The new technological solution for the JT-60SA quench protection circuits

Gaio, E.; Maistrello, A.; Novello, L.; Matsukawa, M.; Perna, M.; Ferro, A.; Yamauchi, K.; Piovan, R.

doi:10.1088/1741-4326/aac1c4

Cited by 17 publications

(5 citation statements)

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“…This function is managed by the operation of a hybrid switch for DC current interruption, and requires a close coordination with the operation of the base PS. The QPC [33] has a function to protect the superconducting coil by dissipating the large amount of energy stored in the coil by inserting in the circuit a dump resistor in case of coil quench or other faults requiring a fast discharge, with the requirement to complete the 20 kA DC current interruption within 350 ms. The QPC components involve a hybrid switch for DC current interruption, a pyrobreaker (explosive fuse) for backup, and a dump resistor for coil energy consumption.…”

Section: Power Supplymentioning

confidence: 99%

Completion of JT-60SA construction and contribution to ITER

et al. 2022

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Construction of the JT-60SA tokamak was completed on schedule in March 2020. Manufacture and assembly of all the main tokamak components satisfied technical requirements, including dimensional accuracy and functional performances. Development of the plasma heating systems and diagnostics have also progressed, including the demonstration of the favourable electron cyclotron range of frequency (ECRF) transmission at multiple frequencies and the achievement of long sustainment of a high-energy intense negative ion beam. Development of all the tokamak operation control systems has been completed, together with an improved plasma equilibrium control scheme suitable for superconducting tokamaks including ITER. For preparation of the tokamak operation, plasma discharge scenarios have been established using this advanced equilibrium controller. Individual commissioning of the cryogenic system and the power supply system confirmed that these systems satisfy design requirements including operational schemes contributing directly to ITER, such as active control of heat load fluctuation of the cryoplant, which is essential for dynamic operation in superconducting tokamaks. The integrated commissioning (IC) is started by vacuum pumping of the vacuum vessel and cryostat, and then moved to cool-down of the tokamak and coil excitation tests. Transition to the super-conducting state was confirmed for all the TF, EF and CS coils. The TF coil current successfully reached 25.7 kA, which is the nominal operating current of the TF coil. For this nominal toroidal field of 2.25 T, ECRF was applied and an ECRF plasma was created. The IC was, however, suspended by an incident of over current of one of the superconducting equilibrium field coil and He leakage caused by insufficient voltage holding capability at a terminal joint of the coil. The unique importance of JT-60SA for H-mode and high-β steady-state plasma research has been confirmed using advanced integrated modellings. These experiences of assembly, IC and plasma operation of JT-60SA contribute to ITER risk mitigation and efficient implementation of ITER operation.

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Section: Power Supplymentioning

confidence: 99%

Completion of JT-60SA construction and contribution to ITER

et al. 2022

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“…Fig. 8 shows the FDU circuit model implemented in Ansys Simplorer in which the stray inductances of the DRs and of its connections to the SCB (Lstray) have been inserted: these components, which play an important role on voltage waveforms, have been set equal to 10 H [22,23]. Furthermore, to limit the peaks of transient voltages associated to the high TF current, a clamp capacitor of 3 mF has been connected in parallel to the SCB, while suitable snubber circuits have been positioned in each branch of the SCB and DR.…”

Section: ) Bps Arc-modellingmentioning

confidence: 99%

Transient Electrical Behavior of the TF Superconducting Coils of Divertor Tokamak Test Facility During a Fast Discharge

Messina

Lopes

Zito

et al. 2022

IEEE Trans. Appl. Supercond.

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The paper is focused on the electromagnetic analysis of the Toroidal Field superconducting coils (TFCs) of the Divertor Tokamak Test facility (DTT) when electrical transients occur in the TFCs system: for example, during the operations of the Fast Discharge Units (FDUs) and considering also, the simultaneous occurrence of a fault condition. During the FDU intervention, a transient voltage excitation lasting few milliseconds occurs at the TFC terminals and it electrically stresses the insulations of TFCs itself. To investigate the voltage distribution across, inside and between different Double Pancakes (DPs) of each TFC, a lumped parameters circuital model has been developed and implemented in Ansys Simplorer simulation environment. This model includes both the detailed sub-model of each TFC and FDU. The transient analyses have been carried out for two different scenarios: a reference one and a failure scenario, considering three different fault resistance values and also two different values of the resistance connecting the TF case to ground. In order to verify the correct sizing of the coil insulation and the TF case-to-ground resistance value inserted in the circuit of each TFC, the voltages of each TFC (terminal-to-terminal, terminal-to-ground, across of adjacent DPs and between other circuit points) were computed in the time domain (in the range of milliseconds) for both scenarios. An overview of calculations and simulation results is presented and discussed, pointing out a high sensitivity of fault conditions and of overvoltage values and addressing mitigation strategies.

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“…In 2018, the vacuum vessel of JT-60SA was closed with 18 TF coils in place with good positioning accuracy, as shown in figure 6 [22]. Other auxiliary systems such as cryogenic/cryodistribution systems, a cryostat, high temperature superconducting current leads, and magnet power supplies [23], have been jointly provided by the EU and Japan, the commissioning of which has already started. The first plasma of JT-60SA is expected in September 2020.…”

Section: Iter Technologiesmentioning

confidence: 99%

Progress of fusion technology: summary of FIP, FNS, MPT, and SEE from the 27th IAEA Fusion Energy Conference

Inoue¹

2019

Nucl. Fusion

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Two hundred and twenty-five papers relevant to fusion technology and engineering were presented at the 27th IAEA Fusion Energy Conference. The ITER project has reached 57.4% of the total construction work scope through to first plasma. Construction of ITER is indeed progressing at full speed, with some ITER components having already been manufactured, such as the toroidal field coil structures and the gyrotrons of the electron cyclotron heating and current drive system, as a result of decades of technological development. Construction of JT-60SA and WEST is also progressing on schedule to support ITER in various engineering and physics aspects. The EU and Japan are advancing with their pre-conceptual designs for DEMO, and the experience and lessons learned from ITER are already being applied to both designs. China reported on the status of the China Fusion Engineering Test Reactor engineering design. One of the technical issues evident from these DEMO designs is the interfacing of the plasma-facing, in-vessel components with plasmas. Advanced plasma-facing elements having liquid metals and an advanced in situ boron coating technology were applied to existing fusion reactors, the results of which were reported at this conference. It was also reported that commissioning of the injector for the International Fusion Materials Irradiation Facility engineering validation and engineering design activities (IFMIF/EVEDA) project has been completed and testing of the Radio Frequency Quadrupole accelerator has begun. Europe and Japan presented their plans to construct neutron irradiation test facilities: the DEMO-Oriented Neutron Source (DONES) and Advanced Fusion Neutron Source (A-FNS), respectively. A new strategy based on a probability-based design method was proposed to mitigate the difficulty of defining the allowable limit for irradiation-induced degradation with limited empirical evidence.

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The new technological solution for the JT-60SA quench protection circuits

Cited by 17 publications

References 50 publications

Completion of JT-60SA construction and contribution to ITER

Completion of JT-60SA construction and contribution to ITER

Transient Electrical Behavior of the TF Superconducting Coils of Divertor Tokamak Test Facility During a Fast Discharge

Progress of fusion technology: summary of FIP, FNS, MPT, and SEE from the 27th IAEA Fusion Energy Conference

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