The US ITER Domestic Agency is responsible for supplying seven Central Solenoid Modules (CSM) to the ITER organization. The modules are fabricated by General Atomics (GA). As part of the fabrication process, all CSMs undergo factory acceptance testing (FAT) prior to shipment to the IO. The FAT includes Paschen testing the CSMs up to 15 kV between 1e-3 and 100 mbar, and up to 30 kV at ambient conditions. During post-cooldown Paschen testing of CSM6, there was a fault on one of the terminal breakout locations which required a repair. This location of the fault consisted of complex geometry that required development of advanced insulation repair methods to return the module to Paschen-tight condition. Successful insulation repairs typically require sufficient compression to achieve a Paschen-tight seal of the applied insulation to the underlying surfaces. Typically for circumferential shapes, compression is achieved utilizing shrink tape or silicone tape wrapped around the perimeter. The complex geometry of CSM6 terminal required research into other compression methods including vacuum bagging, expanding foam, and externally pressurized bladders of complex shapes. Multiple test articles were created to replicate the shape of the fault area and repair methods were developed and Paschen tested to 30 kV, from 1e-3 to 1000 mbar. This paper will discuss the development of the qualified repair process for the complex geometry of the CSM6 terminal, and present to the magnet community the lessons learned from that development.

The ITER Central Solenoid (CS) is under fabrication by the US ITER organization and its subcontractors. US ITER will supply seven modules to ITER IO, six of which will be assembled in a stack that forms the ITER Central Solenoid. All CS modules (CSM) were or will be tested at 40 kA in the Final Test facility at General Atomics (GA). CSM 5, 6, and 7 were tested in 2023 and 2024. Some instrumentation was updated to obtain information on the suppression of the inductive noise in the CSMs at high dB/dt events, which will lead to improved quench detection and protection of the modules. All the standard tests performed on previous CSMs to validate the properties of the CSM have also been performed on CSMs 5-7 to confirm the consistency of the CSM properties for ITER CS. The Tcs margin demonstration was done for the first time at the GA Facility on CSM6. Test results and analysis are presented and discussed.

Two systems used in factory acceptance power testing of the ITER Central Solenoid Module (CSM) at General Atomics’ Magnet Technologies Center are the Alpha Scientific 50kA dc Power Supply (DCPS) and the Siemens 50kA dc circuit breaker (DCB). Both systems were designed specifically for this application; capable of charging the CSM to 50kA and safely discharging its stored energy, up to 1GJ. Nominally the DCPS and DCB would have been fully commissioned after completion of CSM1 testing. However, several issues occurred during the first three test campaigns, precluding completion of the full power test plan. This paper discusses these issues, their investigations, and upgrades implemented to both the DCPS and DCB; including the design and build of a superconducting inductor (SCL) used as a test load to debug the DCPS. All of which culminated in successful completion of CSM4 power testing, verifying the commissioning of both these systems.

General Atomics (GA) is under contract to UT-Battelle c/o Oak Ridge National Laboratory for the fabrication of ITER Central Solenoid Modules (CSM). GA will provide seven modules to ITER Organization (IO), six of which will be assembled in a stack that forms the ITER Central Solenoid. All CSMs are required to pass factory acceptance testing (FAT) at General Atomics’ Magnet Technology Center (MTC) test facility prior to shipment to IO. Currently, CSMs 1, 2, and 4 have completed FAT and have been delivered to IO. CSM5 has completed FAT and CSM3 will repeat FAT after resuming its test campaign. FATs on CSMs 6 and 7 are planned as the modules complete fabrication. The MTC test facility was designed and built to conduct CSM factory acceptance tests. The test facility consists of the test chamber, high vacuum system, 4.5 K recirculating supercritical helium refrigeration plant, 50 kA DC power supply, capacitor-pulsed DC circuit breakers, 1 GJ discharge resistor, high-temperature superconducting current feeders, data acquisition system, supervisory control and magnet quench protection system, and a multitude of supporting equipment. Where possible, the test facility utilizes similar equipment planned for use at IO for magnet operation. The test facility operational lessons learned as a result of CSM 1-4 FATs are presented and discussed in this paper.

General Atomics (GA) is fabricating seven ITER Central Solenoid Modules (CSM) for the ITER Organization (IO). As part of the fabrication process, all CSMs undergo factory acceptance testing (FAT) prior to shipment to the IO. The FAT includes charging the modules to 40 kA and performing fast discharges (7.3 second decay time constant) to measure alternating current (AC) losses. These fast discharges generate high voltages at the electrical connections between the CSM and the test facility. Due to a fast discharge fault during the CSM 3 FAT, Paschenization methods of high voltage connections between the CSM and the test facility needed to be developed, qualified, and implemented. These connections included the coaxial and twinbox joints, all in-chamber instrumentation voltage tap wire splices, and voltage tap chamber feedthroughs. A test article was manufactured to replicate these connections and joints, and qualify the locally removable Paschenized insulation designs with a Paschen Test at 4.5 K. The 4.5 K Paschen test was comprised of 15 kV tests between 1E-03 and 1 mbar. This paper will present and discuss the Paschenization methods, lessons learned from research, and the CSM implementation in the test facility.

This paper describes critical assembly process qualifications, acceptance criteria, and worker training of ITER Central Solenoid Assembly. Coaxial joint assembly was qualified and trained to achieve resistance below 4.1 nOhm. The electrical insulation process was qualified to 30 kV and 15 kV under Paschen conditions. Shear pin drilling and installation within specified tolerance was achieved. Modules were lifted and positioned within 2 mm. The lessons learned, and subsequent work execution onsite within the IO facility assembly hall are also presented.

The ITER Central Solenoid is under fabrication by the US ITER organization and its subcontractors. US ITER will supply seven modules to ITER IO, six of which will be assembled in a stack that forms the ITER Central Solenoid (CS). All CS modules were or will be tested at 40 kA in the Final Test facility at General Atomics, Poway, CA. Testing included high voltage, as well as Paschen testing in the vacuum and global leak tests before and after the cooldown to 4.5 K and EM cycling to 40 kA. In the paper we present the results of the CS Module 4 performance, after modifications to the test facility to improve reliability and instrumentation. We measured critical temperatures in several pancakes, AC losses before and after 10 cycles to 40 kA, joints resistance and hydraulic characteristics of the coils. We also measured displacements of the coil height and vertical strain of the CSM (central solenoid module) to verify structural mechanical characteristics of the coil along with cooldown shrinkage of the coil. We studied performance of the cowound quench detectors, confirmed their effectiveness in suppression of the inductive noise, but also developed a plan to improve sensitivity of the quench detection in ITER CS. This information is necessary for verification of the stack behavior of CS in ITER operation. The test results, preliminary analyses, comparisons to the other tested modules are presented and discussed.

The ITER Central Solenoid is under fabrication by the U.S. ITER organization and its subcontractors. U.S. ITER will supply seven modules to ITER IO, six of which will be assembled in a stack that forms the ITER Central Solenoid. The first modules that were built by GA at their facility, went into high voltage testing, including Paschen testing in the vacuum, and then they were tested at 4.5 K and up to 40 kA to demonstrate compliance of the coil with the ITER requirements. In this article, we present the Test Plan and results of the central solenoid (CS) module's performance, especially at the full current. We measured critical temperatures in several pancakes, we measured ac losses, joint resistance, and hydraulic characteristics of the coils. We also measured displacements of the coil height and hoop strain of the CS module (CSM) to verify the structural mechanical characteristics of the coil along with the cooldown shrinkage of the coil. We studied the performance of the cowound quench detectors and confirmed their effectiveness in the suppression of inductive noise. This information is necessary for verification of the stack behavior of CS in ITER operation. The test results and preliminary analyses are presented, compared to expectations, and discussed.

The ITER Central Solenoid (CS) consists of a stack of six independent coil packs called modules. It features a total height of 18 m and a diameter of over 4 m. The modules are in an advanced stage of fabrication and testing by the US ITER Project Office (USIPO) and its subcontractor General Atomics (GA). A qualification module mockup at one to one scale but of reduced height was wound and Vacuum Pressure Impregnated (VPI) by GA to validate final manufacturing, using tooling and processes fully representative of a series module. The module was submitted to a thermal cycle down to the temperature of 4.5 K at which the coils will be cooled by supercritical helium. During plasma operation, the CS modules are subjected to a complex combination of static and dynamic forces. The understanding of the mechanical behaviour of the CS module coils is of paramount importance to analyse and predict the overall response of the CS stack. To this purpose, an extensive programme of investigation of the module mockup has been defined and applied. This allowed assessing, through examination and testing of a large number of VPI conductor array samples extracted from the mockup, the soundness of the coil through advanced non-destructive examination techniques including X-ray microtomography, dimensional metrology measurements and micro-optical observations. Moreover, additional testing of physical and mechanical properties carried out at room and cryogenic temperature allowed the behaviour of the conductor stacks to be assessed. The paper summarises the results of these investigations and their interpretation through mechanical analyses based on the individual properties of the coil constituents.

The Central Solenoid (CS) is the core element of the ITER magnet system, contributed as in-kind procurement by the US Domestic Agency. Made up of six modular inter-exchangeable module coils, vertically stacked, forming a 15 m high and 4 m outer diameter solenoid, to be inserted inside the central tokamak core, after assembly of the 18 D-shaped Toroidal Field (TF) coils. Each module uses a Nb 3 Sn conductor internally cooled by circulation of supercritical helium at 4.5 K and supplied, for each module, with a 45 kA current by the way of two vertical leads exiting from the module outer radius. The available space between the CS and TF magnets being very limited, the US DA has developed a compact - so called Coax Joint (CJ) - devoted to connect the respective twelve module leads to the feeders located at top and bottom of the CS via dedicated busbar extensions. The CS coax joint assembly procedure as developed by US DA would make use of CS assembly onsite soldering process, to be executed under supervision of the ITER Organization (IO) in the tokamak assembly hall. In order to mitigate risks related to these soldering activities needed at assembly stage, IO has proposed an alternative assembly process based on indium wires compaction - so called Coax Compacted Joint (CCJ)- and initiated its prototype development and qualification in time. The hereby presented CCJ design solution is based on four copper quadrants, each including an embedded straight Rutherford-type superconductor cable-strip to transport the current. The current is transferred from the lead to the quadrants by the way of compacted indium wires. A steel jacket welded around the joint ensures the mechanical support as well as the needed leak tightness. The paper describes developments made by CEA under IO supervision from the conceptual design to the testing of joints in relevant cryogenic and operative conditions.

The ITER Central Solenoid (CS) is under fabrication by the US ITER organization and its subcontractors. US ITER will supply seven modules to ITER IO, six of which will be assembled in a stack that forms the ITER Central Solenoid, with one as a spare. The first module fabrication has been completed by General Atomics (GA) at their facility and has begun testing including high voltage testing, Paschen testing in the vacuum and then testing at 4.5 K and up to 40 kA in order to demonstrate compliance of the coil to ITER requirements. In the paper we present the Test Plan and results of the CS Module performance tests, especially at 40 kA current. AC losses, joint resistances and hydraulic characteristics of the coil are all measured. Displacements of the coil height and hoop strain of the CS Module are also measured to verify structural and mechanical characteristics of the coil along with cooldown shrinkage of the coil. This information is used for verification of the stack behavior of CS in ITER operation. The test results and preliminary analyses results are presented, compared to expectations, and discussed. All measured parameters suggest that the CS module will perform well in ITER machine.

The Central Solenoid (CS) is a key element of the ITER Magnet system, including six identical coils, called modules, assembled together to form a 4 m outer diameter, 13 m high solenoid. It is a superconducting magnet, using a 45 kA Nb3Sn conductor internally cooled by circulation of supercritical helium at 4.5 K with a peak field up to 13 T. It is enclosed inside a structure providing vertical pre-compression and mechanical support. Procurement of the components and the special assembly tooling of the ITER CS is the responsibility of US ITER, the ITER Domestic Agency of the USA, while the ITER Organization (IO) will carry out the assembly of these components. US ITER has awarded several contracts since 2011 to supply seven modules, including a spare, structure components, and the special tooling required for the CS pre-assembly. All deliveries are organized with the objective to start the CS assembly at IO site by the end 2021. IO has organized special process training and is now starting first phases of the assembly mostly focused on on-site assembly contractor. The paper describes the CS module manufacturing and delivery status, reports the special process final development and training, and assembly status. In particular, the outcomes from first modules factory acceptance tests results will be reported as well as the development and training for special activities to start the first module stacking. The bus bar joint and pre-compression processes with their related tooling qualifications will be detailed.

General Atomics has commissioned the final test facility at the central solenoid module (CSM) manufacturing site in Poway, CA, USA. The facility includes a number of critical subsystems including the feeder system (FS), supplied by the Institute of Plasma Physics Chinese Academy of Science (ASIPP), that connects the test chamber to the cryogenic and electrical systems. It includes a coil termination box, high-temperature superconducting current leads, and a feeder duct. The FS carries the current (50 kA) and supercritical helium (4.5 K, 5.5 bara) to the CSM and its supporting structure, while monitoring and controlling the temperature, pressure, flow, and voltage drop through all elements of the superconducting components. It functions as an integral part of the system to rapidly (6-s decay time) dissipates 1-GJ energy stored in the coils, and to protect the cryogenic system. The system is complex, requiring multidisciplinary engineering including: high-temperature superconductivity, cryogenic-temperatures (77, 50, and 4.5 K), high vacuum (1.0 x 10(-5) Pa), redundant quench detection (voltage, temperature), high-voltage insulation (15 kV), low thermal loads (70 W), low electrical joint resistance (2 n Omega), Paschen testing, high-voltage signal measurements, and high-current electronics. The system presented significant challenges for design and analysis, complex manufacturing assembly processes, measurement and control, and stringent quality and safety requirements.

The ITER central solenoid (CS) components are currently being manufactured. This Nb3Sn superconducting magnet will provide the magnetic flux swing required to induce up to 15 MA as plasma current. It includes six identical coils, called modules, stacked on top of each other to form a solenoid, enclosed inside a structure split into nine subsets, to provide vertical precompression and mechanical support. High mechanical stresses in materials and high voltages call for the use of structural materials with high strength and toughness and high dielectric strength insulating materials, respectively. The pulsed operation imposes materials with high fatigue strength at cryogenic temperatures. Unlike for the structure, where large existing manufacturing tools were usable, the modules required the construction of a dedicated manufacturing line. A comprehensive qualification programme is performed at the manufacturers before applying procedures for the production of the CS components. The main characteristics of the CS components, their manufacturing routes and the different elements of the qualification programme are described. The overall plan for the manufacture is reported. The status of the first series production components manufactured is presented as well as the planned delivery schedule to the ITER site.

The manufacturing line of the ITER Correction Coils (CC) at ASIPP in Hefei (China) was completed in 2013 and the manufacturing line of the ITER Central Solenoid (CS) modules is under installation at General Atomic premises in Poway (USA). In both cases, before starting production of the first coils, qualification of the manufacturing procedures is achieved by the construction of a set of mock-ups and prototypes to demonstrate that design requirements defined by the ITER Organization are effectively met. For each qualification item, the corresponding mock-ups are presented with the tests to be performed and the related acceptance criteria. The first qualification results are discussed. (C) 2015 ITER Organization. Published by Elsevier B.V. All rights reserved.

ITER magnets are all designed using superconducting conductors with a high current carrying capability. The Poloidal Field (PF) coils are operated in pulsed mode with maximum operating currents of 48 kA for PF 1 and 6, 55 kA for PF 2,3, and 4 and 52 kA for PF 5. The PF system consists of 6 ring coils, PF1 through PF6, that serve to stabilize the position and control the shape of the plasma in the tokamak. The six PF coils are attached to the outside of the Toroidal Field (TF) coil cases through flexible plates or sliding supports allowing radial displacements. The PF coil positions and sizes have been optimized for the plasma requirements consistent with the constraints imposed by allowing access to the vacuum vessel and by considering pumping ducts to the in-vessel components. The PF coils will all be wound with Niobium-Titanium (NbTi) cable-in-conduit conductors (CICC), and range in diameter from ~8 m to ~24 m. The winding pack consists of stacked double pan cakes, with joints only on the outer radius for access/repair and eddy current/AC loss reasons, while the helium inlets are located at the inner radius. Since the 2001 design option, the PF coil windings and their sub components have been redesigned to satisfy new operational requirements. The final detailed design has been established in 2009 and validated by the design review held the same year. In this paper, the up-to-date design of the PF coils and each sub-component such as winding pack, electrical insulation, joints and terminations, helium inlet, jumpers, and coils' supports are discussed together with their fabrication methods.