Overview of ASDEX Upgrade results
The ASDEX Upgrade (AUG) programme is directed towards physics input to critical elements of the ITER design and the preparation of ITER operation, as well as addressing physics issues for a future DEMO design. Since 2015, AUG is equipped with a new pair of 3-strap ICRF antennas, which were designed...
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| Format: | Article |
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IOP Publishing
2018
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| Online Access: | http://hdl.handle.net/1721.1/117295 https://orcid.org/0000-0003-2951-9749 |
| _version_ | 1826211555299033088 |
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| author | White, Anne E. |
| author2 | Massachusetts Institute of Technology. Plasma Science and Fusion Center |
| author_facet | Massachusetts Institute of Technology. Plasma Science and Fusion Center White, Anne E. |
| author_sort | White, Anne E. |
| collection | MIT |
| description | The ASDEX Upgrade (AUG) programme is directed towards physics input to critical elements of the ITER design and the preparation of ITER operation, as well as addressing physics issues for a future DEMO design. Since 2015, AUG is equipped with a new pair of 3-strap ICRF antennas, which were designed for a reduction of tungsten release during ICRF operation. As predicted, a factor two reduction on the ICRF-induced W plasma content could be achieved by the reduction of the sheath voltage at the antenna limiters via the compensation of the image currents of the central and side straps in the antenna frame. There are two main operational scenario lines in AUG. Experiments with low collisionality, which comprise current drive, ELM mitigation/suppression and fast ion physics, are mainly done with freshly boronized walls to reduce the tungsten influx at these high edge temperature conditions. Full ELM suppression and non-inductive operation up to a plasma current of Ip= 0.8 MA could be obtained at low plasma density. Plasma exhaust is studied under conditions of high neutral divertor pressure and separatrix electron density, where a fresh boronization is not required. Substantial progress could be achieved for the understanding of the confinement degradation by strong D puffing and the improvement with nitrogen or carbon seeding. Inward/outward shifts of the electron density profile relative to the temperature profile effect the edge stability via the pressure profile changes and lead to improved/decreased pedestal performance. Seeding and D gas puffing are found to effect the core fueling via changes in a region of high density on the high field side (HFSHD). The integration of all above mentioned operational scenarios will be feasible and naturally obtained in a large device where the edge is more opaque for neutrals and higher plasma temperatures provide a lower collisionality. The combination of exhaust control with pellet fueling has been successfully demonstrated. High divertor enrichment values of nitrogen EN≥ 10 have been obtained during pellet injection, which is a prerequisite for the simultaneous achievement of good core plasma purity and high divertor radiation levels. Impurity accumulation observed in the all-metal AUG device caused by the strong neoclassical inward transport of tungsten in the pedestal is expected to be relieved by the higher neoclassical temperature screening in larger devices. |
| first_indexed | 2024-09-23T15:07:51Z |
| format | Article |
| id | mit-1721.1/117295 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T15:07:51Z |
| publishDate | 2018 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/1172952022-10-02T00:48:33Z Overview of ASDEX Upgrade results White, Anne E. Massachusetts Institute of Technology. Plasma Science and Fusion Center White, Anne E. The ASDEX Upgrade (AUG) programme is directed towards physics input to critical elements of the ITER design and the preparation of ITER operation, as well as addressing physics issues for a future DEMO design. Since 2015, AUG is equipped with a new pair of 3-strap ICRF antennas, which were designed for a reduction of tungsten release during ICRF operation. As predicted, a factor two reduction on the ICRF-induced W plasma content could be achieved by the reduction of the sheath voltage at the antenna limiters via the compensation of the image currents of the central and side straps in the antenna frame. There are two main operational scenario lines in AUG. Experiments with low collisionality, which comprise current drive, ELM mitigation/suppression and fast ion physics, are mainly done with freshly boronized walls to reduce the tungsten influx at these high edge temperature conditions. Full ELM suppression and non-inductive operation up to a plasma current of Ip= 0.8 MA could be obtained at low plasma density. Plasma exhaust is studied under conditions of high neutral divertor pressure and separatrix electron density, where a fresh boronization is not required. Substantial progress could be achieved for the understanding of the confinement degradation by strong D puffing and the improvement with nitrogen or carbon seeding. Inward/outward shifts of the electron density profile relative to the temperature profile effect the edge stability via the pressure profile changes and lead to improved/decreased pedestal performance. Seeding and D gas puffing are found to effect the core fueling via changes in a region of high density on the high field side (HFSHD). The integration of all above mentioned operational scenarios will be feasible and naturally obtained in a large device where the edge is more opaque for neutrals and higher plasma temperatures provide a lower collisionality. The combination of exhaust control with pellet fueling has been successfully demonstrated. High divertor enrichment values of nitrogen EN≥ 10 have been obtained during pellet injection, which is a prerequisite for the simultaneous achievement of good core plasma purity and high divertor radiation levels. Impurity accumulation observed in the all-metal AUG device caused by the strong neoclassical inward transport of tungsten in the pedestal is expected to be relieved by the higher neoclassical temperature screening in larger devices. 2018-08-07T15:24:38Z 2018-08-07T15:24:38Z 2017-06 2016-11 2018-07-20T14:34:29Z Article http://purl.org/eprint/type/JournalArticle 0029-5515 1741-4326 http://hdl.handle.net/1721.1/117295 “Overview of ASDEX Upgrade Results.” Nuclear Fusion 57, 10 (June 2017): 102015 © 2017 Max-Planck-Institut fur Plasmaphysik https://orcid.org/0000-0003-2951-9749 http://dx.doi.org/10.1088/1741-4326/aa64f6 Nuclear Fusion Creative Commons Attribution 3.0 Unported license http://creativecommons.org/licenses/by/3.0/ application/pdf IOP Publishing IOP Publishing |
| spellingShingle | White, Anne E. Overview of ASDEX Upgrade results |
| title | Overview of ASDEX Upgrade results |
| title_full | Overview of ASDEX Upgrade results |
| title_fullStr | Overview of ASDEX Upgrade results |
| title_full_unstemmed | Overview of ASDEX Upgrade results |
| title_short | Overview of ASDEX Upgrade results |
| title_sort | overview of asdex upgrade results |
| url | http://hdl.handle.net/1721.1/117295 https://orcid.org/0000-0003-2951-9749 |
| work_keys_str_mv | AT whiteannee overviewofasdexupgraderesults |