Abstract
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.
| Original language | English |
|---|---|
| Article number | 042002 |
| Journal | Nuclear Fusion |
| Volume | 62 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 2022 |
| Externally published | Yes |
Funding
The authors thankfully acknowledge all members of the EU-JA Integrated Project Team, including both EU-JA Implementing Agencies as well as the EU Voluntary Contributors, for their persistent efforts towards the achievement of the JT-60SA Project. The authors also appreciate the members of the European and Japanese fusion communities, who have made great contribution to prepare the JT-60SA Research Plan. This work has been supported by the EUROfusion Consortium and has received funding from the EURATOM research and training programme 2014\u20132018 and 2019\u20132020 under Grant Agreement No. 633053.
| Funders | Funder number |
|---|---|
| Horizon 2020 Framework Programme | |
| European Commission | |
| Eurofusion consortium | |
| H2020 Euratom | 633053 |
| H2020 Euratom | |
| Not added | 19K03805 |
Keywords
- Assembly
- Broader approach
- ITER risk mitigation
- Research plan
