CICC).
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An important Issue is to predict the Joule Energy for all the magnet systems,... -
20/09/2021, 14:15
In a dark matter Axion research context, the MADMAX project acts as a figurehead in the physics research field. The purpose of the project is to use a dipole, composed of 18 coils, with a Figure of Merit of 100 T²m². The MADMAX’s coils have several specific features though, as the use of Cable-In-Conduit-Conductor (CICC) in a copper stabilizer or the use of stagnant superfluid helium inside...
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20/09/2021, 14:40
Conventional cables for fusion magnets make use of low temperature superconductors (LTS) to achieve high current densities, which are necessary to generate the magnetic field for fusion plasma confinement. Compared to LTS, high temperature superconductors (HTS) offer the possibility to increase the magnetic field strength for plasma confinement, as well as the operation at higher temperatures....
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20/09/2021, 15:05
Methodological aspects of modeling of the quench process in insulated and non-insulated ("metal-insulated") multi-double-pancake HTS REBCO-tape-wound coils are considered consistently and systematically, taking into account all important effects and inputs affecting the quench behavior and characteristics. Examples of comprehensive quench simulation in real magnetic systems are demonstrated...
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21/09/2021, 12:00
An extensive experimental campaign, supported by the EUROfusion consortium, is ongoing at SULTAN to investigate the quench propagation in High Temperature Superconducting (HTS) Cable-In-Conduit Conductors (CICCs) and provide support for the calibration and validation of the numerical tools used for the analysis of quench propagation in HTS CICCs.
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The H4C code (an upgraded version of the 4C... -
21/09/2021, 12:25
In the framework of Cold Test Facility (CTF) at CEA Saclay, JT-60SA TF coils (TFC) were tested in nominal operating conditions (25.7 kA and 5 K) followed by experimental study and numerical modelling of the quench. An additional experimental activity was conducted in order to perform further measurements on the two TFC spares. The first aim of this test program was to allow further...
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21/09/2021, 12:50
Inter-strand coupling loss in superconducting Rutherford cables subjected to weak transient operation is well understood, resulting in induced currents much lower than critical current of strands due to short enough twist-pitch and high enough transverse resistance. If these conditions are not fulfilled, the coupling loss saturates to hysteresis loss of an entire cable cross-section. Although...
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21/09/2021, 13:15
The EDIPO test facility is undergoing a major upgrade of its magnet assembly, which will provide ground for testing both fusion and high-energy physics superconducting samples at variable temperature and with a background field of 15 T. Unlike the former magnet, which was wound with cable-in-conduit conductors cooled by a forced-flow of supercritical He, the upgraded magnet assembly will be...
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21/09/2021, 13:50
In the context of the different fusion machines using superconducting magnets that are currently in development or exploitation phase (DEMO, JT-60SA, ITER…), reliable numerical models are required to perform analyses of the magnet design performances. In the design phase, after a conductor and associated magnet structured is proposed, extensive analyses are carried out to verify the compliance...
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21/09/2021, 14:15
In the framework of tokamak design studies, the magnet system dimensioning stands as a crucial point, magnets being strong drivers for reactor performances. In this aim superconducting magnets design path to manufacture and integration should prior undergo several stages of development, including the detailed analysis for defined operation cases. Those studies are linked to several physic...
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21/09/2021, 14:40
In fusion reactors, large and complex systems of cryolines distribute supercritical helium to the different cryogenic users. Space constraints often impose to deport the pressure relief equipment several meters away from the protected volumes.
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The loss of insulating vacuum is a major accidental situation for cryogenics systems. As the driving parameter for sizing the pressure relief devices... -
21/09/2021, 15:05
Thermal–hydraulic analyses of forced-flow cooled superconducting conductors designed for fusion magnets are typically based on 1-D mathematical models, which demand reliable predictive correlations for the transverse mass-, momentum- and energy transport processes occurring between different conductor components. Friction factor correlations, derived from pressure drop tests or Computational...
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22/09/2021, 12:00
The European DEMOnstration Fusion Power Plant (EU-DEMO) is planned as an intermediate step between the ITER experimental reactor and the future prototype fusion power plant. The core of EU-DEMO is a tokamak equipped with a fully superconducting magnet system, which includes six Poloidal Field (PF) coils. Two concepts of the PF winding packs (WP) are being developed by CEA IRFM (France) and...
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22/09/2021, 12:25
In the framework of thermo-hydraulic studies for tokamaks using superconducting magnets, the TACTICS code was developed at CEA. This tool is based on the same pseudo 3D approach as the one used by similar codes such as SuperMagnet, Venecia or 4C. TACTICS thus allows the simulation of the thermal and thermo-hydraulic behavior of a superconducting coil comprising CICCs, and possibly includes the...
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22/09/2021, 12:50
The pre-conceptual design phase of the EU DEMO magnet system relies on mechanical, electromagnetic and thermal-hydraulic analyses of different conductor designs for the Toroidal Field (TF) coils, the Poloidal Field coils and the Central Solenoid magnet. The cryo-magnetic system includes the superconducting magnets cooled by forced flow of supercritical helium at about 4.5 K, the...
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22/09/2021, 13:15
For large scale fusion magnets of the ITER tokamak, wound with cable-in-conduit conductors, the application of sophisticated numerical models able to analyse the thermal-hydraulic behaviour during plasma scenario is of paramount importance to guarantee adequate stability margin during the operating conditions. The SuperMagnet code has been developed by CryoSoft with the intent to simulate...
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22/09/2021, 13:50
Finite Element Modelling (FEM) is the common practice for the design and performance evaluation of superconducting magnets. Electromagnetic models are combined with structural ones to first compute the forces that are applied to the magnet during its operation and then evaluate the stress distribution that is attained in its subcomponents. Due to the computational size of the global problem, a...
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22/09/2021, 14:15
New cable concepts for the magnetic field coils of the upcoming fusion reactors are under development, with circular or rectangular cross-section. Some prototypes have been tested for DC transport current and AC loss in the Sultan facility (SPC) and for inter-strand contact resistance and AC loss at the University of Twente. The facilities both provide experimental data on the AC loss...
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22/09/2021, 14:40
Several design proposals have been envisaged for the Toroidal Field (TF) coils of the future European DEMO fusion reactor, which are based on a Nb3Sn conductor cable made with the react&wind (RW) or wind&react technologies.
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Among them, Swiss Plasma Center (SPC) is proposing a RW solution combined with a layer winding technique for the coil, which is expected to permit the conductor grading as... -
22/09/2021, 15:05
Magnetic field and current variations are responsible for AC losses in superconductive magnets. These losses may induce an increase of temperature within the material and negatively affect the performance of the magnet. In case of fusion energy experiments, it is essential to model and predict AC losses to ensure safe and reliable tokamak utilisation.
Developed at CEA, the new fully...
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26. A Numerical Investigation on AC Losses in one module of the Central Solenoid of the ITER tokamak23/09/2021, 12:00
The investigation of electromagnetic transients in the superconducting coils of the ITER magnet system is important in order to compute the losses arising during time-varying operating conditions. The challenge of this analysis is related to the high number of degrees of freedom required to discretize large-scale magnets at the level required for AC loss computation. The Central Solenoid (CS)...
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23/09/2021, 12:25
The Roadmap to Fusion Electricity draws on innovative experiments pivotal for the accomplishment of the European DEMO, i.e. the demonstration fusion power plant by the EUROfusion Consortium.
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At the end of the pre-conceptual design phase, the machine comprises three main magnetic systems: 6 poloidal field (PF) coils, 16 or 18 toroidal field (TF) coils and the central solenoid (CS), primary... -
23/09/2021, 12:50
In large size conductors for the Central Solenoid (CS) and Poloidal Field (PF) coils of tokamaks, the AC losses set the operating limits for the magnets, especially during the plasma start up. In terms of losses, the startup of the plasma current (breakdown) can be particularly challenging, as the flux density rate can reach values as high as 10 T/s. At such high-field rates, the cable is...
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23/09/2021, 13:15
This talk demonstrates the capabilities of the open source FEM library Sparselizard
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(sparselizard.org) through mini-examples focused on the physics of interest for particle
accelerator magnets. The equations and simulations are set up on the 3D geometry of
CERN’s Feather M2 particle accelerator magnet for the following physics:
DC electric current flow through the magnet conductor
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23/09/2021, 13:50
The Toroidal Field (TF) system of the WEST tokamak comprises 18 NbTi superconducting coils, cooled in a static superfluid helium bath at 1.8 K and carrying a nominal current of 1255 A. The 19th December 2017, at the end of plasma run #52205, a quench of TFC-09 was detected first on a secondary thermohydraulical signal (helium level) and triggered the current Fast Safety Discharge (FSD)....
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23/09/2021, 14:15
During the integrated commissioning of JT-60SA tokamak, the superconducting magnets have experienced several tests such as current ramps or fast discharges. The time variations of the associated magnetic field have induced AC losses in the winding pack (WP), i.e. hysteresis and coupling losses, and in the casing, i.e. eddy currents losses, of the toroidal field (TF) coils.
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From the... -
23/09/2021, 14:40
In framework of the Broader Approach research and development for fusion activities, involving Japan and Europe, the JT-60SA tokamak has been jointly constructed in Naka, Japan to support the operation of ITER and to study advanced plasma scenarios for future fusion power plants.
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The integrated commissioning of the tokamak started mid 2020 with a Japanese and European team, composed of QST,... -
23/09/2021, 15:05
Within the framework of Open Science, set as a priority by the European Commission in Horizon Europe, the OPENSC2 code has been developed to grant the entire research community the possibility to simulate thermal-hydraulic transients in LTS and HTS cable-in-conduit conductors (CICC) for fusion and power applications.
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A Test-Driven Development (TDD) approach has been adopted for the code... -
24/09/2021, 12:00
Recent developments are introduced to improve the performance of the SuperMagnet model. Since an attempt to implement a momentum-conserving nodal branch, a series of study has been carried out shedding a light to the next step to the improved performance, by means of careful investigations to the numerical structure of the integrated model. From the latest quench model with adaptive time-step...
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24/09/2021, 12:25
The magnetic confinement of the plasma in existing and future nuclear fusion reactors is often provided by superconducting magnets. To show their superconducting properties, they must be kept sufficiently colder than the current sharing temperature during the pulsed reactor operation; therefore, they are usually cooled by supercritical He obtained by a refrigeration process. The technological...
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24/09/2021, 12:50
Superconducting high-field magnets working in He II are usually immersed in a pressurized static He II bath. This pressurized He II bath is then connected through a heat exchanger to a saturated He II bath acting as a cold source. Due to the peculiar He II properties (very high heat conductivity), the conventional heat exchanger designs are not suitable here. In addition, a compact design is...
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24/09/2021, 13:15
We describe in this paper how the analysis of current distribution and redistribution in Nb3Sn Rutherford cables can be used to assist in the analysis of manufacturing issues and decision on the closure of major non-conformities. After describing the method and the model in detail, we apply it to the case of a cable defect next to the coil termination, a single strand breakage in a...
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Within the EUROfusion Roadmap, the helical-axis advanced stellarator (HELIAS) is investigated as a possible long-term alternative to a tokamak fusion power plant. Its superconducting magnet system is based on modular field coils with a complex 3D shape (similar to but a lot larger than Wendelstein 7-X coils), and faces therefore several engineering challenges. The W7-X magnet system is based...
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ITER superconducting magnet system design is based on Cable-In-Conduit Conductors (CICC) cooled at cryogenic temperatures by forced circulation of supercritical helium. As part of the as-built performance assessment of the superconducting magnet system of ITER, a new 15 MA DT plasma scenario baseline was analysed. Using the updated SuperMagnet models (FLOWER 1D hydraulic network, THEA dual...
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Welcome the participants and presentation by M. Liao on the status of the TIER Superconducting magnets.
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