2018 Fiscal Year Research-status Report
First-principle simulation study of a novel self-heating channel for burning plasmas
| Project/Area Number |
16K18341
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| Research Institution | National Institutes for Quantum and Radiological Science and Technology |
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Principal Investigator |
Bierwage Andreas 国立研究開発法人量子科学技術研究開発機構, 六ヶ所核融合研究所 核融合炉システム研究開発部, 主幹研究員(定常) (10584691)
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| Project Period (FY) |
2016-04-01 – 2020-03-31
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| Keywords | Abrupt large events / Anomalous self-heating / Energetic particles / Hybrid simulation / Gyrokinetic simulation / Tokamak plasma |
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| Outline of Annual Research Achievements |
1) Having successfully simulated multiple cycles of so-called Abrupt Large relaxation Event (ALE), which were seen in beam-driven JT-60U tokamak plasmas, we have reached an important milestone and published our results in a high-impact journal (Nature Communications). This work was subsequently featured in 2 press releases in the local print media. 3 invited talks about this research were given at conferences in Japan and abroad.
2) We have made progress in modeling the kinetic plasma response, which governs energy transfers between resonant particles and collective modes (such as MHD waves), and which ultimately leads to plasma heating. For this purpose, the PI visited IPP Garching/Germany, where he and his collaborators tested the role of magnetic drift effects of energetic particles. It was found that the present 2nd-order model is not sufficient and work is now underway to include 4th-order corrections. Meanwhile, the LIGKA code was modified to be independent of proprietary libraries and successfully ported to Linux PCs and clusters at QST in Japan. This allows us to carry out our research more efficiently and independently of IPP cluster resources in Germany. Moreover, this is a key step for using LIGKA in next-generation integrated simulation frameworks for energetic-particle-driven instabilities in heated and burning plasmas.
3) Our simulation results concerning reconnecting instabilities and their effects on energetic particle confinement in JT-60SA were presented as an invited talk at 2018 EPS Conference in Prague and published in Plasma Phys. Control. Fusion.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
* Our milestone results of ALE simulations were published in a high-impact journal and reported at several conferences as invited talks. The novel but preliminary results showing driven magnetic reconnection during ALEs were confirmed in follow-up simulations with higher spatio-temporal resolution. This lays the foundation for simulations with lower dissipation (electrical resistivity, viscosity, diffusivity), which are expected to throw more light on the driven magnetic reconnection process that we discovered during ALEs in our simulations.
* The study of low-frequency modes (originally planned for FY2016) was postponed to FY2019. The main reason is our decision to dedicate more time to new effects that we have recently discovered - namely, driven magnetic reconnection and the resulting topology change - since we anticipate a bigger impact on plasma physics in general and on the theme of the present project (self-heating channels in fusion plasmas) in particular.
* Extensions to the LIGKA model, which are required for the gyrokinetic simulations planned for FY2019, have moved forward. Our verification tests of the model and code have identified further necessary extensions, whose implementation and testing are currently in progress.
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| Strategy for Future Research Activity |
* Our discovery of magnetic reconnection induced by fast-ion-driven modes (such as ALEs) was chosen as a new high-priority item for this project due its potentially strong effect on both the bulk plasma and fast ion dynamics. In FY2019, we will analyze the role of dissipation (electrical resistivity, viscosity, diffusivity) using the new supercomputer JFRS-1. We also expect new insights concerning the ALE trigger mechanism. The results will be reported at the IAEA and ITPA Technical Meetings on Energetic Particles.
* In order to put the acquired knowledge to good use, we will intensify activities concerned with the development of predictive integrated models and codes for energetic ion confinement. For this purpose, the PI has joined as a consultant a new collaboration project called "Multi-scale Energetic particle Transport in fusion devices (MET)" headed by Dr. Fulvio Zonca at ENEA Frascati/Italy. In July 2019, the PI will visit ENEA in combination with his annual collaboration trip to IPP Garching/Germany. The PI plans to make contributions to the subject of self-consistent modeling of MHD equilibria including energetic ion effects. Such self-consistent equilibria are crucial for making reliable predictions for any kind of instabilities as well as the resulting anomalously enhanced self-heating of beam-driven and burning fusion plasmas.
* Low-frequency modes will be studied in connection with dedicated experiments scheduled for summer 2019 at DIII-D tokamak in San Diego/USA. The PI will perform numerical analyses of the wave spectra and instabilities in those experiments.
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| Causes of Carryover |
* 250,000 JPY: Purchase a new personal computer that is needed for this project.
* 78,411 JPY: Upgrades for data analysis software used in this project.
* 550,000 JPY: Cover expenses for an international business trip to ENEA Frascati/Italy and IPP Garching/Germany in summer 2019. The main purpose of this collaboration trip is to contribute to integrated modeling activities (MET project) and continue verification tests of the latest version of the LIGKA code. This work can be performed efficiently only if the PI meets the developer Dr. Lauber for about 1-2 weeks at least once a year. The integrated models and LIGKA code will be useful for energetic particle research in Japan, even far beyond the scope of this Kakenhi project (e.g., ITER Broader Approach JT-60SA and Japan Fusion DEMO projects).
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