Fusion magnet typically consists of an array of cable-in-conduit conductors (CICC’s) and liquid cryogen is supplied by a cryogenic network. As the cryogen supply is one of the decisive factors for magnet operation, a complete modeling including cryogenic network is necessary. In order to cope with a variety of cryogenic components, such as circulator, valves and pipes, a numerical node joining...
A quality control technique is proposed that enables numerical reconstruction of distortions occurred during the manufacture and assembly of the PF1 coil for the ITER machine. The technique utilizes field maps measured near the surface of every pancake and the entire winding pack when the warm coil is energized with a low current. The measured data are used to evaluate parameters of the coil...
The ITER magnet system consists of 18 toroidal field (TFC) coils, a central solenoid, 6 poloidal field coils and a set of correction coils. The TFCs provide the required toroidal field (≈5.3T at plasma radius R=6.2m) mainly needed to confine the plasma. Since the magnets are under manufacturing, non-conformity (NCR) and/or deviation requests (DR) can be provided by the manufacturers. Fast...
A detected loss-of-flow accident (LOFA) in the cryogenic cooling circuit of the ITER superconducting magnets will initiate a series of actions aimed at guaranteeing the protection and the integrity of the magnets. In the case of the Toroidal Field (TF) coils, the protection strategy following a LOFA triggered by, for instance, the stop of the cold circulator, is foreseen to determine an...
Previous studies indicated that the use of high-temperature superconductor (HTS) sections in the highest field allows maintaining the magnetic flux in the central solenoid (CS) reducing the outer diameter compared to the nominal size specified by EUROfusion. A reduced outer diameter of the CS coil would provide the possibility to reduce overall size and cost of DEMO. The proposed winding pack...
Princeton Plasma Physics Laboratory is currently developing a targeted superconducting magnet R&D program in support of its leading design studies of Fusion Nuclear Science Facility (FNSF) and Pilot Plant using the most promising magnetic confinement configurations including Spherical Tokamak and Stellarator. An innovative magnet design approach is required to ensure success of the FNSF,...
The cooling of the ITER Toroidal Field (TF) coils winding pack is guaranteed by the circulation of supercritical Helium (He) in 134 Nb3Sn Cable in Conduit Conductor (CICCs) and in 74 channels devoted to the cooling of the Stainless Steel (SS) case supporting the winding pack. A simplified tool aimed at computing the temperature distribution and the He temperature in the cooling channels of the...
The consortium of Russian researchers is discussing further works on new fusion devices. One of the goals is the development of superconducting magnets of the demonstration hybrid facility - Fusion Neutron Source (DEMO FNS) based on the tokamak concept with the conventional aspect ratio ~3 [1, 2]. This device should have 5 T on the plasma axis and ~12 T on the toroidal coils. Because of high...
Princeton Plasma Physics Laboratory is currently leading the design studies of Fusion Nuclear Science Facility and pilot plants based on the most promising magnetic confinement configurations including the low aspect ratio Spherical Tokamaks. An innovative magnet design approach is needed to close the gap between rapid advances in High Temperature Superconductor (HTS) and the maximal fusion...
It was declared [1] that large superconducting winding will be saved from current degradation resulting from mechanical perturbations, if the winding has strong and rigid supporting structure, and each turn is rigidly fixed transmitting its force directly to the structure. The superconductor itself shouldn’t be used as a structural material. So far the only option was proposed that...
The system architecture of a fusion reactor demands an enhanced magnetic field and downsizing to improve plasma-confinement and reduce the difficulties in construction. Since an electromagnetic force induced by a magnet system is proportional to the square of the magnetic field intensity ratio, the stress on the magnet system can be extremely severe. For FFHR, a helical fusion reactor, several...
In the framework of the European-Japanese project JT-60SA, quench tests are performed for each one of the 18 NbTi superconducting Tokamak Toroidal Field (TF) coils in a Cold Test Facility at CEA Saclay. While launching these experimental quench tests, the conductors’ Tcs are reached by progressively increasing the inlet helium temperature so as to trigger a fast discharge of nominal current...
The toroidal field (TF) magnet in Tokamak system is required generate a high-steady field to confine and shape the high-temperature plasma. To secure high current density and high thermal stability, the no-insulation(NI) winding technique is used in the fabrication of TF magnet. During plasma operation, heat generated in the TF magnet due to the interaction with central solenoid(CS) coils,...
The JT-60SA Toroidal Field Coils (TFC) are currently being manufactured in Europe, and their assembly is progressing at full speed in QST, Naka. As part of their final acceptance, the coils are tested in working conditions and at full current in a dedicated facility in Europe. To help defining the cool down strategy for the testing of the TFCs, and also to anticipate their behavior during the...
One of the key systems of a fusion device is its magnet system producing high magnetic fields to confine plasma. The main component of the magnet system of a tokamak device consists of toroidal field (TF) coils, poloidal field (PF) coils and central solenoid (CS) coils. The shape of the TF coil has a big impact on its structural performance. When the shape is not mechanically optimized the...
The Toroidal Field system of the JT-60SA tokamak comprises 18 NbTi superconducting coils. In each TF coil (TFC), 6 Cable-In-Conduit Conductor (CICC) lengths are wound in 6 double-pancakes (DP) and carry a nominal current of 25.7 kA at a temperature of 4.7 K. After fabrication and before delivering to Japan, each coil is tested in the Cold Test Facility (CTF, CEA Saclay), the test program...
In the framework of the design activities conducted in EU for dimensioning the future fusion demonstration reactor (DEMO), extensive analyses were led through in the EUROfusion context, aiming at ultimately defining the design of the DEMO magnets system. In this objective CEA has developed ad-hoc pre-dimensioning tools and associated methods in order to size the different magnets: Toroidal...
Operation stability study for a large-scale superconducting magnet is of particular importance to protect the magnet from permanent damage. Especially, for a fusion magnet, severe heat load by AC loss needs to be effectively removed during operation to achieve required temperature margin. A unique feature of KSTAR PF (poloidal field) magnet is that all the liquid cryogen inlets and outlets of...
In the framework of the European fusion program for energy, EUROfusion funds the studies for the future fusion power demonstrator reactor DEMO. CEA is involved on the conceptual design of the superconducting conductors for the Toroidal Field (TF) and Central Solenoid (CS) magnets. The CEA design proposal corresponds to Wind and React Nb3Sn pancake-wound coils using Cable-In-Conduit Conductors...
