Central Solenoid Model Coil Test Research Articles

Development of cable-in-conduit conductor for ITER CS in Japan

The National Institutes for Quantum and Radiological Science and Technology has the responsibility to develop a cable-in-conduit conductor (CICC) for the ITER central solenoid (CS). Qualification tests of CICCs fabricated in the initial development stage were carried out at the SULTAN test facility; the superconducting performance (Tcs = current-sharing temperature) was found to be degraded by the repeated cyclic loading that simulates realistic ITER operating conditions. From destructive examination and neutron diffraction tests, this degradation appears to result from bending strain on the strands generated by electromagnetic forces. In response, the cabling of the CICC was optimized by shortening the twist pitch to make it stiffer against electromagnetic forces. No Tcs degradation of the optimized CICC was seen in the subsequent SULTAN test; further, a CS insert (CSI) test was performed at the CS model coil test facility, which included hoop strain for a more realistic simulation of ITER conditions. Good performance was also achieved in the CSI test.

Structural Design and Analysis of the Feeder in the CFETR CS Model Coil Cryogenic Test Facility

According to the Chinese fusion engineering testing reactor (CFETR) central solenoid model coil (CSMC) properties test requirements, a large cryogenic test platform will be built. The feeder, as one of the important components of the platform, should be studied to afford the much valued help for the basic test facilities. This paper focuses on the feeder structural design and the stress analysis in conditions of different loads. All of the work could not only provide necessary help for building CFETR CSMC test platform but also provide the important service experience of the large cryogenic test platform in the future.

${\boldsymbol T}_{{\mathbf{cs}}}$ Measurement Result of ITER Toroidal Field Insert Coil Tested in 2016

Quantum and radiological science and technology performed a toroidal field (TF) insert coil (TFIC) test in 2016–2017, which was newly developed in 2014 with the ITER TF conductor, in the central solenoid model coil test facility. According to the test program, the TFIC underwent more than 1000 cycles of energization to 68 kA under a 10.8 T background field, which represents the lifetime electromagnetic loads of ITER TF coils. Then, five cycles of warm-up to 290 K and cool-down to a temperature lower than 5 K were also performed. Through the test campaign, the transition of the current sharing temperature ( T cs) was measured under the above energization condition. In parallel, two SULTAN test samples fabricated from the same TF conductor as the TFIC were tested by the similar test sequence to that of the TFIC, and the T cs measurement results of the TFIC and the SULTAN samples were compared. In this paper, the test results mentioned above are reported.

ITER-CS インサート･コイル試験

The Japan Atomic Energy Agency (JAEA) is procuring conductors for the ITER central solenoid (CS). To evaluate the superconducting performance of the CS conductor, a test coil “CS insert” was fabricated and tested at the CS model coil test facility in JAEA Naka. The CS insert is a single-layer, nine-turn solenoid using a piece of the actual CS conductor. The test was performed in 2015, and its duration was five months including initial cool-down and final warm-up. At the beginning, the nominal conditions of 40 kA - 13 T and 45.1 kA - 12.5 T were achieved. The change in current-sharing temperature (Tcs) was then measured during 16,000 cycles of electromagnetic force and three cycles of warm-up to room temperature and cool-down. There was no apparent degradation of Tcs observed. The variation in Tcs resulting from conductor strain in the longitudinal direction was also measured using direct and reverse charges. Quenching behavior was measured using an inductive heater installed at the middle point of the CS insert. From the tests, a database to estimate the performance of the CS conductor for the actual ITER CS was established.

Fabrication of an Insert to Measure Performance of ITER CS Conductor

The Japan Atomic Energy Agency (JAEA) and Mitsubishi Electric Corporation are fabricating the insert coil needed to evaluate the performance of final design conductor for the International Thermonuclear Experimental Reactor (ITER) Central Solenoid (CS). The insert, designed by the US ITER Project Office, is a nine-turn single-layer solenoid of 1.5-m diameter. Major operations, such as winding, terminal fabrication, heat treatment, and turn insulation, have thus far been successfully completed. Fabrication will be completed in September 2014, and testing will begin at JAEA's CS Model Coil test facility in early 2015. The results of qualification and fabrication of the insert are reported.

Development and Test of JT-60SA Central Solenoid Model Coil

A central solenoid (CS) model coil (CSMC) was manufactured by using real manufacturing jigs and procedure to validate the CS manufacturing processes for JT-60SA. The winding accuracy and the temperature control precision during the heat treatment met the requirements. The vacuum pressure impregnation process was also successfully finished. The cold test of the CSMC was performed as a final check of the manufacturing process. The joint resistance, the Ic, and the pressure drop measurements were conducted as the verification test. The results of verification test satisfied the design requirements. These results indicate that the manufacturing processes of the JT-60SA CS has been established. The manufacturing of real CS pancakes just started after finishing the CSMC test.

Hydraulics of KSTAR Central Solenoid Model Coil 2nd Campaign

KSTAR (Korea Superconducting Tokamak Advanced Research) superconducting magnet consists of a CICC (Cable-In-Conduit Conductor) and is cooled down less than 5 K using supercritical helium. The length of CICC is 610 m for TF coil and maximum about 2,500 m for PF coil respectively, especially the cooling channel is about maximum 300 m in PF coil because of continuous winding scheme. There are many cooling channels in KSTAR coils especially 84 channels in TF magnet system and 100 channels in PF magnet system. Flow imbalance affects cool down of magnet and leads to a difficulty of flow control. The pressure drop between CICC terminals has a close relationship with CICC hydraulic characteristic, helium refrigerator's performance and efficiency. The friction factor which is a representative parameter can be obtained under cryogenic operation condition. We attempt to find out the friction factor of KSTAR CS and PF CICC according to the test result of KSTAR CSMC (Central Solenoid Model Coil) 2nd campaign and compare the results with previous tests. The hydraulic characteristics of KSTAR superconducting magnet system like mass flow distribution, friction factor in conductor, pressure drop and etc during CSMC test and initial commissioning of KSTAR are presented. We can confirm the KSTAR CICC's unique hydraulic behavior in states of cool down and current charging period. Also, we expect that measured data will help to operate KSTAR and be a reference for thermo-hydraulic simulation.

Manufacture of the poloidal field conductor insert coil (PFCI)

Within the framework of the R&D programme for international thermonuclear experimental reactor (ITER) the European team European Fusion Development Agreement (EFDA) has been charged with the design and manufacture of the poloidal field conductor insert coil (PFCI). The purpose of the PFCI is to test and demonstrate the performance of long-length full-scale NbTi conductors in ITER-relevant conditions. The PFCI will be tested in the central solenoid model coil test facility at the JAEA, Naka, Japan. This paper details the complete manufacturing of the PFCI including development, forming machining, pre-assembly, impregnation, final assembly and testing. The PFCI is a single-layered wound solenoid of nine turns with a transition joggle in the centre section of the winding and an intermediate joint connection between the upper termination and the main coil winding. To give the required overall dimensions to fit in the testing facility, preformed and machined glass resin composite filler pieces are assembled with the winding and is finally vacuum pressure impregnated (VPI) to create a single assembly unit. The PFCI is enclosed for assembly in a support structure, which consists of an upper and lower flange, each made up of four electrically insulated machined stainless steel castings, and 12 tie rods preloading the complete assembly in the vertical direction. The upper flange is equipped with four radial restraining jacks and the lower flange is equipped with four sets of studs and shear keys to withstand the net vertical and lateral electromagnetic forces. The PFCI is equipped with inductive heaters, voltage taps, temperature transducers, strain gauges and other instrumentation as diagnostics to monitor the performance. The current status of the manufacture is that the coil has passed the final acceptance tests and it is in the support structure assembly stage.

Test of the ITER TF insert and central solenoid model coil

The Central Solenoid Model Coil (CSMC) was designed and built by ITER collaboration between the European Union, Japan, Russian Federation and the United States in 1993-2001. Three heavily instrumented insert coils have been also built for testing in the background field of the CSMC to cover a wide operational space. The TF Insert was designed and built by the Russian Federation to simulate the conductor performance under the ITER TF coil conditions. The TF Insert Coil was tested in the CSMC Test Facility at the Japan Atomic Energy Research Institute, Naka, Japan in September-October 2001. Some measurements were performed also on the CSMC to study effects of electromagnetic and cooldown cycles. The TF Insert coil was charged successfully, without training, in the background field of the CSMC to the design current of 46 kA at 13 T peak field. The TF Insert met or exceeded all design objectives, however some interesting results require thorough analyses. This paper presents the overview of main results of the testing - magnet critical parameters, joint performance, effect of cycles on performance, quench and some results of the post-test analysis.

Test of the NaAl insert and ITER central solenoid model coil

The Central Solenoid Model Coil (CSMC) was designed and built by an ITER collaboration in 1993-2001. Three heavily instrumented Inserts have been also built for testing in the background field of the CSMC. The Nb/sub 3/Al Insert was designed and built by Japan to explore the feasibility of an alternative to Nb/sub 3/Sn superconductor for fusion magnets. The Nb/sub 3/Al Insert coil was tested in the CSMC Test Facility at the Japan Atomic Energy Research Institute, Naka, Japan in March-May 2002. It was the third Insert tested in this facility under this program. The Nb/sub 3/Al Insert coil was charged successfully without training in the background field of the CSMC to the design current of 46 kA at 13 T peak field and later was successfully charged up to 60 kA in 12.5 T field. This paper presents the test results overview.

Test of the ITER central solenoid model coil and CS insert

The Central Solenoid Model Coil (CSMC) was designed and built from 1993 to 1999 by an ITER collaboration between the U.S. and Japan, with contributions from the European Union and the Russian Federation. The main goal of the project was to establish the superconducting magnet technology necessary for a large-scale fusion experimental reactor. Three heavily instrumented insert coils were built to cover a wide operational space for testing. The CS Insert, built by Japan, was tested in April-August of 2000. The TF Insert, built by Russian Federation, will be tested in the fall of 2001. The NbAl Insert, built by Japan, will be tested in 2002. The testing takes place in the CSMC Test Facility at the Japan Atomic Energy Research Institute, Naka, Japan. The CSMC was charged successfully without training to its design current of 46 kA to produce 13 T in the magnet bore. The stored energy at 46 kA was 640 MJ. This paper presents the main results of the CSMC and the CS Insert testing-magnet critical parameters, ac losses, joint performance, quench characteristics and some results of the post-test analysis.

ＩＴＥＲトロイダル磁場インサート・コイルの開発 ロシアとのハードウエアの研究協力

The Central Solenoid (CS) model coil programme was performed since 1992 as one of the projects in the Engineering Design Activity (EDA) of the International Thermonuclear Experimental Reactor (ITER). The CS model coil programme involves a plan to develop the Toroidal Filed (TF) insert to demonstrate the conductor performance of ITER TF coils under a magnetic flux density of 13T. The TF insert was fabricated by Russia and tested by Japan under the framework of the ITER-EDA. The TF insert developed a single-layer solenoid with nine turns. It is wound with a cable-in-conduit (CIC) conductor which consists of 1, 152 Nb3Sn strands, a thin titanium jacket and a central channel. The outer diameter, height and weight of the TF insert are 1.56m, 3.2m and 3.1ton, respectively. Fabrication of the TF insert was completed in May 2001 at the D. V. Efremov Scientific Research Institute for Electrophysical Apparatus (Efremov institute) in St. Petersburg, Russia. The TF insert was then transported to the Japan Atomic Energy Research Institute (JAERI). Installation of the TF insert to CS model coil test facility was completed in August, 2001. Experiments including the cooldown and warmup processes, were completed in November 2001. The TF insert was charged to 13T with 46kA without any instability under a back up magnetic field from the CS model coil. This report introduces an overview of the fabrication, installation and experiments for the TF insert conducted under collaboration between Japan and Russia.

ＩＴＥＲ‐ＣＳモデル・コイルとＣＳインサート・コイルの実験結果 ＩＴＥＲ中心ソレノイド（ＣＳ）モデル・コイル計画

The Central Solenoid (CS) Model Coil project was started in 1992 as one of the most important R & D programs in the International Thermal Experimental Reactor (ITER) Engineering Design Activity (EDA). The purpose is to confirm the design criteria and performance of the ITER conductor, to develop and verify manufacturing tooting and processes, and to verify material performance following fabrication processes. The CS model coil was fabricated by using full-size ITER CS conductor and consisted of an inner module of 10 layers and an outer module of 8 layers. The coil, which has an inner diameter of 1.58m, an outer module of 3.6m, and a height of 2.78m, including two 0.5m lead regions. The coil was completed in 1999 and tested at the CS model coil test facility in JAERI in 2000. It achieved successfully 13T at 46kA under the pulsed operation condition of 0.4T/s for a ramp-up rate and 1.2T/s for a ramp-down rate, which is targeted as development. And the CS insert, which was a one-layer solenoid to investigate the performance of the ITER conductor in detail, was constructed and tested by being installed inside the CS model coil. The inset was operated up to 13T with a ramp-up rate of 1.2T/s.

ＩＴＥＲ‐ＣＳモデル・コイルとＣＳインサート・コイルの実験結果 ＣＳモデル・コイルとＣＳインサート・コイルの初期冷凍・定常熱負荷・昇温特性

In International Thermonuclear Experimental Reactor (ITER) Engineering Design Activities, the Central Solenoid Model Coil (CSMC) and the CS Insert Coil (CSIC) have been fabricated, and installed into the ITER CSMC test facility at Naka Fusion Establishment, Japan Atomic Energy Research Institute (JAERI). The CSMC and CSIC conductors are applied to the cable-in-conduit conductors cooled by forced-flow supercritical helium (SHe) at 4.5K. There are 48 parallel cooling channels for the CSMC, the CSIC and the structures. In the CSMC experiment, the cool-down and the warm-up were finished successfully. The cool-down time was within 480 hours. The steady head load without coil current was measured and evaluated.